SYSTEMS AND METHODS FOR DEPLOYING COASTAL UNDERWATER POWER GENERATING STATIONS, and

SYSTEMS AND METHODS FOR FUEL HANDLING IN AN OFFSHORE MANUFACTURED NUCLEAR PLATFORM, and

SYSTEMS AND METHODS FOR DEFENSE OF A PREFABRICATED NUCLEAR PLANT

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This International PCT Patent Application relies for priority on U.S. Provisional Patent Application No. 62/720,803, filed on August 21, 2018, and U.S. Provisional Patent Application No. 62/720,823, filed on August 21, 2018, and U.S. Provisional Patent Application No. 62/720,831, filed on August 21, 2018, the entire contents of all of which are incorporated herein by reference.

FIELD OF THE INVENTION

Aspect A

[0002] The present invention relates to the establishment of near-coastal underwater platforms housing power generation facilities.

Aspect B

[0003] The present invention also relates to fuel handling systems for nuclear power plants.

Aspect C

[0004] The present invention relates to defensive systems for nuclear power plants.

BACKGROUND

Aspect A

[0005] The global need for reliable, safe, secure, and inexpensive energy is growing rapidly.

Consumers of electricity, heat, utilities, agricultural products, and industrial commodities require energy sources that are sustainable, low-cost, produce low carbon emissions, and have high capacity factor. Novel nuclear power plant designs can meet this need. To overcome the drawbacks of earlier nuclear plant designs, such plants should be adaptable to areas with existing nuclear plant infrastructure, minimize development footprint (e.g., near expanding coastal population centers), and entail the least possible development of new transmission infrastructure. To be secure and sustainable, they must be robust against potential impacts of climate change, including sea level rise and dwindling supplies of freshwater for cooling. They should also be robust against mechanical failures, malicious attack, human error, and natural disasters, including seismic events and tsunamis. Low population density in proximity to development sites is preferable because it mitigates emergency -planning concerns. Also, novel designs should avoid the high cost and exceedingly long construction times that result from complex processes involved in finding and approving suitable sites, from accessing remote sites, and from ad-hoc construction processes that vary from site to site. Site-specific design, approval, and construction processes result in high construction costs and long project durations that make nuclear power projects difficult to finance and insure. A need thus exists for methods and systems that standardize nuclear plant design and construction and allowing for faster design and deployment to a wider range of available sites.

[0006] Prefabricated nuclear platforms (PPPs), e.g., units that house or support nuclear power plants, may be partly or wholly produced in maritime or terrestrial manufacturing facilities and then towed via seas or waterways to coastal deployment sites, and can meet the entire range of foregoing needs. For example, PPPs stationed in the near-shore zone require relatively little onshore land development (mostly for landfall of transmission lines and logistics support hubs) and are surrounded by an inexhaustible supply of coolant water. Security concerns are strongly mitigated by underwater deployment, which provides effective shielding against aircraft crashes, attacks involving aircraft or standoff weapons, and approach by attackers lacking underwater mobility. Underwater facilities are also secure against tsunamis.

[0007] Sectional manufacture and modular assembly using well-known“design for build” techniques that consider manufacturing facility capabilities can lower PPP cost as compared to terrestrial construction of a comparable-sized plant because preassembled module size is severely constrained on land by the difficulties of overland transport and the limited lifting capacities of construction cranes. The design of such a module can be organized on the basis of efficiency and engineering considerations. (Herein, the term“shipyards” includes manufacturing facilities that can receive or deliver relatively large components, vessels, platforms, and other units by flotation, and the term“factories” includes manufacturing facilities that are confined to receiving and delivering various built units by overland transportation.) Additionally, site-specific variations in context (terrain, geohydrology, settlement patterns, etc.), which have invariably raised construction costs for land-based nuclear plants despite efforts to standardize designs, are greatly mitigated for PPPs. Also, in some design cases PPPs can be relocated after deployment (e.g., for re-deployment, in response to changing security concerns, or for transport to a decommissioning location), in contrast to standard terrestrial nuclear power plants.

[0008] Thus, PPPs potentially offer an elegant solution to some of the most intractable costs of conventional, onshore nuclear power plants. Moreover, PPPs can be advantageously combined with another important recent innovation in nuclear power, i.e., commercially viable small modular reactors

(SMRs), e.g., the NuScale Power Module which generates a quantity of steam capable of supporting an electrical power output of approximately 50 megawatts (MWe). SMRs offer a number of potential advantages over the relatively large (gigawatt-scale) nuclear reactors conventionally employed for commercial power generation; these advantages include but are not limited to lower accident risk due to passive internal coolant circulation, standardized mass manufacture, adjustment of total generating capacity of a multi-SMR facility by addition or removal of SMRs, swap-out and refueling capability for individual SMRs at a multi-SMR facility without shutdown of the whole facility, and ability to be delivered by truck or barge as enabled by small SMR form factor (e.g., <5 meters wide by 15 meters high).

[0009] It is desirable that the advantages of coastal, underwater PPPs be combined with the advantages of SMRs. However, in the prior art, proposals for oceanic PPPs entail shipbuilding on a very large structural scale not hitherto demonstrated, most likely with novel challenges and high

corresponding costs difficult to mitigate by economies of scale, while proposals of the prior art for grounded (non-floating) PPPs do not provide for the most rapid, flexible, and affordable establishment of platforms at submerged sites. Hereinafter, for simplicity, any ground surface that is usually or always submerged shall be referred to as“the seabed.”

[0010] There is therefore a need for systems and methods of stably stationing underwater PPPs, preferably PPPs comprising SMRs, upon the coastal seabed in coastal settings in a relatively rapid, flexible, affordable manner.

Aspect B

[0011] The global need for reliable, safe, secure, and inexpensive energy is growing rapidly.

Consumers of electricity, heat, utilities, and industrial commodities require energy sources that are sustainable, low-cost, produce low carbon emissions, and have high capacity factor. Novel nuclear power plant designs can meet this need. To overcome the drawbacks of earlier designs, such plants should be adaptable to areas with existing grid infrastructure, minimize development footprint (e.g., be located near expanding coastal population centers), and entail little development of new transmission infrastructure. To be secure and sustainable, they must be robust against potential impacts of climate change, including sea level rise and dwindling supplies of freshwater for cooling. They should also be robust against mechanical failures, malicious attack, human error, and natural disasters, including seismic events and tsunamis. Low population density in proximity to development sites is preferable because it tends to mitigate emergency -planning concerns. Also, novel designs should preferably avoid the exceedingly long lead times that result from complex processes involved in finding and approving suitable sites and from ad-hoc construction processes that vary from site to site. Site-specific design, approval, and construction processes results in high construction costs and long project durations that make nuclear power projects difficult to finance and insure and more complex to operate. A need thus exists for methods and systems that standardize nuclear power design and construction, allowing for faster design and deployment to a wider range of available sites. Finally, novel baseload generating sources should preferably complement increasing availability of renewable energy sources and provide capacity for load following and alternative product support in the form of process heat generation.

[0012] Offshore prefabricated nuclear plants (PNPs) can meet the whole range of the foregoing needs. For example, they require relatively little onshore land development (mostly for landfall of transmission lines) and are immersed in an inexhaustible supply of coolant water. If floating, they are inherently secure against sea-level rise, the direct impacts of earthquakes, and (if sufficiently far offshore) tsunamis. Security concerns are mitigated by the PNP’s open sea-and-air environment, which make any form of approach relatively easy to detect. Also, a structure sealed against the oceanic environment is inherently more difficult to infiltrate, ceteris paribus , than a sprawling terrestrial facility. Further, sectional manufacture and assembly using well-known shipyard techniques can lower PNP cost as compared to terrestrial construction of a comparable-sized plant, because preassembled module size is severely constrained on land by the difficulty of overland transport. Practical shipyard module size for PNP construction is at least an order of magnitude greater than for terrestrial construction and can be organized on the basis of efficiency and engineering considerations. Additionally, site-specific variations in context (terrain, geohydrology, settlement patterns, etc.), which have invariably raised construction costs for land-based plants despite efforts to standardize designs, are greatly mitigated for PNPs. Also, PNPs can be easily relocated at any time (e.g., for re-deployment, in response to changing security concerns, or for transport to a decommissioning location), in contrast to terrestrial nuclear power plants, which are non-re-locatable.

[0013] Thus, PNPs potentially offer an elegant solution to some of the most intractable costs of conventional, onshore nuclear power plants. Moreover, as shown and described in U.S. Provisional Patent Application Serial No. 62/646,614, the entire disclosure of which is incorporated herein by reference, a PNP may be advantageously constructed in a standardized, modular manner using shipyard techniques and towed to its service location, where it may be anchored as a floating unit or grounded in relatively shallow water. However, PNPs also present novel design challenges. In particular, various aspects of the handling of fuel assemblies (FAs), both fresh and used, and of the management of bodies of water associated with FAs will tend to differ in PNPs from similar aspects of fuel in conventional, terrestrial reactor systems. These differences arise for several reasons, including but not limited to: (a) that floating (i.e., non-grounded) PNPs must cope with wave motion, (b) that extensive vertical movement of FAs is required in certain PNP designs, and (c) that the contained overall configuration of a PNP relative to a terrestrial plant may impose different space and movement constraints relative to a more expansive conventional terrestrial plant. Regarding vertical movement of FAs, it may for example be necessary to transfer fresh FAs from a ship to the PNP, to vertically move spent FAs within the PNP (such as, in embodiments, in a continuously cooled manner), to remove FAs (such as, in embodiments, cached and/or cooled FAs) from the PNP (such as to a ship), and to perform various other vertical and horizontal movements of FAs within the PNP itself. Herein, a“vertical” movement of an FA refers to any movement having a significant non-horizontal component, such as relative to sea level; for example, movements along paths having average or approximate angles of 20, 45, or 90 degrees to the horizontal are all“vertical” movements as the term is used herein. In general, an FA movement is herein considered significantly vertical if any mechanical provision must be made specifically to accommodate the vertical component of the movement. Also herein, a“transfer” of fuel-related material refers to the movement of the material from one transport modality to another (e.g., from a truck to a ship) or from a transport modality to a facility (e.g., from a ship to a PNP) or vice versa, while a“transport” of fuel-related material refers to movement of the material by a set of one or more transport modalities (e.g., ship, truck, train).

[0014] Fuel-handling mechanisms and methods have not previously been described in the context of PNP applications, as all marine refueling according to the prior art (e.g., of nuclear-powered vessels) is historically done in drydock. In terrestrial nuclear plants, fuel assemblies are stored in spent fuel pools as they cool for at least 5 years, then transferred to large concrete air-filled storage casks for dry storage.

FAs may be transported to and from nuclear plants in transportation canisters designed for truck and rail transport (e.g., 25 and 125 tons respectively).

[0015] In terrestrial nuclear power plants, horizontal, vertical, and angled access tubes have been used to transfer individual nuclear fuel assemblies to and from containment structures. Typically, in a light water reactor, a lay -down machine exists at either end of a horizontal transfer tube that passes through the containment vessel wall. A lay -down machine rotates FAs from a vertical to a horizontal orientation, or the reverse. Passage through a horizontal transfer tube is the most common kind of access structure for spent nuclear fuel assemblies to get from the containment structure to a spent fuel pool where the FAs’ intense but declining heat output can be managed until it is low enough to allow transport and storage in dry casks. Spent-fuel storage pools will have cask loading pits where fuel canisters and casks are filled with fuel assemblies and capped. In a PNP not all stages of this process may be available or possible, and such it may not be possible to lay out such systems as are present in a solely horizontal fashion.

[0016] Vertical handling notably occurs in terrestrial nuclear plants during the insertion of FAs into and removal of FAs from the spent fuel pool. Also, though to a lesser extent, vertical movement of FAs in and out of the reactor vessel occurs during refueling. Typically, the top of the submerged reactor vessel is removed to provide access to vertically oriented FAs comprised by the water-filled reactor core. A specialized crane (“refueling machine” or“fuel-handling machine”) is then employed to lower fresh FAs into the core or lift used FAs out of the core. Such movements are preceded or followed by relatively short horizontal transports of FAs by the fuel-handling machine to and from a laydown machine. A second fuel-handling machine is typically found in the area for pool storage of spent FAs. Handling of spent FAs typically occurs in an entirely submerged manner, lest the FA be damaged by its own heat output.

[0017] A typical PNP must contain fuel-handling systems whose functions correspond to all those found, as just described, in typical terrestrial nuclear plants, but adapted to non-terrestrial conditions obtaining within the PNP. These conditions can include, without being limited to, partial submersion of the PNP in cool liquid, a more vertical or stacked arrangement of reactor systems and components than is found in a terrestrial plant, transfer of FAs and casks between the PNP and watercraft, and (for floating PNPs) platform motion. PNP-specific needs for novel fuel-handling systems and methods can thus arise in connection with the handling and storage of fresh and spent FAs within a deployed PNP. In the prior art for marine nuclear systems, fuel handling and storage has not occurred on board the operational watercraft, but in dry dock; thus, the prior art is not adequate for fuel handling within a typical PNP.

[0018] Some aspects of PNP fuel handling for which novel systems and methods would be advantageous are as follows.

[0019] Bodies of water contained in various PNPs and associated with handling of FAs present novel challenges that are not met by the prior art. For example, bodies of water in a spent fuel pool, a reactor containment, and a reservoir containing refueling makeup water (i.e., water used to raise water levels around and above a reactor vessel to enable continuously -cooled removal of spent FAs therefrom) must of necessity be in at least occasional fluid communication with each other; but fluid communication between bodies of liquid having free surfaces (i.e., not entirely fdling their respective storage volumes) creates the possibility of hazardous free surface effects. A free surface effect is a tendency of a liquid within a watercraft to move in response to changes in the attitude of the vessel. Such movements may include, for example, flows of liquid from one compartment to another or from one or more parts of a compartment to one or more other parts of the compartment, or the resonant movement of liquid within or between one or more compartments. Such movements produce forces that act upon the PNP as a whole or upon components of the PNP; beyond certain thresholds, such forces are hazardous. For example, movement of water from one part of a vessel to another can exert a destabilizing moment around the metacenter of the vessel, causing the vessel to list or capsize. It is therefore desirable that systems be devised that preclude or mitigate free surface effects potentially arising from the movement and storage of liquids within a PNP in association with FAs.

[0020] Keeping spent FAs cool is an important aspect of fuel handling in typical reactor systems, including PNPs. A PNP, in contrast to a terrestrial reactor system, is immersed in a body of liquid (e.g., the ocean) that can support cooling of FAs; however, there has been no occasion in the prior art for marine nuclear power plants to utilize the water environment for cooling of stored spent FAs, as prior marine systems have not stored spent FAs.

[0021] Proper operation of an in-containment refueling machine (the fuel-handling machine inside the containment) and/or a spent-fuel handling machine (in the spent-fuel storage area) can be adversely impacted by tilting of the PNP platform, such as may be caused by wave action, severe wind conditions, or other hazards. Since these machines typically use a telescoping mast (or column) to reach the tops of fuel assemblies that are ~25 feet below the water surface, tilt will result in horizontal forces acting on the extended mast that can cause the mast to deflect or bend, especially when lifting or lowering an FA or other heavy item. Another problem is that an FA will hang vertically from the end of the mast, making it even more difficult to properly align the bottom of the FA correctly for reinsertion into the core matrix and/or to keep the FA properly aligned while it is actually being inserted or withdrawn from the core matrix without excessive contact with and rubbing or scraping of neighboring FAs. [0022] There is therefore, for the foregoing and other reasons, a need for systems and methods of handling fuel (e.g., transporting, cooling, storing, and manipulating fuel) and water associated with the cooling of spent fuel within a PNP.

Aspect C

[0023] The global need for reliable, safe, secure, and inexpensive energy is growing rapidly.

Consumers of electricity, heat, utilities, and industrial commodities require energy sources that are sustainable, low-cost, produce low carbon emissions, and have high capacity factor. Novel nuclear power plant designs can meet this need. To overcome the drawbacks of earlier designs, such plants should be adaptable to areas with existing grid infrastructure, minimize development footprint (e.g., near expanding coastal population centers), and entail the least possible development of new transmission infrastructure. To be secure and sustainable, they must be robust against potential impacts of climate change, including sea level rise and dwindling supplies of freshwater for cooling. They should also be robust against mechanical failures, malicious attack, human error, and natural disasters, including seismic events and tsunamis. Low population density in proximity to development sites is preferable because it tends to mitigate emergency -planning concerns. Also, novels designs should avoid the exceedingly long lead times that result from complex processes involved in finding and approving suitable sites and from ad-hoc construction processes that vary from site to site. Site-specific design, approval, and construction processes results in high construction costs and long project durations that make nuclear power projects difficult to finance and insure and more complex to operate. A need thus exists for methods and systems that standardize nuclear power design and construction, allowing for faster design and deployment to a wider range of available sites. Finally, novel baseload generating sources should complement increasing renewables penetration and provide capacity for load following and alternative product support in the form of process heat generation.

[0024] Prefabricated nuclear plants (PNPs), e.g., nuclear power plants manufactured in shipyards and towed to locations on or near shorelines, can meet the whole range of foregoing needs. For example, offshore PNPs they require relatively little onshore land development (mostly for landfall of transmission lines) and are immersed in an inexhaustible supply of coolant water. If floating, they are inherently secure against sea-level rise, the direct impacts of earthquakes, and (if sufficiently far offshore) tsunamis. Security concerns are mitigated by the PNP’s open sea-and-air environment, which make any form of approach relatively easy to detect. Also, a structure sealed against the oceanic environment is inherently more difficult to infiltrate, ceteris paribus , than a sprawling terrestrial facility. Further, sectional manufacture and assembly using well-known shipyard techniques can lower PNP cost as compared to terrestrial construction of a comparable -sized plant, because preassembled module size is severely constrained on land by the difficulty of overland transport. Practical shipyard module size for PNP construction is at least an order of magnitude greater than for terrestrial construction and can be organized on the basis of efficiency and engineering considerations. Additionally, site-specific variations in context (terrain, geohydrology, settlement patterns, etc.), which have invariably raised construction costs for land-based plants despite efforts to standardize designs, are greatly mitigated for PNPs. Also, PNPs can be easily relocated at any time (e.g., for re-deployment, in response to changing security concerns, or for transport to a decommissioning location), in contrast to terrestrial nuclear power plants, which are non-re locatable.

[0025] Thus, PNPs potentially offer an elegant solution to some of the most intractable costs of conventional, onshore nuclear power plants. Moreover, as shown and described in US Provisional Patent Application Number 62/646,614, the entire disclosure of which is incorporated herein by reference, a PNP may be advantageously constructed in a standardized, modular manner using shipyard techniques and towed to its service location, where it may be anchored as a floating unit or grounded in relatively shallow water. However, PNPs also present novel design challenges. In particular, various aspects of the defense of PNPs will tend to differ from those of conventional, terrestrial reactor systems. These differences arise for several reasons, including but not limited to the fact that PNPs are typically reachable by air, on the water surface, or underwater, but not overland. However, a PNP located close to land could be threatened from nearby land, or a threat to such a PNP could be assisted by activity on the land, so a PNP defensive system may need to surveil and secure areas of land as well as volumes of airspace, areas of water surface, volumes of water, and areas of sea floor.

[0026] The situation of a typical offshore PNP in some respects simplifies enhances security, e.g. by enabling radar, sonar, and other remote detection modalities to be more effective, but also exposes the PNP to novel threats. For example, attacking vessels may be orders of magnitude more massive than the largest ground vehicle that could plausibly approach a terrestrial installation: thus, thousands of tons of explosives and large numbers of attackers could potentially be delivered to a PNP by oceangoing vessels. Surface or underwater torpedoes could potentially deliver large, hard-to-interdict explosive loads to a PNP from standoff launch platforms. Both conventional aircraft and drones can threaten both terrestrial and offshore nuclear installations: e.g., helicopters may deliver explosives and/or attacking personnel, sufficiently small, agile drones may enter a facility, attack personnel, gather intelligence, manipulate controls, or otherwise cause mischief; and conventional aircraft of any size piloted by suicide attackers may deliver explosives. Possible attacks relying partly or wholly on ruse, sabotage, or inside help rather than on external force must also be anticipated. Cyberattack may be a primary form of attack or may be ancillary to physical attack.

[0027] Security is a pressing concern for a PNP because a PNP not only can be attacked in many modes but is a high-value target. Its large inventory of highly radioactive materials must be kept safe from seizure or significant environmental release, and significant economic harm could be caused by shutting down such a large power plant temporarily or permanently.

[0028] No facility can be made proof against sufficiently violent attack; military -scale threats can be countered only by host-country military forces. Moreover, host-country military and police forces are the ultimate response to all forms of attack on a PNP. However, a PNP can and should be made resistant to a wide range of sub-military and internal attacks. Inadvertent threats (e.g., oil spills, out-of-control air and water craft, cyberfailures) can also be anticipated.

[0029] There is therefore a need for systems and methods of rendering a PNP resistant to various forms of threat.

SUMMARY

Aspect A

[0030] Provided herein are methods and systems for the flexible, rapid installation of underwater premanufactured power plants (PPPs), preferably comprising small modular nuclear reactors (SMRs), upon the sea floor and for enabling unobstructed access to such underwater PPP installations from adjacent land.

[0031] Various embodiments of the invention include nuclear power generating stations comprising submersible facilities preferably manufactured in a modular, standardized manner in shipyards or custom-built construction facilities and delivered by flotation to coastal sites. The modules, once installed, essentially constitute a nuclear power generating station and are installed in a multistage process. In an example, this process entails installation of a floatable, movable modular structure configured to be supported upon or affixed to the seabed by means of pilings or of a foundation, using techniques to be exampled hereinbelow. Multiple modules are installed adjacent to and mated with one another in a manner that permits movements of power, fluids, air, personnel, and materiel between the modules. The modules are also placed in communication with a transportation facility (e.g., tube or tunnel) that conveys power, fluids, air, personnel, material, vehicles, and the like between the underwater modules and a surface access facility and points beyond (e.g., a power grid). Thus, in an illustrative embodiment, one or more seabed modules (e.g., a reactor module) are manufactured, floated to a coastal site, sunk to rest upon pilings founded upon the seabed, and interconnected with each other and with a coastal surface-access facility so as to produce a power generation facility.

[0032] Nuclear power plants of any physical size or power rating are contemplated and within the scope of the invention in various embodiments. However, PPPs containing SMRs are preferred because SMRs are of small size compared to traditional terrestrial nuclear power plants. The latter would be relatively difficult to house in mobile modules of practical size, whereas SMRs can be so housed, and moreover can in some scenarios be delivered to and removed from a modular coastal installation separately from the modules that house them. Thus, modularization of a nuclear power generating station that relies on SMRs can extend to the reactors comprised by the station, not only to the supportive and ancillary physical plant of the station. Discussion hereinbelow therefore focuses upon PPPs comprising SMRs, extension and scaling of concepts to other forms of nuclear plant being understood.

[0033] The prior art has provided for manufacture of SMRs of various types and for their deployment, singly or in groups, in nuclear power stations of various configurations. The prior art has also provided for the installation by various means of single or multiple SMRs in floating or grounded configurations in bodies of water. All such deployments and configurations, and the methods by which they are built, are readily distinguishable from the methods and systems of embodiments of the invention, as shall be made clear hereinbelow.

[0034] In particular, the prior art includes a number of types of constructed sites (a.k.a.“artificial islands”) for nuclear power plants either adjacent to, surrounded by, or floating upon bodies of water such as rivers, lakes, oceans, or seas; the text Islands for Offshore Nuclear Power (Binnie & Partners, London, 1982), the content of which are incorporated herein by reference in its entirety, describes a range of such constructed sites, which are further discussed hereinbelow with reference to several of the Figures. Herein, for simplicity, all sites at which PPPs are affixed to the sea floor (as defined

hereinabove) are termed“coastal” or“littoral” sites. Also comprised by the prior art are methods for the delivery of certain components of power plants by flotation to prepared onshore or near-shore sites. The methods of the prior art include the use of dredged channels to enable the delivery of power-plant components to a coastal site where the components may be grounded (e.g., by flooding and filling). The methods of the prior art also include partial disassembly of large reactor containments to enable passage along constrained delivery routes (e.g., the St. Lawrence Seaway); such disassembly requires technically difficult and therefore expensive welding assembly of the unified containment at the final installation site. The methods of the prior art also include the delivery and positioning (e.g., by grounding) of caissons for the construction of breakwaters or protective barriers around coastal plants. The methods of the prior art also include the deployment of SMRs in common enclosures, e.g., proposals by NuScale Power, Inc. for the colocation of some number of SMRs (e.g., six SMRs) of approximately 50 MW capacity each within a single structure, where the number of SMRs are immersed in a single coolant pool. The methods of the prior art also provide for the construction of vertically -oriented floating structures and structures grounded on the sea floor containing nuclear reactors.

[0035] The prior art has also provided for the installation of facilities for the storage and distribution of liquefied natural gas and/or other fluids using seabed base structures and various methods employing pilings, including what are herein termed staged-pilings methods, e.g., WO 2016/085347 Al,“Sea Bed Terminal for Offshore Activities” and WO 2017/168381 Al,“Seabed Base Structure and Method for Installation of Same,” the entire disclosures of which are incorporated herein by reference in their entireties.

[0036] All this prior art, as well as prior art not described herein, is fundamentally distinguishable from embodiments of the invention. Embodiments comprise systems and methods for the delivery of nuclear generation facilities or portions of such facilities, including but not limited to SMRs, structures to house and service multiple SMRs, and turbine houses, by flotation and/or land transport in a manner that provides for the special security needs of modern nuclear power stations and exploits the small size and other unique properties of integrated SMRs (e.g., self-containment of cores with primary heat-exchange loops). Embodiments of the invention advantageously enable potential separate delivery by water and/or land of one or more SMRs, reactor facilities (structures that will house and service the SMRs), turbine facilities (structures that will house and service the turbines, generators, condensers, and auxiliary power conversion equipment), and aircraft impact shields to coastal sites and the installation of such modules and objects at such sites. Embodiments of the invention advantageously provide for the modular deployment of portions of a nuclear power generating facility in a completely submerged manner while retaining convenient access to such modules from an above-surface facility.

[0037] Moreover, embodiments are not restricted to nuclear power plants: various embodiments comprise other types of power plant, e.g., when it is advantageous for reasons of safety, space, or aesthetics to place a power plant underwater.

[0038] Moreover, the invention is not restricted to power plants that supply power to a grid. Various embodiments co-locate power plants with intensely energy -consuming enterprises also deployed in submersible modules or adjacent to the power plant on the land surface. In an example, server farms (a.k.a., data centers) account for approximately 7% of all US commercial electricity consumption. A conventional server farm typically requires about a third of its energy budget for cooling (rejecting waste heat to the atmosphere): this energy demand could be greatly reduced by stationing the server farm in the midst of the sea, i.e., an essentially inexhaustible heat sink having manyfold-higher thermal conductivity than air. The reduced remainder of the underwater server farm’s energy budget would in this example be supplied without significant transmission loss (normally ~6-10% in the USA) from the approximately co-located power plant.

[0039] These and other distinguishing aspects of embodiments of the invention, along with various advantages of embodiments, will be clarified hereinbelow with reference to the Figures.

[0040] Of note, a system of terminology is adopted herein that succinctly classifies various units comprised by embodiments of the invention:

Aspect B

[0041] Provided herein are methods, systems, components, and the like that enable the transporting, cooling, storing, and otherwise manipulating of fuel assemblies (FAs) and of water associated with the handling of FAs within an offshore prefabricated nuclear plant (PNP).

[0042] Various embodiments of the invention advantageously comprise systems and methods for FA systems in PNPs by providing adequate rates of heat transfer from FAs stored aboard an offshore PNP to the marine environment of the PNP, by providing for storage of fresh FAs aboard a PNP in a manner that resists neutron-moderated chain reaction in the event of flooding of the storage area, by providing for horizontal and vertical movements of FAs aboard a PNP by means of transfer tubes, locks, tanks, chambers, and carriers bathed with coolant and rejecting heat to their environment by various specific means, by safely restricting the movements of bodies of water associated with FA cooling under conditions peculiar to a floating PNP (tilt, rocking), and by assuring rapid return of FAs in temporary transit containers to larger bodies of coolant in the event of power or other system failures.

[0043] In embodiments, the term“system” may be understood to encompass, except where context indicates otherwise, a set of interacting components, processes, services, units, or the like, such as located on one or more structural modules that enables a capability of or for a PNP unit or performs a function of interest. A system may comprise various subsystems and components, which may include hardware elements, software elements, data communication elements, electrical elements, elements for handling fluids, elements for handling heat, and many other functions. Systems may include interfaces, such as among sub-systems and components and with other systems that enable the foregoing. Among other systems, systems disclosed herein may include auxiliary systems, plant systems (such as nuclear plant systems), marine systems, contingency systems (including emergency systems), defense systems, control systems, integral systems, accessory systems, associated systems, and interface systems.

[0044] In embodiments, the term“integral” may be understood to denote systems or functions of systems that are directly and innately comprised by a PNP unit. The reactor itself and systems for handling nuclear fuel within the PNP are examples of integral systems.

[0045] In embodiments, the term“associated” may be understood to denote systems or functions of systems, including operational environments and power grids, that are not integral, but which nevertheless contribute to physical, financial, and other functional aspects of the PNP. Systems for delivering fuel to a PNP, ownership and purchase agreements, and defensive systems are examples of associated systems.

