CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 62/407,237, filed October 12, 2016, entitled "Reactor Vessel Containment Silo," the entirety of which is incorporated by reference.

BACKGROUND

Field

[0002] Embodiments of the present disclosure relate generally to nuclear reactors and, more particularly, to energy production through the operation of a molten chloride fast reactor that includes modular containment of reactor fluids in the event of a reactor breach.

[0003] The global demand for energy has largely been fed by fossil fuels. This typically involves taking reduced carbon out of the Earth and burning it. However, those hydrocarbons are in limited supply and burning the hydrocarbons can produce carbon dioxide. According to the U.S. Environmental Protection Agency, more than 9 trillion metric tons of carbon are released into the atmosphere each year. Nuclear power is an appealing alternative to fossil fuels due to relative abundance of nuclear fuel and carbon-neutral energy production.

[0004] Light water reactors (LWRs) are the predominant commercial nuclear reactor for electricity production. In LWRs, light water (ordinary water) is used as a moderator as well as a cooling agent and the mechanism by which heat is removed to produce steam for use in generating electricity (e.g., turning turbines of electric generators).

[0005] LWRs have significant drawbacks, however. In one example LWRs can use solid fuels that have long radioactive half-lives. As a result, LWRs can produce dangerous and long-lived waste products. In another example, light water reactors operate at high pressure, requiring expensive engineering and materials. Additionally, LWRs can require expensive safety systems to avoid complicated and expensive accidents.

[0006] Molten salt reactors (MSRs) have been researched since the 1950s to improve on LWR technologies. MSRs are a class of nuclear fission reactors in which the primary coolant, or even the fuel itself, can be a molten salt mixture. In general, MSRs can provide energy more safely and cheaply than LWRs. As an example, MSRs can operate at relatively low pressures and they can be potentially less expensive and passively safer than LWRs. Furthermore, compared to LWRs, MSRs can also provide advantages such as lower levelized cost on a per-kilowatt hour (kWh) basis, fuel and waste inventories of relatively benign composition, and more efficient fuel utilization. Accordingly, as LWR maintenance and upgrade costs continue to rise, there is renewed interest in MSRs, given their advantages over LWRs.

SUMMARY

[0007] Like all nuclear reactors, operation of MSRs can include regulating temperature and reactivity to control fission reactions within safe limits. Passive reactivity control can be desirable in case of a power failure or other conditions that make active control impossible. However, passive reactivity control can present challenges, such as maintaining a constant temperature as a safety measure to reduce dangerous reactor temperatures during a reaction.

[0008] Embodiments of the present disclosure provide a fluid fuel reactor containment system that is configured to contain fluid fuel in the event of a spill or other accident. The fluid fuel reactor containment system can includes a modular containment vessel that can be removed from a containment silo to aid in accident response or facilitate maintenance. The removable containment vessel can be a stainless steel container and it can be lifted by a crane. An entire reactor vessel that operates to generate heat energy (e.g., by nuclear fusion) can sit within the removable containment vessel. Unlike existing containment barriers that are permanent and non-removable, embodiments of the modular containment system discussed herein can allow the reactor vessel to be contained within an enclosed removable containment vessel and also to be easily removed in the event of an accident or for maintenance.

[0009] In one exemplary embodiment, a molten salt reactor containment system is provided. The system can include a containment silo enclosed by a removable cap, a removable containment vessel within the containment silo, and a molten salt reactor vessel within the removable containment vessel. Removing the removable cap and lifting the removable containment vessel from the containment silo can causes the reactor vessel to be removed from the containment silo. [0010] In another embodiment, the removable containment vessel and the reactor vessel can be formed from stainless steel.

[0011] In another embodiment, the containment silo can be formed from reinforced concrete.

[0012] In another embodiment, the reactor vessel can be supported within the removable containment vessel by a layer of a sacrificial salt.

[0013] In another embodiment, the system can further include a heat exchanger in fluid communication with the reactor vessel.

[0014] In another embodiment, the system can further include at least one transfer conduit configured to provide fluid communication between the heat exchanger and a secondary system.

[0015] In another embodiment, the system can also include a crane operable to lift the removable containment vessel from the containment silo.

[0016] In another embodiment, the removable cap can sit within a removable lid of the containment silo.

[0017] In another embodiment, the containment silo can include an inner containment well and an outer shell, wherein the inner containment well is disposed substantially within the outer shell.

[0018] In another embodiment, removing the removable lid from the containment silo can allow the inner containment well to be lifted out of the outer shell.

[0019] In another embodiment, the inner containment well can include a passive heat removal mechanism.

[0020] In another embodiment, the passive heat removal mechanism can include one or more heat pipes passing through the inner containment well.

[0021] In another embodiment, the removable containment vessel can sits within the containment silo on a material including at least one of a sacrificial salt and graphite. [0022] In another embodiment, at least a portion of the one or more heat pipes can pass through the material including at least one of a sacrificial salt and graphite.

[0023] In another embodiment, the containment silo can sits below grade and the system can further include a gantry crane with a hoist. The hoist can be configured to be moved into position above the removable containment vessel and to lift the removable containment vessel and the reactor vessel from the containment silo.

[0024] In other embodiments, a method for removing a reactor vessel from a containment silo is provided. The method can include operating a reactor system to produce thermal energy. In one embodiment, the method can include being alerted of a need for removal of the reactor vessel. The method can also include accessing an interior of the containment silo and the removable containment vessel. The transfer conduits that provide part of a transfer fluid loop between a heat exchanger of the reactor vessel and a secondary system, as well as any electrical or other plumbing connections, can be disconnected. Disconnection of the transfer conduits can isolate the reactor vessel from the transfer fluid loop. The removable containment vessel can be hoisted from the containment silo (e.g., by a crane) and isolated away from the containment silo. This serves to remove and isolate the reactor vessel. In this manner, the conditions that gave rise to the removal and isolation may be addressed.

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] These and other features will be more readily understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

[0026] FIG. 1 is a schematic diagram illustrating one exemplary embodiment of a nuclear thermal generating plant (NTGP) including a molten salt reactor (MSR) system .

[0027] FIG. 2 is a schematic diagram depicting a fuel conditioning system of the MSR system of FIG. 1 in greater detail.

[0028] FIG. 3 is a diagram illustrating one exemplary embodiment of a containment silo for the reactor system.

[0029] FIG. 4 is a diagram illustrating one exemplary embodiment of a molten salt reactor containment system. [0030] FIG. 5 is a diagram illustrating one exemplary embodiment of a method for removing a molten salt reactor vessel from the containment silo.

[0031] FIG. 6 is a diagram illustrating the removal of a removable cap to access the containment silo.

[0032] FIG. 7 is a diagram illustrating one exemplary embodiment of a gantry crane for lifting a removable containment vessel.

[0033] FIG. 8 is a diagram illustrating the removal of the removable containment vessel from the containment silo.

[0034] For a thorough understanding of the present disclosure, reference should be made to the following detailed description, including the appended claims, in connection with the above-described drawings. Although the present disclosure can be described in connection with exemplary embodiments, the disclosure can be not intended to be limited to the specific forms set forth herein. It can be understood that various omissions and substitutions of equivalents can be contemplated as circumstances can suggest or render expedient.

DETAILED DESCRIPTION

[0035] Systems and methods for containing a reactor vessel and removing the reactor vessel from its location within a reactor system are provided. The described systems may be used for any suitable reactor. In preferred embodiments, the systems and methods are used in the context of a fast-spectrum chloride molten salt reactor.

[0036] FIG. 1 schematically illustrates an embodiment of a nuclear thermal generating plant (NTGP) 100 in the form of a molten salt nuclear reactor system configured to use a molten fuel salt or a fuel salt constituent (collectively referred to herein as fuel salt) to generate electrical energy from nuclear fission. As shown, the NTGP 100 includes a reactor system 102 and a secondary system 104. The reactor system 102 includes a primary heat exchanger 106 connected to a reactor vessel 110 having a reactor core 112 containing a fuel salt composition 114. The reactor system 102 also includes a fuel conditioning system 120 in fluid communication with the reactor vessel 110.

[0037] As an example, components of the fuel salt composition 114 can be in the form of one or more chloride salts, fluoride salts, and mixtures of one or more chloride and fluoride salts. In embodiments where the fuel salt composition 114 includes one or more chloride salts, the NTGP 100 can be referred to as a molten chloride fast reactor (MCFR).