[0046] In embodiments, the term“primary” may be understood to denote systems or functions of systems that directly perform a given function. A fuel-handling machine is an example of a primary system.

[0047] In embodiments, the term“auxiliary” may be understood to denote systems or functions of systems, that are ancillary to or enabling or supportive of the operation of primary systems or functions. For example, a generator is primary; systems for cooling, lubricating, controlling and monitoring the generator are auxiliary. In general, all major systems of a PNP comprise both primary and auxiliary systems and functions.

[0048] In embodiments, the term“accessory” may be understood to denote systems or functions of systems that may be comprised by a PNP or its associated systems in various embodiments but may be omitted from other embodiments. Examples of accessory systems include mooring systems, hull systems for impact mitigation, and an interface for moving large pieces of equipment on and off the PNP unit.

[0049] In embodiments, the term“unit” may be understood to encompass, except where context indicates otherwise, an individual thing regarded as single and complete, such as for accomplishing a defined function or purpose, but embodiments referring to units should be understood to encompass multiple units except where context indicates otherwise. In embodiments, the terms“PNP unit” and/or “the unit,” may be understood to encompass, except where context indicates otherwise, a structure containing a nuclear power plant capable of being deployed to and operating in a marine environment, such as assembled in a dry -dock or other berth at a shipyard and floated to a site where it will produce electricity or other products.

[0050] In embodiments, the term“capability,” may be understood to encompass, except where context indicates otherwise, the characteristics of a system that make it useful for an indicated use, process, function, application or deployment.

[0051] In embodiments, the term“constraint” may be understood to encompass, except where context indicates otherwise, a limitation or restriction imposed by the unit environment on PNP unit systems.

[0052] In embodiments, the terms“unit environment” and“site” may be understood to encompass, except where context indicates otherwise, the location, surroundings and/or conditions in which a PNP unit is situated and operates, such as to produce power. The unit’s environment may be defined by the capabilities that various stakeholders require, as well as the physical constraints of the environment, such as a marine environment.

[0053] In embodiments, the term“unit deployment” may be understood to encompass, except where context indicates otherwise, (system configurations) is a configuration of the structural modules and nuclear, marine, accessory, and contingency systems arranged as a unit superstructure that satisfies the requirements of a unit environment.

[0054] In embodiments, the term“function of interest” may be understood to encompass, except where context indicates otherwise, an action, process, or capability involved in the lifecycle of nuclear power plants and marine vessels performed by systems on, interfacing, or associated with one or more PNP Units.

Aspect C

[0055] Provided herein are methods, systems, components, and the like that render an offshore prefabricated nuclear plant (PNP) resistant to attack by external forces.

[0056] In various embodiments, the invention comprises both passive and active structural and other features that deter, slow, delay, or respond to elements of a systematically defined zonal threat matrix. Passive defensive features comprised by various embodiments include architectural features that render access to the PNP unit or to portions thereof more difficult, bulkheads, pressurized bodies of fluid, fences, nets, buoys, barges, breakwaters, pylons, balloons, and other structures and objects that tend to prevent or impede access by an attacker to a PNP. Active defensive features comprised by various embodiments include projected liquids, gasses, foams, and smoke; reactive armor; and robotic and/or human defensive forces (drones, guards, etc.) that prevent or impede access by attackers by means ranging from the generally nonlethal (e.g., water jets, laser light, noise projectors, tear gas, the electromagnetic Active Denial System, etc.) to the generally lethal (guns, explosives, etc.). Some of these methods and systems, as well as additional methods and systems comprised by various embodiments, will be described with reference to the Figures.

[0057] Most generally, the scope of this disclosure encompasses barriers to ingress into or interference with the functions of one or more offshore PNPs. Such barriers may be literal and straightforward (e.g., steel walls) but may also comprise more complex systems and methods of delaying, deterring, or stopping any form of attack or interference.

[0058] In embodiments, the term“system” may be understood to encompass, except where context indicates otherwise, a set of interacting components, processes, services, units, or the like, such as located on one or more structural modules that enables a capability of or for a PNP unit or performs a function of interest. A system may comprise various subsystems and components, which may include hardware elements, software elements, data communication elements, electrical elements, elements for handling fluids, elements for handling heat, and many other functions. Systems may include interfaces, such as among sub-systems and components and with other systems that enable the foregoing. Among other systems, systems disclosed herein may include auxiliary systems, plant systems (such as nuclear plant systems), marine systems, contingency systems (including emergency systems), defense systems, control systems, integral systems, accessory systems, associated systems, and interface systems. [0059] In embodiments, the term“integral” may be understood to denote systems or functions of systems that are directly and innately comprised by a PNP unit. The reactor itself and systems for handling nuclear fuel within the PNP are examples of integral systems.

[0060] In embodiments, the term“associated” may be understood to denote systems or functions of systems, including operational environments and power grids, that are not integral, but which nevertheless contribute to physical, financial, and other functional aspects of the PNP. Systems for delivering fuel to a PNP, operational and purchase agreements, and defensive systems are examples of associated systems.

[0061] In embodiments, the term“primary” may be understood to denote systems or functions of systems that directly perform a given function. A fuel-handling machine is an example of a primary system.

[0062] In embodiments, the term“auxiliary” may be understood to denote systems or functions of systems, that are ancillary to or enabling or supportive of the operation of primary systems or functions. For example, a generator is primary; systems for cooling, lubricating, controlling and monitoring the generator are auxiliary. In general, all major systems of a PNP comprise both primary and auxiliary systems and functions.

[0063] In embodiments, the term“accessory” may be understood to denote systems or functions of systems that may be comprised by a PNP or its associated systems in various embodiments but may be omitted from other embodiments. Examples of accessory systems include mooring systems, hull systems for impact mitigation, and an interface for moving large pieces of equipment on and off the PNP unit.

[0064] In embodiments, the term“unit” may be understood to encompass, except where context indicates otherwise, an individual thing regarded as single and complete, such as for accomplishing a defined function or purpose, but embodiments referring to units should be understood to encompass multiple units except where context indicates otherwise. In embodiments, the terms“PNP unit” and/or “the unit,” may be understood to encompass, except where context indicates otherwise, a structure containing a nuclear power plant capable of being deployed to and operating in a marine environment, such as assembled in a dry -dock or other berth at a shipyard and floated to a site where it will produce electricity or other products.

[0065] In embodiments, the term“capability,” may be understood to encompass, except where context indicates otherwise, the characteristics of a system that make it useful for an indicated use, process, function, application or deployment.

[0066] In embodiments, the term“constraint” may be understood to encompass, except where context indicates otherwise, a limitation or restriction imposed by the unit environment on PNP unit systems.

[0067] In embodiments, the terms“unit environment” and“site” may be understood to encompass, except where context indicates otherwise, the location, surroundings and/or conditions in which a PNP unit is situated and operates, such as to produce power. The unit’s environment may be defined by the capabilities that various stakeholders require, as well as the physical constraints of the environment, such as a marine environment.

[0068] In embodiments, the term“unit deployment” may be understood to encompass, except where context indicates otherwise, (system configurations) is a configuration of the structural modules and nuclear, marine, accessory, and contingency systems arranged as a unit superstructure that satisfies the requirements of a unit environment.

[0069] In embodiments, the term“function of interest” may be understood to encompass, except where context indicates otherwise, an action, process, or capability involved in the lifecycle of nuclear power plants and marine vessels performed by systems on, interfacing, or associated with one or more PNP Units.

[0070] In embodiments, improved containment support structures are provided for a PNP that may be produced from manufacturing materials such as metals or alloys, such as steel, including cellular lattice support structures and columnar support structures. Methods of assembling such structures may include robotic assembly, such as with a special purpose robot that is configured to be disposed within a cell of a cellular lattice.

[0071] In embodiments, an offshore nuclear power unit is provided, which may include a cylindrical containment vessel having a shell for containing pressure and radioactivity of a nuclear reactor; and a support structure configured to transfer load from the shell of the containment vessel shell to the hull of the offshore nuclear power unit. In embodiments the support structure is made of at least one of a metal and an alloy. In embodiments the support structure is made of steel. In embodiments the support structure is a regular cellular lattice structure. In embodiments the cellular lattice structure is a hexagonal lattice structure. In embodiments the cellular lattice structure is a rectangular lattice structure. In embodiments the cellular lattice structure is a triangular lattice structure. In embodiments the support structure is an irregular cellular lattice structure. In embodiments the support structure is a cellular lattice structure and in embodiments the lattice includes a support column positioned at a vertex of the lattice. In embodiments the support structure is a cellular lattice structure, which in embodiments is welded. In embodiments, a robotic welding machine is be configured to be disposed in a cell of the cellular lattice to weld the lattice.

[0072] In embodiments the support structure is a columnar structure. In embodiments the columnar structure is a rectangular columnar structure. In embodiments the columnar structure is a cylindrical columnar structure.

[0073] In embodiments the support structure includes an interface element configured to interface with the curvature of the containment vessel. BRIEF DESCRIPTION OF THE FIGURES

[0074] In the following description, various embodiments of the present invention are described with reference to the following drawings, in which:

Aspect A

[0075] FIG. A1 shows schematically submerged modular construction of a roadway according to the prior art;

[0076] FIG. A2 depicts a typical submersible module;

[0077] FIG. A3A shows schematically a first stage in the transport and installation of submersible modules according to the present invention;

[0078] FIG. A3B shows schematically a second stage in the transport and installation of submersible modules according to the present invention;

[0079] FIG. A3C shows schematically a third stage in the transport and installation of submersible modules according to the present invention;

[0080] FIG. A3D shows schematically a fourth stage in the transport and installation of submersible modules according to the present invention;

[0081] FIG. A4 shows schematically a method for sinking a module upon prepared pilings;

[0082] FIG. A5 shows schematically the firming of a module established upon pilings;

[0083] FIG. A6 shows schematically a method for sinking a module upon a prepared foundation;

[0084] FIG. A7A shows schematically a stage in the mating of two submerged modules;

[0085] FIG. A7B shows schematically another stage in the mating of two submerged modules;

[0086] FIG. A8 shows schematically portions of a power generating station according to illustrative embodiment of the invention;

[0087] FIGS. A9A and A9B show schematically portions of a power generating station according to another illustrative embodiment of the invention;

[0088] FIGS. A10A and A10B show schematically portions of a floating data center associated with a power generating station according to an illustrative embodiment;

[0089] FIGS. AHA and A11B show schematically portions of a data center founded on pilings and associated with a power generating station according to an illustrative embodiment; and

[0090] FIGS. A12A and A12B show schematically portions of a fulfillment center for unmanned aerial vehicles that is associated with a power generating station according to an illustrative embodiment.

Aspect B

[0091] FIG. B1 is a relational block diagram depicting constituent systems of an illustrative offshore nuclear plant (PNP) and associated systems with which the PNP interacts.

[0092] FIG. B2 is a relational block diagram depicting the relationship of fuel systems to containment systems in a PNP. [0093] FIG. B3 is a relational block diagram depicting the relationships of associated, accessory, and integral fuel systems to other systems in a PNP.

[0094] FIG. B4 is a schematic depiction of a deployment scenario for a single PNP.

[0095] FIG. B5 is a schematic depiction of a deployment scenario for three PNPs.

[0096] FIG. B6 is a schematic depiction of a deployment scenario for two PNPs.

[0097] FIG. B7 is a schematic depiction of another deployment scenario for three PNPs.

[0098] FIG. B8A is a schematic depiction of three types of offshore PNP deployment.

[0099] FIG. B8B is a schematic depiction of four types of offshore PNP deployment.

[00100] FIG. B9 is a relational block diagram showing the position of a fuel module in an illustrative PNP unit modularization.

[00101] FIG. B10 is a schematic depiction of modules constituting an illustrative PNP.

[00102] FIG. Bll is a schematic depiction of an illustrative nuclear fuel cycle.

[00103] FIG. B12 is a relational block diagram showing an illustrative set of fuel services for a PNP.

[00104] FIG. B13 is a schematic depiction of portions of an illustrative cooling system for FAs.

[00105] FIG. B14 is a schematic depiction of portions of another illustrative cooling system for FAs.

[00106] FIG. B15 is a schematic depiction of portions of another illustrative cooling system for FAs.

[00107] FIG. B16 is a schematic depiction of portions of another illustrative cooling system for FAs.

[00108] FIG. B17A is a schematic drawing of portions of an illustrative PNP canister magazine spent fuel storage system.

[00109] FIG. B17B is a schematic drawing of two more views of an illustrative PNP canister magazine spent fuel storage system.

[00110] FIG. B18A is a schematic drawing of an illustrative PNP spent-fuel tank system in a locked state of operation.

[00111] FIG. B18B is a schematic drawing of an illustrative PNP spent-fuel tank system in an unlocked state of operation.

[00112] FIG. B19A is a schematic drawing of an illustrative cooled and shielded fuel-handling apparatus before engaging an FA.

[00113] FIG. B19B is a schematic drawing of an illustrative cooled and shield fuel-handling apparatus in the process of engaging an FA.

[00114] FIG. B19C is a schematic drawing of an illustrative cooled and shield fuel-handling apparatus having enclosed an FA for transport.

[00115] FIG. B20 is a schematic drawing of bodies of water whose movements around an epicenter of a PNP are constrained.

[00116] FIG. B21 is a schematic depiction of portions of an illustrative refueling canal system. [00117] FIG. B22 is a schematic depiction of an illustrative compartmentalized coolant tank of a PNP.

[00118] FIG. B23A is a schematic depiction of an illustrative spent fuel pool sub-compartment of an MN.

[00119] FIG. B23B is a schematic depiction of an illustrative spent fuel pool comprising 9 subcompartments.

[00120] FIG. B23C is a schematic depiction of an illustrative spent fuel pool comprising 16 subcompartments.

[00121] FIG. B24 is a schematic depiction of an illustrative spent-fuel PNP storage system.

[00122] FIG. B25A is a schematic depiction of an illustrative spent-fuel PNP storage system in a first stage of transferring an FA.

[00123] FIG. B25B is a schematic depiction of an illustrative spent-fuel PNP storage system in a second stage of transferring an FA.

[00124] FIG. B26A is a schematic depiction of an illustrative gated FA transfer valve located within a transfer tube during a first state of operation.

[00125] FIG. B26B is a schematic depiction of an illustrative gated FA transfer valve located within a transfer tube during a second state of operation.

[00126] FIG. B26C is a schematic depiction of an illustrative gated FA transfer valve located within a transfer tube during a third state of operation.

[00127] FIG. B26D is a schematic depiction of an illustrative gated FA transfer valve located within a transfer tube during a fourth state of operation.

[00128] FIG. B27 is a schematic depiction of an illustrative core refueling coolant system of a PNP.

[00129] FIG. B28 is a schematic depiction of an illustrative coolant stabilizing system of a PNP.

[00130] FIG. B29 is a schematic depiction of another illustrative coolant stabilizing system of a PNP.

[00131] FIG. B30 is a schematic depiction of another illustrative coolant stabilizing system of a PNP.

[00132] FIG. B31 is a schematic depiction of portions of another illustrative coolant stabilizing system of a PNP.

[00133] FIG. B32 is a schematic depiction of another illustrative coolant stabilizing system of a PNP.

[00134] FIG. B33A is a schematic depiction of an illustrative fuel movement canister or enclosure with the ability to transport a single spent FA.

[00135] FIG. B33B is a schematic depiction of an illustrative fuel movement canister or enclosure with the ability to transport four spent FAs.

[00136] FIG. B34 is a schematic depiction of an illustrative system for moving FAs in enclosed volumes.

[00137] FIG. B35 is a schematic depiction of another illustrative system for moving FAs in enclosed volumes. [00138] FIG. B36 is a schematic depiction of another illustrative system for quick return of FAs in enclosed volumes to a cooling pool.

[00139] FIG. B37 is a schematic depiction of another illustrative system for quick return of FAs in enclosed volumes to a cooling pool.

[00140] FIG. B38 schematically depicts an illustrative system for providing sustained, adequate cooling to a mobile FA canister or enclosure.

[00141] FIG. B39 schematically depicts an illustrative FA canister or enclosure.

[00142] FIG. B40 schematically depicts another illustrative FA canister or enclosure.

[00143] FIG. B41 schematically depicts another illustrative FA canister or enclosure.

[00144] FIG. B42 is a schematic depiction of a PNP comprising an illustrative FA storage system that avoids unintended fission in fresh FAs.

[00145] FIG. B43 is a simplified depiction of an illustrative system for loading FAs (e.g., into a vertical transport tube of a PNP.

[00146] FIG. B44 is a schematic depiction of vertical FA handling systems of a PNP.

[00147] FIG. B45 is a schematic depiction of an illustrative mechanism for moving an FA through a coolant-filled vertical transfer tube.

[00148] FIG. B46 is a schematic depiction of another illustrative mechanism for moving an FA through a coolant-filled vertical transfer tube.

[00149] FIG. B47 is a schematic depiction of another illustrative mechanism for moving an FA through a coolant-filled vertical transfer tube.

[00150] FIG. B48 is a schematic depiction of an illustrative PNP fuel-handling machine.

[00151] FIG. B49 is a schematic depiction of another illustrative PNP fuel-handling machine.

[00152] FIG. B50 is a schematic depiction of an illustrative PNP fuel-handling alignment guide.

Aspect C

[00153] FIG. Cl is a relational block diagram depicting constituent systems of an illustrative prefabricated nuclear plant (PNP) and associated systems with which the PNP interacts.

[00154] FIG. C2 is a conceptual schematic depiction of a manner in which Forms and Functions of a PNP can be categorized.

[00155] FIG. C3 is a relational block diagram depicting the relationship of defense systems to other systems of a PNP.

[00156] FIG. C4 is a relational block diagram depicting the relationships between primary and auxiliary defense systems of PNP.

[00157] FIG. C5 is a visual depiction of categories of threat against a PNP.

[00158] FIG. C6 is a tabular depiction of categories of threat against a PNP.

[00159] FIG. C7 is a depiction of exclusion zones around an offshore PNP installation. [00160] FIG. C8 is a depiction of exclusion zones around a near-shore PNP installation.

[00161] FIG. C9 is a depiction of aerial and marine exclusion zones around an offshore PNP installation.

[00162] FIG. CIO is a depiction of a PNP defense perimeter comprising barges.

[00163] FIG. Cll is a depiction of a PNP defense zone comprising windmills as illustrative obstacles to intruder navigation.

[00164] FIG. C12 is a depiction of defensive barges with netting suspended therefrom.

[00165] FIG. C13 is a depiction of a defensive barge and a buoy with netting suspended therefrom.

[00166] FIG. C14 is a depiction of defensive buoys with netting suspended therefrom.

[00167] FIG. C15 is a depiction of a mooring method for defensive buoys and netting.

[00168] FIG. C16 is a depiction of defensive perimeter posts with netting and fencing suspended therefrom.

[00169] FIG. Cl 7 is a depiction of a hybrid defense perimeter barrier comprising barges and fencing.

[00170] FIG. C18 is a depiction of a near-shore PNP installation with a hybrid defense perimeter.

[00171] FIG. C19 is a depiction of an offshore PNP installation with a hybrid defense perimeter.

[00172] FIG. C20 is a depiction of a defense barge of a PNP installation capable of housing and deploying aerial and subsurface drones.

[00173] FIG. C21 is a depiction of surface and aerial drone swarms confronting an intruding vessel.

[00174] FIG. C22 is a depiction of surface drones seeking to foul the propellers of an intruding vessel.

[00175] FIG. C23 is a depiction of defensive hardpoints on a PNP.

[00176] FIG. C24 is a schematic depiction of a pressurizable defensive cofferdam.

[00177] FIG. C25 is a depiction of PNP interior regions partly secured by pressurizable cofferdams.

[00178] FIG. C26 is a depiction of a citadel (interior PNP volume wrapped in protective cofferdams).

[00179] FIG. C27 is a depiction of a topside countermeasure washdown system.

[00180] FIGS. C28A and C28B depict aspects of a topside countermeasure washdown system releasing foam.

[00181] FIG. C29 is a depiction of a countermeasure washdown system for an interior space.

[00182] FIG. C30 is a depiction of the stages of fluid flow in a generalized countermeasure washdown system.

[00183] FIG. C31 is a depiction of a protective artificial fogbank in relation to defensive zones of a PNP.

[00184] FIG. C32 is a depiction of part of a PNP flow barrier defense system.

[00185] FIG. C33 is a depiction of the overall layout of a PNP flow barrier defense system.

[00186] FIG. C34 is a depiction of a water-jet PNP defense system in action. [00187] FIG. C35 is a depiction of a boarding-resistant cornice of a PNP deck.

[00188] FIG. C36 is a depiction of a first type of passive reactive armor.

[00189] FIG. C37 is a depiction of a second type of passive reactive armor.

[00190] FIG. C38 is a depiction of passive reactor armor deployed on the exterior of a PNP.

[00191] FIG. C39 is a schematic depiction of an integral cyberdefense system of a PNP.

DETAILED DESCRIPTION OF THE FIGURES

[00192] In the drawings, like reference characters generally refer to the same parts throughout the different views. Like parts are depicted in a like manner throughout the Figures except where otherwise described. Also, the drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the invention.

[00193] Reference throughout the specification to“one embodiment” or“an embodiment” means that a particular feature, structure, or characteristic described in connection with an embodiment is included in at least one embodiment of the subject matter disclosed. Thus, the appearance of the phrases“in one embodiment” or“in an embodiment” in various places throughout the specification is not necessarily referring to the same embodiment.

Aspect A

[00194] FIG. A1 depicts portions of an illustrative transportation facility A100 according to the prior art. The transportation facility A100 comprises a number of submersible modules (e.g., module A102) supported upon pilings (e.g., piling A104) founded upon a seabed A106 beneath a body of water A108. The modules are mated end-to-end to form an at least partly air-filled underwater roadway A110. At its ends, the underwater roadway A110 communicates with access tunnels A112, A114 that ascend to surface access ports A116, A118, where surface roadways A120, A122 lead to and from the tunnels A112, A114. The submersible modules A102 of the underwater roadway A110 are often constructed in a temporary floodable, artificial or modified natural harbor near to the site of the transportation facility A100, floated thereto, sunk upon previously prepared pilings A104, and mated to each other to produce a secure tube through which move traffic, air, power, and the like.

[00195] FIG. A2 depicts portions of an illustrative submersible module A200. Such a submersible module A200 is typically on the order of tens of meters tall and scores of meters long. The cross- sectional form of the submersible module A200 may be rectangular (as depicted), elliptical, circular, or other, and it typically comprises a number of internal chambers or volumes (e.g., chamber A202).

Various bulkheads (not depicted) may divide the internal chambers one from another and/or cap the endward portions of the submersible module A200 to exclude the sea (e.g., during installation). One, two, or more of the faces or sides of the submersible module A200 comprise one or more openings that can be mated to similar openings in other modules or structures. In the illustrative submersible module A200, a single opening occupies the forward end of the submersible module A200 and a similar opening (not depicted) occupies the opposite end. It will be clear that such submersible modules A200 may be mated, end-to-end, to produce an extended underwater structure.

[00196] FIG. A3A schematically depicts portions of one stage of an illustrative method for adding submersible modules A308, A310 to an illustrative power generating facility A300. The submersible modules A308, A310 are constructed employing principles similar to those described hereinabove with reference to FIG. A1 and FIG. A2 and, in the completed state of the facility A300, are submerged beneath a body of water A302. An artificial or modified natural harbor A304, separable from the body of water A302 by a floodgate A306, contains facilities for pumping the harbor A304 free of water. In its emptied state, as depicted in FIG. A3A, the harbor A304 is used as a stage for manufacturing or assembling submersible modules, e.g., a reactor module A308 and a power conversion module A310, both resting on the floor of the harbor A304 in FIG. A3A. The modules A308, A310, depicted in side view, are air-filled, and their transverse ends can be sealed against water ingress by openable-closeable bulkheads (not depicted). Interior module components such as SMRs and turbine generators are not depicted in FIG. A3A for simplicity. An access tunnel A312 provides communication between the seabed installation site of the modules A308, A310 and an access port A314. Pilings capable of supporting the modules A308, A310 (e.g., piling A316) are founded upon the seabed A318. Only three pilings A316 are depicted in FIG. A3A, but there is no restriction on the number of pilings A316 that may be employed. The methods for installing prefabricated modules of a nuclear power generating station upon pilings A316 that are shown and depicted in US Provisional Patent Application No.

62/646,614, entitled,“SYSTEMS AND METHODS FOR RAPID ESTABLISHMENT OF OFFSHORE NUCLEAR POWER PLATFORMS,” the entire disclosure of which is incorporated herein by reference, are among those used in various embodiments of the present invention for the installation of prefabricated modules upon a seabed.

[00197] FIG. A3B, depicts the facility A300 of FIG. A3A in a later stage of assembly. In the state depicted in FIG. A3B, water from the body of water A302 has been permitted to fill the harbor A304 to a matching depth. The modules A308, A310 are depicted floating upon the water A320 admitted to the harbor A304. Barges, supportive floats for the modules A308, A310, vessels used to guide and otherwise manipulate the modules A308, A310, and various other components are not depicted in FIG. A3B and FIG. A3C for simplicity.

[00198] FIG. A3C depicts the facility A300 of FIG. A3A in a still later stage of assembly. In the state depicted in FIG. A3C, the modules A308, A310 have been maneuvered through the opened floodgate A306 and moved upon the surface of the body of water A302 to a position above the seabed assembly site.

[00199] FIG. A3D depicts the facility A300 of FIG. A3A in a yet later stage of assembly. In the state depicted in FIG. A3D, the modules A308, A310 have been lowered through the body of water A302 to rest upon the pilings A316 at the assembly site. Moreover, the modules A308, A310 have been mated both with each other and with the underwater opening of the access tunnel A312. Appropriate bulkheads have been opened and other connections established to enable transfer of power, fluids, air, personnel, various materiel, vehicles, and the like among the modules A308, A310 as well as between the underwater portion of the installation A300 and facilities on the land surface. In the state depicted in FIG. A3D, the basin A304 has been pumped dry again in preparation for the manufacture of additional modules. In various other embodiments, modules are manufactured at a shipyard rather than in a local, special-purpose harbor A304; or, are manufactured in a harbor A304, floated to a shipyard for outfitting, and then floated to the installation site. Various embodiments comprise any number of modules A308, A310 equal to or greater than 1, one or more access tunnels A312, one or more surface access ports A314, various ancillary facilities and security measures upon the land surface, or the water surface, or under the water, and various other components not depicted in FIGS. A3A-A3D. These and many similar variations upon the procedure of FIGS. A3A-A3D may be readily imagined without entailing significant inventive novelty, and all such are contemplated and within the scope of the invention.

[00200] FIG. A4 depicts, in schematic cross section, portions of an illustrative method for lowering a prefabricated submersible module A400 of a power generating facility to the module’s final position in the facility. Pilings (e.g., piling A402) have been previously established upon the seabed A404 beneath a body of water A406, preferably in a prepared channel, bed, or depression A407. The illustrative module A400 is presumed to have a specific gravity at least slightly greater than 1 and, thus, to sink unless supported by a barge, floats, or other devices; in various other embodiments, the submersible module A400 has a specific gravity less than 1 and must therefore either be ballasted (e.g., by filling internal ballast tanks with water) to cause it to sink, or winched into place using pulldown cables (not depicted), or otherwise caused to descend through the body of water A406. In FIG. A4, the submersible module A400 is supported via cables A408, A410 from a barge A412 that comprises hulls or floats A414, A416 sufficiently buoyant to support both the barge A412 itself and the submersible module A400, the latter being at least partly immersed. In a typical installation procedure, the barge A412 with submersible module A400 is maneuvered to a position above the pilings, lowered into place, and secured to the pilings A402. Precision positioning of the module A400 upon the pilings A402 may be achieved by several well-known methods, including the use of guidance fenders or computer-controlled guidance cables or submersible tug drones. After the submersible module A400 has been secured to the pilings A402, the cables A408, A410 are detached from the submersible module A400 and the barge A412 is re used elsewhere.

[00201] FIG. A5 depicts the submersible module A400 of FIG. A4 after the submersible module A400 has been installed upon the pilings A402. To stabilize the submersible module A400 against water currents, ship strikes, earthquake, piling shift, and other forces that may tend to dislodge it from the pilings A402, the submersible module A400 is stabilized by an illustrative supportive bed A500. The supportive bed A500 may be injected under and around the submersible module A400 in the form of fluidized sand, concrete, or other able sufficiently substances. Although depicted as lying mostly under the submersible module A400, the supportive bed A500 is in various embodiments deepened to partly or completely cover the submersible module A400. Additionally or alternatively, embankments or coverings of different materials (e.g., crushed rock) be combined to protect and stabilize the submersible module A400.

[00202] FIG. A6 depicts, in schematic cross section, portions of an illustrative method for lowering a prefabricated submersible module A400 of a power generating facility to the module’s correct position in the facility. A foundation or prepared bed A600 consisting of concrete, compressed crushed rock, or other sufficiently stable material has been previously established upon the seabed A404 beneath the body of water A406, preferably in a prepared channel, bed, or depression A602. The barge A412 of FIG. A4 is again depicted in FIG. A6, here too lowering the submersible module A400 to its resting position. The submersible module A400 is affixed to the prepared bed A600 by bolts, augurs, or other means (not depicted). In various embodiments, the submersible module A400 is further stabilized and protected by the addition of an embankment or covering (not depicted) of one or more materials (sand, concrete, crushed rock, etc.) as discussed hereinabove with reference to FIG. A5. FIG. A6 illustrates that there is no restriction with regard to the means by which submersible modules A400 of an underwater nuclear power generating station are, in various embodiments, stabilized and protected upon the seabed A404.