[0038] In certain embodiments, the fuel salt composition 114 can include a carrier salt and a fuel salt. The carrier salt can include a chloride salt of an alkali or alkaline earth metal. The fuel salt can include a chloride salt of at least one actinide. The actinide chloride fuel salt can include fissile isotopes, fertile isotopes, and combinations thereof. Examples of fissile materials can include, but are not limited to, thorium (Th), protactinium (Pa), uranium (U), neptunium (Np), plutonium (Pu), americium (Am), curium (Cm), and any combination thereof. In certain embodiments, the fissile materials can include one or more of the following isotopes, in any combination: Th-225, Th-227, Th-229, Pa-228, Pa-230, Pa-232, U-231, U-233, U-235, Np-234, Np-236, Np-238, Pu-237, Pu-239, Pu-241, Am-240, Am-242, Am- 244, Cm- 243, Cm- 245, and Cm- 247. Examples of fertile materials can include, but are not limited to, ²³² ThCl ₄ , ²³⁸ UC1 ₃ and ²³⁸ UC1 ₄ .

[0039] Further embodiments of fuel salt compositions suitable for use with the NTGP 100 are discussed in greater detail in U.S. Provisional Patent Application No. 62/340,754, filed on May 24, 2016, entitled "Chloride and Fluoride Salt Composition For Molten Salt

Reactor," U.S. Provisional Application No. 62/340,762 filed on May 24, 2016, entitled "Salt Composition With Phase Modifiers For Molten Salt Reactor," U.S. Provisional Application No. 62/269,525, filed on December 18, 2015, entitled "Salt Composition for Molten Salt Reactor," and U.S. Application No. 15/380,473, filed on December 15, 2016, entitled "Salt Compositions for Molten Salt Reactors," each of which is hereby incorporated by reference in its entirety.

[0040] In general, fluids of three types can be contained in and/or circulated through the NTGP 100, namely fuel, coolant, and moderator (e.g., any substance that slows neutrons). Various fluids can perform one or more of the fuel, coolant, and moderator functions simultaneously. One or more fluids, including more than one fluid of each functional type, can be contained within or circulated through the reactor core 112. Examples of fluids contained within or circulated through the reactor core 112 can include, but are not limited to, liquid metals, molten salts, supercritical ¾0, supercritical CO ₂ , and supercritical N ₂ O.

[0041] Upon absorbing neutrons, nuclear fission can be initiated and sustained in the fuel salt composition 114 by chain-reaction within the NTGP 100, generating heat that elevates the temperature of the fuel salt composition 114 (e.g., about 650°C or about 1,200°F). The heated fuel salt composition 114 can be transported from the reactor core 112 to the primary heat exchanger 106 via a primary fluid loop 122 via a pump, discussed in greater detail below. The primary heat exchanger 106 can be configured to transfer heat generated by nuclear fission occurring in the fuel salt composition 114.

[0042] Transfer of heat from the fuel salt composition 114 can be realized in various ways. For example, the primary heat exchanger 106 can include a pipe 124 and a secondary fluid 126. The fuel salt composition 114 can travel through the pipe 124, while the secondary fluid 126 (e.g., a coolant) can surround the pipe 124 and absorb heat from the fuel salt composition 114. Upon heat transfer, the temperature of the fuel salt composition 114 in the primary heat exchanger 106 can be reduced and fuel salt composition 114 can be subsequently transported from the primary heat exchanger 106 back to the reactor core 112.

[0043] The secondary system 104 can also include a secondary heat exchanger 130 configured to transfer heat from the secondary fluid 126 to a tertiary fluid 132 (e.g., water). As shown in FIG. 1, the secondary fluid 126 is received from primary heat exchanger 106 via fluid loop 134 and circulated through secondary heat exchanger 130 via a pipe 136.

[0044] Additionally or alternatively, in another embodiment (not shown), heat exchange can occur within the reactor core 112 prior to heat exchange within the secondary heat exchanger 130. As an example, heat from the fuel salt composition can pass to a solid moderator, then to a liquid coolant circulating through the reactor. Subsequently, the liquid coolant circulating through the reactor can be transported to the secondary heat exchanger. As required by basic thermodynamics, after one or more stages of exchange, heat can be finally delivered to an ultimate heat sink, e.g., the overall environment (not shown).