[00203] FIG. A7A depicts, in schematic cross-section, portions of a stage in an illustrative method for mating two illustrative submerged modules A700, A702 (e.g., a reactor module and a power conversion module) in a secure manner. The facing ends of the two submerged modules A700, A702 are depicted. The submerged modules A700, A702 are surrounded by water A704 at pressure (e.g., pressure such as is produced at tens of meters or more of depth) significantly greater than surface atmospheric pressure. Each submerged module A700, A702 comprises an air-filled interior space A706, A708 at a pressure (e.g., atmospheric pressure) significantly lower than that of the surrounding water A704. In the state depicted in FIG. A7A, water at ambient pressure fills the intermodular space A710. The edges of the two submerged modules A700, A702 are of matching shape and size and form an uninterrupted annular contact zone when the two submerged modules A700, A702 are aligned and brought together, e.g., during addition of one of the submerged modules A700, A702 to an underwater power station as exampled hereinabove. A crushable gasket A712 is attached to one of the submerged modules (here, module A702) and interposes itself along the entire annular contact zone between the two submerged modules A700, A702. Further, a flexible internal fluid barrier A714, attached to both of the submerged modules A700, A702, runs around the entire annular contact zone. Further, openable or removable bulkheads A716, A718 form at least a portion of the facing endwalls of the two submerged modules A700, A702 and separate the interior air-filled spaces A706, A708 of the submerged modules A700, A702 from the intermodular space A710. In the state depicted in FIG. A7A, submerged module A700 is stationary (affixed to pilings or a foundation, not shown) and the submerged module A702 is mobile (in the process of installation). In the state depicted, the two submerged modules A700, A702 have been approximated so that the crushable gasket A712 is in contact with the stationary, submerged module A700 with a force sufficient to form a water-tight seal between the submerged modules A700, A702.

[00204] FIG. A7B depicts the submerged modules A700, A702 of FIG. A7A in a later stage of installation. In the state depicted in FIG. A7B, the water in the intermodular space A710 has been pumped out by means of pumps and channels not depicted in the Figure, and air has been introduced into the intermodular space A710 at a pressure (e.g., atmospheric) significantly lower than that of the surrounding water A704. As a result, differential hydrostatic pressure on the exterior of the two submerged modules A700, A702 forces them together, compressing both the crushable gasket A712 and the fluid barrier A714. Since the submerged module A700 is stationary and the submerged module A702 is mobile, this closer approximation of the two submerged modules A700, A702 has occurred through a shifting of the mobile submerged module A702 toward the stationary submerged module A700. In a later stage of the illustrative method, the mobile submerged module A702 is affixed to pilings or a foundation and the removable bulkheads A716, A718 are opened or removed to enable communication between the interior spaces A706, A708 of the submerged modules A700, A702. Additional modules may be similarly mated to other surfaces of either or both of the submerged modules A700, A702. It will be clear that by such means, a linear, two-dimensional, or three-dimensional array of submersible modules may be interconnected so as to form a seabed installation that comprises power generation and other functions.

[00205] FIG. A8 depicts in schematic cross-section portions of an illustrative underwater power generating installation A800 according to an embodiment. A nuclear power module A802 is installed into a seabed base structure A804 that is founded upon a number of pilings A806 driven into a seabed A808 beneath a body of water A810. The methods of installation upon pilings using seabed base structures are described in US Provisional Patent Application No.62/646, 614, identified above, incorporated by reference hereinabove. In the setting of the installation A800, the geography of the coast A812 is steep and rocky. In this case, access to the land-side surface can be advantageously provided by means of a first, horizontal access tunnel A814 and a second, vertical or steeply sloping access tunnel A816. The installation A800 of FIG. A8 is illustrative of a class of embodiments whose methods of modular installation and arrangements for surface access differ in some respects from those depicted in FIGS. A9A and A9B.

[00206] In FIGS. A9A and A9B, portions of an illustrative seabed installation A900 comprising power generation facilities are depicted in schematic cross section and in aligned top-down view. The installation A900 is stationed upon pilings A902 founded upon a seabed A904 beneath a body of water A906 and comprises six modules A908, A910, A912, A914, A916, A918. The module A910 is a nuclear power module comprising several SMRs (e.g., SMR A911), the module A908 is a power conversion module comprising turbine -generator equipment A909, and the other modules perform various other functions, e.g., control, personnel housing, spent-fuel storage, and server farm housing. The modules A908, A910, A912, A914, A916, A918 are interconnected at their adjacent or abutting surfaces so as to create a common intercommunicating interior space: e.g., module A916 is connected to modules A910, A914, and A918. Removable or closeable bulkheads permit the closure of intercommunicating openings between modules. Also, the two modules A912, A918 that are landward (i.e., proximate to the shoreline A919) are connected to parallel surface access tunnels A920, A922 that ascend to surface roadways A924, A926 which in turn ascend upon a sloped surface access port A928. Pipelines, powerlines, rail lines, and other facilities for transporting power, fluids, materiel, and the like to and from the underwater portion of the installation A900 are also comprised but are not depicted in FIG. A9 for simplicity.

[00207] It will be clear that many variations on the number, disposition, and functions of the elements depicted in the illustrative installation of FIG. A9 are contemplated, because they are within the knowledge of those of ordinary skill in the art. All such variations are contemplated and within the scope of the invention.

[00208] In FIGS. A10A and A10B, portions of an illustrative seabed installation A1000 comprising power generation facilities are depicted in schematic cross section and in aligned top-down view. The installation A1000 is stationed upon pilings A1002 founded upon a seabed A1004 beneath a body of water A1006 and comprises six modules A1008, A1010, A1012, A1014, A1016, A1018. Module A1010 is a nuclear power module comprising several SMRs (e.g., SMR A1011), module A1008 is a power conversion module comprising turbine-generator equipment A1009, and the other modules perform various other functions, e.g., control, personnel housing, spent-fuel storage, and server farm housing.

The modules A1008, A1010, A1012, A1014, A1016, A1018 are interconnected as for the similar modules of system A900 in FIGS. A9A and A9B. The two landward modules A1012, A1018 are connected to parallel surface access tunnels A1020, A1022 that ascend to surface roadways A1024, A1026 which in turn ascend upon a sloped surface access port A1028. Pipelines, powerlines, rail lines, and other facilities for transporting power, fluids, materiel, and the like to and from the underwater portion of the installation A1000 are also comprised but are not depicted in FIGS. A10A and A10B for simplicity. The system A1000 of FIGS. A10A and A10B also comprises an illustrative“server farm barge (super-computing center, data center)” A1030 that comprises a service or barge portion A1032 and a bulk computational facility A1034. The bulk computational facility A1032 may store data, perform intensive computations, or perform other computational or communicative tasks requiring a significant amount of energy. Advantages realizable by locating a bulk computational facility on a floating platform in various embodiments include but are not limited to proximity to a nonvariable source of electricity, freedom from on-land siting constraints, efficient shipyard production of multiple identical units as opposed to on-site construction of customized on-land facilities, easy relocation of the facility, easy swap-out for an updated facility, immunity to earthquakes, and enhanced security due to the relatively greater difficulty of attack over water. [00209] The barge A1032 is connected by at least one mooring cable A1036 to at least one seabed anchor or mooring A1038, and receives power from the generator module A1008 via a suspended cable A1040. The barge A1032 comprises supportive machinery, crew quarters, security measures, backup generators, and other features that support the functioning of the bulk computational facility A1034.

Data are exchanged between the data barge A1030 and one or more networks (not depicted) via wireless communications (e.g., microwaves), via high-speed solid-state data links (e.g., optical fibers) routed through portions of the facility A1000 or independently thereof, or via some combination of various communication methods.

[00210] Floating bulk computational facilities have been proposed in the prior art (e.g., in US Patent Number 7,525,207,“WATER-BASED DATA CENTER,” whose entire disclosure is incorporated herein by reference), but such disclosures have not featured the provision of power by underwater generating facilities such as those depicted and described herein. Various other embodiments comprise two or more data barges, data barges configured otherwise than as depicted in FIGS. A10A and A10B, data centers housed in one or more piling-supported underwater modules of the system A1000 (e.g., modules A1014, A1016, A1018), and data centers coexisting with other enterprises housed in the system A1000.

[00211] FIGS. AHA and A11B depicts portions of an illustrative seabed installation A1100 in schematic side view and aligned top-down view according to an embodiment. System A1100 resembles system A1000 except that the data barge A1030 is replaced by a bulk computational facility A1102 that is supported by pilings A1104 and a seabed base structure A1106 according to methods similar to those disclosed in WO 2016/085347 A1 and WO 2017/168381 Al, referenced hereinabove. The electrical power connection from the power conversion module A1108 to the facility A1102 is omitted from FIGS. A11A and AllB for simplicity. Advantages realizable by an installation such as the installation AllOO are similar to those realizable by installation A1000 of FIGS. A10A and A10B.

[00212] FIGS. A12A and A12B depicts portions of an illustrative seabed installation A1200 in schematic cross section and in aligned top-down view according to an embodiment. The installation A1200 comprises an illustrative multi-level fulfillment center A1202 for unmanned aerial vehicles (UAVs), e.g., UAV A1204. The fulfillment center A1202 comprises ports A1206 through which UAVs A1204 carrying loads (e.g., consumer goods or raw materials) to points of destination may depart and through which UAVs A1204 may return after having delivered their loads. The center A1202 is founded upon pilings A1208 and a seabed base structure A1210 according to methods similar to those disclosed in WO 2016/085347 Al and WO 2017/168381 Al, referenced hereinabove. The center A1202 comprises an access hub A1212 stationed within a gap in the pilings array and accessed through an underwater transportation roadway A1214 similar to the underwater roadway AllO of FIG. Al. Goods and materials are delivered to the fulfillment center A1202 through the roadway A1214 for distribution by the fulfillment center A1202. The center A1202 receives power from the power conversion module A1216. The fulfillment center A1202 resembles that disclosed in US Patent Number 2017/0175413 Al, “MULTI-LEVEL FULFILLMENT CENTER FOR UNMANNED AERIAL VEHICLES,” whose entire disclosure is incorporated herein by reference. Advantages realizable by locating a fulfillment center on a floating or piling-founded platform associated with an underwater power generation facility in various embodiments include but are not limited to proximity to a nonvariable source of electricity, freedom from on-land siting constraints, efficient shipyard production of multiple identical fulfillment center units as opposed to on-site construction of customized on-land facilities, easy relocation of the fulfillment center, easy swap-out for an updated fulfillment center, immunity to earthquakes, proximity to coastal urban areas, and enhanced security due to the relatively greater difficulty of attack over water.

[00213] It will be clear from the illustrative systems of the Figures that a diversity of energy-intensive industrial, computational, and other enterprises may be advantageously co-located, either by flotation or founded upon the seabed by means of staged pilings or using other techniques, with underwater generating facilities according to various embodiments. All such embodiments are contemplated and within the scope of the invention.

Aspect B

Modularization of a PNP

[00214] Provided herein are methods, systems, components and the like for the handling of fresh and spent fuel assemblies (FAs) and of bodies of water associated with such handling in offshore nuclear power (PNP) units.

[00215] FIG. B1 is a relational block diagram depicting illustrative constituent systems of an offshore nuclear plant (PNP), also herein termed a Unit, and illustrative associated systems that interact with the Unit and each other. A Unit Deployment B100 comprises a Unit Configuration B102 and the associated systems with which the Unit Configuration directly interacts via material and non-material means. In the illustrative Unit Deployment B100 of FIG. Bl, the associated systems with which the Unit Deployment B100 interacts are Operation B104, Deployment B106, Consumers B108, and Environment B110. Overlap of the boundaries of associated systems B104, B106, B108, B110 with the Unit Configuration is shown to indicate that the Configuration B102 and its associated systems B104, B106, B108, B110 overlap in practice, and cannot be meaningfully considered in isolation from one another.

The Unit Configuration B102 comprises Unit Integral Plant B112, the primary constituent physical systems of the PNP; the Unit Integral Plant B112 is a supports the operation of the PNP unit regardless of the particulars of the Unit Deployment B100. The Unit Configuration B102 incorporates the Unit Integral Plant into a form factor suitable for a given Unit Deployment scenario B100; preferably, the Unit Integral Plant B112 is designed, built, assembled, and maintained as a structure of discrete physical modules, where the sense of“module” shall be clarified with reference to Figures herein. The Unit Integral Plant in turn comprises nuclear power plant systems B114, which produce energy from nuclear fuel and manage nuclear materials such as fuel and waste; power conversion plant systems B116, by which energy from the nuclear power plant systems B114 is, typically, converted to electricity; auxiliary plant systems B118, which support the operation of the individual PNP unit; and marine systems B120, which enable the PNP to subsist and function in a marine environment.

[00216] The associated systems B104, B106, B108, B110 interact with the Unit Configuration via Interface Systems B122, B124, B126, B128. In embodiments, the terms“interface,”“interface system,” and“interfacing system” may be understood to encompass, except where context indicates otherwise, one or more systems, services, components, processes, or the like that facilitate interaction or interconnection of systems within a PNP or between one or more systems of the PNP with a system that is external to the PNP, or between the PNP and associated systems, or between systems associated with a PNP. Interface Systems may include software interfaces (including user interfaces for humans and machine interfaces, such as application programming interfaces (APIs), data interfaces, network interfaces (including ports, gateways, connectors, bridges, switches, routers, access points, and the like), communications interfaces, fluid interfaces (such as valves, pipes, conduits, hoses and the like), thermal interfaces (such as for enabling movement of heat by radiation, convection or the like), electrical interfaces (such as wires, switches, plugs, connectors and many others), structural interfaces (such as connectors, fasteners, inter locks, and many others), or legal and fiscal interfaces (contracts, loans, deeds, and many others). Thus, Interface Systems may comprise both material and non-material systems and methods. For example, the Interface System B122 for interfacing the Unit Configuration B102 with Operation B104 will comprise legal arrangements (e.g., deeds, contracts); the Interface system B128 for interfacing the Unit

Configuration B102 with the Environment B110 will comprise material arrangements (e.g., tethers, tenders, sensor and warning systems, buoyancy systems).

[00217] The Operation system B104 comprises Operators B130 and Interface Systems B122; the Deployment system B106 comprises Deploy ers (e.g., builders, defenders, maintainers) and Interface Systems B124; the Consumers system comprises Consumers B134 and Interface Systems B126; and the Environment system comprises the natural Physical Environment B136 and Interface Systems B128.

The physical environment for a PNP may be characterized by various relevant aspects, including topography (such as of the ocean floor or a coastline), seafloor depth, wave height (typical and extraordinary), tides, atmospheric conditions, climate, weather (typical and extraordinary), geology (including seismic and thermal activity and seafloor characteristics), marine conditions (such as marine life, water temperatures, salinity and the like), and many other characteristics. Associated systems not depicted in FIG. B1 may also be comprised by a Unit Deployment; stakeholders informing the design, manufacture, and operation of a PNP unit may include power consumers, owners, financiers, insurers, regulators, operators, manufacturers, maintainers (such as those providing supplies and logistics), de commissioners, defense forces (public, private, military, etc.), and others. Moreover, the systems B104, B106, B108, B110 interact with each other through one or more additional Interface Systems B138.

[00218] FIG. B2 is a conceptual schematic depiction of portions of an illustrative embodiment of the nuclear power plant systems B114 of FIG. Bl, which are part of the unit integral plant B112. The portions of the power plant systems B114 depicted in FIG. B2 pertain to the handling of FAs within the PNP and include fuel systems B302 and containment systems B304. Fuel systems B302 comprise systems for FA receiving and shipping B304, fuel storage B306, and general handling (e.g., rotating and translating) B308 outside the containment. Containment systems B309 comprise one or more nuclear reactors B310 and systems for primary heat transport B312, in-containment fuel handling B314, in containment auxiliary functions B316, and in-containment contingency functions B318. Inputs and outputs of the fuel systems B302 include fresh fuel B320 and spent fuel B322 exchanged with non integral deployment interface systems B124 of FIG. B1 as well as exchanges of fuel, both fresh and spent, with the in-containment fuel handling system B314. Heat (not depicted) is also typically exported by the fuel storage system B306 to the PNP environment. Inputs and outputs of the containment systems B304 include heat (e.g., heat exported to the power conversion plant systems B116 of FIG. Bl) and other wastes.

[00219] FIG. B3 is a conceptual schematic depiction of portions of an illustrative unit configuration B102 of FIG. Bl and of an illustrative deployment B106. In particular, the relationships are depicted of fuel-handling systems and methods that include but are not limited to the systems and methods discussed herein to the schema of FIG. Bl. The unit configuration B102 comprises the unit integral plant B112 of FIG. Bl and auxiliary plant systems B406. The unit integral plant B112 comprises nuclear power plant systems B114, which in turn comprises integral fuel-service systems B402 and auxiliary fuel-service systems B404. The unit configuration B102 also comprises accessory fuel service systems B408 and accessory fuel service modules B410. The fuel service systems B408 in turn comprise primary systems B412 and auxiliary systems B414. The accessory fuel service systems B408 and modules B410 are comprised both by the unit configuration B102 and by the associated fuel service systems B416 of the associated deployment B106. The associated fuel service systems also comprise onshore facilities B418 (both primary B424 and auxiliary B426), offshore facilities B420 (both primary B428 and auxiliary B430), and transport systems B422 (both primary B432 and auxiliary B434). Examples of onshore facilities include facilities for receiving and holding FAs and reprocessing or disposing of FAs.

Watercraft for transporting fresh fuel and dry-casked spent FAs are examples of transport systems B422.

[00220] An additional system associated with fuel is operation B104. Operation B104 comprises fuel service agreements B436.

[00221] FIG. B4 is an overhead-view schematic depiction of portions of an illustrative Unit system arrangement B500 that can comprise embodiments of the invention. A single PNP unit B502 is located in a body of water B504 (e.g., ocean, lake, artificial harbor). In FIG. B4, a power transmission line 506 conducts electricity and/or thermal energy to and from a body of land B508 (e.g., island, mainland) or, in some cases, a vessel, platform, or other artificial body. In FIG. B5, the land body B508 supports an electrical grid B510 to which the line B506 connects at a connection facility B512. All PNPs depicted herein comprise at least one nuclear reactor with equipment for producing heat and/or electricity therefrom. Also herein, a“power transmission line” may include provisions for the transmission of electrical power, or thermal energy, or both.

[00222] FIG. B5 is an overhead-view schematic diagram depicting portions of an illustrative PNP system arrangement B600 comprising a multiplicity of PNPs B602, B604, B606 that exchange power with a land body B508 or other power-consuming location via a power transmission line (e.g., line B608). The PNPs B602, B604, B606 also exchange power with each other via one or more local power transmission lines (e.g., line B610). The cluster of PNPs interfaces with a grid B612 at a connection facility B614 that is associated with a support facility B616. The support facility B616 has access to both the ocean B504 and the land body B508. In the cluster-style arrangement of FIG. B5, the power lines interconnecting the PNPs and the power line B608 connecting the PNP cluster to the mainland grid B612 reduce, relative to the single-unit configuration of FIG. B4, the probability that any PNP will be subject to a loss of external power or that the grid B612 will lose access to power from the PNPs.

[00223] FIG. B6 is an overhead-view schematic diagram depicting portions of an illustrative PNP system arrangement B700 comprising two PNPs B702, B704 that exchange power with a land body B508 or other power-consuming location. Each PNP B702, B704 has been transported in a floating manner to its service location and the grounded sufficiently near the shore to be integrated with an associated auxiliary structure, i.e., structure B706 for PNP B702 and structure B708 for structure B704.

A shared facility B710 provides support functions (e.g., control, crew housing, onshore fuel handling, defense, maintenance and supply, other) to the two PNPs B702, B704. The auxiliary structures B706, B708 exchange power with a grid B712 via power lines (e.g., line B714) and a power connection facility B716.

[00224] FIG. B7 is an overhead-view schematic diagram depicting portions of an illustrative PNP system arrangement B800 comprising a multiplicity of PNPs B802, B804, B806 that exchange power with a land body B508 or other power-consuming location via a power transmission line (e.g., line B808). The PNPs B802, B804, B806 also exchange power with each other via one or more local power transmission lines (e.g., line B810). The cluster of PNPs interfaces with a grid B812 at a connection facility B814. An offshore support facility B816 is located in relatively close proximity to the cluster of PNPs B802, B804, B806. Functions provided by the support facility B816 can comprise control, crew housing, offshore fuel handling, defense, maintenance and supply, and other.

[00225] Any of the PNPs of FIGS. B5, B6, B7, and B8 or similar arrangements may be of any of the basic types depicted herein with reference to other Figures, or of other PNP types not depicted herein.

[00226] FIGS. B8A and B8B schematically depict aspects of illustrative Unit Configuration scenarios comprising embodiments of the invention. FIG. B8A depicts three illustrative simplex configurations, that is, configurations where the PNP Unit is deployed substantially as a single relocatable unit assembled in a modular manner in a shipyard and floated to its service location. A first simplex configuration B902 is herein denoted the“PNP-B” configuration, where a PNP B904 is grounded on the seafloor B906, e.g., by filling its ballast tanks with water after towing the unit B904 to the site. The PNP-B configuration B902 is typically suitable for relatively shallow water (for example, approximately 10-30 meters depth). A second simplex configuration B908 is herein denoted the“PNP- E” configuration, where a floating PNP B910 having a relatively flat, wide, barge-like form factor is anchored to the seafloor B906 at its service site by tethers, e.g., tether B912. The PNP-E configuration B908 is typically suitable for water of moderate depth (for example, approximately 60-100 meters depth). A third simplex configuration B914 is herein denoted the“PNP-C” configuration, where a floating PNP B916 having a relatively cylindrical form factor is anchored at its service site by tethers, e.g., tether B918. The PNP-C configuration B914 is typically suitable for water of greater depth (for example, 100+ meters depth).

[00227] FIG. B8B depicts four illustrative compound configurations, that is, configurations where the PNP Unit is deployed substantially as two units, at least one of which is a re-locatable unit assembled in a modular manner in a shipyard and floated to its service location. In the three compound configurations of FIG. B8B, a nuclear module is combined with an accessory module to realize various advantages (e.g., submersion of a nuclear reactor to realize protection from aircraft or surface-vessel impacts; or, capability of swapping out the nuclear module in order to prevent long down-times dining refueling or other maintenance or repairs of nuclear systems). A first compound configuration B918 is herein denoted the“PNP-D” configuration, where a nuclear module B920 is grounded on the seafloor B906 at a shoreline, e.g., by filling the nuclear module B920’s ballast tanks with water after towing the module B920 to the site. The nuclear module B920 is interfaced with an accessory unit B922, also preferably manufactured in a modular manner at a shipyard, towed to the service location, and hauled ashore. The PNP-D configuration B918 is typically suitable for relatively shallow water (for example, approximately 0-10 meters depth).

[00228] A second compound configuration B921 is herein denoted a“PNP-P” configuration, where “-P” refers to the fact that the facility is founded upon the seabed B906 by means of a number of pilings (e.g., piling B925). The PNP-P deployment B921 comprises a seabed base structure, founded upon pilings, that proffers an artificial harbor into which a nuclear power unit has been delivered by flotation. The illustrative PNP-P B921 comprises a modular nuclear reactor B923 that is positioned below the waterline and supported by the seabed B906. In various other embodiments, PNP-Ps comprise different types of modular nuclear reactors than that depicted for PNP-P B921, more than one modular nuclear reactor, and other structural geometries (e.g., modular nuclear reactors positioned above the waterline). Modular units having various functionalities may be established by such methods, which are described in detail in US Provisional Patent Application Serial No. 62/646,614, the entirety of which is incorporated herein by reference. In an example, a nuclear reactor unit, a power-generation unit, and a support- functions unit are delivered into separate seabed base structures founded upon pilings and in proximity to each other, then interconnected to establish a nuclear power generating station. [00229] In all examples and Figures herein where a floating nuclear power plant is mentioned or depicted, or any portion of a PNP in contact with a sea or other large body of water is mentioned or depicted, similar examples might be adduced that comprise modular nuclear reactor units and other units supported by seabed base structures according to the methods disclosed in US Provisional Patent Application Serial No. 62/646,614. These and various other forms of PNP configuration, construction, and stabilization, without restriction, are contemplated and within the scope of the invention.

[00230] A third compound configuration B924 is herein denoted the“PNP-M” configuration, where a nuclear module B926 is grounded on the seafloor B906 and interfaced with an accessory unit B928, also preferably manufactured in a modular manner at a shipyard and towed to the service location. The PNP- M configuration B924 is typically suitable for water of moderate depth (for example, approximately 20- 60 meters depth).

[00231] A fourth compound configuration B930 is herein denoted the“PNP-S” configuration, where a floating nuclear module B932 is interfaced with a floating accessory unit B934, also preferably manufactured in a modular manner at a shipyard and towed to the service location. The floating accessory unit B934 is anchored to the seafloor B906 at its service site by tethers, e.g., tether B936. The PNP-S configuration B930 is typically suitable for water of greater depth (for example, 100+ meters depth).

[00232] It will be clear that the categories of“simplex” and“compound” PNP configurations, and the particular examples shown herein, are illustrative only, and not restrictive of the range of PNP configurations in various embodiments.

[00233] FIG. B9 is a conceptual schematic depiction of an illustrative Unit Modularization B1000, that is, a high-level schema for the modularization of a PNP. Systems comprised by a PNP are, in embodiments, classified as (1) integral, (2) accessory, or (3) associated. Integral systems are typically part of the PNP, regardless of configuration or deployment scenario. The two integral systems are assigned in this illustrative modularization to corresponding modules, i.e., the Power Conversion Plant Module B1002 and the Nuclear Plant Module B1004. The Power Conversion Plant Module, in turn, comprises a Turbine Module B1006 that employs high-pressure steam from the Nuclear Plant Module B1004 to turn one or more turbines and generators, a Condenser Module B1008 that condenses steam from the Turbine Module B1006 for return to the Nuclear Plant Module B1004, and some number of Auxiliary Modules B1010. Accessory systems are systems that are typically included with or that directly interface with a PNP unit depending upon the particular configuration and deployment of the PNP; for example, seafloor tether systems are categorized as accessory because they may be omitted from some embodiments where the PNP is grounded on the seafloor. Associated systems are those that typically interface with one or more Units and are part of the greater context in which a PNP Unit is deployed. For example, power transmission systems conveying power between a PNP and an on-land grid perform an associated function. [00234] Also herein, primary systems are those performing functions definitive of the purpose of the PNP, e.g., generating steam from nuclear heat or generating electrical power from steam; primary systems are closely aligned with integral systems. Auxiliary systems (typically instantiated in corresponding Auxiliary Modules B1010) are those that typically support the reliable operation of primary systems, e.g., by cooling, lubricating, powering, controlling, and monitoring primary systems, and the like.

[00235] The Nuclear Plant Module B1004 comprises a Containment Module B1012 that contains the nuclear reactor, a Fuel Module B1014 that performs fuel handling and spent-fueling storage functions, and some number of Auxiliary Modules B1016.

[00236] Accessory Modules B1018 are also comprised by the Unit Modularization; these include modularized systems for handling aspects of interaction with associated systems of operation B1020, deployment B1022, physical environment B1024, and consumers B1026, among others.

[00237] Unit Modularization is preferably responsive to at least two sets of criteria, requirements, or constraints (collectively referred to simply as“constraints”), which are in aspects peculiar to the marine situation of a PNP and which may occasionally be in tension: (1) internal constraints on form and organization (e.g., it may be inherently advantageous to locate turbines and generators close together, or to have a direct interface between the Containment Module B1012 and the Fuel Module B1014), and (2) external constraints, such as those derived from the PNP’s environment (e.g., physical, electrical, operational, fiscal, or the like). In various embodiments, a particular Modularization may be configured to satisfy the foregoing criteria and others while taking advantage of shipyard assembly and manufacturability .

[00238] Of note, modules and systems are not synonymous. Although in many cases a single system may be implemented in a single module, a system may extend across multiple modules, or a single module may comprise more than one system, in whole or part. Moreover, in embodiments modules are combinable and nestable.

[00239] FIG. B10 is a schematic vertical cross-sectional depiction of the Block and Megablock modules constituting an illustrative PNP Unit B1100 of the floating cylindrical type defined with reference to FIG. B8A. In embodiments, the term“Block” or“Block module,” may be understood to encompass, except where context indicates otherwise, a closed structural form assembled from Panel modules, Skid modules, and components in a factory at a shipyard and then relocated to a dry dock for further assembly into the final PNP Unit. The block module may or may not have one or more of its edges acting as the hull of a unit. Also, the term“mega-block module” may be understood to encompass, except where context indicates otherwise, a closed structural form assembled from multiple Block modules, such as joined in a dry -dock. Megablock modules may be suitable for transport between shipyards; which may help distribute the construction work, such as between a variety of shipyards. Toroidal Blocks appear as symmetrically positioned shapes marked with a common indicator number. In FIG. BIO, Block boundaries are denoted by dashed lines and Megablock boundaries by solid lines. The PNP B1100 comprises an Upper Hull Megablock B1102 and Lower Hull Megablock B1104. The Upper Hull Megablock B1102 comprises a Power Conversion System Megablock B1106, a Crew

Accommodation Block B1108, an External Access and Security Block B1110, an External Access and Security Block B1112, a Turbine Generator Set Block B1114, a Condenser Block B1116, and an OP (operations) Block B1118. The Lower Hull Megablock B1104 comprises a Nuclear Island Megablock B1120, a Ballast Tank Block B1122, a Base Plate Block B1124, a Stability Skirt Block B1126, and two Water Storage Blocks B1128, B1130. The Nuclear Island Megablock B1120 comprises a Reactor Containment Block B1132, an Emergency Electrical Block B1134, a Nuclear Fuel Block B1136, a Chemical Volume Control System Block B1138, and a Cooling System Block B1140.

[00240] FIG. Bll is a schematic depiction of an illustrative nuclear fuel cycle B1200, including fuel- related processes, manipulations, and transports, that are typical of various nuclear power systems, including systems comprising embodiments of the invention. Fuel ores (e.g., uranium ores) undergo mining B1202 and refining into metallic form B1204. Refined fuel metal then undergoes enrichment B1206 in order to increase its concentration of more-fissile isotopes. Enriched fuel is used in fuel fabrication B1208, that is, in the manufacture of shaped fuel units (e.g., cylindrical pellets) that are combined and housed in fuel assemblies (FAs) suitable for installation in a reactor core. Fabricated FAs are transported to the vicinity of a reactor where they undergo fuel staging B1210, that is, storage in a system accessible to refueling mechanisms B1212 that can transfer the FAs to a reactor B1214.

“Refueling” systems are also used for initial fueling of the reactor B1214.

[00241] Notably, all exchanges of material up to this point in the nuclear fuel cycle B1200— from mining B1202 to refining B1204 to enrichment B1206 to FA fabrication B1208 to staging B1210 to the refueling mechanism B1212— typically occur in a non-shielded, non-cooled manner, as the nuclides composing the fresh fuel material have relatively long half-lives and emit radiation and heat at a relatively low rate. After exposure to neutron flux in the core of a reactor B1214, however, the nuclidal composition of the fuel material changes, and the fuel becomes intensely radioactive and hot. The heat emitted by a used or“spent” FA can be sufficient to melt the FA itself, potentially leading to environmental release of radioactive nuclides. Therefore, after an FA has participated in nuclear chain reactions in the reactor B1214, it is not typically extracted from the reactor B1214 or subsequently moved, whether within a given facility or between facilities, without being both continuously cooled and often shielded as well. FA cooling is typically provided by immersion of a hot FA in water, which transfers heat from the hot FA to the environment by convection, conduction, and phase changes (such as boiling and condensation of material that is in thermal contact with the FA). In FIG. Bll, transfers and transports that are cooled and shielded are denoted by solid arrows, while those that are neither cooled nor shielded are denoted by dashed arrows. [00242] When a spent FA is removed from the reactor B1214 by the refueling mechanism B1212, it is moved immediately via a cooled (i.e., submerged) transfer procedure to cooled storage, i.e., either in containment storage B1216 or a spent fuel storage pool B1218. In typical practice, a spent FA is kept in spent fuel storage B1218 for a number of years (e.g., 5 years) to allow its nuclidal composition to change and its radiation and heat output to decline correspondingly. When it is deemed practical to handle the FA, it is enclosed in a cooled transfer canister B1220 for movement to a facility where the FA may undergo casking B1222, that is, placement in a heavy container typically consisting of reinforced concrete. When fdled with spent FAs, a cask is sealed and moved to temporary dry storage B1224 (“dry” because the FA heat output is now low enough that the cask need not contain water or other liquids) and thence, ideally, to final disposal, such as in deep subsurface geological storage B1226. Alternatively, after canistering B1220 an FA may be transported to a facility for reprocessing B1228, that is, for the separation of useful nuclides from unwanted nuclides. Extracted nuclides may be employed in the production of reactor fuel (i.e., returned to the enrichment step B1206) or of nuclear weapons. Unwanted nuclides from reprocessing are directed, for example, to near surface disposal B1230 or deep subsurface geologic storage B1226.

[00243] The systems and methods disclosed herein pertain, in various embodiments, to transfers and storage of FAs within a PNP, and particularly to transfers between the reactor B1214 and refueling mechanisms B1212, between the refueling mechanisms B1212 and in-containment storage B1216 or spent fuel pool storage B1218, from storage to canistering B1220, and from canistering B1220 to casking B1222. Transfers of FAs and the management of water associated with FA cooling and transport and of heat produced by FAs during storage and transport are enabled with various advantages by embodiments of the invention.

[00244] FIG. B12 is a schematic depiction of an illustrative set of fuel services B1300 provided by systems and methods both integral to and associated with a PNP in various embodiments. The fuel services B1300 comprise those provided both by primary systems B1302 and auxiliary systems B1304. Primary systems B1302 include those enabling transfer B1306, transport B1308, storage B1310, and processing B1312 of FAs; auxiliary systems B1304 include those enabling cooling of FAs 1314, control of FA-handling systems B1316, security B1318, monitoring B1320, and chemistry filtration B1322 of water associated with fuel handling. In general, for a PNP as distinct from a typical terrestrial plant, any given auxiliary system can provide functions for any given primary system or for more than one primary system, enabling various economies (e.g., of space). The fuel services B1300 of FIG. B12 are provided by the associated fuel service systems B416, accessory fuel service systems B408, and integral fuel service systems B402 of FIG. B3. The systems and methods of this disclosure pertain particularly, though not necessarily exclusively, to the integral fuel service systems of B402 of FIG. B3, that is, to the handling of fresh and spent fuel and of associated bodies of water and flows of heat within a PNP. Spent Fuel Pool Cooling Systems

[00245] Cooling systems are critical in nuclear plant design. The purpose of a spent fuel pool cooling system is to prevent heat damage to FAs held in the pool. That is, the system must prevent the FAs from reaching a predetermined unsafe or damaging temperature at all times, including and after all plausible accident scenarios (e.g., a total station power blackout). Since this is such a critical purpose, it is desirable for the spent fuel pool cooling system to operate passively (i.e., without an external AC power source), indefinitely (i.e., with an effectively inexhaustible ultimate heat sink and supply of intermediate coolant), and durably (i.e., with resistance to breakage, degradation, or external interference). Herein, the body of water serving as the ultimate heat sink is referred to as the“ocean,” but there is no restriction to any particular form of water body. Also, where coolant fluids are herein referred to as“water,” no restriction to H ₂ 0 is intended.

[00246] Disclosed herein are methods and systems that can be deployed either alone or in various combinations to function as a system for cooling fuel pools and other heat-generating PNP components using an external body of water as the ultimate heat sink. Four categories of systems according to embodiments of the invention are shown in FIGS. B14-B17. The present disclosure offers a passive system of rejecting heat indefinitely from a PNP without any intervention from plant operators or active powering of pumps or other devices. Although rejection of heat from a spent fuel pool is primarily depicted and discussed herein, rejection of heat from any and all sources within a PNP is contemplated and within the scope of the invention.

[00247] FIG. B13 is a schematic depiction of portions of a cooling system B1400 according to an illustrative embodiment. A PNP spent fuel pool compartment B1402 is located between a containment structure B1404 and the outer hull B1406 of the PNP. The pool compartment B1402 contains a body of water B1408 and, typically, some number of spent FAs B1410. A pipe 1412 or multiplicity of pipes conveys a flow of intermediate coolant fluid, which is not in fluid communication with the water B1408 within the pool compartment B1402, through a loop that passes through the interior of the pool compartment B1402, through the hull B1406, and through the ocean B1414. A first heat exchanger B1416 that is internal to the pool compartment B1402 transfers heat B1418 from the FAs B1410 to the coolant in the intermediate loop, and a second heat exchanger B1420 that is external to the pool compartment B1402 transfers heat B1422 from the intermediate loop to the ocean B1414. The heat exchangers B1416, B1420 are at different elevations; moreover, loop fluid that has passed through the external heat exchanger B1420 will be cooler and therefore have higher density, even without a phase change (e.g., for water that remains liquid throughout the intermediate loop), than loop fluid that is passing through or has recently passed through the interior heat exchanger B1416. The coolant fluid will therefore circulate, driven by convection, around the intermediate loop without the assistance of pumps, conveying heat from the pool compartment B1402 to the ocean B1414. [00248] In embodiments, the system may be configured such that convective circulation will occur even if the system is inverted (i.e., if the PNP capsizes). Provision of multiple loops with different orientations can assure continued circulation in any PNP orientation (e.g., in conditions of tilting or listing that diminish the driving impact of gravitation between the heat exchangers of any one intermediate loop).

[00249] Various other embodiments resembling that depicted in FIG. B13 incorporate the following variations. First, in various embodiments resembling that depicted in FIG. B13, a working fluid is employed in the intermediate loop that changes phase at a desired operational temperature and pressure, enabling the intermediate loop to operate passively (without pumps) with a very small gravitational driving head (i.e., elevation difference between the two heat exchangers) due to the large difference in density between the two phases of the working fluid. In embodiments, a phase-changing fluid also enables the intermediate loop to be tuned to begin operating at a particular temperature threshold. At temperatures below the threshold, the loop does not extract significant heat from the spent fuel pool (which may be extracted by another or preferred system, e.g., an actively pumped system). As temperatures rise above this threshold, the working fluid changes to a lower density phase (boils);

pressure in the loop increases and the vapor-phase coolant rapidly (via buoyancy) travels to the heat exchanger B1420 immersed in the ocean B1414, where it cools and condenses back to its original phase. Preferably, the condensing heat exchanger B1420 is located above the boiling heat exchanger B1416. In embodiments, such a design may be configured to employ multiple channels (e.g., two, as in a thermosyphon) between the heat exchangers B1416, B1420 for the working fluid to pass through or a single channel (as is the case for a traditional heat pipe).

[00250] In embodiments, the heat exchanger B1416 inside the spent fuel pool compartment B1402 may be located near the highest elevation inside the compartment B1402, e.g., in a gas-filled portion of the compartment B1402, so that it condenses the steam that accumulates there. The spent fuel pool compartment B1402 may be configured such that this condensing water runs back into the body of water B1408 within the compartment B1402, such as to maintain a water level above the fuel assemblies B1410. In embodiments, water is used as the working fluid of the heat-exchange loop. In embodiments, a water-ammonia mixture (such as the working fluid used in a Kalina cycle) is used to export heat through the heat-exchange loop. In yet other embodiments, other fluids are employed with properties favorable to heat-exchange by a loop having one end immersed in an effectively ultimate heat sink (e.g., ocean) and the other in a spent-fuel pool. In various embodiments, the heat-rejection portion B1420 of the heat-exchange loop comprises surfaces resistant to biofouling, e.g., alloys of copper or titanium.

[00251] In embodiments, a manual actuation valve (normally closed) and passive actuation valve (normally open) act in parallel to initiate flow through the heat-exchange loop B1412. The passive valve is actuated by a variety of initiating events that could lead to the heating of the spent fuel pool including, but not limited to, loss of offsite power causing a solenoid valve to open or altered gas pressure in the fuel pool B1402 causing a relief valve to open.

[00252] FIG. B14 is a schematic depiction of portions of a cooling system B1500 according to an illustrative embodiment. This illustrative embodiment uses an array of thermally conductive pipes or channels through which water from the external body of water flows to exchange and transfer heat from the spent fuel pool to the external body of water. In FIG. B14, a PNP spent fuel pool compartment

B1502 is located between a containment structure B1504 and the outer hull B1506 of the PNP. The pool compartment B1502 contains a body of water B1508 and, typically, some number of spent FAs B1510.

A network or multiplicity of pipes B1512 conveys a flow of piped water, which is not in fluid communication with the water B1508 within the pool compartment B1502, through a loop or loops that pass within the thermally conductive walls of the compartment B1502, through the hull B1506, and to the ocean B1514. Pool water B1508 transfers heat from the FAs B1510 to the walls of the compartment B1502, which in turn convey them to heat exchangers (e.g., heat exchanger B1516) within the walls of the compartment B1502. Ocean water is admitted to the pipe network B1512 through an intake B1518 and exhausted to the ocean B1514 through an outlet B1520. The inlet B1518 and outlet B1520 are at different elevations; moreover, water that has passed through the heat exchangers will be hotter and therefore have lower density, even without a phase change, than water entering the inlet B1518. Ocean water will therefore spontaneously convect through the pipe network B1512 without the assistance of pumps, conveying heat from the compartment B1502 to the ocean B1514. Convective circulation will occur even if the system is inverted (i.e., if the OP capsizes).

[00253] Various other embodiments resembling that depicted in FIG. B14 incorporate the following variations. First, an air/steam outlet may be provided to prevent air bubbles from forming inside the channels B1512.

[00254] In embodiments, check valves may be located on the outlet B1520 to the channels to control the flow of water when the system is first started.

[00255] In embodiments, the channels B1512 may be machined into the outside of the steel spent fuel pool walls.

[00256] In embodiments, the channels B1512 may be welded onto the outside of the spent fuel pool.

[00257] In embodiments, the channels B1512 may be thermally adhered to the outside of the spent fuel pool.

[00258] In embodiments, the channels B1512 may pass through the inside of the spent fuel pool B1502 along the pool walls.

[00259] In embodiments, a manual actuation valve (normally closed) and passive actuation valve in parallel may be provided to initiate flow through the channels B1512. The passive valve may be actuated by a variety of initiating events that would lead to the heating of the spent fuel pool B1502, including, but not limited to, loss of offsite power. [00260] FIG. B15 is a schematic depiction of portions of a cooling system B1600 according to an illustrative embodiment. This illustrative embodiment uses water from the ocean to directly fill the spent fuel pool in cases where the water level inside the spent fuel pool has nearly boiled off, i.e., been reduced to the point where it is covers the tops of the FAs either shallowly or not at all. In FIG. B15, a PNP spent fuel pool compartment B1602 is located between a containment structure B1604 and the outer hull B1606 of the PNP. The pool compartment B1602 contains a body of water B1608 and, typically, some number of spent FAs B1610. Provisions for removing heat from the spent fuel compartment B1602 are not depicted in FIG. B15 but are typically present. An inlet B1612 permits entry of water from the ocean B1614 through pipe B1616 that passes through the hull B1606 and into the interior of the spent fuel compartment B1602 via a valve B1618. The valve B1618 remains closed as long as water levels within the pool chamber B1602 are within an acceptable depth range. A sensor (e.g., a float sensor B1620) communicates by a control line B1622 (preferably a passive direct connective, e.g., a passive hydraulic or pressure-activated connection) with the valve B1618. If the sensor B1620 detects that the level of pool water B1608 has fallen below a certain threshold, the valve B1618 opens, allowing ocean water to augment the water inside the pool chamber B1602. FIG. B15 depicts a state of operation in which ocean water is being admitted to the pool chamber B1602.

[00261] Various other embodiments resembling that depicted in FIG. B15 incorporate the following variations. In embodiments, the valve B1618 in the ingress path of the external water may comprise a check valve, so that once the water enters the spent fuel pool, B1602 it cannot exit via that same path.

[00262] In embodiments, two parallel paths may be provided for ingress of external water: one path with a manual valve that is normally closed (so that water can be let into the pool manually) and a second path with a manual valve that is normally open in series with a passively actuated valve that is normally closed but opens when the water level of the spent fuel pool drops below a specified level. In the latter path, the normally open manual valve allows the operator to manually shut off flow regardless of the state of the passively actuated valve.

[00263] FIG. B16 is a schematic depiction of portions of a cooling system B1700 according to an illustrative embodiment. This embodiment comprises a watertight compartment enclosing the spent fuel pool functioning as a heat pipe to expel heat to the external body of water and maintain an inventory of coolant in the spent fuel pool. As water in the pool boils off from the decay heat of the spent FAs, steam travels up towards the cooled ceiling of the compartment, condenses, and then rains and/or flows as liquid water back into the pool to keep the FAs fully submerged. The ceiling is cooled by spontaneous circulation of ocean water passing over it in sheets, passing over or through it via channels, or located above it en masse (e.g., in a volume open to or interfacing with the ocean). The geometry of the ceiling and walls of the spent fuel compartment may be shaped so as to encourage the condensed liquid water to quickly flow back into the pool towards the spent FAs and so as to induce rapid heat transfer between the spent fuel pool and the cooling water. In FIG. B16, a PNP spent fuel pool compartment B1702 is located between a containment structure B1704 and the outer hull B1706 of the PNP. The pool compartment B1702 contains a body of water B1708 and, typically, some number of spent FAs B1710. A network or multiplicity of pipes B1712 conveys a flow of water, which is not in fluid communication with the water B1708 within the pool compartment B1702, through a loop or loops that pass within the thermally conductive ceiling of the compartment B1702, through the hull B1706, and to the ocean B1714. Pool water B1708 is boiled by heat from the FAs B1710; steam rises and condenses upon the ceiling of the compartment B1702, heating the ceiling, which conveys the heat to circulating ocean water in the pipes B1712 via heat exchangers (e.g., heat exchanger B1716) within the ceiling. Heat exchange may also be accomplished by direct conduction to the pipe network B1712, without the assistance of discrete heat exchangers. Ocean water is admitted to the pipe network B1712 through an intake B1718 and exhausted to the ocean B1714 through an outlet B157. The inlet B1718 and outlet B1720 are at different elevations; moreover, water that has passed through the ceiling of the compartment B1702 will be hotter and therefore have lower density, even without a phase change, than water entering the inlet B1718. Ocean water will therefore spontaneously convect through the pipe network B1712 without the assistance of pumps, conveying heat from the compartment B1702 to the ocean B1714. Condensed water B1722 will rain and/or flow back to the main body of water B1708 in the fuel pool compartment B1702, maintaining an approximately constant water level.

Canister Magazine Spent Fuel Storage

[00264] The following figures pertain to a fuel storage system, according to embodiments, that avoids the need of a separate long-term spent fuel storage pool by using a smaller, in-containment fuel pool to temporarily cool FAs before transferring them through a tube to a storage canister. These canisters are kept on a rack or magazine in a flooded tank or chamber in the PNP, preferably located near the outer hull of the PNP, that can be removed at the end of platform life. The free water surface associated with spent fuel is thus minimized by such a system, which is advantageous in a floating PNP. Also, during decommissioning of a PNP, removal of spent fuel is facilitated by canistering of the FAs.

[00265] FIG. B17A is a schematic, top-down, cross-sectional view of portions of a PNP canister magazine spent fuel storage system B1800 according to an illustrative embodiment. A short-term spent fuel holding pool B1802 is located within a containment structure B1804. A canister magazine B1806 is located between the containment B1804 and the outer hull B1808 of the PNP. Individual FAs (e.g., FA B1810) are removed from the temporary holding pool B1802, rotated to a horizontal position, and passed through the walls of the containment B1804 and of the magazine B1806 via a water-filled tube B1812. Provisions are made (but not shown in FIG. B17A, for simplicity) for keeping FAs immersed in water during all stages of such handling. In the magazine B1806, FAs are loaded into steel canisters, e.g., canister B1814. For simplicity, FIG. B17A depicts each canister B1814 as holding a single FA, but canisters B1814 will preferably hold more than one FA. The magazine B1806 contains both loaded canisters (e.g., canister B1814) and empty canisters (e.g., canister B1816). Provision is made (but not shown in FIG. B17A, for simplicity) for extracting individual canisters from the magazine B1806, as needed. Canisters are registered or aligned with the transfer tube B1812 by moving them on a conveyor belt or equivalent system. Although a single layer of canisters, one rank deep, is portrayed in FIG.

B17A, in various embodiments canisters are multiply layered and ranked. Both canisters and the space around them in the magazine B1806 are filled with water. Heat is removed from the magazine B1806 to the environment (e.g., ocean) by mechanisms not depicted in FIG. B17A, but in various embodiments may comprise the various systems and methods depicted elsewhere herein.

[00266] FIG. B17B provides two aligned, close-up, schematic, cross-sectional views of portions of the illustrative canister magazine spent fuel storage system B1800 of FIG. B17A. The lower portion of FIG. B17B is a closer view of the view of FIG. B17A, and the upper portion of FIG. B17B is a vertical cross-sectional view of the same mechanism. For simplicity, in FIG. B17B, the wall of the containment B1804 is depicted, but not the outer hull of the PNP. Depicted in greater detail in FIG. B17B than in FIG. B17A are the fuel pool compartment B1802, the transfer tube B1812, the water-fdled canister magazine B1806, a filled canister B1814, an empty canister B1816, and a horizontally positioned FA B1810. Vertically positioned FAs (e.g., FA B1818) and a conveyor mechanism B1820 within the magazine B1806 are also depicted in FIG. B17B. Mechanisms for laying down an FA, keeping an FA submerged at all times, moving an FA through the transfer tube B1812, loading an FA into a canister, sealing a canister, registering an empty canister, and performing related tasks are not depicted in FIG. B17B, but a number of viable mechanisms are known to persons familiar with mechanical engineering and nuclear plant design. For example, the transfer tube B1812 can be arranged to terminate under the waterline in the fuel pool compartment B1802. A lay -down machine similar to that found in land-located nuclear plants can, in this example, be used to lay down FAs under water in the compartment B1802 and introduce them to a mechanism for transfer through the tube B1812.

Access Controlled Passively Cooled Spent Fuel Tank

[00267] Because hot spent FAs are highly radioactive and toxic, and depriving them of cooling can result in significant environmental releases of radioactivity, it is desirable make human access to spent FAs inherently difficult. Further, it is desirable to mitigate free-surface effects that can arise in open pool spent-fuel storage systems in a floating PNP rocked by waves. Embodiments of the present disclosure address these needs by providing a completely flooded tank for spent fuel storage. In embodiments, such embodiments may be provided with a selectively floodable air-lock for transferring spent fuel into and out of the storage tank. The decay heat generated by the spent fuel may be passively transferred to seawater from the storage tank through natural thermal conduction to tank walls or other heat sinks, and thence, such as by convection, ultimately to the environment (e.g., ocean).

[00268] FIG. B18A is a schematic, vertical, cross-sectional view of portions of an illustrative PNP spent-fuel tank system B1900. The system B1900 comprises a spent fuel tank B1902 that contains a number of vertically oriented spent FAs (e.g., FA B1904). A number of hatches (e.g., hatch B1906) are positioned in the ceiling of the tank B1902, which is filled with water B1908. In this embodiment, each hatch B1906 is built to open downward, into the interior of the tank B1902; however, in alternative embodiments, hatches that open upward, or both upward and downward, may be provided. A standpipe B1910 is in fluid communication with the interior of the tank B1902 via a pipe B1912 by which the tank B1902 is also in fluid communication with a heat exchanger B1914, which transfers heat to the environment (e.g., ocean). Circulation through the heat exchanger B1914 and tank B1902 may be either driven by pumps or may circulate by passive convection. The standpipe B1910 is partly fdled with water B1916. Water may be pumped into, or withdrawn from, the standpipe B1910 via a makeup pipe B1918. Water returns from the heat exchanger B1914 to the tank B1902 via a second pipe B1920. In various embodiments, separate paths of fluid communication are provided for the standpipe B1910 and the tank B1902.

[00269] The system B1900 further comprises a fuel-handling mechanism B1922 capable of lifting an FA vertically. The fuel-handling mechanism B1922 is housed inside an airlock B1924. The fuel- handling mechanism B1922 and its airlock B1924 can be both vertically and horizontally translated; within limits, vertical translation of the fuel-handling mechanism B1922 and the airlock B1924 are independent. The operation of these two devices shall be further clarified with reference to FIG. B18B.

[00270] In the state of operation of the system B1900 depicted in FIG. B18A, i.e. the locked state, the level of water B1916 in the standpipe B1910 is significantly higher than the ceiling of the tank

B1902. Thus, as indicated by open arrows (e.g., arrow B1926), there is significant water pressure acting upward on the ceiling of the tank B1902 and on the valves of the hatches. Closing force may also be exerted on the hatch valves by a spring or other mechanism (not depicted). Since the valves only open downward, the hydraulic force resisting the opening of each hatch B1906 is approximately proportional to the water pressure at the ceiling of the tank B1902 times the area of the hatch. The tank B1902 is thus, in the locked state of operation depicted, inherently resistant to entry. In embodiments, the airlock B1924 and fuel-handling mechanism B1922 are designed so that their vertical translation mechanisms do not have sufficient strength to force a hatch B1906 open when the system B1900 is locked.

[00271] FIG. B18B depicts system B1900 of FIG. B18A in an unlocked state of operation, that is, a state where the level of water B1916 in the standpipe B1910 has been lowered to approximately the level of the ceiling of the tank B1902. In this condition, the upward closing pressure exerted on the hatches by the tank water B1908 is approximately zero.

[00272] In the unlocked condition, a fuel-handling machine and airlock can access FAs inside the tank B1902 via one or more of the hatches.

[00273] Although in embodiments the system B1900 comprises only a single airlock and fuel- handling machine, for clarity, FIG. B18B depicts four airlocks B1924, B1928, B1930, B1932 and four fuel-handing machines B1922, B1934, B1936, B1938 accessing four FAs B1904, B1940, B1942, B1944 through four hatches B1946, B1906, B1948, B1950. Each of these ensembles is depicted in a different stage of accessing an FA and removing it from the tank B1902: [00274] Stage 1. Hatch B1946 is closed. The airlock B1924 approaches by being translated downward. Its nether end, shaped to complement the upper surface of the hatch B1946, has not yet made contact therewith.

[00275] Stage 2. Hatch B1906 has been forced open by downward translation of the airlock B1928, which has passed therethrough. The sides of the airlock B1928 hold the valves of the hatch B1906 open. Valves (e.g., valve B1952) at the nether end of the airlock B1928 have opened after the nether end of the airlock B1928 passed through the hatch B1906, admitting water into the interior of the airlock B1928.

[00276] Stage 3. Fuel handling machine B1936 has been vertically translated through the open airlock B1930 to enable its gripping end B1954 to grasp the FA B1942. Hatch B1948 is, similarly to hatch B1906, held open by an airlock.

[00277] Stage 4. Fuel handling machine B1938 has been translated upward into the airlock B1932, drawing with it the FA B1944, and the airlock B1932 has also been translated upward, though not yet sufficiently to allow self-closure of hatch B1950. The valves of airlock B1944 having been closed while the airlock B1944 was still approximately at the depth shown in FIG. B18B for airlock B1930, and the airlock B1944 contains trapped water sufficient to cover the captured FA B1944.

[00278] Stage 5 (not depicted in the figure). It will be clear that withdrawing airlock B1932 entirely from the opening of hatch B1944 will permit hatch B1950 to close. When all airlocks have been withdrawn and all hatches are closed, the water B1916 in the standpipe B1910 can be raised and the system B1900 returned to the Locked condition. After airlock closure around a captured FA, the airlock is free to ascend and deliver the FA to further handling mechanisms regardless of whether or not the system B1900 is locked or unlocked.

Cooled and Shielded Fuel Assembly Manipulator

[00279] Movement of hot FAs within a PNP will occasionally be necessary, e.g., during refueling, when spent FAs must be removed from the reactor core. Handling and movement of FAs fully and continuously submerged in large pools of water is the norm in terrestrial nuclear plants, but can be disadvantageous in a PNP, particular a floating PNP, where free surface effects are of concern.

Embodiments of the present disclosure provide for the manipulation and movement of spent FAs, such as FAs that are contained in canisters. In embodiments, a cooling system is provided for cooling the FAs during manipulation and movement.

[00280] FIG. B19A is a schematic, vertical cross-sectional depiction of portions of an illustrative cooled and shielded apparatus B2000 comprising a fuel handling machine of a PNP, herein referred to in some cases as an“FA manipulator,” according to an embodiment. The vertically oriented manipulator B2000 comprises a tubular case B2002; an FA gripper B2004 mounted on a shaft B2006 that can, within a limited range, be translated vertically independently of the manipulator case B2000, such as through a gasketed feed-through 2008; a steam relief valve B2010; a water makeup line B2012 that is in fluid communication with the interior of the case B2002 and through which water may enter and/or leave the case B2002; hoist rings (e.g., ring B2014); and heat-dissipation fins B2016. The manipulator B2000 also comprises openable valves B2018 at its nether end (e.g., clamshell doors) that are capable of sealing the interior of the case B2002 and containing pressurized fluids therein. Each valve B2018 turns upon a hinge B2020. For each valve B2018, a cable B2022 enters the interior of the case B2002 through a gasketed feedthrough B2024, runs over a pulley B2026, and attaches to the valve B2018. Retraction of the cable B2022 causes the valve B2018 to rise. Opening the valves opens the nether end of the manipulator B2000. The valves are weighted so that they close gravitationally when the control cables are relaxed; in various embodiments, a spring-powered, hydraulic, or other closure mechanism can be additionally provided.

[00281] Lifting cables are attached to the hoist rings B2014 but not depicted, for simplicity, in FIG. B19A. The manipulator B2000 can be vertically translated by shortening its lifting cables and horizontally translated by horizontally translating the attachment point of its lifting cables. In some states of operation, as shall be made clear with reference to FIG. B19B and FIG. B19C, the manipulator

B2000 contains an FA suspended from the gripper B2004 and is filled partly or wholly with water, enabling an FA to be moved within a PNP in a cooled manner. Moreover, the walls and valves of the manipulator B2000 are preferably shielded, to reduce irradiation of objects approached by the manipulator B2000 while transporting a hot FA.