[0045] Heat received from the fuel salt composition 114 can be used to generate power (e.g., electric power) using any suitable technology. For example, when the tertiary fluid 132 in the secondary heat exchanger 130 is water, it can be heated to a steam and transported to a turbine 140 by a fluid loop 142. The turbine 140 can be turned by the steam and drive an electrical generator 144 to produce electricity. Steam from the turbine 140 can be conditioned by an ancillary gear 148 (e.g., a compressor, a heat sink, a pre-cooler, and a recuperator) and it can be transported back to the secondary heat exchanger 130 through the fluid loop 142. [0046] Additionally, or alternatively, the heat received from the fuel salt composition 114 can be used in other applications such as nuclear propulsion (e.g., marine propulsion), desalination, domestic or industrial heating, hydrogen production, or combinations thereof.

[0047] It can be desirable to operate the reactor system 102 in the fast neutron spectrum, as opposed to the thermal spectrum. While significant nuclear energy can be produced from U- 235, U-235 is only about 0.7% uranium. More energy could be produced from uranium if U- 238 could be consumed in the reaction. If U-238 captures a neutron, it becomes plutonium- 239, which is fissile. When P-239 captures a neutron, it undergoes a fission reaction and produces energy. However, thermal neutrons tend to be absorbed by Pu-239 without leading to a fission reaction of Pu-239. Thus, thermal spectrum reactors can fail to provide a sustained burn of U-238. By contrast, a fast spectrum reactor can provide the ability to use substantially more of the energy potentially available through U-238 than would be provided by a thermal spectrum reactor.

[0048] During the operation of the NTGP 100 to generate power, fission products can be generated in the fuel salt composition 114. In general, the fission products can be radioactive noble metals and/or radioactive noble gases. Non-limiting embodiments of fission products can include, but are not limited to, one or more of the following, in any combination:

rubidium (Rb), strontium (Sr), cesium (Cs), barium (Ba), lanthanides, palladium (Pd), ruthenium (Ru), silver (Ag), molybdenum (Mo), niobium (Nb), antimony (Sb), technetium (Tc), xenon (Xe), and krypton (Kr).

[0049] The buildup of fission products in the fuel salt composition 114 can impede or interfere with the nuclear fission in the reactor core 112 by poisoning the nuclear fission. For example, xenon-135 and samarium-149 can have a high neutron absorption capacity and they can lower the reactivity of the fuel salt composition 114. Fission products can also reduce the useful lifetime of the NTGP 100 by clogging or corroding components, such as heat exchangers or piping. Therefore, it can be desirable to keep concentrations of fission products in the fuel salt composition 114 below certain thresholds to maintain proper functioning of the NTGP 100.

[0050] This goal can be accomplished by the fuel conditioning system 120. As discussed in greater detail below, the fuel conditioning system 120 can be configured to remove at least a portion of fission products generated in the fuel salt composition 114 during nuclear fission. As an example, the fuel salt composition 114 can be transported from the reactor core 112 to the fuel conditioning system 120 (e.g., via a fluid loop 146), which can process the fuel salt composition 114 and allow the reactor vessel 110 to function without loss of efficiency or degradation of components due to development of fission products. As shown in FIG. 1, the fuel conditioning system 120 can be contained within the reactor system 102 along with the reactor vessel 110 and the primary heat exchanger 106. However, in alternative

embodiments (not shown), at least one of the primary heat exchanger and the fuel- conditioning system can be located external to the reactor system.

[0051] FIG. 2 illustrates the fuel conditioning system 120 in greater detail. During normal operation of the reactor system 102, the fuel salt composition 114 can be circulated continuously or near-continuously from the reactor core 112 through one or more of functional sub-units of the fuel conditioning system 120 via fluid loop 146 by a pump 150. As discussed below, examples of the sub-units can include, but are not limited to, a corrosion reduction unit 152, a mechanical separation unit 154, and a chemical exchange unit 156. The fuel conditioning system 120 can also include a tank 160 for storage of waste extracted from the fuel salt composition 114.

[0052] In an embodiment, the corrosion reduction unit 152 can be configured to inhibit or mitigate corrosion of components of the NTGP 100 by the fuel salt composition 114. At least a portion of the reactor core 112 can be constructed of metallic alloy including one or more of the following elements: iron (Fe), nickel (Ni), chromium (Cr), manganese (Mn), carbon (C), silicon (Si), niobium (Nb), titanium (Ti), vanadium (V), phosphorus (P), sulfur (S), molybdenum (Mo), nitrogen (N), cermet alloys, stainless steels (austenitic stainless steels), zirconium alloys, or tungsten alloys, and variants thereof.