[00282] FIG. B19B is a schematic, vertical cross-sectional depiction of portions of the manipulator B2000 of FIG. B20A during retrieval of an FA B2028 from a reactor vessel B2030. In the state of operation depicted in FIG. B19B, the top of the reactor vessel B2030 has been removed and the valves (e.g., valve B2020) of the manipulator B2000 have been refracted, opening the nether end of the manipulator B2000, which has been lowered partly into the water B2032 within the reactor vessel B2030. Manipulator lifting cables have been omitted from the Figure for simplicity. The FA gripper B2004 has been lowered on its shaft B2006 to enable the gripper B2004 to engage with an FA B2028. In subsequent stages of operation, the gripper B2004 can be raised so that the FA B2028 is enclosed in the manipulator B2000 and the valves closed, capturing both the FA and a sufficient quantity of water to keep the FA immersed within the manipulator B2000.

[00283] FIG. B19C depicts a state of operation of the manipulator B2000 in which an FA B2028 and a quantity of water B2032 have been captured and the valves at the nether end of the manipulator B2000 have been closed, trapping the FA B2028 and the water B2032. Additional water is being added through the water makeup line B2012. Heat generated by the FA can escape from the manipulator B2000 by one or more of radiation from the sides of the case B2002 and the radiator fins B2016, release of gas through the steam relief valve B2010, or circulation of water through the interior of the manipulator B2000 via the makeup line B2012, which may contain parallel conduits for bidirectional flow.

[00284] The manipulator B2000 in the state of operation of FIG. B19C can be translated vertically and/or horizontally to any desired location in the PNP, where it can be immersed in water and the capture process reversed, such as to deliver the FA to another fuel-handling subsystem, to a storage location, or the like. Advantageously, the liquid free surface within the manipulator B2000 is minimal; further, the water B2032 in the manipulator B2000 may be in fluid communication with other bodies of water in the PNP such as via the makeup line B2012, through which flow may be managed by the narrowness of the line B2012 and by valves (not depicted).

Precluding or Mitigating the Free Surface Effect of Inventories of Water Related to

Spent Fuel Removal or Reactor Cooling

[00285] Embodiments of this disclosure address the need in a PNP, particularly a floating PNP, to remove spent FAs from the core and perform critical safety -related core cooling functions while keeping the platform protected from large free surface effects. The traditional refueling strategy of a terrestrial light water reactor would, if transposed directly to a PNP, entail risk for potentially destabilizing free surface effect or large, rapid relocation of mass in an offshore platform. Likewise, the traditional strategy of maintaining large open pools of coolant in a containment structure to serve passive core-cooling functions would, if transposed directly to a PNP, constitute another high-risk source of a potentially destabilizing free surface effect. Therefore, various embodiments of systems and architectures are provided for transferring spent fuel assemblies and maintaining liquid coolant inventories while avoiding or mitigating large, rapid, or resonant mass transfers that could compromise the stability of the platform.

[00286] FIG. B20 is a schematic vertical cross-sectional depiction of portions of a PNP B2100 according to illustrative embodiments of the invention, in which volumes of water in the PNP are arranged so that the PNP remains stable even if water routing systems fail. In the illustrative embodiment, every volume of liquid with a free surface open to a cofferdam or compartment, the containment volume, or connected by a fluid routing to another volume of water is sufficiently small in total volume so as to be incapable of applying a destabilizing moment to the PNP relative to the platform’s metacenter if the total mass of each volume of liquid were to be redistributed due to contingency or failure of systems used to place the volumes in fluid communication. Moreover, the total number of discrete water volumes connected by potential flow paths, and their total mass, is such that even if all the discrete water volumes were to relocate through flow paths upon failure of flow control, the resulting moment on the PNP would not be destabilizing. FIG. B20 depicts a number of cofferdams (e.g., cofferdams B2102, B2104), all of which are capable of containing water. A flow path B2106 between a higher cofferdam B2102 and a lower cofferdam B2104 is depicted. In example, the higher cofferdam B2012 is a refueling makeup water reservoir and the lower cofferdam 2012 is a refueling chamber within a reactor containment comprised by the PNP B2100. If water B2108 is present in the higher cofferdam B2012, it may flow by gravity through the flow path B2106 to the lower cofferdam B2014. While in the higher, centrally located cofferdam B2012 the water B2108 exerts no moment around the metacenter“M” of the PNP B2100; upon moving to the lower cofferdam B2104, the water B2110 does exert such a moment. While any nonsymmetrical rearrangement of mass within a floating vessel must alter the vessel’s orientation to some degree, the positions and masses of water bodies in the PNP B2100, and the interconnections between them, comprise in various embodiments a system such that no possible rearrangement or movement thereof, gravitational, pumped, or resonant, even in combination with any other possible rearrangement of moveable materials aboard the PNP (e.g., fuel, vehicles, ballast), causes the PNP to list or oscillate beyond an acceptable safety threshold. In an example, a multiplicity of water-fdled cofferdams constituting a first set A, arranged around the perimeter of the PNP B2100, is severally connected to a multiplicity of similar but empty cofferdams constituting a second set B. Each of the set B cofferdams is on the far side of the metacenter M from the set B cofferdam’s connected partner in set A. By elementary mechanics, the maximum shift in the center of gravity of the PNP B2100 achievable in such a counterpoised system by moving water from any subset of cofferdams in set A to any subset of cofferdams in set B is less than that which would be achievable if all the set A cofferdams were on one side of the metacenter M and all the set B cofferdams were on the other side. Indeed, given complete symmetry of the moment arms of the set A and set B cofferdams around the metacenter M, transferring all water from set A to set B would not shift the PNP’s center of gravity at all. The number of specific PNP cofferdam shapes, locations, sizes, and

interconnections that can meet the stated stability criteria is clearly without limit; however, all such configurations are contemplated and within the scope of the invention.

[00287] FIG. B21 is a schematic cutaway depiction of portions of an illustrative refueling canal system B2200 comprising a number of adjacent, coolant-filled compartments according to embodiments. Adjacent compartments have tall lock doors through which vertically oriented FAs can pass. The doors are equipped with interlock mechanisms such that every compartment remains sealed and full of coolant except for the 1 or 2 compartments in which a spent FA is resident, or through which a spent FA is passing, at any given moment. In FIG. B21, the canal system B2200 comprises an overhead crane (refueling machine) B2202 that is capable of raising and lowering an FA B2204, e.g. to remove the FA B2204 from a reactor vessel B2206, and a number of compartments B2208, B2210, B2212, B2214 that are filled largely or wholly with water. Four compartments are depicted in FIG. B21, but various embodiments comprise any number of compartments greater than zero. Each compartment is topped by an openable lid, e.g., lid B2216 (closed) and lid B2218 (open). Each compartment communicates with two of its neighbors via two openable doors shaped and sized to admit the passage of an FA B2204; e.g., compartment B2210 communicates with compartment B2208 via a first door 2220 and with compartment B2212 via a second door B2222. To move an FA B2204 from one compartment to the next, two lids and a single door are opened, the FA B2204 is translated through the open door, the lid of the first compartment is closed, and the door is closed: e.g., to move the FA B2204 from compartment B2210 to compartment B2212, lids B2218 and B2224 are opened, door B2222 is opened, the FA is translated through the door B2222 by the refueling machine B2202, lid B2218 is closed, and the door B2222 is closed. Passage of an FA or other load through a canal B2200 of any length or number of compartments can be achieved by repeating such manipulations. In various embodiments, an interlock mechanism enforces the rule that a lid cannot open if both its neighbors are already open and/or if two lids anywhere along the canal are already open. The compartmentalized and interlocked design of the refueling canal B2200 assures that free surface effect is minimized, most of the water in the canal B2200 being contained inside sealed compartments at all times.

[00288] FIG. B22 is a schematic depiction in top and side views of portions of an illustrative compartmentalized coolant tank B2300 of a PNP according to embodiments of the invention. This illustrative embodiment comprises an arc-shaped, compartmentalized in-containment refueling water storage tank B2300 with radial dividers defining compartments B2302, B2304, B2306, B2308. In embodiments, an arc-shaped reservoir is preferable, though not essential, due to the usually cylindrical form of a containment. Coolant flow between the tank’s compartments B2302, B2304, B2306, B2308 is controlled by a set of valves B2310, B2312, B2314. Each valve offers fluid communication between two compartments, passively opening when there is a pressure differential between the two compartments above a certain value for a certain duration of time. Thus, continued withdrawal of coolant from any one chamber will eventually enable withdrawal of coolant from all the chambers. The time duration threshold for valve activation is set to be longer than any natural period of sloshing for a given overall tank geometry and coolant type. The number of compartments and valves differs in various embodiments, as does the overall shape of the tank B2300 and of the compartments; various embodiments comprise horizontal dividers as well as, or instead of, vertical dividers.

[00289] FIG. B23A is a schematic depiction in top and side views of portions of an illustrative spent fuel pool sub-compartment B2400 of a PNP according to embodiments of the invention. This illustrative embodiment comprises a spent fuel pool sub-compartment bounded by tall grid-like walls that prevent large transverse flow of coolant between adjacent compartments. The sub-compartment walls or dividers (e.g., divider B2402) extend from the floor B2404 of the spent fuel pool to the free surface B2406 of the coolant. The dividers also have vertically oriented openable doors in the upper portion of each divising plane (e.g., door B2410) that enable FAs (e.g., FA B2412) to be moved between into and out of each compartment. The dividers and doors are perforated by holes B2414 near the bottom and top of the subcompartment B2400, enabling coolant to flow in and out of the sub-compartment B2400 in a constrained manner, e.g., as driven by convection. Walls are preferably shared between adjacent sub-compartments, as depicted in FIG. B23B, and doors are preferably omitted from dividers that are not adjacent to another sub-compartment.

[00290] FIG. B23B is a top view of portions of an illustrative spent fuel pool B2416 comprising 9 sub-compartments similar to the sub-compartment B2400 depicted in FIG. B23A. An outer wall B2418 confines the coolant inventory of the fuel pool B2416. Open arrows indicate examples of coolant flow B2420 between a body of water B2422 surrounding the 9 sub-compartments and of coolant flow B2424 between adjacent compartments. FIG. B23B also depicts movement of an FA B2426 from a first compartment B2428 to a second compartment B2430 through an opened door B2432. [00291] FIG. B23C is a view of a spent fuel pool B2434 similar to the pool B2416 depicted in FIG. B23B but comprising 16 sub-compartments. The outer wall of the pool B2434 is, for simplicity, not depicted in FIG. B23C.

[00292] FIG. B24 is a schematic vertical cross-sectional depiction of portions of an illustrative spent- fuel PNP storage system B2500 according to an embodiment. The system B2500 comprises a spent fuel tank B2502 (i.e., a compartment serving the same function as a spent fuel pool but with its volume entirely filled with coolant) connected to a refueling canal (transfer tube) B2504. The refueling cavity B2506 and reactor B2508 are inside a containment B2510 and the spent-fuel tank is outside. The spent- fuel tank B2502 is positioned sufficiently far below the floor of a refueling cavity B2506, with respect to the vertical axis of the PNP, so that for a given angle theta of the refueling canal B2504, tip or list of the PNP below some design threshold does not cause the coolant in the spent fuel tank to rise above the point of connection of the canal B2504 to the refueling cavity B2506 relative to the direction of gravity. The elevation difference B2512 between the tank B2502 and the cavity B2406 is also great enough to prevent the coolant in the tank B2502 from passing substantially into the refueling cavity B2506 by impetus, e.g., when subjected to wave-induced pitching, within a certain design threshold. FIG. B24 depicts the movement of an FA B2514 through the canal B2504, and the storage of some number of FAs B2516 within the spent fuel tank B2502.

[00293] FIG. B25A is a schematic vertical cross-sectional depiction of portions of an illustrative spent-fuel PNP storage system B2600 according to an embodiment. The system B2600 comprises a compartmentalized water-lock connection (i.e., water-filled refueling canal or transfer tube) B2602 between a refueling cavity B2604 within a containment B2606 and a spent fuel pool B2608. The transfer tube B2602 provides an intermediate volume of water that is only in fluid communication with either the refueling cavity water B2610 or the spent fuel pool water B2612 at any given time during transfer of an FA B2614 from the refueling cavity B2604 to the spent fuel pool B2608 or in the opposite direction. For example, in passing an FA B2614 from the refueling cavity B2604 into the transfer tube B2602, the first door B2616 is opened. A mechanical interlock mechanism assures that the first door B2616 can only open if the second door B2618 is shut and likewise that the second door B2618 can only open if the first door B2616 is shut, preventing free flow of water between the spent fuel pool B2608 and the refueling cavity B2608. The FA B2614 is then passed by a conveyor mechanism (not depicted) into the transfer tube B2602, whereupon the first door B2616 is closed. At some time during the residence of the FA B2614 in the transfer tube B2602, the second door B2618 is opened. This state of operation is depicted in FIG. B25B. The conveyor mechanism then transfers the FA B2614 into the spent fuel pool B2608, where a standup machine and fuel-handling machine (not depicted) add the FA B2614 to a set of other FAs B2620. The process is reversed to extract an FA from the spent fuel pool B2608. The water lock system just described clearly precludes or mitigates free surface effect by limiting the amount of coolant and mass that can be exchanged between these two watertight sectors of the PNP (i.e., the fuel pool B2608 and the refueling cavity B2604) at any given time.

[00294] FIGS. B26A-B26D are schematic cross-sectional views of portions of an illustrative gated FA transfer valve B2700 located within a transfer tube B2702 of a PNP according to embodiments of the invention. The transfer valve B2700 allows an FA to pass in either direction but limits the amount of coolant that can pass through the transfer tube B2702 during passage of the FA B2704, thus mitigating free surface effect between any bodies of coolant that are in fluid communication through the tube

B2702. The valve B2700 comprises two or more hinged flaps B2706, B2708 that substantially or entire block passage of liquid through the tube B2702. The flaps B2706, B2708 are capable of rotation in either direction, enabling the valve B2700 to open. The opening thus created is closely similar in size and shape to the cross-sectional shape of the FA B2704. The flaps B2706, B2708 are preferably latched together by a mechanism (not depicted, for simplicity) that keeps the valve B2700 closed unless impinged upon, from either side of the valve B2700, by an FA B2704. When an FA B2704 does impinge upon the closed valve B2700, the latch is disengaged and the flaps B2706, B2708 are free to rotate when pushed by the FA B2704. A restorative mechanism (e.g., springs), not depicted, exerts a closing force on the flaps B2706, B2708 whenever they are displaced from their closed position. FIG. B26A depicts a state of operation before the FA B2704 has impinged on the valve B2700; FIG. B26B depicts a state of operation when the FA B2704, moved by a conveyor mechanism (not depicted), has unlatched the flaps B2706, B2708 and forced them to partially open; FIG. B26C depicts a state of operation when the FA B2704 has forced the flaps B2706, B2708 fully open and is passing through the opening thus created; and FIG. B26D depicts a state of operation when the FA B2704 has passed entirely through the valve B2700 and the flaps B2706, B2708 have been restored to a closed and latched condition. Latching prevents coolant flow through the valve B2700 up to some design threshold of pressure difference across the valve B2700; the fitting of the valve B2700 around the FA B2704 limits passage of coolant with and around the FA B2704 during the passage of the FA B2704 through the valve B2700. In an example, one or more valves similar to valve B2700 are located in an FA transfer tube connecting a refueling cavity to a spent fuel pool (e.g., the transfer tubes depicted in FIG. B24 and FIG. B25A). In various embodiments, the valve B2700 is located at the beginning or end of a transfer tube, rather than in a midwise location, as in FIGS. B26A-B26D; also, while the transfer tube B2702 of FIGS. B26A-B26D is depicted as fitting the FA B2704 closely, in various embodiments the valve B2700 may fit the FA B2704 closely while the transfer tube B2702 does not. Also, the number of flaps in various embodiments may be 1 or any greater number. Also, the flaps need not be rigid, as implicitly depicted in FIGS. B26A-B26D. Also, the flaps may be provided with a powered opening and/or closing mechanism, and may be activatable by a control system, not only by an impinging FA.

[00295] FIG. B27 is a schematic depiction of portions of an illustrative core refueling coolant system B2800 of a PNP according to embodiments of the invention. In system B2800, the entire core refueling operation is carried out in a single or multiple closed volumes of coolant (e.g., volumes B2802, B2804, B2806) that are either filled to the top (i.e., function as tanks rather than as open-surface pools) or covered by roofs or coverings B2808, B2810, B2812 that are adjustable in height and that prevent large redistributions of coolant within or between the covered volumes B2802, B2804, B2806. In an example, a reactor cavity, refueling canal, and spent fuel pool are all sealed and full (or nearly full) of coolant. This configuration prevents any large redistribution of coolant mass in the platform while enabling continuous immersion in coolant of spent FAs.

[00296] FIG. B28 is a schematic depiction of portions of an illustrative coolant stabilizing system B2900 of a PNP according to embodiments of the invention. The system B2900 comprises baffles (e.g., baffle B2902) immersed in a coolant pool or tank B2904 to impede the movement of coolant throughout the volume. The baffles B2902 are perforated by openings (e.g., opening B2906) to allow coolant to move throughout the volume without resonating or building too much momentum, e.g., when the PNP is moved by wave action. Free surface effect in such a coolant body is mitigated. In various embodiments, the baffles are spaced and/or perforated so as to provide openings specifically designed to allow FAs to be moved through the volume, whether vertically (space B2908) or endwise (opening B2910).

[00297] FIG. B29 is a schematic depiction of portions of an illustrative coolant stabilizing system B3000 of a PNP according to embodiments of the invention. System B3000 comprises a coolant pool B3002 and a membrane, fabric, or highly articulate metal surface restraint B3004 that contacts and envelops the free surface of the coolant contained within the pool B3002 in order to effectively enclose and/or dampen the surface dynamics of the coolant’s free surface, e.g., waves induced by the impact of wave motion, winds, or other impacts on the PNP. The surface restraint B3004 is preferably retractable; in the illustrative system B3000 of FIG. B29, the surface restraint B3004 comprises a pair of flexible metal shutters B3006, B3008 that can be retracted to enable a pipe B3010, fuel-handling machine, or other device to access the interior of the pool B3002. Free surface effect in such a coolant body is mitigated.

[00298] FIG. B30 is a schematic depiction of portions of an illustrative coolant stabilizing system B3100 of a PNP according to embodiments of the invention. System B3100 comprises a coolant pool B3102 and flat horizontal surfaces or shelving B3104 approximately parallel to and overhanding the perimeter of the free surface of the coolant in the pool B3102. The shelving B3104 caps or interrupts waves reflecting off the vertical side walls of the pool B3102, e.g., waves induced by wave motion of the PNP. Free surface effect in such a coolant body is mitigated.

[00299] FIG. B31 is a schematic depiction of portions of an illustrative coolant stabilizing system B3200 of a PNP according to embodiments of the invention. System B3200 comprises a coolant pool B3202 whose walls have irregular, e.g., many-sided, shapes to prevent resonant sloshing with the PNP platform’s period of tilt or heave. In FIG. B31 the irregular walls are depicted as vertical and planar, but in various embodiments the walls are non-planar. Free surface effect, particularly resonant wave motion, in such a coolant body is mitigated. [00300] FIG. B32 is a schematic vertical cross-sectional depiction of portions of an illustrative coolant stabilizing system B3300 of a PNP according to embodiments of the invention. System 3300 comprises a tank (e.g., spent fuel pool or refueling makeup water reservoir) B3302 having a primary chamber B3304 and a smaller, secondary chamber B3306. The two chambers are partly divided by a barrier B3308, which comprises a vertical lower portion B3310 and a tilted upper portion or weir B3312. Further, the two chambers B3304, B3306 are in fluid communication through a makeup pipe B3314. When waves are induced (e.g., by wave motion of the PNP) in the primary chamber B3304 that are of sufficient amplitude, water will ride up the weir B3312 and spill over into the secondary chamber B3306. Waves induced in the secondary chamber B3306 will tend to be confined thereto, since the smaller mass and dimensions of the water in the secondary chamber will constrain wave development; further, the overhanging weir B3312 will tend to confine waves within the secondary chamber B3306. By elementary hydrostatics, a quantity of water equal to any which crosses over into the secondary chamber B3308 will return via the makeup pipe B3314 to the primary chamber B3308, maintaining an approximately equal surface height in the two chambers. In effect, the tank B3302 constitutes a nonlinear system that constrains the development of larger waves. In various embodiments the weir B3308 is mounted on a hinge B3316 that is adjustable in angle via a mechanism, or on a sprung hinge that tends to return the weir B3308 to a certain angle. Also in various embodiments, the hinge spring angle and/or resistance are adjustable and/or the fixed divider B3310 can be raised or lowered in order to adjust the height of the weir B3308. Such adjustability enables the resonant properties of the tank B3302 to be altered, e.g. in response to changing ocean wave excitation spectra and directionality. In embodiments, adjustment may be provided by an electro-mechanical system, such as under control of a processor, which may occur automatically (such as according to a model, algorithm, or the like that provides automated adjustment in response to conditions, such as detected ocean wave conditions, predicted conditions, or the like) or under user control, such as via a user interface that allows a user to set the angle, resistance or other parameter of the system to optimize the properties of the tank 3302.

Free surface effect in such a coolant body is mitigated.

[00301] FIGS. B33A-B42 pertain to devices for moving spent FAs in a canister or enclosed volume by moving the enclosed volume within a PNP, as opposed to moving the FA within a continuous volume of coolant as is traditionally done for moving spent fuel assemblies in a terrestrial nuclear power plant. The fully enclosed volume, whether fully fdled with coolant or not, ensures that spent FAs within are adequately cooled while the enclosure moves the FAs to a new location inside the ONBP.

[00302] FIG. B33A schematically depicts an illustrative fuel movement canister or enclosure B3400 with the ability to transport a single spent FA B3402 according to embodiments of the invention. The enclosure B3400 is in various embodiments thermally self-sufficient, that is, radiates sufficient heat to its environment (through, e.g., fins, vanes, a portable heat exchanger, or the like) that no coolant flow through the enclosure is required for thermal stability. In the illustrative embodiment depicted in FIG. B33A, the enclosure B3400 is fed coolant through an intake pipe B3404. The coolant is removed via an outlet pipe B3406. The enclosure B3400 may be attached to the pipes B3404, B3406 only while stationary, and disconnected while in motion: or, the pipes B3404, B3406 may be connected to an umbilical or sliding-connection system that enables them to supply the enclosure with coolant flow throughout some allowed transport space. In the illustrative embodiment depicted in FIG. B33A, the pipes B3404, B3406 are connected to a flexible umbilical arrangement (not depicted) that enables the enclosure B3400 to translate along a conveyor mechanism B3408.

[00303] FIG. B33B schematically depicts an illustrative fuel movement enclosure B3410 with the ability to transport four spent FAs, e.g., FA B3412, according to embodiments of the invention. Like the single-FA enclosure B3400 of FIG. B33A, the four-FA enclosure of FIG. B33B is supplied by a mobile cooling pipes B3404, B3406 and capable of translation along a conveyor mechanism B3408. One FA and four FAs are illustrative enclosure capacities only; FA enclosures in various embodiments have capacity for conveying a single FA or any greater number.

[00304] FIG. B34 is a schematic depiction of portions of an illustrative system B3500 for moving FAs in enclosed volumes according to embodiments of the invention. The system B3500 loads one or more spent FAs (e.g., FA B3502) inside a mobile FA enclosure B3504 under water within a refueling cavity B3506. Movement of the FA B3502 within the refueling cavity B3506 and placement within the enclosure B3504 is accomplished by a refueling machine B3508. The system B3500 raises the FA enclosure B3504 above the coolant level of the refueling cavity B3506 (e.g., by the refueling machine B3508 or a hydraulic lift B3510). An FA extracted from the refueling cavity B3506 (e.g., FA B3512) is then transported horizontally (e.g., by a conveyor mechanism B3514) to another part of the PNP, e.g., to a vertical transport system such as will be discussed with reference to several figures hereinbelow.

[00305] FIG. B35 is a schematic depiction of portions of an illustrative system B3600 for moving FAs in enclosed volumes according to embodiments of the invention. Rather than moving a mobile FA enclosure vertically out of a refueling cavity using a crane or lift, followed by horizontal movement on a conveyor mechanism, as shown in FIG. B34, the system B3600 performs both vertical and horizontal movements of FAs (e.g., FAs B3602, B3604) by an articulated arm or crane B3606.

[00306] FIG. B36 and FIG. B37 pertain to systems and methods having the ability to quickly return any spent FA that is in transit in a mobile enclosure (e.g., the mobile enclosure depicted in FIG. B35A) to a large pool or volume of coolant during any scenario in which the device moving the mobile enclosure loses power. This failsafe feature may be necessary if the enclosure requires active cooling systems to keep the enclosed spent FAs sufficiently cool. For quick-return systems to be effective, moreover, the FA fuel assembly enclosure must be able to passively expel heat at an adequate rate when immersed in coolant.

[00307] FIG. B36 schematically depicts portions of an illustrative quick-return PNP mechanism B3700, according to embodiments of the invention, comprising an inclined track B3702 along which a mobile FA enclosure B3704 rolls back to the location of a pool B706 of coolant if the conveyor mechanism moving the enclosure B3704 or the system cooling the enclosure loses power. Upon being braked to a standstill by a preferably unpowered mechanism at the end of the track B3702, the enclosure B3704 is automatically (i.e., without human intervention or power) lowered by a hydraulic lift B3708 into the coolant pool B3706 for sustained passive cooling. The coolant pool B3706, in turn, has mechanisms (e.g., those described elsewhere herein) for passively rejecting heat to the outside environment indefinitely without the need for onsite or offsite power.

[00308] FIG. B37 schematically depicts portions of an illustrative quick-return PNP mechanism B3800, according to embodiments of the invention, comprising an inclined rail B3802 along which a crane B3804 carrying a mobile FA enclosure B3806 slides back to a location above a pool B3808 of coolant if the mechanism moving the crane B3804 and enclosure B3806, or the system cooling the enclosure B3806, loses power. Upon being braked to a standstill by a preferably unpowered mechanism when the crane B3804 reaches a point above the water B3808, the enclosure B3806 is automatically (i.e., without human intervention or power) lowered by the crane B3804 into the coolant pool B3808 for sustained passive cooling. Preferably the lowering of the enclosure B3806 is braked in an automatic, non-powered manner so that the enclosure B3806 does not impact the floor of the coolant pool B3808.

[00309] FIG. B38 schematically depicts an illustrative system B3900 for providing sustained, adequate cooling to a mobile FA canister or enclosure B3902 according to embodiments of the invention. System B3900 comprises a coolant umbilical cord B3904 that enables a bidirectional flow of coolant between the enclosure B3902 and a heat exchanger B3906 immersed in the ocean B3908, outside the PNP hull B3910. The umbilical cord B3904 provides a flexible coolant loop that adjusts its shape as the enclosure moves about within the PNP (e.g., between the reactor vessel and the spent fuel pool). This coolant loop may be either actively pumped (pump not depicted in FIG. B38) or powered by convection. For the loop to operate by convection, it is necessary that there be a height differential with respect to gravity for the inlets and outlets of both the heat exchanger B3906 and the umbilical connections to the enclosure B3902, as depicted in FIG. B38.

[00310] FIG. B39 schematically depicts an illustrative FA canister or enclosure B4000 according to embodiments of the invention. Enclosure B4000 comprises a hollow main cylinder B4002 containing a hot FA B4004 and a quantity of coolant B4006 sufficient to immerse the FA B4004. The enclosure B4000 also comprises some number of hollow condensation tubes, e.g. tube B4008, whose upper ends are sealed and whose lower ends are in fluid communication with the interior of the main cylinder

B4002. Moreover, a number of heat radiation fins B4010 are affixed to the condensation tubes. As the hot FA B4004 boils coolant B4006, steam is created above the liquid portion of the coolant B4006 and rises into the condensation tubes, as indicated by open arrows (e.g., arrow B4012). Steam condenses in the condensation tubes and runs back down into the interior of the main cylinder B4002, as indicated in FIG. B39 by droplets (e.g., droplet B4014). The whole FA enclosure B4000 thus acts as a heat pipe to transport heat away from the FA B4004 and deliver it to the ambient environment of the enclosure

B4000.

[00311] FIG. B40 schematically depicts an illustrative FA canister or enclosure B4100 according to embodiments of the invention. Enclosure B4100 comprises a hollow main cylinder B4102 containing a hot FA B4104 and a quantity of coolant B4106 sufficient to immerse the FA B4004. The enclosure B4100 also comprises a number of horizontally oriented, air-cooled heat radiation fins B4108 affixed along the length of the main cylinder B4102. The fins B4108 are cooled by passive circulation of air.

The exterior of the FA enclosure B4100 thus acts as a radiator to transport heat away from the FA B4104 and deliver it to the ambient environment of the enclosure B4100. Many arrangements of fins or vanes other than that depicted in the figure would serve the purpose in various embodiments, as will be clear to a person familiar with radiator engineering; all such are contemplated and within the scope of the invention.

[00312] FIG. B41 schematically depicts top and side views of an illustrative FA canister or enclosure B4200 according to embodiments of the invention. Enclosure B4200 comprises a hollow main cylinder B4202 containing a hot FA B4204 and a quantity of coolant B4206 sufficient to immerse the FA B4204. The enclosure B4200 also comprises a number of vertically oriented, air-cooled heat radiation fins B4208 affixed along the length of the main cylinder B4202. The fins B4208 are cooled by passive circulation of air and/or by vertical airflow, such as driven by fans, e.g., electric fan B4210. Air flow along the fins B4208 is indicated by open arrows, e.g., arrow B4212. The exterior of the FA enclosure B4200 thus acts as a radiator to transport heat away from the FA B4204 and deliver it to the ambient environment of the enclosure B4200.

Staging of Fresh Fuel for a PNP

[00313] Fresh fuel FAs do not normally represent a direct hazard: they are only mildly radioactive and do not radiate significant heat. However, if immersed in a liquid (e.g., water) that acts as a neutron flux moderator, fresh FAs can participate in an accelerated nuclear chain reaction and become hot and radioactive (as they do in a reactor core). Therefore, it is desirable that fresh FAs do not become in immersed in water that can act as a neutron moderator. Onboard a PNP that is itself immersed in water, a need exists for facilitating avoidance of fresh fuel FA immersion.

[00314] Embodiments of the invention facilitate avoidance of fresh fuel FA immersion. In particular, FIG. B42 is a schematic depiction of a PNP B4300 comprising an illustrative FA storage system that avoids unintended fission in fresh FAs. The illustrative system comprises a waterproof chamber B4302 in which a number of fresh FAs B4304 are stored. The chamber B4302 provides a first line of defense against entry by water from the environment of the PNP or from volumes of water stored or flowing aboard the PNP; however, it is possible that the chamber B4302 could be breached or that access hatches could be inadvertently opened. Therefore, a quantity B4306 of a dry“poisoning” agent (e.g., a block of an appropriate salt, such as a dry boron salt) is built into the interior of the fresh FA storage chamber B4302. The poisoning agent, when dissolved in water, reduces the neutron-moderating efficacy of the water. Thus, if water does enter the chamber B4302, the dry poisoning agent will prevent significant fission from occurring in the fresh FAs B4304. Since it is possible that the chamber B4302 will, in an accident scenario, be repeatedly filled and emptied of water, removing the original dose of poisoning agent, in embodiments a number of poisoning-agent units are installed in the chamber B4302. One of units (the primary unit) is open at all times and is operative the first time the chamber 4302 is invaded by water. The additional N units are in containers equipped with water exposure locks that open the container after a certain number of exposures to water followed by exposures to air. The first of the additional N units opens after 1 such exposure cycle, the second after 2 such cycles, and so forth.

Poisoning is thus assured for A+l flooding cycles. Alternatively or additionally, a slow-release mechanism can continue to release poisoning agent into water within the chamber B4302 as long as the water is present, mitigating the probability that water circulating through the chamber B4302 will dilute the poisoning agent to inefficacy during an accident scenario.

Vertical Transport of Spent Fuel Assemblies in a PNP

[00315] Fuel assemblies in a PNP must proceed through a series of storage and movement stages. After manufacture, fresh fuel must be transported to the PNP and staged for refueling. In refueling, FAs are placed into a reactor core. After an operational time, FAs are removed from the reactor core, stored in a cooled pool, and ultimately transferred off the PNP to long-term dry storage or reprocessing facilities. In contrast to terrestrial plants, where vertical movements of FAs are few in number and modest in scope, FAs in a PNP will typically travel relatively large vertical distances both within the PNP and during transfer to and from vessels. FAs will, between horizontal and vertical movements within the PNP, reside in various platform structures in various numbers and for varying amounts of time, depending on the design and operation of the PNP. For example, spent FAs may be stored in pool racks, canisters, and casks progressively as they age.

[00316] Typically, spent FAs on a PNP will go through some combination of one or more of the following steps after removal from the reactor: storage in a temporary in-containment storage pool; loading into canisters or mobile FA enclosures in the storage pool after an initial decay interval;

movement up a lift access structure, whether as single assemblies or as loaded canisters; arrival at a staging area near the top deck of the platform; and finally, transfer to a transport ship that brings the canisters to a dock form whence they will be taken to a facility for casking or reprocessing.

[00317] Advantageous arrangements that address needs for vertical movement of FAs in a PNP must ensure that lifting mechanism failure modes are acceptable. In embodiments, FAs, whether as individual assemblies or canisters, may be lifted by hoist, worm gear, elevator, hydraulic lift, crane, buoyancy, magnetic lift, or other mechanisms along a vertical access tube with appropriate measures taken to safely lock the moving load into place or limit falling velocity upon failure of power or any other aspect or component enabling the movement mechanism. Features comprised by embodiments include flooding the lift access with water and having appropriate water locks at each end to retain water in tube during transport. Approximate sizing of a fluid-filled column or tube to the objects transported therewithin will tend to slow falling objects hydraulically if a failure of lifting system occurs.

[00318] FIGS. B43-B46 pertain to systems and methods for vertical movement of FAs within a PNP that are comprised by embodiments of the invention.

[00319] FIG. B43 is a schematic depiction of portions of an illustrative fuel-handling system of a PNP B4400 according to an embodiment. A fuel-exchange facility B4402 receives fresh FAs, preferably via a transfer mechanism from a surface delivery vessel. The receiving facility B4402 delivers fresh FAs B4404 to a fresh-fuel storage chamberB 4406, which may comprise provisions for suppressing unwanted fission, e.g., as depicted in FIG. B42. A fresh-fuel vertical transfer tube B4408 transfers fresh FAs (e.g., by gravity) from the storage chamber B4406 to a fresh-fuel elevator B4410 within the containment B4412. The fresh-fuel elevator B4410 receives FAs and orients the FAs vertically before lowering them into the primary fuel-handling pool B4414 where they are loaded into the reactor B4416 by a fuel- handling machine (not depicted). Spent FAs extracted from the reactor B4416 are delivered to an acute angle laydown/standup machine B4418 submerged within the containment, which can rotate FAs to any angle for passage through the spent fuel vertical transfer tube B4420. The coolant-filled spent fuel vertical transfer tube B4420 conveys each spent FA to the coolant-filled spent fuel storage module (a.k.a. spent fuel storage tank, a.k.a. spent fuel storage pool) B4422, where spent FAs B4424 are stored. A second acute angle laydown/standup machine B4426 handles FA orientation upon receipt within the storage pool B4422. A coolant-filled spent fuel vertical removal transfer tube B4428 moves spent FAs that have cooled sufficiently for removal from the PNP B4400 from the spent fuel pool B4422 to the fuel-exchange facility B4402. Various embodiments comprise alternative or additional arrangements for storing dry-casked FAs aboard the PNP B4400.

[00320] FIG. B44 is a simplified depiction of portions of an illustrative system B4500 for loading FAs (e.g., FA B4502) into a spent-fuel vertical transport tube B4504 in a PNP according to embodiments of the invention. The system B4500 comprises a temporary storage and cooling pool B4506 (only two walls of which are depicted, for clarity) in which reside a number of spent FAs. The pool B4506 is mostly or entirely fdled with water and is equipped with systems (not depicted) for the rejection of heat to an external heat sink (e.g., the ocean). The pool B4506 may be located inside a reactor containment or between a containment and outer hull of the PNP. The system B4500 also comprises a fuel-handling machine B4508 capable of movement along three orthogonal axes and a load-unload chamber B4510 at the base of the vertical transport tube B4504 (only a nether portion of which is depicted). The load- unload chamber B4510 comprises an opening sized for the admission of an FA or of a canister containing an FA or more than one FA, as well a sliding shell door B4512 that can be rotated into place to cover the opening. Both the load-unload chamber B4510 and the transport tube B4504 are fdled with coolant. A lock valve B514 (depicted in FIG. B44 as a simple disk) is closed when the chamber door B4512 is open, separating the loading chamber B4510 from the upper portion of the transport tube B4504 to prevent the tube head from raising the water level in the pool B4506. Preferably, a mechanical interlock prevents the lock valve B4514 and the chamber door B4512 from being open simultaneously. The nether end of the transport tube B4504, approximately coincident with the floor of the pool B4506, is closed.

[00321] The load-unload chamber B4510 contains a load carrier B4516, upon or within which the FA or FA canister is placed for transport. A suitable mechanism (not depicted) installs or removes a load carrier B4516 in the load-unload chamber B4510, as needed. In FIG. B44 the load carrier B4516 is depicted as a simple supportive disk; in various embodiments, the load carrier B4516 comprises a frame, hander, net, rack, bucket, grip, pincer and/or capsule, fitting the load carrier B4510, into which an FA or FA canister is loaded. In various embodiments, a load platform B4516 also typically comprises arrangements for securing its load, communicating wirelessly with a control system (e.g., for telemetric reporting of load status, platform position, and other data), and mechanisms providing unpowered, automatic self-braking (e.g., by lateral shoes, wedges, or the like) in the event that free fall through the transport tube commences.

[00322] In a typical sequence of operations of system B4500, one or more FAs have been stored in the temporary pool B4506 until their radioactivity and heat output have declined to levels which the transport tube B4504 and other downstream FA-handling systems have been designed to accommodate. The fuel-handling machine B4508 picks up an FA B4502 and transports it through the coolant in the pool B4506 to the loading chamber B4510, where the FA B4502 is placed upon the load carrier B4516. The chamber door B4512 is then rotated and locked in a closed position and the lock valve B4504 is opened. The load platform B4516 with its associated FA, together designated a“load,” now has access to an open, water-filled path within the vertical access tube B4504 and is raised therethrough. One or more of worm gears, a cable hoist, water pressure, and other mechanisms are employed to raise the load through the vertical transport tube to a receiving system at a higher level in the PNP. In embodiments the receiving system resembles the system B4500, except that it comprises the upper rather than the nether end of the transport tube B4504 and the lock valve is below rather than above the load-unload chamber; in such case, unloading of a load by the receiving system is accomplished by essentially reversing the loading process described for system B4500. In other embodiments, the receiving system may consist simply of a fuel-handling machine capable of reaching down into the open upper end of the transfer tube, grasping a load, and lifting it out.

[00323] In various embodiments, the walls of the transport tube B4504 comprise provisions for cooling and/or shielding (e.g., a water sheath) and/or the tube B4504 is surrounded by a larger body of water. Also in various embodiments, checkpoint lock valves similar to lock valve B4514 are located at intervals throughout the length of the vertical transport tube B4504, opening and closing in sequence to allow passage of load carriers while constraining coolant flow through the transport tube B4504. Various embodiments comprise provisions for provisioning the transport tube B4504 with coolant (e.g., by recirculating coolant from the top of the tube to the bottom). Coolant may pass around or through a moving load, or be circulated from one end of the tube to the other to accommodate a moving load, or both. Moreover, although the transport tube B4504 is depicted in FIG. B44 as orthogonally vertical, a transport tube in various embodiments need not be so throughout its length but may turn through any angle. Turns may be enabled by allowing slack space between load carriers and in the walls of the tube B4504, either along the whole tube length or in selected turning zones; or by making load carriers suitably flexible; or by other means.

[00324] FIG. B45 is a schematic cross-sectional depiction of portions of an illustrative mechanism for moving an illustrative FA load B4600 through a coolant-filled vertical transfer tube. An FA B4602 is capped by two endpieces, an upper endpiece B4604 and a nether endpiece B4606. Both endpieces

B4604, B4606 serve as spacers to position the FA B4602 within the vertical transfer tube B4608. Two coolant-filled side tubes B4610, B4612 are positioned lengthwise along the transfer tube B4608 and connected thereto so that the lumens of the three tubes communicate. The nether endpiece B4606 comprises teeth or projections (e.g., projection B4614). Each projection extends horizontally from the endpiece B4606 into the lumen of a side tube: e.g., projection B4614 extends into the lumen of side tube B4612. Each side tube contains a worm gear (e.g., worm gear B4616). The endpiece projections mesh with the worm gears: e.g., projection B4614 meshes with worm gear B4616. As the worm gears in the side tubes are rotated, the projections are translated along the gear and the load comprising the FA B4602 and endpieces B4604, B4606 is lifted or lowered through the vertical transfer tube B4608. Preferably, components are sized and so that either worm gear alone is capable of safely lowering or raising the load.

[00325] FIG. B46 is a schematic cross-sectional depiction of portions of an illustrative mechanism for moving an illustrative FA load B4700 through a vertical transfer tube. An FA B4702 is capped by or affixed to two endpieces, an upper endpiece B4704 and a nether endpiece B4706. Both endpieces

B4704, B4706 serve as spacers to position the FA B4702 within the vertical transfer tube B4708. Each endpiece also comprises one or more cable connection points (e.g., cable connection point B4710) which is attached to a cable (e.g., cable B4712). As the cables are drawn up or down with respect to the tube B4708, the load B4700 is correspondingly raised or lowered. In case of cable failure, fluid-driven safety flaps B4714 deploy to assure braking of the load and prevent free fall. The safety flaps may either engage with the inner walls of the transfer tube B4708 to halt FA motion or may serve as hydraulic resistance breaks to assure slow fall.

[00326] FIG. B47 is a schematic cross-sectional depiction of portions of an illustrative mechanism for permitting an illustrative FA load B4800 to descend through a vertical transfer tube. An FA B4802 is capped by or affixed to two endpieces, an upper endpiece 4804 and a nether endpiece B4806. Both endpieces B4804, B4806 serve as spacers to position the FA B4802 within the vertical transfer tube B4808. Each endpiece is sized and perforated to allow coolant to pass from one side of the endpiece to the other in a resistive manner. The hydraulic resistance of the endpieces is gauged to permit the load B4800 to descend through the vertical transfer tube B4808 at a desired pace.

Improved Refueling Machine and Methods for a PNP

[00327] The proper operation of a PNP refueling machine inside the containment and of a spent fuel handling machine in the spent fuel storage area can be adversely impacted by any tilting of the PNP platform, such as caused by wave action, wind action, or other causes. Since these refueling machines typically use a telescoping mast or column to reach the tops of FAs that are ~25 feet below a water surface, tilt will result in lateral forces being applied to the extended mast. These forces can cause the mast to deflect or bend, especially when lifting or lowering an FA or other heavy item. Another problem is that the FA will hang vertically from the end of the mast, making it even more difficult to properly align the bottom of the FA correctly for insertion into a core matrix and to keep the FA properly aligned while it is actually being inserted into or withdrawn from the core matrix, without excessive contact and rubbing or scraping of the neighboring fuel assemblies. Moreover, wave action may introduce pendulum-like oscillations in a long mast suspending an FA.

[00328] Various embodiments of the invention comprise improved in-containment refueling machines and the spent fuel handling machines and improved controls for such machines to prevent excessive horizontal forces from being applied to their telescoping masts, to allow these machines to accurately connect and disconnect from FAs, to keep the connected FA aligned with the core’s vertical axis while an FA is being withdrawn from or inserted into the core, and to enable proper alignment during other fuel handling operations.

[00329] FIG. B48 is a schematic depiction of portions of an illustrative PNP fuel-handling machine B4900 according to embodiments of the invention. Herein, the terms“fuel-handling machine” and “refueling machine” are used interchangeably to signify any machine capable of grasping, lifting, and moving an FA. The machine B4900 comprises a telescoping fuel-handling mast B4902 having a gripping head B4904 that is capable of retrieving an FA (e.g., FA B4906) that is located, for example, in a reactor pressure vessel B4908. To prevent significant horizontal forces caused by any listing of the PNP being applied to the mast, the mast is connected at its top end with a socket-and-ball type attachment B4910 so that the mast B4902 can rotate freely at its attachment point and will always stay aligned in a true vertical alignment due to gravity. In the state of operation depicted in FIG. B48, the PNP lists at an angle phi; thus, the mast B4902, aligned with gravity, hangs at an angle with respect to the vertical axis B4912 of the PNP and its major components, including the reactor pressure vessel B4908. The fuel handling machine hoist B4914 can be translated along a bridge B4916 that can in turn be translated orthogonally to its own length along runways, in the manner typical of overhead cranes.

[00330] To enable the fuel handling machine B4900 to properly position itself such that the bottom end of the extended mast B4902 properly engages with the top end of the FA B4906 in preparation for lifting, or so that the bottom end of an FA is properly positioned directly above the empty location in a core matrix or storage rack in preparation for assembly re-insertion, the fuel-handling machine positioning control is modified to account for the platform or ship tilt. In an example, if the PNP platform is tilted 1° to the left in the plane of the bridge B4916, the extended mast B4902 (~41 feet long) will, if the attachment point of the mast B4902 is aligned with the FA B4906 parallel to the vertical axis of the PNP, hang ~8.6 inches to the left of its intended position (the head of the FA B4906). Therefore, the machine positioning control, based on measured tilt, adjusts the hoist position by L = 8.6 inches to the right so that the gripping head B4904 of the vertically hanging mast B4902 is properly positioned. This requires that system B4900 comprise tilt-measuring instrumentation. In various embodiments, the machine positioning control actively measures tilt of the PNP and repositions the hoist B4914 as the tilt of the PNP changes, such that the mast or the lower end of the FA is kept in position even as the platform/ship tilts from side to side and/or end to end, such as due to wave motion. Using a control algorithm such as a reflecting application of control theory, movements of the bridge B4916 and hoist B4914 can be controlled, such as by taking inputs that indicate the dynamic behavior of the platform (such as rocking in response to periodic wave motion), and the system can compensate for not only static list of the PNP but for dynamic movement (e.g., rocking) of the PNP. Alternatively or additionally to bridge and hoist movements, devices comprised by the hoist B4914 can apply torques to the ball joint B4910 to enable compensation for static of dynamic list, such as induced by wave motion.

[00331] In embodiments, to assure that FAs in a tilted or rocking PNP are lifted from or lowered (e.g., into a core, fuel transfer carriage, spent-fuel storage racks, or spent-fuel shipping casks) without excessive rubbing or scraping against nearby components, the tilt measuring and positioning compensation control may be interlocked such that fuel insertion (e.g., the final 14 feet into the core matrix or storage rack) and the removal (e.g., first 14 feet from the core matrix or storage rack) is permitted while the platform/ship tilt is near 0°. Thus, a fuel insertion control system may be provided that is based on measurement of static and/or dynamic tilt of a PNP in which the fuel insertion control system operates.

[00332] In embodiments, the fuel handling machine positioning control may be interlocked with a separate and independent local tilt measuring device, such that a global tilt measurement device (such as for the PNP as a whole) and the local tilt measuring device (or multiple such devices) are required to “agree” on a level of tilt, such as before the machine can lift or lower FAs under control of a fuel handling control system. In embodiments, this second, local measuring device may be mounted directly on fuel handling machine or on other structures of or on the PNP. One way to provide this local tilt measurement is to provide a measurement of the position of the free hanging machine mast at the base deck elevation that senses the mast position compared to its 0° tilt position. The length of the mast (distance from the top of the mast to the machine deck just above the water level) amplifies the horizontal displacement caused by tilt; for example a 1° tilt causes a sin(l°) · 14 ft · 12 in/ft = 2.9 inch

displacement. [00333] FIG. B49 is a schematic cross-sectional depiction of portions of an illustrative PNP fuel- handling machine B5000 according to embodiments of the invention. The machine B5000 comprises a telescoping fuel-handling mast B5002 having a gripping head B5004 and suspended from a hoist B5006 that is translatable along a bridge B5008 that can in turn be translated orthogonally to its own length along runways. Machine B5000 also comprises a telescoping mast support B5010 that moves with the mast and is strong enough to provide the rigidity needed to support the lateral forces created by gravity acting on the mast B5002, the mast support B5010, and an FA (not shown) depending from the gripping head B5004. The mast support B5010 comprises collars or similar structures (e.g., collar B5012) that confer lateral support upon segments of the telescoping mast B5002 without preventing the axial telescoping motions thereof. The machine B5000 is rigid enough to remain aligned with the vertical axis of the PNP of its major components regardless of PNP tilt within some design range. In various embodiments, an extension of the support B5010 beyond the gripper head B5004 extends support to an FA lifted by the machine B5000, creating an adequately rigid mast-and-FA unit for FA movement.

[00334] FIG. B50 provides top and side schematic cross-sectional views of portions of an illustrative PNP fuel-handling alignment guide B5100 according to embodiments of the invention. The fuel handling guide B5100 comprises a grid of beveled openings, e.g., opening B5102, and is positioned near the top of a volume (e.g., reactor pressure vessel B5104) containing FAs (e.g., FA B5106). The gripper head B5108 and shaft B5110 of a fuel-handling machine, having passed through an opening B5102 of the guide B5100, is constrained in its lateral movements by the guide and is thus assisted in aligning with a given FA and prevented from damaging adjacent components by unexpected movements of the PNP, within a certain design amplitude range. In various embodiments, guide fingers (not depicted) comprised by the mast or by a mast support structure extend beyond the gripper head B5108 and pre-engaged with openings in the guide B5100 before mast insertion through the guide, increasing stability and accuracy of engagement.

[00335] The grid openings of the fuel-handling guide B5100 are depicted in FIG. B50 as square but in various embodiments are circular or otherwise shaped. A guide having only four openings is depicted, but guides having any number of openings are contemplated. A single-level guide is depicted, but guides having multiple levels (i.e., stacked guides to enforce alignment along the stacking axis) are

contemplated.

Aspect C

[00336] Provided herein are methods, systems, components and the like for responding to multifaceted threats to an offshore prefabricated nuclear plant (PNP) unit. Herein, the term “prefabricated nuclear plant” is interchangeable with the term“offshore nuclear plant” (ONP) as used, for example, in U.S. Provisional Patent Application Serial No. 62/646,614, the entire content of which is hereby incorporated by reference. Defense of a Modularized PNP

[00337] FIG. Cl is a relational block diagram depicting illustrative constituent systems of a prefabricated nuclear plant (PNP), also herein termed a Unit, and illustrative associated systems that interact with the Unit and each other. A Unit Deployment C100 comprises a Unit Configuration C102 and the associated systems with which the Unit Configuration directly interacts via material and non material means. In the illustrative Unit Deployment C100 of FIG. Cl, the associated systems with which the Unit Deployment Cl 00 interacts are Operation Cl 04, Deployment Cl 06, Consumers Cl 08, and Environment C110. Overlap of the boundaries of associated systems C104, C106, C108, C110 with the Unit Configuration is shown to indicate that the Configuration C102 and its associated systems C104, Cl 06, Cl 08, C110 overlap in practice, and cannot be meaningfully considered in isolation from one another. The Unit Configuration Cl 02 comprises Unit Integral Plant Cl 12, the primary constituent physical systems of the PNP; the Unit Integral Plant 012 is a supports the operation of the PNP unit regardless of the particulars of the Unit Deployment Cl 00. The Unit Configuration 002 incorporates the Unit Integral Plant into a form factor suitable for a given Unit Deployment scenario C100; preferably, the Unit Integral Plant 012 is designed, built, assembled, and maintained as a structure of discrete physical modules, where the sense of“module” shall be clarified with reference to Figures herein. The Unit Integral Plant in turn comprises nuclear power plant systems 014, which produce energy from nuclear fuel and manage nuclear materials such as fuel and waste; power conversion plant systems 016, by which energy from the nuclear power plant systems 014 is, typically, converted to electricity;

auxiliary plant systems 018, which support the operation of the individual PNP unit; and marine systems 020, which enable the PNP to subsist and function in a marine environment.

[00338] The associated systems 004, 006, 008, C110 interact with the Unit Configuration via Interface Systems 022, 024, 026, 028. In embodiments, the terms“interface,”“interface system,” and“interfacing system” may be understood to encompass, except where context indicates otherwise, one or more systems, services, components, processes, or the like that facilitate interaction or interconnection of systems within a PNP or between one or more systems of the PNP with a system that is external to the PNP, or between the PNP and associated systems, or between systems associated with a PNP. Interface Systems may include software interfaces (including user interfaces for humans and machine interfaces, such as application programming interfaces (APIs), data interfaces, network interfaces (including ports, gateways, connectors, bridges, switches, routers, access points, and the like), communications interfaces, fluid interfaces (such as valves, pipes, conduits, hoses and the like), thermal interfaces (such as for enabling movement of heat by radiation, convection or the like), electrical interfaces (such as wires, switches, plugs, connectors and many others), structural interfaces (such as connectors, fasteners, inter locks, and many others), or legal and fiscal interfaces (contracts, loans, deeds, and many others). Thus, Interface Systems may comprise both material and non-material systems and methods. For example, the Interface System C122 for interfacing the Unit Configuration C102 with Operation C104 will comprise legal arrangements (e.g., deeds, contracts); the Interface system C128 for interfacing the Unit Configuration C102 with the Environment C110 will comprise material arrangements (e.g., tethers, tenders, sensor and warning systems, buoyancy systems).

[00339] The Operation system C104 comprises Operators C130 and Interface Systems C122; the Deployment system C106 comprises Implemented C132(e.g., builders, defenders, maintainers) and Interface Systems C124; the Consumers system comprises Consumers C134 and Interface Systems C126; and the Environment system comprises the natural Physical Environment C136 and Interface Systems C128. The physical environment for a PNP may be characterized by various relevant aspects, including topography (such as of the ocean floor or a coastline), seafloor depth, wave height (typical and extraordinary), tides, atmospheric conditions, climate, weather (typical and extraordinary), geology (including seismic and thermal activity and seafloor characteristics), marine conditions (such as marine life, water temperatures, salinity and the like), and many other characteristics. Associated systems not depicted in FIG. Cl may also be comprised by a Unit Deployment; stakeholders informing the design, manufacture, and operation of a PNP unit may include power consumers, owners, financiers, insurers, regulators, operators, manufacturers, maintainers (such as those providing supplies and logistics), de commissioners, defense forces (public, private, military, etc.), and others. Moreover, the systems C104, C106, C108, C110 interact with each other through one or more additional Interface Systems C138.

[00340] FIG. C2 is a conceptual schematic depiction of an illustrative manner in which some of the Functions of a PNP can in various embodiments be assigned to physical Forms, and of the relationships of the Functions and Forms so assigned to Integral, Accessory, and Associated categories. In various embodiments, a PNP Unit C200 (double outline) comprises one or more functional Systems C202, which may include one or more Integral Systems C204, Accessory Systems C206, and Associated Systems (“systems associated with PNP unit fleet”) C208. In general, Integral and Accessory Systems are physically comprised by the PNP Unit C200, while Associated Systems are not. In embodiments, the term“Accessory System” may be understood to encompass, except where context indicates otherwise, a secondary, supplementary or supporting system to help facilitate a function.

[00341] The Systems C202 may include one or more Plant Systems C210. In embodiments, the terms“plant system” or“nuclear plant system” may be understood to encompass, except where context indicates otherwise, a system involved in the operation of a nuclear reactor, the transport of heat, the conversion and transmission of power, and the support of the normal operations of the aforementioned.

[00342] In embodiments, PNP Systems C202 may include one or more Marine Systems 212. In embodiments, the term“marine system” may be understood to encompass, except where context indicates otherwise, a system associated with the function of the unit as a marine vessel, including navigation, stability, structural integrity, and accommodation of crew.

[00343] In embodiments, PNP Systems C202 may include one or more Interface Systems C214. Interface systems C214 may include software interfaces (including user interfaces for humans and machine interfaces, such as application programming interfaces, data interfaces, network interfaces (including ports, gateways, connectors, bridges, switches, routers, access points, and the like), communications interfaces, fluid interfaces (such as valves, pipes, conduits, hoses and the like), thermal interfaces (such as for enabling movement of heat by radiation, convection or the like), electrical interfaces (such as wires, switches, plugs, connectors and many others), structural interfaces (such as connectors, fasteners, inter-locks, and many others), and others.

[00344] In embodiments, PNP Systems C202 may include one or more Control Systems C216. In embodiments, the term“control system” may be understood to encompass, except where context indicates otherwise, a system of devices or set of devices (including enabled by various hardware, software, electrical, data, and communications systems, that manages, commands, directs or regulates the behavior of other device(s) or system(s) to achieve desired results. Control systems may include various combinations of local and remote control systems, human-operated control systems, machine-based control systems, feedback-based control systems, feed-forward control systems, autonomous control systems, and others.

[00345] In embodiments, PNP Systems C202 may include one or more Contingency Systems C218. In embodiments, the terms“contingency system” or“emergency system” may be understood to encompass, except where context indicates otherwise, a system on or interfacing with a PNP that prevents, mitigates, or assists in recovery from accidents, which may include design-basis accidents (accidents that may occur within the normal operating activities of the PNP) and beyond-design-basis accidents and events, including both human initiated events (terrorism or attacks), significant failure of PNP facilities, environmental events (weather, seismic activity, and the like) and“acts of God.”

[00346] In embodiments, PNP Systems C202 may include one or more Auxiliary Systems C220. In embodiments, the term“auxiliary system” may be understood to encompass, except where context indicates otherwise, a system which, when included in or interfacing with a PNP unit, tailors the unit to operating in different deployment scenarios and/or that provides or enables an accessory function for the PNP (such as a function occurring episodically like maintenance, refueling or repair that may involve moving items around the PNP). Accessories may be related to the plant functions, marine functions, and contingency functions, among others. For example, an accessory marine system could improve the stability of the foundation of a seafloor mounted PNP or act as a breakwater depending on local wave conditions. An accessory plant system could provide an interface for transport of power/utility products or might use process heat to manufacture value-added industrial products local to the unit. An accessory system like a crane might be used to move units around during refueling or maintenance operations. These and many other accessory systems are encompassed herein.

[00347] In embodiments, a PNP system may include one or more Associated Systems C208. In embodiments, the term“associated system” may be understood to encompass, except where context indicates otherwise, a system interfacing with a single unit or a fleet of PNP units which performs a function related to the design, configuration, awareness, defense, operation, manufacturing, assembly, and/or decommissioning of PNP units. In embodiments, this may include a system that performs a function that is not necessarily core to the operation of the PNP but that may involve interaction with a PNP, such as a weather prediction system, a tsunami or extreme-wave warning system, a smart grid system, an agricultural or industrial production system that uses power from the PNP, a desalination system, and many others.