[0053] During operation of the NTGP 100, the fuel salt composition 114 can be transported from the reactor core 112 to the corrosion reduction unit 152 and from the corrosion reduction unit 152 back to the reactor core 112. Transportation of the fuel salt composition 114 at a variably adjustable flow rate can be driven by the pump 150. The corrosion reduction unit 152 can be configured to process the fuel salt composition 114 to maintain an oxidation reduction (redox) ratio, E(o)/E(r), of the fuel salt composition 114 in the reactor core 112 (and elsewhere throughout the NTGP 100) at a substantially constant level, where E(o) is an element (E) at a higher oxidation state (o) and E(r) is that element (E) at a lower oxidation state (r). [0054] In one embodiment, the element (E) can be an actinide (e.g., uranium, U), E(o) can be U(IV) and E(r) can be U(III). In this embodiment, U(IV) can be in the form of uranium tetrachloride (UC1 ₄ ), U(III) can be in the form of uranium trichloride (UCI ₃ ), and the redox ratio can be a ratio E(o)/E(r) of UCI ₄ /UCI ₃ . Although UCI ₄ can corrode the reactor core 112 by oxidizing chromium according to:

Cr→ Cr ³⁺ + 3e

Cr ⁺ + 3UCl ₄ → CrCl ₃ + 3UCl ₃ the existence of UCI ₄ can reduce the melting point of the fuel salt composition 114.

Therefore, the level of the redox ratio, UCI ₄ /UCI ₃ , can be selected based on at least one of a desired corrosion reduction and a desired melting point of the fuel salt composition 114. For example, the redox ratio can be substantially constant and selected between about 1/50 to about 1/2000. More specifically, the redox ratio can be at a substantially constant level of about 1/2000.

[0055] The mechanical separation unit 154 can be configured to remove at least part of insoluble fission products and/or dissolved gas fission products from the fuel salt composition 114. Examples of insoluble fission products can include one or more of the following in any combination: krypton (Kr), xenon (Xe), palladium (Pd), ruthenium (Ru), silver (Ag), molybdenum (Mo), niobium (Nb), antimony (Sb), and technetium (Tc). Examples of gas fission products can include one or more of xenon (Xe) and krypton (Kr). As an example, the mechanical separation unit 154 can generate a froth from the fuel salt composition 114 that includes the insoluble fission products and/or the dissolved gas fission products. The dissolved gas fission products can be removed from the froth, and at least a portion of the insoluble fission products can be removed by filtration.

[0056] The chemical exchange unit 156 can be configured to remove at least a portion of the soluble fission products dissolved in the fuel salt composition 114 and return the actinides to the fuel salt composition 114. Examples of the soluble fission products can include one or more of the following, in any combination: rubidium (Rb), strontium (Sr), cesium (Cs), barium (Ba), and lanthanides. The removal of soluble fission products can be realized through various mechanisms. [0057] Comprehensive lists of fission products applicable to various embodiments to the present disclosure are provided below. A person skilled in the art will appreciate that these lists are illustrative and not meant to be exhaustive.

[0058] Fission products sufficiently noble to maintain a reduced and insoluble state in the fuel salt composition 114 can include, but are not limited to:

• Germanium - 72, 73, 74, 76

• Arsenic - 75

• Selenium - 77, 78, 79, 80, 82

• Yttrium - 89

• Zirconium - 90 to 96

• Niobium - 95

• Molybdenum - 95, 97, 98, 100

• Technetium - 99

• Ruthenium - 101 to 106

• Rhodium - 103

•Palladium - 105 to 110

• Silver - 109

• Cadmium - 111 to 116

• Indium - 115

•Tin - 117 to 126

• Antimony - 121, 123, 124, 125

•Tellurium - 125 to 132

[0059] Fission products that can form gaseous products at the typical operating temperature of can include, but are not limited to:

• Bromine - 81

•Iodine - 127, 129, 131

•Xenon - 131 to 136

• Krypton - 83, 84, 85, 86

[0060] Fission products that can remain as chloride compounds in the fuel salt composition 114, in addition to actinide chlorides (Th, Pa, U, Np, Pu, Am, Cm) and carrier salt chlorides (Na, K, Ca), can include, but are not limited to: • Rubidium - 85, 87