[00348] In embodiments, a PNP system may also comprise Associated Vessels and Facilities C222 that are associated with the system but are not inextricable physical portions of it, e.g., tenders, crew transports, fuel transports, vehicles of defensive forces, supply depots, on-shore grid substations, and many more.

[00349] As also indicated in FIG. C2, both the Integral and Accessory components of a PNP Unit C200, and the portions of various Systems physically comprised by a PNP Unit C200, are, in various embodiments, designed, constructed, and assembled as“modules” C224, also herein termed“structural modules.” Herein, a module is a standardized, discrete part, component, or structural unit that can be used to construct a more complex structure, with assembly typically occurring in a shipyard. Modules comprised by various embodiments are derived from categories used in shipbuilding, and include, among other units, Skids, Panels, Blocks, and Megablocks. These terms shall be clarified with reference to Figures hereinbelow. Systems (e.g., Marine Systems C212) may be substantially confined to single modules or distributed across multiple modules; the terms“system” and“module” are thus not interchangeable.

[00350] FIG. C3 is a conceptual schematic depiction of portions of an illustrative unit configuration C102 of FIG. Cl and of an illustrative deployment C106. In particular, relationships are depicted of defensive systems and methods that include but are not limited to the systems and methods discussed herein with reference to the schema of FIG. Cl. The unit configuration Cl 02 comprises the unit integral plant 012 of FIG. Cl; the unit integral plant 012 comprises internal defense systems C302, marine systems C304, auxiliary systems C306, power conversion/generation plant systems C308, and nuclear plant systems 014. The unit configuration 002 also comprises accessory defense systems C310 and accessory defense modules C312. The accessory defense systems C310 in turn comprise primary systems C314 and auxiliary systems C316. The accessory defense systems C310 and modules C312 are comprised both by the unit configuration 002 and by the associated defense systems C318 of the associated deployment 006. The associated defense systems C318 comprise onshore facilities C320 (both primary C322 and auxiliary C324), offshore facilities C326 (both primary C328 and auxiliary C330), defensive vehicular systems C332 (both primary C334 and auxiliary C336) associated with one or more PNP units, and the accessory defense systems C310. The accessory defense systems C310 are modularized to be incorporated in a PNP in its deployment scenario and defense systems comprised by the unit integral plant 012. Accessory defense systems C310 help other associated defense systems C318 interface with PNP units. Examples of primary onshore facilities C322 comprised by the associated defense systems C318 include security personnel housing, radars, perimeter detection devices, and facilities for servicing drones; examples of primary offshore defense facilities C328 include barges, breakwaters, buoys, and fencing. Host-nation military aircraft and watercraft and PNP-stationed drones are examples of primary defensive vehicular systems C332.

[00351] The associated defense systems C318 also comprise defenders C338. Defenders C338 comprise organized groups of persons, with all their equipment and physical plant, that in any manner defend PNP units and parties servicing them. Defenders C338 defend against both violent threats such as force attacks and against cyberattack, blackmail, bribery, and other non-force attacks. Defenders C338 comprise host-nation military and police forces C340 and security contractors C342. Defense agreements C344 govern relationships and responsibilities between defenders C338, operation parties C346 (e.g., subsidiary corporations, regulators, insurers, fmancers) and deployment parties C348 (e.g., those performing logistics, maintenance, fuel services, operations, and other services pertaining to PNP units). Defenders C338 use defense systems whose functions including detection, identification, evaluation, and response. Local or onboard defenders will preferentially delay attacker access to the unit integral plant 012 until a response can be coordinated with external defense forces (e.g., host military forces C340), as opposed to continually maintaining the capability to deal with large threats onboard a PNP. Automation of primary defense systems C314, C322, C328, C334 is a high priority, as will reduce staffing requirements for security on PNP units— a key economic advantage for offshore operations, where personnel costs are very high compared to terrestrial operations.

[00352] All defensive activity takes place in a threat environment C110 that includes state actors C348 and non-state actors C350. Of note, not all threats are necessarily deliberate: for example, out-of- control vessels or aircraft, oil spills, and software errors may be as threatening as deliberately guided craft, chemical attacks, or cyberattacks. Herein, discussions of deliberate or malicious attack should be interpreted as including accidental or inadvertent threats, even where the latter are not specified.

[00353] FIG. C4 is a schematic block diagram of defense systems C400 for one or more PNP units, classified as primary systems C402 and auxiliary systems C404. Defense systems C400 are used by defenders to defend PNP units and associated entities, as determined by the defense agreements C344 of FIG. C3. The primary defense systems C402 perform functions that secure zones in and around a PNP unit: among the primary defense systems C402 are systems for threat detection and identification C406, threat evaluation C408, denial of access to the PNP and other facilities C410, direct response to threats C412, and command and coordination of defense C414. The auxiliary defense systems C404 ensure proper provision of materiel and personnel to the primary defense systems C402: among the auxiliary defense systems C404 are systems for logistics support C416, personnel security C418 (e.g., making sure that persons aboard a PNP are qualified to be there, internal surveillance systems, other internally directed defensive measures for human-mediated threats), communications C420, and control and information technology C422. Multi-Faceted Threat Response

[00354] Embodiments comprise process elements for a threat response system that addresses external threats originating in three spatial zones (i.e., air, surface, subsurface), internal threats and sabotage, and cyber threats. This multi-faceted approach to secure and defend a PNP comprises the following stages or aspects:

[00355] 1) Threat detection and identification. This comprises the detection of approaching agent and the identification of whether the agent is a threat to PNP.

[00356] 2) Threat evaluation and determination of local response. The PNP threat response system establishes a tiered level of scaled response depending on the nature of the detected agent or agents.

[00357] 3) On-platform and/or local response. Includes mechanisms to prevent an intruder with or without potential help by an adversary insider from gaining access to the PNP, including cyberaccess.

[00358] 4) External response. Comprises external forces and mechanisms that come to the assistance of the plant security forces and mechanisms to prevent intruder force access to the PNP and/or to regain control of PNP and its fissionable material.

[00359] FIG. C5 is a schematic depiction of a three-zone threat environment C500 or threat taxonomy to which various embodiments respond defensively in a multi-faceted manner. A PNP C502 is stationed in a body of water C504 and subject to general categories of internal and external threat.

Internal threat possibilities comprise cyberattack C506 and sabotage C508. Sabotage C508 may be carried out by internal agents (e.g., corrupted PNP staff), external agents (e.g., persons planting explosives in materiel delivered to the PNP), or attackers that have surreptitiously boarded the PNP

C502. External force threat possibilities comprise air threats (e.g., aerial drones C510, aircraft C512), surface threats (e.g., small surface vessels C514, large surface vessels C516), subsurface threats (e.g., divers C518, and large submarines C520). Additional aerial threat possibilities, not depicted in FIG. C5, include but are not limited to chemical clouds, missiles, balloons, and aircraft ranging in size from parachutes and ultralight aircraft to commercial jetliners and military aircraft. Appropriate defensive countermeasures will tend to vary with speed and size of attacking aircraft. Additional surface threat possibilities, not depicted in FIG. C5, include but are not limited to chemical slicks, buoys, and marine surface drones. Small surface craft C514 tend to represent a distinct threat type from large surface craft C516, as the former are speedy and agile while the latter may carry extremely large masses of explosives and/or large numbers of attacking personnel into the vicinity of the PNP C502. Additional subsurface threat possibilities, not depicted in FIG. C5, include but are not limited to mini-subs, torpedoes, and bottom crawlers. Attacking personnel, having gained access to the PNP, can potentially cause harm by a wide range of means not depicted, including explosions, killing, hostage-taking, deliberately destructive operation of PNP nuclear or other system, and the like. Attacking personnel can gain access to the PNP C502 by stealth, force, or ruse. Ruses (e.g., claims of authorization or distress) may be combined with other forms of attack. Projectiles or missiles may be directed at the PNP C502 from nearby land masses. Moreover, this threat taxonomy is illustrative and partial, not exhaustive.

[00360] FIG. C6 is an illustrative table that partially specifies responding defense authorities of a PNP defense system by threat category and mechanism. In general, mechanical, electronic, and structural security features integral to and associated with a PNP, along with PNP security personnel, are tasked with stopping, deterring, or at least delaying or slowing all types of violent attack most likely to be available to non-state actors, including air attacks using light drones and aircraft, chemical attacks, surface attacks using non-military aircraft, and subsurface attacks using divers, mini-subs, and other relatively small-scale devices. Host nation military and police forces are in general tasked with ultimate response to all threat categories and with all aspects of response to extreme or high-intensity threats such as those posed by military aircraft, surface craft, and subsurface craft and by hijacked commercial aircraft. Onboard PNP systems and personnel are entirely responsible for responding to onboard threats, including sabotage, personnel corruption or collusion, cyberattack, and the like.

[00361] FIGS. C7-C9 depict aspects of illustrative zonal defense schemes for a PNP faced by the threat taxonomy described with reference to FIGS. C5 and C6. In general, the overall geometry and functional details of systems and methods for defending a PNP according to embodiments of the invention will vary according to the geography of the PNP’s deployment site, e.g., the PNP’s proximity to land, the shape of any proximate coasts or landmasses, and water depths in the vicinity of the PNP.

[00362] FIG. C7 is a schematic top-view depiction of portions of an illustrative zonal defense schema C700 for physical surface threats only against a PNP C702 stationed 8 or more nautical miles from any landmass. For a PNP so stationed, the entire surface area of concern to defenses is a water surface, so defense zones are preferably circular in shape and centered on the PNP C702. A first zone is the monitored area C704, which extends to a radius of ~8 nautical miles (nmi) from the PNP C702. The entire monitored area C704 is surveilled by radar. Circular areas of smaller radii nested within the monitored area C704 are preferably also surveilled by other sensing modalities, including sonar and visual systems. Radars and other gear for surveillance of the monitored area C704 may be based on the PNP or on buoys, vessels, drones, artificial breakwaters, or other bases.

[00363] Within the monitored area C704 is nested a large-ship exclusion area C706, which extends to a radius of ~6 nmi from the PNP C702. The large-ship exclusion area C706 is sized to protect the PNP from excessive blast effects from an explosion such as might be produced by the largest possible explosive cargo transportable by existing vessels.

[00364] Within the large-ship exclusion area C706 is nested a controlled access area C708 having a radius of ~1 nmi. Only authorized vessels, regardless of size, are permitted within the controlled access area. Finally, a protected area C710 of radius <1 nmi is centered on the PNP C702. Active defense systems based on the PNP 702 operate primarily within the protected area C710. The protected area C710 is also preferably bounded, in part or whole, by barrier defenses such as will be described with reference to Figures below.

[00365] Primary defense systems for detection and identification C406 (FIG. C4), as well as primary systems for threat evaluation C408 and command and coordination C414, operate throughout the entire monitored area C704 at all times. Access denial C410 and direct response C412 for large vessels entering the large-ship exclusion area C706 of FIG. C7 are provided by host nation military forces. Access denial C410 and direct response C412 for any size or type of vessels entering the controlled-access area C708 or protected area C710 are provided by both host nation military forces and PNP security forces and features, both integral and associated. Threats that make contact with the PNP are stopped, deterred, or impeded by PNP security forces and integral defense features.

[00366] FIG. C8 is a schematic top-view depiction of portions of an illustrative zonal defense schema C800 for physical surface threats only against a PNP C702 stationed< 1 nmi from a landmass C802. For a PNP so stationed, only a portion of the surface area of concern to defenses is a water surface. Surface defense zones overlying water are preferably circular in shape and centered on the PNP C702; defense zones over land are preferably shaped to the topography and other features of the land mass (e.g., development and settlement patterns), hills). A monitored area C804, large-ship exclusion area C806, and controlled access area C808 are centered on the PNP C702 and defined over water as described with reference to FIG. C7. On land, a monitored area C810, possibly irregular in shape, is surveilled by radar and preferably by other modalities as well (e.g., visual methods). Within the monitored area is an approach exclusion area C812 from which all nonauthorized persons and vehicles are excluded at all times. Finally, a protected area C814 is centered on the PNP as for the open-water case shown in FIG. C7, within which area active defense systems based on the PNP C702 primarily operate and which is preferably bounded, in part or whole, by defensive barriers. Additional zones of overland defense and/or zones variously adapted or indifferent to geography and terrain, are also contemplated. Typically, defensive system geometry and operational parameters are adjusted to accommodate the context of each particular PNP deployment.

[00367] FIG. C9 is a schematic side-view depiction of portions of an illustrative zonal defense schema C900 for aerial and subsurface physical threats only against a PNP C702 stationed 8 or more nautical miles from any landmass. For a PNP so stationed, aerial and subsurface defense zones are preferably approximately cylindrical in shape and centered on the PNP C702. A first aerial zone is the monitored volume C902, of height A1 and radius Rl centered on the PNP C702. The entire monitored volume C902 is surveilled by radar. Some or all of the monitored volume C902 is also preferably surveilled by other sensing modalities, such as visual systems. Radars and other gear for surveillance of the monitored volume C902 may be based on the PNP or on buoys, vessels, drones, artificial breakwaters, satellites, aircraft, or other bases. A second aerial zone is the large -aircraft exclusion zone C904, of height A2 and radius R2. A third aerial zone is the aerial protected area C906, of height A3 and radius R3, from which all unauthorized aircraft are excluded at all times.

[00368] A first subsurface zone is the monitored volume C908, of radius R4 centered on the PNP C702 and extending from the water surface to the sea floor C910. The entire monitored subsurface volume C908 is surveilled by sonar. Some or all of the monitored subsurface volume C908 is also preferably surveilled by other sensing modalities, such as visual systems. A second subsurface zone is the subsurface-vessel exclusion zone C912, of radius R5. A third subsurface zone is the subsurface protected area C914, of radius R6, from which all unauthorized divers and subsurface craft are excluded at all times. Finally, a protected volume C916 is defined around the PNP both above and below the water surface. Active defense systems based on the PNP C702 operate primarily within the protected volume C916.

[00369] Although FIGS. C7-C9 depict defensive zones for single PNPs, it will be clear that similar zonal schemas can be appropriately devised for installations comprising multiple PNPs.

Multi-Purpose Defensive Barges for a PNP

[00370] The need for establishing and maintaining a protected area or No Entry Zone around a PNP may be served by positioning floating and/or semi-floating barges or pontoons around the periphery of the protected area. Thus, embodiments of the invention comprise a physical floating barrier system partly or wholly circumferential to a PNP that protects the unit from collision and/or any other marine vessel induced damage. The floating barrier system may include any floating object, including barges and/or pontoons made preferably of steel, composite, and/or concrete. Segments of the barrier system may be moored, e.g. to the seabed, each other, pylons, the PNP, or a landmass. Herein, all such floating objects are termed“barges.” In various embodiments, partial filling of individual floating segments with liquid and/or solid substances enhances overall collision resistance by increasing inertia and absorbing collision energy. Storage room within components of a floating barrier is used in some embodiments to store PNP -related substances, devices, or materiel: for example, floating barriers can store drinking water, low-level radioactive liquid waste, or noxious or hazardous liquid collected during mitigation of a deliberate or accidental surface spill or after defensive washdown of PNP decks by a liquid repellent. Alternatively or additionally, floating barriers can house drones, surveillance equipment, and other devices pertaining to defense of a PNP.

[00371] FIG. CIO is a schematic top-down depiction of an illustrative defensive barge perimeter system C1000 for a PNP C1002 according to embodiments of the invention. A number of barges (e.g., barge C1004) are positioned in a manner that circumscribes the PNP C1002. The PNP C1002 is, in this illustrative case, based far enough from any landmass that complete encirclement of the PNP Cl 002 by the barges is appropriate: in general, the location and number of barges of such a defensive system is varied according to the topographical graphical of the PNP site. [00372] Individual barges are preferably moored, e.g., by mooring cables (not depicted) attached to bottom anchors. Depending on the amount of positional play permitted to each barge by its mooring, the geometry of the barge barrier system C1000 will vary slightly but insignificantly over time, depending on wind, currents, and waves. Also, barges are also preferably linked one to the next (e.g., by cables or jointed or gimbaled rods, e.g., linkage C1006) to constrain their relative positions and assure that the distances between individual barges remain within certain limits. Either the linkages between barges constitute a barrier or impediment to passage of vessels through the spaces between barges, or the distances between barges maintained by the linkages do not allow approaching marine vessels/boats to pass through the barrier without losing speed and inertia. In various embodiments one or more gateway barges (e.g., barges C1008, C1010 in FIG. CIO) are positioned so as to allow craft below a certain size threshold (e.g., vessel 0012) to approach the PNP 0002, but only by making an S-curve or detour at low speed, mitigating the threat of deliberate or accidental collision with the PNP 0002. Gateway barges 0008, C1010 may be either permanently positioned outside of a gap in the barge barrier or may be temporarily shifted out of the barrier to form such a gap, or may be temporarily shifted, on occasion, into the gap (e.g., if unauthorized approach is detected by the defense system).

[00373] FIG. Cll is a schematic top-down depiction of an illustrative adjunct system C1100 to a PNP barge perimeter system such as the system C1000 of FIG. CIO according to embodiments of the invention. In the adjunct system C1100, which is typically located inside a protected area defined by a barrier such as barrier system Cl 000 of FIG. CIO, pylon-mounted wind turbine towers (e.g., turbine Cl 102) are disposed at intervals in the vicinity of a PNP Cl 104. The turbine towers present a barrier to very large vessels and impede the rapid progress of relatively small vessels in the vicinity of the PNP 0104, increasing PNP security. Moreover, large modem turbines with maximum blade-sweep heights on the order of 200 meters also present a defensive obstacle to aerial approach by winged aircraft, which must either dive at a steep angle to strike the PNP 0104 (with corresponding loss of fine control) or attempt lower-angle approach through a wall of moving turbine blades. Moreover, underwater netting or cabling (not depicted) is in some embodiments supported between turbine towers to impede subsurface approach. In various other embodiments, some or all wind turbines are omitted in favor of pylons that can impede attack and provide other functions. Pylons deploying barrage balloons, kites, and other impediments to aerial navigation rather than supporting wind turbines are also comprised by various embodiments.

[00374] FIG. C12 is a schematic side-view of portions of an illustrative barge barrier C1200 similar to that depicted in FIG. CIO. The barrier segment depicted comprises two barges C1202, C1204 that are joined by a jointed or gimbaled rod C1206. The barges C1202, C1204 are preferably secured by mooring lines (not depicted). The water surface Cl 208 is indicated by a wavy dashed line. Above the surface, fencing 0210 is strung along the tops of (and between) the barges 0202, 0204, presenting an impediment to attackers who might attempt to board the barges 0202, 0204 and continue progress toward a PNP on the far side of the barrier, e.g. by swimming or by hauling lightweight craft over the barge barrier. Herein, fencings depicted may be of a single or multiple types, electrified, capable of sensing contact, and otherwise combined with devices and features well known in the field of security engineering. Below the water surface C1208, netting 0212 is strung from the barges 0202, 0204. The netting 0212 is preferably strong enough to stop or impede the progress of swimmers and small subsurface vessels or devices and to resist rapid cutting; it is also preferably, where water depth permits, extensive enough to make contact with the sea floor even at high tide. Preferably, the nether edge of the netting 0212 is anchored to the sea floor to prevent underwater attackers from simply lifting its edge and passing beneath.

Fence and Hybrid Barge- Fence Barriers for a PNP

[00375] The embodiments in this disclosure address the need of barrier systems comprising fences, including hybrid barge/fence barrier systems, to defend a PNP in shallower waters. In embodiments, the functionality of the hybrid physical barrier system may be maintained with only low maintenance during its lifetime. Disclosed are embodiments that physically separate a protected area and a controlled access area around a PNP. The barrier system may be suitable for a variety of purposes; the novelty resides in the flexible arrangement and deployment of the barge and/or fence system around a PNP. Aerial defenses, in contrast, will be radially symmetric around most PNP installations, since only unusually dramatic topography (e.g., nearby mountains) will significantly modify the airspace threat picture of its own accord.

[00376] FIG. C13 is a schematic side-view of portions of an illustrative hybrid barge-fence barrier C1300. The barrier segment depicted comprises barges C1302 and a buoy C1304. The barge C1302 is preferably secured by mooring lines (not depicted). Typically, the barge Cl 302 will be joined to one or more additional barges (not depicted), continuing the barrier Cl 300 into deeper water, while the buoy C1304 will be joined to a series of one or more additional buoys, continuing the barrier C1300 into shallower water. Above the surface, fencing C1306 is strung along the top of the barge C1302, while below the water surface, netting C1308 similar to that depicted in FIG. C12 is strung from the barge C1302 and buoy C1304 and between additional barges and buoys (not depicted). The buoy C1304 is moored by a buoy line 0310. In general, buoys are suitable for barrier maintenance in shallower waters whose depth tends to exclude vessels large enough to require blockade by a massive barge. Fencing runs between adjacent buoys may comprise spacing rods or members (not depicted) to prevent fence slacking as buoys drift together; alternatively or additionally, fence tensioning or the method of buoy anchoring depicted in FIG. 05 may be employed to stabilize buoy positions and control slacking due to lateral buoy drift.

[00377] FIG. 04 is a schematic side-view of portions of an illustrative hybrid barge-fence barrier 0400. The barrier segment depicted comprises buoys 0402, 0404 which support fencing 0406 above the waterline and netting 0408 below it. The buoys 0402, 0404 are moored to the sea floor by lines 0410, 0412 and anchors 0414, 0416. The lines 0410, 0412 are preferably of an elastic material and/or are tensioned on reels (e.g., a reel within each buoy) in a manner that can accommodate height variations of the waterline caused by tides and waves while keeping a sufficient portion of the fencing 0406 above water at all times. As for the fencing depicted in FIG. 04, fence slacking due to lateral buoy movement may be mitigated by rigid spacers and/or fence tensioning and/or the mooring technique depicted in FIG. 05. One end of the fencing 0400 preferably interfaces, at a critical water depth, with a barge that continues the defensive barrier into deeper water, e.g., as depicted in FIG. 03. The other end of the fencing 0400 preferably interfaces either with another barge or with a land-based fence or fencing terminus.

[00378] FIG. 05 is a schematic top-down view of portions of an illustrative hybrid barge-fence barrier 0500. The barrier segment depicted comprises a number of buoys (e.g., 0502) which support fencing 0504 above the waterline and netting (not depicted) below it. Each buoy is moored to multiple anchors (e.g., anchor 0506) by one or more mooring lines (e.g., line 0508). The mooring lines may be elastic, reel-tensioned, catenary, or otherwise tensioned to further constrain buoy lateral movement and thus mitigate fencing slacking. The segment of the barrier 0500 depicted in FIG. 05 preferably interfaces at one end with a barge that continues the defense barrier into deeper water and at the other with either another barge or with a land-based fence or fencing terminus.

[00379] FIG. 06 is a schematic top-down view of portions of an illustrative hybrid barge-fence barrier 0600. The barrier segment depicted comprises approximately rigid piles or stanchions 0602, 0604 which support fencing 0606 above and below the waterline and netting 0608 below it. The stanchions 0602, 0604 are driven into the sea floor and are preferably anchored by pilings. The fencing 0606 is positioned vertically so that at high tide a sufficient height of fencing remains exposed to air to assure adequate function. Like the segment of barrier depicted in FIG. 05, that depicted in FIG. 06 is preferably a portion of a larger barrier system comprising barges. As shall be shown and discussed further hereinbelow, barrier systems including components other than or additional to fences and barges are contemplated.

[00380] FIG. 07 is a schematic overhead depiction of aspects of an illustrative hybrid defensive barrier system 0700 for an illustrative near-shore PNP installation comprising a PNP 0702. The illustrative system 0700 exemplifies the customization of a barrier system, as in various embodiments, to site geography and other installation characteristics. The PNP 0702 is located in a channel between two landmasses 0704, 0706 that deepens out to sea in one direction (leftward in drawing) and becomes shallower in the other (rightward in drawing), e.g., debouches into a bay. The barrier system 0700 must thus address threats from a deep-water direction, a shallow-water direction, and two landward directions while enabling access to the PNP 0702 from at least the deep-water direction (preferably from all directions). The barrier system 0700 defines a protected zone around the PNP 0702 and comprises two barges 0708, 0710 anchored at the channel inlet and connected to each other by a jointed or gimbaled rod 0712. The shoreward ends of the barges 0708, 0710 are connected to shallow-water fencing sections 0714, 0716 similar to the system 0600 of FIG. 06. Fencing may also be extended over the barges 0708, 0710. One shoreward fence 0716 comprises a gate 0718 that can be opened to allow passage of relatively small authorized vessels through a channel (openability indicated by double-headed arrows). Alternatively or additionally, one or both of the barges 0708, 0710 can be temporarily rotated to allow passage of relatively large authorized vessels.

Another shallow-water fencing segment 0720 defends the PNP 0702 against non-aerial approach from the shallow end of the channel. Also, two overland fencing segments 0722, 0724 restrict overland access to the vicinity of the PNP 0702. The defensive barrier of FIG. 07 is preferably combined with various other defensive measures.

[00381] FIG. 08 is a schematic overhead depiction of aspects of an illustrative hybrid defensive barrier system 0800 for an illustrative near-shore PNP installation comprising three PNPs 0802, 0804, 0806. The PNPs 0802, 0804, 0806 are relatively close to (e.g., within a kilometer of) a landmass 0808. A protected area around the PNPs 0802, 0804, 0806 is at least partly enclosed by at least three barrier components: (1) a fence 0810 of sufficient density, height, and strength to impede persons and at least small watercraft, (2) three large grounded blocks, piers, or moles (e.g., block 0812), preferably touching or nearly touching end-to-end, and (3) an at least partly hardened access facility 0814 located on the landmass 0808. Buoys or stanchions (e.g., buoy 0816) support the fencing 0810 over a water portion of the defended border, while posts (e.g., post 0818) support the fencing 0810 over the block portion of the border. Underwater netting is preferably slung below all water portions of the fence 0810, and at least one fence segment (e.g., segment 0820) is gated to admit passage of authorized vessels to and from the PNPs 0802, 0804, 0806. In the illustrative barrier system of FIG. 08, the blocks provide hard defense against both surface and subsurface approaches while the fenced water portion of the barrier is removable or openable to enable PNPs to be added to or removed from the area within the barrier and to enable vessels to come and go from the PNPs.

[00382] FIG. 09 is a schematic overhead depiction of aspects of an illustrative composite defensive barrier system 0900 for an illustrative near-shore PNP installation comprising three PNPs 0902, 0904, 0906. The PNPs 0902, 0904, 0906 are relatively close to (e.g., within several kilometers of) a landmass 0908, but are in deeper water than that presumed for system 0800 of FIG. 08. A protected area around the PNPs 0902, 0904, 0906 is at least partly enclosed by at least three barrier components: (1) a fence 0910 of sufficient density, height, and strength to impede persons and at least small watercraft, (2) six barges (e.g., barge 0912), and (3) three artificial breakwaters (e.g., breakwater 0914). The PNPs 0902, 0904, 0906 communicate electrically through a line 0916 with a power exchange point 0918 on the shore of the landmass 0908 that interfaces with a grid 0920. Buoys or piers (e.g., buoy 0922) support the fencing 0910 over a water portion of the defended border.

Underwater netting (not depicted) is preferably slung below all water portions of the fence 0910.

Preferably, additional fence segments (e.g., segment 0924) run between and over the barges. In the illustrative barrier system C1900 of FIG. C19, the breakwaters and barges provide hard non-aerial defense against approaches from deeper water while the fenced portion of the barrier provides non-aerial defense for threats approaching from landward.

[00383] FIGS. C10-C19 exemplify barrier systems comprised by illustrative PNP installations according to embodiments of the invention. The barrier systems depicted are primarily directed to obstructing or impeding access by surface and subsurface threats, but barriers (e.g., barrage balloons) directed partly or wholly to aerial threats are also contemplated and within the scope of the invention. Multilayered barrier systems (e.g., fences within fences) are also contemplated. Combinations of stationary or quasi-stationary barrier systems with active or mobile barriers are also contemplated.

[00384] FIG. C20 is a schematic depiction of portions of an illustrative defensive perimeter barge C2000 that performs defensive functions additional to direct blockade. The barge C2000 serves as a platform for landing and launch aerial drones (e.g., drone C2002) and subsurface drones (e.g., drone C2004). The barge C2000 also supplies auxiliary functions that support the defensive drones (e.g., shelters C2006, C2008, charging/fueling C2010, and communications C2012). Surface drones (not depicted) can also be deployed from the barge C2000. The interior of the barge C2000 is also employed for storage of liquids, gasses, or materiel in various embodiments. Security forces (e.g., security contractors C342 of FIG. C3) are stationed on the barge C2000 in various embodiments. Stationing of active defense forces, both robotic and human, on portions of the defensive barrier is advantageous in that (1) the forces are more dispersed than if concentrated aboard the PNP, therefore more difficult for an attacker to neutralize, and (2) the forces are stationed closer to approaching threats than forces concentrated aboard the PNP.

Drone Defensive Systems for a PNP

[00385] The embodiments in this disclosure address the need for active, mobile components of a PNP defensive system to stop, delay, or deter mobile attackers. In embodiments, drones are employed to provide active, mobile defense. Drones comprised by embodiments include aerial, surface, overland, and subsurface vehicles that are directed autonomously, remotely, or both. Swarm or collective behavioral control algorithms increasingly well-known in the fields of artificial intelligence and robotics are employed, in some embodiments, to direct drone activities individually, in swarms or groups, or in hierarchically nested groups of groups. The primary goal of all such direction is the defense of a PNP and the personnel associated therewith. It is desirable that attacking or apparently attacking persons or machines be harmed to the minimum degree that is compatible with defending the PNP, its associated systems, and its personnel.