• Strontium - 88, 89, 90

•Cesium - 133, 134, 135, 137

•Barium - 138, 139, 140

• Lanthanides

o Lanthanum - 139

o Cerium - 140 to 144

o Praseodymium - 141, 143

o Neodymium - 142 to 146, 148, 150

o Promethium - 147

o Samarium - 149, 151, 152, 154

o Europium - 153, 154, 155, 156

o Gadolinium - 155 to 160

o Terbium - 159, 161

o Dysprosium - 161

[0061] FIG. 3 shows a containment silo 301 for the containment silo 301. In the event of an accident or breach of the reactor system 102, the containment silo 301 can be configured to accommodate and contain any fuel salt or fission products from the reactor vessel 110. The containment silo 301 is shown as being below grade 303, although other arrangements are possible. Starting at the outside, the containment silo 301 can include an outer shell 305, a middle layer 309, and an inner containment well 315. The inner containment well 315 can be capped by a removable lid 319. The removable lid 319 can also include a removable cap 323.

[0062] Optionally, the inner containment well 315 can include a passive heat removal mechanism 325. The passive heat removal mechanism 325 can include heat pipes passing through a portion of the inner containment wall 315. A material that includes at least one of sacrificial salt 327 and graphite 329 can also be contained within the inner containment wall 315. When present, the heat pipes of the passive heat removal mechanism 325 can pass through the material containing the sacrificial salt 327 and/or graphite 329.

[0063] When the reactor system 102 is in operation, the containment silo 301 can house the reactor vessel 110. FIG. 4 is a diagram illustrating one exemplary embodiment of a molten salt reactor containment system 401. The molten salt reactor containment system 401 can include the containment silo 301 enclosed by a removable cap 323. A removable containment vessel 331 can sit within the containment silo 301 and the reactor vessel 110 can sit within the removable containment vessel 331. The molten salt reactor containment system 401 can be configured such that removing the removable cap 323 and lifting the removable containment vessel 331 from the containment silo 301 operates to remove the reactor vessel 110 from the containment silo 301

[0064] The removable containment vessel 331 can houses the reactor vessel 110. Within the removable containment vessel 331, the reactor vessel 110 can sit on or at least partially within a bed of a sacrificial salt 347. Within the containment silo 301, the removable containment vessel 331 can sits on or within at least one of sacrificial salt 327 and graphite 329. The removable containment vessel 331 can also include secondary heat transport connections 343. In certain embodiments, the removable containment vessel 331 can also include electrical connections (not shown). In the event of an accident, the molten salt reactor containment system 401 can be used according to methods described herein to mitigate hazards and contain harmful materials.

[0065] The removable containment vessel 331, the reactor vessel 110, or both can include or be made of stainless steel. In certain embodiments, the inner containment well 315 can be formed from reinforced concrete. Additionally or alternatively, the outer shell 305 can be formed from reinforced concrete.

[0066] The molten salt reactor containment system 401 can also include at least one transfer conduit 408 providing fluid communication between the primary heat exchanger 106 and the secondary system 104. The primary heat exchanger 106 may be contained partially or fully within the reactor vessel 110. Using the depicted system in the event of an accident, the reactor vessel 110 can be removed from the containment silo 30 while keeping it sealed within the removable containment vessel 331

[0067] FIG. 5 is a flow diagram illustrating one exemplary embodiment of a method 501 for removing the reactor vessel 110 from the containment silo 301. As shown, the method 501 can include operations 513-557. However, embodiments of the method 501 can include greater or fewer operations and the operations can be performed in an order different than that illustrated in FIG. 5. Furthermore, while embodiments of the method 501 are discussed below in the context of the NTGP 100, other embodiments of the method 501 can be employed for containment in other systems, without limit. [0068] The method 501 can include operating 513 a reactor system (e.g., reactor system 102) to produce thermal energy. In one embodiment, the method 501 can includes being alerted 519 of a need for removal of the reactor vessel 110, such as by learning of a hazard in operation of the reactor system 102. To remove the reactor vessel 110 from the reactor system 102, the method 501 includes accessing 525 the interior of the containment silo 301 and the removable containment vessel 331. The transfer conduits 408, which can provide part of the transfer fluid loop 134, and any electrical connections can be disconnected to disconnect 527 the reactor vessel 110 from the transfer fluid loop 134. A crane can be connected to the removable containment vessel 331 and operated to hoist 539 the removable containment vessel 331 from the containment silo 301. The removable containment vessel 331 can be isolated 545 from the containment silo 301 and while the condition that gave rise to the hazard is addressed 557.

[0069] It will be noted that the molten salt reactor containment system 401 has been described above in terms of accident containment or hazard mitigation. However, the molten salt reactor containment system 401 can also be used for routine servicing, maintenance, or operation of the reactor system 102. In fact, some embodiments can provide for the uninterrupted production of thermal energy, with periodic maintenance of the reactor system 102. This can be done by providing two reactor systems 102, each within its own molten salt reactor containment system 401. The method 501 can be used to "swap out" one reactor system for maintenance, while the other of the reactor systems continues to operate to provide thermal energy, e.g., to the secondary system 104. Whether for accident response or routine maintenance, the molten salt reactor containment system 401 can provides for the safe isolation of the reactor vessel 110 by lifting the reactor vessel 110 out of the containment silo 301. The reactor vessel 110 can be accessed 525 through the removable cap 323.

[0070] FIG. 6 shows the molten salt reactor containment system 401 after removal of the removable cap 323 from the removable lid 319 to access 525 the interior of the containment silo 301 and the removable containment vessel 331. In some embodiments, the removable containment vessel 331 can sit within the containment silo 301 on a layer of graphite 329 overlaying a bedding of the sacrificial salt 327. As shown, the removable cap 323 can sit within a removable lid 319 of the containment silo 301. The removable lid 319 can be separately removable to allow for the removal of the inner containment well 315 from the outer shell 305. A low-friction middle layer 309 (e.g., rollers or a low-friction material) can be included to facilitate that removal.

[0071] Removing the removable cap 323 can allows the removable containment vessel 331 to be lifted out of the containment silo 301. The molten salt reactor containment system 401 can include a crane operable to lift the removable containment vessel 331 from the containment silo 301.

[0072] FIG. 7 shows a gantry crane 601 useful to lift the removable containment vessel 331 from the containment silo 301. The gantry crane 601 can include a hoist 605 supported by a gantry 613. Optionally, the containment silo 301 can be built at or below grade 303. The gantry crane 601 can use the hoist 605 to lift the removable containment vessel 331 and the reactor vessel 110 from the containment silo 301. In some embodiments, the gantry 613 can be capable of motion in one horizontal direction while the hoist 605 can be capable of motion in a second horizontal direction (e.g., substantially orthogonal to the horizontal direction). By such mechanism, the hoist 605 can be moved into position above the removable containment vessel 331 for the removal of the removable containment vessel 331.

[0073] FIG. 8 shows the removal of the removable containment vessel 331 from the containment silo 301. Because the removable containment vessel 331 houses the reactor vessel 110, this operation can remove the reactor vessel 110 from the containment silo 301.

[0074] Embodiments of the disclosed systems and methods can be particularly useful for a fast-spectrum molten chloride salt reactor. A removable containment vessel 331 can be well suited to a molten salt reactor such as reactor system 102. In the event of a spill, any fuel salt composition 114 that leaves the reactor vessel 110 can generally solidify and not flow into the surrounding environment. The fuel salt composition 114 remaining in the reactor vessel 110 can remain molten and it can be contained by the removable containment vessel 331. The removable containment vessel 331 can be subsequently moved (e.g., by the gantry crane 601) to a backup containment structure, such as a shallow pool or a tank, that can the fuel salt composition 114 and cause it to solidify.

[0075] All references cited throughout this application, for example patent documents including issued or granted patents or equivalents, patent application publications, and nonpatent literature documents or other source material, are hereby incorporated by reference herein in their entireties, as though individually incorporated by reference, to the extent each reference is at least partially not inconsistent with the disclosure in this application. For example, a reference that is partially inconsistent is incorporated by reference except for the partially inconsistent portion of the reference.

[0076] One of ordinary skill in the art will appreciate that starting materials, biological materials, reagents, synthetic methods, purification methods, analytical methods, assay methods, and biological methods other than those specifically exemplified can be employed in the practice of embodiments of the disclosure without resort to undue experimentation. All art-known functional equivalents, of any such materials and methods are intended to be included in the disclosed embodiments.

[0077] When a group of substituents is disclosed herein, it is understood that all individual members of that group and all subgroups, including any isomers, enantiomers, and diastereomers of the group members, are disclosed separately.