[00386] FIG. C21 is a schematic overhead depiction of an illustrative drone-swarm defensive system C2100 deployed outside the protected zone of a PNP C2102. The drones are depicted in an early stage of response to an approaching apparent threat, i.e., a surface vessel C2104 that has crossed a marked perimeter line C2106. A swarm of aerial drones (e.g., aerial drone C2108) and a swarm of surface vessel drones (e.g., surface drone C2110) have been dispatched to meet the approacher C2104 with a calibrated range of portable responses, as described below. Preferably, the drones are stationed in a distributed manner upon barges defining a protected area around the PNP C2102 (e.g. barge C2112) and are dispatched toward an approaching threat from one or more barges closest to the approacher. The number and type of drones dispatched preferably depends on information about the character of the approacher derived from surveillance systems (e.g., radar and imaging buoys stationed near the perimeter line

C2106). Drones are advantageous in comparison to human-piloted craft, in this application, in that they are expendable, less costly and therefore potentially more numerous, subject to real-time computer- controlled coordination, and in some cases more maneuverable; however, interception of approachers by human-guided craft is also contemplated.

[00387] In various embodiments, a threat response ladder is envisaged whereby automated systems, alternatively or additionally with direction by human overseers and in cooperation with on-site human responders, respond in an escalating way to apparent or possible threats as they approach the PNP. An illustrative series of escalations is as follows: (1) Authorization status of all craft within a monitoring radius of a PNP installation is monitored by one of the wireless encrypted methods known to persons familiar with the art of encrypted communication. (2) A defensive zone outer perimeter is defined within the monitoring radius. Marker buoys, navigation lights, warning beacons, and other standard methods of directing air and water vehicular traffic away from sensitive sites are deployed to deflect traffic around some or all of the outermost defensive zone perimeter. (3) A vehicle (e.g., surface vessel C2104) that passes the outermost warning line without confirmed authorization is presumed to be a possible threat. Since accidental trespass is a possibility, response to the possible threat begins with lowest-impact measures. Thus, first, direct communication by standard means (e.g., marine VHF mobile band) is attempted with the possible threat. For craft meeting site-dependent dynamic criteria (e.g., heading, speed), drones are dispatched to limit interception time to a specified minimum, should interception prove necessary. Drones may be aerial, surface, subsurface, overland, amphibious, or all of the above.

(4) If communication is not established by standard means, intercepting drones are tasked with attempting nonstandard communications: e.g., one or more drones may hail a vessel using loudspeakers, display directional signals and warning lights, form up as shaped, lighted swarms to indicate directional symbols or other symbols, or land upon a vessel’s deck to act as point relays for one-way or two-way audiovisual communications with personnel. (5) If communications are not successful in altering an approacher’ s behavior within a set time and other parameters that will in general depend on the range, speed, and nature of the approacher, minimal interventions are attempted while standard and nonstandard communications efforts continue. In a series of examples, drones deploy impediments such as tangle ropes (using, e.g., a version of the BCB International Buccaneer Ship-Borne Shore Launcher, which lays a propeller-entangling line across the bow of a threatening vessel); specially equipped drones occlude or foul combustion-air intakes or feed them with combustible gasses (e.g., propane) or noncombustible gasses (e.g., CO2) that cause engines to fail; water intakes are fed with fouler pellets that release entangling lines once they have passed intake gratings; a drone swarm makes coordinated direct contact with a vessel to apply a thrust vector that significantly opposes or diverts the vessel’s progress; drone swarms, adapting their behavior intelligently to shifting winds and other conditions, release smoke that hinders visual navigation; drones release electromagnetic pulses that disable electrical equipment; drones release chaff or deploy radar reflectors that confound navigational radar; and drones employ nonlethal weapons against personnel such as tear gas, noise generators, and other measures known in the field of security engineering. The number of possible nonlethal interventions is large, as will be clear to persons familiar with the field of security engineering. Defending drones may act autonomously under the guidance of a centralized or distributed artificial intelligence, possibly modified by real-time human direction. Drones may act individually or as swarm members, their roles changing over time; drones of different physical types may cooperate with each other; entire swarms may act as cooperating entities.

(6) When certain site- and threat-specific criteria are met with high certainty, increasingly hazardous and ultimately lethal means may be employed to stop an approaching apparent threat. Drones can deliver shaped charges, floating mines, gunfire, or other measures to halt the imminent approach of a threatening vessel. In various embodiments, dedicated PNP defensive systems employ no lethal methods, which remain entirely in the control of host-nation military and police forces.

[00388] FIG. C22 depicts an illustrative low-impact defense measure C2200 deployed by two drones C2202 dispatched from a defensive barge (not shown) against an unauthorized propeller-driven vessel C2204 that has crossed a security perimeter C2206. A tangler dragnet C2208 or dragline, supported at or near the water surface by alignment buoys (e.g., buoy C2210) and attached to the drones by quick- disconnect buoys C2212, C2214, is maneuvered across the path of the oncoming vessel C2204. As the vessel C2204 passes over the tangler dragnet C2208, it is likely that the dragnet C2208 will become entangled with the propeller(s) of the vessel C2204. To this end, the drones C2202 will be steered intelligently to maintain tension on the dragnet C2208. If the vessel C2204 passes completely over the dragnet C2208 without entanglement, the drones C2202 reverse course and attempt entanglement from aft of the vessel C2204. The alignment buoys (e.g., buoy C2210) contain small explosive charges that can be detonated, automatically or remotely, when they are entangled with or proximate to the propellers in order to propulsively disable the vessel C2204.

[00389] In general, at each escalation level, any technical measure that can be deployed by a single drone of a given size and type, or by two or more cooperating drones, may be employed by drone swarm defenses, e.g., those depicted in FIG. C21. Drones will be more likely to self-sacrifice as the estimate of threat rises (e.g., as minimal time-to-contact decreases).

Defensive Hardpoints for a PNP

[00390] The embodiments of this disclosure address the need of integrated defensive hardpoints on a PNP to defend against surface and air originated threats. In particular, threats that are not deterred by barrier defenses, drone defenses, and other distributed defenses must be dealt with as they approach or make contact with a PNP. PNP design features, including defensive hardpoints, increase PNP defensibility in various embodiments. Embodiments comprise deck designs and hardpoint locations which provide a full visual 360° free view around the platform, allowing defenders to track and combat threats approaching the PNP by air and/or by sea. Defensive hardpoints may be human, autonomously operated, or both. Hardpoints may be supported with radar and/or other sensor technology to detect, identify, evaluate, and counter threats. Hardpoints may have implemented and automated targeting systems and/or may receive target information with the awareness required to respond to the highest priority threat.

[00391] FIG. C23 schematically depicts portions of an illustrative PNP C2300 comprising integrated defensive hardpoints according to embodiments. A number of hardpoints, e.g., hardpoint C2302, are arrayed around the upper perimeter of the PNP C2300. The upper portion of the PNP C2300 is beetling or overhung and the hardpoints further project from the PNP’s perimeter so that clear lines of sight (designated by dashed lines, e.g., line of sight C2304) are obtained from the nether point of each hardpoint to points on the sides of the PNP C2300, including the waterline. Preferably the hardpoints are numbered and positioned so that at least two hardpoints have a clear line of sight to every point on the side of the PNP C2300 and along its waterline, so that disabling a single hardpoint does not create a blind spot. Hardpoints perform an observational role and may be equipped with a variety of technical measures for deterring or repelling various attacking activities (e.g., attempted boarding). Such measures may include, for example, water cannon, noise cannon, nonlethal electromagnetic weapons, and many other devices well known to the field of security engineering. Hardpoints may be remote-controlled, inhabited, autonomous, or some combination thereof. Preferably, a centralized hardpoint or control tower C2306 is positioned on the upper surface of the PNP in a manner that provides it with complete overview of the PNP’s upper surface, the perimeter, and the hardpoints.

Access Control Cofferdams

[00392] Embodiments of this invention address the need to distribute cofferdams (fluid-fillable chambers on a PNP in a manner that denies or delays access to various parts of the PNP by intruders and/or any non-authorized personnel. The novelty of the conceptual usage of cofferdams is to secure system and/or platform critical sectors from attackers that have gained access to the surface or interior of the PNP. Once activated, access control cofferdams may secure deck access points as well as the system critical interior of a PNP including the control room, safety rooms, and sanitary facilities as well as an emergency path to reach self-propelled lifeboats.

[00393] FIG. C24 is a top-down, cross-sectional, schematic depiction of portions of an illustrative defensive cofferdam system C2400 according to embodiments. The cofferdam C2400 is part of a barrier or wall that can be interior to a PNP or part of its outer hull. The continuations of the barrier or wall on either side or both sides of the cofferdam C2400 may be additional cofferdams or of another nature. The cofferdam C2400 comprises two parallel walls C2402, C2404 through which two inward-swinging doors C2406, C2408 can provide passage if both doors are opened. In an unsecured state, the cofferdam C2400 is air-fdled at a pressure approximately equal to that found on either exterior side of the cofferdam C2400 and the doors C2406, C2408 can open without obstruction. In a secured state, the cofferdam C2400 is fdled with water and the pressure differential between the outer air and the interior water places a strong net closing force on both doors C2406, C2408. The cofferdam C2400 thus provides a reversible hardened security barrier between one of its sides and the other. Preferably, a water supply

communicates with the interior of the cofferdam C2400 through piping (not depicted) that can supply, up to some design rate, any losses of water from the cofferdam C2400 and that pressurizes the interior of the cofferdam C2400. Cutting through any portion of the cofferdam C2400 when it is in a secured state will thus release a jet of water through the opening, and through passage will continue to be deterred. In general, the higher the relative pressure of the water within the cofferdam C2400 compared to the exterior air, and the more copious the makeup supply for the pressurized water, the more effective a barrier the cofferdam C2400 will present. Alternatively, the cofferdam C2400 may be pressurized with any fluid or fluids (e.g., steam, air, noxious gasses, noxious or medicated liquids, or the like) that places sufficient closing force upon the doors C2406, C2408 to make the doors unopenable by ordinary means and that, preferably, deters entry by attackers if released.

[00394] Cofferdams such as cofferdam C2400 of FIG. C24 or differing from cofferdam C2400 in various details of design but functioning as a reversibly hardenable barrier in a similar manner, can be positioned throughout the interior of a PNP so as to increase security in the event or danger of a threat interior to the PNP (e.g., boarding by persons or robots).

[00395] FIG. C25 is a schematic, cross-sectional depiction of portions of an illustrative PNP C2500 comprising cofferdams for reversible hardening of access to critical areas. A first cofferdam C2502 (seen in endwise cross-section) is interposed between the deck C2504 of the PNP C2500 and a stairwell C2506 descending therefrom. A second cofferdam C2508 (also seen in endwise cross-section) is interposed between a passageway C2510 and an elevator C2512. The cofferdams C2502, C2508 can be secured by pressurization with steam from a stem generation system C2514. The cofferdams C2502, C2508, as depicted, secure against approach from a single direction only: however, cofferdams in various embodiments enwrap or encircle critical areas, hardening them against access from a wider range of directions or, potentially, from all directions. Cofferdam sections not provided with doorways are also contemplated.

[00396] FIG. C26 is a schematic, cross-sectional depiction of portions of an illustrative PNP C2600 comprising cofferdams for reversible hardening of access to critical areas. The PNP C2600 comprises a citadel or keep C2602, that is, an especially defensible portion of the PNP that comprises modules and systems for critical function such as reactor control C2604, medical care C2606, crew quarters C2608, a safe room C2610, a vertical transport capability C2612 (e.g., elevator and stairwell), and an escape route, and to which personnel would withdraw during an attack. A cofferdam blanket C2614 enwraps the citadel C2602; in typical practice, crew of a PNP thought to be under attack would first withdraw to the citadel C2602, after which the cofferdams comprising the cofferdam blanket C2614 would be pressurized. An escape vessel C2616 with an armored nose-plate C2618 that normally acts as a portion of the outer hull of the PNP C2600 provides failsafe, unpowered crew egress through an opening in the cofferdam blanket C2614 and means of subsequent escape from the vicinity of the PNP C2600;

alternatively, the escape vessel C2616 can be isolated from the exterior of the PNP C2600 by a cofferdam section (not depicted) that can be manually depressurized from within the citadel C2602, preferably by means of a failsafe, unpowered mechanism. The cofferdam blanket C2614 provides a hardened barrier around most or all of the surface of the citadel C2602, impeding attack from within the PNP C2600 as well as from exterior threats (e.g., an aircraft C2620 landing on the upper deck).

Countermeasure Washdown System

[00397] This disclosure addresses the need of a countermeasure washdown system for a PNP to recover from a containment failure or chemical, biological and/or radiological warfare.

[00398] FIG. C27 schematically depicts a portion of a PNP C2700 and portions of an illustrative countermeasure washdown system comprising spray towers (e.g., tower C2702) capable of projecting a foam or liquid spray C2704 upon most or all of the upper deck of the PNP C2700. The towers are fed by a piping system (not shown) supplied by seawater and/or a specially formulated washdown solution from tanks located on the PNP C2700. In case of contamination of the deck of the PNP C2700 by biological, chemical, or radiological agents, the towers spray liquid over the deck. Crowning (not depicted) of the deck assures that even when the PNP is level, the sprayed liquid with entrained contaminants will flow to sumps set into the deck, e.g., peripheral sump channel C2706. Liquid collected in sumps can be diverted by valves (e.g., valve C2708) either overboard (via pipe C2710) or to a storage tank (not shown; via pipe C2710). Foaming agents with catalyzers, chelating agents, fire retardants, or the like can be added to the washdown fluid to increase decontamination efficiency, improve the operation of filters in the drainage system, and accomplish other purposes. The system enables PNP crew to avoid contact with contaminants during attack and/or cleanup while preventing concentrated contamination in the ocean immediately around the PNP platform C2700 after attacks or containment failures. In embodiments, the countermeasure washdown system doubles as a fire suppression system. In embodiments the countermeasure washdown system serves, additionally or alternatively its contaminant-removal function, as an antipersonnel or anti-robot system and/or as a camouflage system. Human or robot boarders may be impeded or disabled by sufficiently high-pressure and/or copious liquid output from the spray towers. In embodiments, a human operator or an artificial intelligence directs a concentrated portion of the spray output from one or more towers so as to impede or damage boarders. Also in various embodiments, the countermeasure spray down system comprises a capability to spray diverse fluids, foams, fogs, smokes, and gasses simultaneously and/or sequentially from one or more spray towers; thus, in a series of examples, (1) the spraydown system blankets part or all of the deck with a fluid chosen or tailor-mixed to respond to a specific threat type (e.g., fire, toxic chemical, radiological contaminant), (2) the spraydown system first blankets the deck with one type of fluid, then with a second type to remove the first, and (3) the spraydown system first covers the deck with foam, then breaks down the foam with a suppressant spray, then washes away the resulting liquid with desalinated water.

[00399] FIG. C28A schematically depicts portions of an illustrative PNP C2700 comprising an illustrative countermeasure washdown system similar to that of FIG. C27. Washdown towers (e.g., tower C2702) are depicted in the process of flooding the upper deck of PNP C2700 with foam C2800. The foam C2800 accumulates to a significant depth (e.g., ~3 meters) and may perform one or more functions while resident on the deck, e.g., fire suppression, contaminant removal, visual concealment of the deck from approaching attackers, local blinding of human or robot boarders, and delivery of irritating or incapacitating agents to human or robot boarders. After spilling over the edge of the deck of the PNP C2700, the foam C2800 tends to flow down the outer hull, where it is partly or wholly recovered by a collection gutter C2802.

[00400] FIG. C28B schematically depicts portions of an illustrative PNP C2804 comprising an illustrative countermeasure washdown system similar to that of FIG. C28A. Washdown towers (e.g., tower C2702) are depicted in the process of flooding the upper deck of PNP C2804 with foam C2800. After spilling over the edge of the deck of the PNP C2804, the foam C2800 tends to flow down the outer hull, where it is partly or wholly recovered by a collection gutter C2802. The PNP C2804 of FIG. C28B differs from the floating PNP C2700 of FIG. C28A in a number of respects; e.g., the PNP C2804 is established upon the seabed C2806 by means of a number of pilings (e.g., piling C2808). The pilings support a seabed base structure C2810 that proffers an artificial harbor into which a nuclear power unit C2812 can be installed by flotation. The nuclear power unit C2812 comprises a modular nuclear reactor C2814. Various embodiments comprise other forms of multi-part, flotation-delivered, piling-supported PNPs including different types and numbers of modular reactors or other types of nuclear reactor. PNPs in various embodiments may also comprise groupings of multiple floating, piling-supported, or otherwise stationed or supported structures, e.g., structures arranged in groups where each structure performs a distinct function pertinent to power generation, including steam generation, power generation from steam, security, fuel handling, and the like. In all Figures herein that depict nuclear power plants, including FIG. C28B, the forms and types of PNP depicted are illustrative only, and no restriction on PNP forms and types is intended.

[00401] FIG. C29 is a schematic depiction of portions of a PNP C2700 comprising an illustrative countermeasure washdown system located in a portion of an interior module rather than on the top deck of the PNP C2700 (as in FIGS. C27 and C28). The PNP C2700 comprises a chamber or room C2902 that is served by sprayers or sprinkler heads (e.g., sprinkler C2904). The sprinklers are fed by a piping system (not shown) supplied by seawater and/or a specially formulated washdown solution from tanks located on the PNP C2700. Fluid from the sprinklers exits the chamber via a sump C2906, whence it is directed by a valve C2908 to (1) piping C2910 that passes through the PNP hull C2912 to the exterior of the PNP C2700 or (2) piping C2914 that conducts the fluid to recovery tanks (not shown).

[00402] FIG. C30 is a schematic depiction of the architecture of portions of an illustrative countermeasure washdown system C3000 comprised by a PNP. Water is acquired via an ocean water intake C3002 and directed to a desalination system C3004 either directly or via a storage system C3006. Desalinated water is then directed to a delivery system C3008. The delivery system C3008 comprises water conditioning subsystems (e.g., systems to add various agents to the water, filter the water, cool or heat the water, or the like) and delivery subsystems (e.g., pumps, piping, spray towers). The delivery system C3008 delivers conditioned fluid to at least one contaminated or threatened area C3010. Fluid is removed from the contaminated area C3010 by a drainage system C3012, which may route the fluid either to an overboard vent C3014 or to a waste storage system C3016, whence the fluid may also be routed to the overboard vent C3014.

External Deck Access Prevention Systems for a PNP

[00403] This disclosure addresses the need of an exterior fouling system for a PNP to prevent intruders from getting access to the platform. In embodiments, a variety of access prevention mechanisms seek to impede any non-authorized personnel or devices approaching the platform.

[00404] FIG. C31 is a schematic depiction of portions of an illustrative PNP installation comprising an illustrative fog-screen fouling system C3100. Herein, a“fog” is a cloud of aerosolized liquid, a cloud of solid smoke particles, or a mixture of liquid and solid particles. In the system C3100, fog generators arranged upon the upper deck of the PNP C3102 (e.g., as in the countermeasure washdown system of FIG. C27), or around the perimeter of the deck of the PNP C3102, or around the PNP C3102 on booms, barges, buoys, drones, or other mounts, produce an obscuring fog bank C3104 that conceals at least the PNP C3102 and preferably the entire protected area C3106 and/or controlled access area C3108 centered on the PNP C3102. The activity of fog generators may be directed by a human operator or artificial intelligence to adjust fog generation to wind conditions.

[00405] FIG. C32 is a schematic top-down depiction of portions of an illustrative flow barrier system C3200 that impedes surface access to the hull of a PNP C3202. The flow barrier system C3200 comprises pressurized-water outlets (e.g., outlets C3204, C3206, C3208) located at or just below the waterline of the PNP C3202. A first type of outlet (e.g., outlets C3204, C3208) direct pressurized water flows (e.g., flow C3210) along the hull waterline. Because of the Coanda effect (the tendency of a fluid jet to stay attached to a convex surface), the flows from this first type of outlet will tend, for some distance, to hug the PNP hull. Outlets generating hull-hugging flows are spaced around the PNP waterline closely enough that each flow (e.g., flow C3210), before it can detach significantly from the PNP hull, is met by a countervailing hull-hugging flow (e.g., flow C3212); upon meeting, the two flows tend to combine into a joint outward flow (e.g., flow C3214). Preferably, every hull-hugging flow around the PNP waterline is met by a countervailing flow of approximately equal velocity and volume so that approximately zero net radial forces is exerted on the PNP C3203 by the flow barrier. Such a balanced arrangement is depicted illustratively in an overhead schematic view in FIG. C33, where countervailing hull-hugging flows (e.g., flow C3300) originating from outlet stations (e.g., station

C3302) surround a PNP C3304.

[00406] Reference is again made to FIG. C32. Any swimmer, surface drone, or small craft attempting to approach the hull waterline will tend to be diverted or swept aside by the hull-hugging flows or combined outflows. However, this is not true of the points where paired, back-to-back outlets (e.g., outlets C3204, C3206) are located. Thus, the illustrative embodiment of FIG. C32 comprises a second type of outlet, e.g., outlet C3206. The output of outlet C3206 is directed outward from the PNP waterline toward a rotatable, controllable flow plate C3216 which can be mounted on an underwater boom (not depicted). The flow impinging on the flow plate C3216 is diverted accordingly. The flow plate C3216 can be oriented by a human operator or an artificial intelligence to direct the output of outlet C3206 toward any approaching surface or near-surface threat, e.g., a small vessel C3218. Such a directable flow constitutes a point defense for the outlets generating the flow-barrier system C3200. In various embodiments, the flow barrier may be extended below the waterline by additional outlets at depth.

[00407] FIG. C34 schematically depicts portions of another illustrative exterior fouling system

C3400 of a PNP C3402. In system C3400, a high-pressure water jet C3404 is directed from a steerable nozzle C3406 against an approaching aircraft C3408. Steering of the nozzle C3404 is by a human operator or artificial intelligence. In various embodiments, jets or pulses of water are directed against threats of various types in addition to aerial threats, e.g., boarders, surface vessels. Preferably, jets are stationed upon the PNP C3402 at stations closely spaced enough to provide complete coverage of at least the PNP upper deck perimeter.

[00408] FIG. C35 schematically depicts portions of another illustrative exterior fouling system

C3500 of a PNP C3502. In system C3500, the upper deck of the PNP C3502 is bounded or edged by a cornice C3504 that is rounded and free of catch-points upon which a grappling hook C3506 or similar device can find purchase. Moreover, the upper deck of the PNP C3502 is, for most or all of its area and/or within a significant distance of the cornice C3504, similarly smooth and free of catch-points. Boarding of the PNP is rendered more difficult by system C3500.

Reactive Armor for Vector Defense of a PNP

[00409] In embodiments, exterior fouling systems of a PNP comprise structural reactive armor. Herein,“reactive armor” denotes a plate-like material or device that, when impacted by a projectile, reacts in a way that liberates stored energy to repel the projectile or mitigate its impact. Explosive reactive armor, herein termed“active” reactive armor, is well-known in military applications; herein, discussion focuses on“passive” reactive armor, defined as reactive armor that, when triggered, liberates only elastically stored energy, not chemical explosive energy. Both active and passive reactive armor are contemplated and within the scope of the invention. Passive reactive armor tends to be effective against a narrower range of challenge forces, but has the advantages of lower cost, of not necessarily being exhausted by a single impact, and of greater safety.

[00410] Herein two preferred types of structural passive reactive armor (PRA) are described. FIG. C36 depicts in schematic cross section an illustrative form of a first type of PRA. The PRA plate C3600 is oriented to be effective against a projectile coming more or less from the upper right quadrant (open arrow). The PRA plate C3600 comprises a passivated outer layer C3602, an outer hard layer C3604 (e.g., a layer of a hard steel such as Brinell, ZDP-189), a central layer C3606 comprising a compressible multilayer laminate of hard and elastic materials (e.g., steel for the hard material and rubber, plastic, or carbon fiber for the elastic material), and an inner hard layer C3608 (e.g., a layer of a hard steel). The plate C3600 is mounted (e.g., to a PNP) by a baseplate C3610 and a number of stout supports (e.g., support C3612). An initial phase of impact of a projectile or explosive shock wave (not depicted) delivers kinetic energy to the laminate layer C3606 via the outer hard layer C3604, compressing the laminate layer C3606. The elastic modulus of the laminate layer C3606 is high enough so that the laminate layer C3606 is capable of absorbing much or all of the kinetic energy of a projectile of plausible mass. Re-expansion of the layer C3606 commences while the projectile is still deforming and/or penetrating the hard layer C3604, delivering a coimterforce to the projectile and tending to decelerate the projectile. Expansive force will tend to be exerted by the compressed laminate layer C3606

symmetrically on the front hard layer C3604 and back hard layer C3608, but the latter is positionally constrained by the mounting hardware, which communicates with the relatively very large mass of the PNP, so momentum is preferentially imparted outward (i.e., counter to initial direction of projectile motion). This coimterforce is delivered until the elastic energy stored in the laminate layer C3606 is spent, the projectile is repelled, or the laminate layer C3606 is penetrated by the projectile. In essence, the design idea is to cause the projectile to bounce elastically off the plate C3600. PRA plate C3600 will have partially accomplished its protective purpose even if penetrated by a projectile if the projectile delivers significantly less energy to objects in the region behind the plate C3600 (e.g., the deck of a PNP).

[00411] FIG. C37 depicts in schematic cross section an illustrative form of a second type of PRA. The PRA plate C3700 is oriented to be effective against a projectile coming approximately from the upper right quadrant (open arrow). The PRA plate C3700 comprises a passivated outer layer C3702, an outer layer C3704 of steel-fiber-reinforced high performance concrete with steel fibers running between edge-mounted tensioning plates (e.g., steel fiber C3706, tensioning plate C3708), a middle layer C3710 of fiber-reinforced engineered cementitious composite, and a back layer C3712 similar to front layer C3704. Plate C3700 is mounted on supports (e.g., support C3714) and a baseplate C3716 similar to those of FIG. C36. The operative principles of plate C3700 are similar to those of plate C3600 of FIG. C36, except that the rigid front and back plates of plate C3600 are here, in effect, replaced by reinforced concrete. It will be clear that the forms and dimensions of the plates C3600 and C3700, as well as the form and type of their supports and internal structures, are illustrative only.

[00412] FIG. C38 depicts in schematic cross section an illustrative PNP C3800 comprising PRA plates disposed in a plurality of distinct defensive zones. A Missile Shield or first ring C3802 of PRA plates confers resistance to aerial attacks, a Localized Shield or second ring C3804 of PRA plates hardens the outer hull of the PNP C3800 to protect above-waterline critical systems (e.g., containment, control room, diesel fuel storage), and a Splash Zone Shield C3806 of PRA plates confers resistance to surficial attacks (e.g., speedboats). In embodiments, other zones of PRA plates are comprised by the PNP C3800, e.g., PRA plate zones below waterline.

Cyberdefense of a PNP

[00413] This disclosure addresses the need of a cyberdefense system for a PNP to prevent intruders from gaining access to computerized control systems, either to directly disrupt operations or to assist a physical attack. In embodiments, a variety of access prevention mechanisms impede or block cyberattack.

[00414] FIG. C39 is a schematic block diagram of aspects of an illustrative cyberdefense system C3900 integral to a PNP. Access to in situ physical controls C3902 is guarded by a biometric filter C3904 (e.g., fingerprint and retinal scanner) that refuses all access to non-recognized or non-authorized persons. Physical users that pass biometric verification C3904, as well as all control inputs arriving through communications channels C3906 (e.g., from offsite controllers), must pass a cryptographic verification filter C3908 (e.g., password verification and/or more rigorous authorization verification techniques well known to persons familiar with cybersecurity). Local or remote controllers that pass the filters C3904, C3908 are granted access to the control software C3910, which can issue commands to the control mechanisms of PNP defense systems C3912, nuclear system C3914, maritime systems C3916, and other systems (not depicted). However, all commands issued by the control software are filtered by a hardwired command filter C3918. The command filter C3918 is a computational device that algorithmically compares all commands from the control software C3910 to a set of internally stored criteria and, potentially, data inputs from sensors or telemetry associated with controlled systems (e.g., nuclear systems C3914) and the PNP environment. The command filter prevents self-destructive commands from being issued to the controlled systems, e.g., maritime system commands that would cause the PNP to capsize or nuclear system commands that would cause the reactor core to melt. The command filter C3918 is proof against real-time cyberattack because its program is preferably stored in read-only memory (e.g., PROM or EPROM chips) and can only be altered by physical swap-out of the chips. Preferably, moreover, quantum and/or conventional cryptographic techniques are used at most or all steps of data transfer symbolized by black lines in FIG. C39 in order to assure integrity of data transfer by detecting tampering and interception, if any. [00415] The foregoing has been a detailed description of illustrative embodiments of the invention. Various modifications and additions can be made without departing from the spirit and scope of this invention. Each of the various embodiments described above may be combined with other embodiments in order to provide multiple features. Furthermore, while the foregoing describes a number of separate embodiments of the apparatus and method of the present invention, what has been described herein is merely illustrative of the application of the principles of the present invention. Accordingly, this description is meant to be taken only by way of example, and not to limit the scope of this invention.