[0078] When a Markush group, or other grouping is used herein, all individual members of the group and all combinations and sub-combinations possible of the group are intended to be individually included in the disclosure.

[0079] When a compound is described herein such that a particular isomer, enantiomer, or diastereomer of the compound is not specified, for example, in a formula or in a chemical name, that description is intended to include each isomers and enantiomer of the compound described individual or in any combination. Additionally, unless otherwise specified, all isotopic variants of compounds disclosed herein are intended to be encompassed by the disclosure. For example, it will be understood that any one or more hydrogens in a molecule disclosed can be replaced with deuterium or tritium. Isotopic variants of a molecule are generally useful as standards in assays for the molecule and in chemical and biological research related to the molecule or its use. Methods for making such isotopic variants are known in the art. Specific names of compounds are intended to be exemplary, as it is known that one of ordinary skill in the art can name the same compounds differently.

[0080] As used herein, and in the appended claims, the singular forms "a," "an," and "the" include plural reference unless the context clearly dictates otherwise. Thus, for example, reference to "a cell" includes a plurality of such cells and equivalents thereof known to those skilled in the art, and so forth. Additionally, the terms "a" (or "an"), "one or more" and "at least one" can be used interchangeably herein.

[0081] As used herein, the term "comprising" is synonymous with "including," "having," "containing," and "characterized by" and each can be used interchangeably. Each of these terms is further inclusive or open-ended and do not exclude additional, unrecited elements or method steps.

[0082] As used herein, the term "consisting of excludes any element, step, or ingredient not specified in the claim element.

[0083] As used herein, the term "consisting essentially of does not exclude materials or steps that do not materially affect the basic and novel characteristics of the claim. In each instance herein any of the terms "comprising", "consisting essentially of," and "consisting of may be replaced with either of the other two terms.

[0084] The embodiments illustratively described herein suitably may be practiced in the absence of any element or elements, limitation or limitations which is not specifically disclosed herein.

[0085] The expression "of any of claims XX- YY" (where XX and YY refer to claim numbers) is intended to provide a multiple dependent claim in the alternative form and in some embodiments can be interchangeable with the expression "as in any one of claims XX- YY."

[0086] Unless defined otherwise, all technical and scientific terms used herein have the same meanings as commonly understood by one of ordinary skill in the art to which the disclosed embodiments belong.

[0087] Whenever a range is given in the specification, for example, a temperature range, a time range, a composition range, or a concentration range, all intermediate ranges and subranges, as well, as all individual values included in the ranges given, are intended to be included in the disclosure. As used herein, ranges specifically include the values provided as endpoint values of the range. For example, a range of 1 to 100 specifically includes the end point values of 1 and 100. It will be understood that any subranges or individual values in a range or sub-range that are included in the description herein can be excluded from the claims herein.

[0088] In the descriptions above and in the claims, phrases such as "at least one of or "one or more of may occur followed by a conjunctive list of elements or features. The term "and/or" may also occur in a list of two or more elements or features. Unless otherwise implicitly or explicitly contradicted by the context in which it is used, such a phrase is intended to mean any of the listed elements or features individually or any of the recited elements or features in combination with any of the other recited elements or features. For example, the phrases "at least one of A and Β;" "one or more of A and Β;" and "A and/or B" are each intended to mean "A alone, B alone, or A and B together." A similar interpretation is also intended for lists including three or more items. For example, the phrases "at least one of A, B, and C;" "one or more of A, B, and C;" and "A, B, and/or C" are each intended to mean "A alone, B alone, C alone, A and B together, A and C together, B and C together, or A and B and C together." In addition, use of the term "based on," above and in the claims is intended to mean, "based at least in part on," such that an unrecited feature or element is also permissible.

[0089] The terms and expressions which have been employed herein are used as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding any equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the claimed embodiments. Thus, it should be understood that although the present application may include discussion of preferred embodiments, exemplary embodiments and optional features, modification and variation of the concepts herein disclosed may be resorted to by those skilled in the art. Such modifications and variations are considered to be within the scope of the disclosed embodiments, as defined by the appended claims. The specific embodiments provided herein are examples of useful embodiments of the present disclosure and it will be apparent to one skilled in the art that they may be carried out using a large number of variations of the devices, device components, and methods steps set forth in the present description. As will be obvious to one of skill in the art, methods and devices useful for the present methods can include a large number of optional compositions and processing elements and steps.