AND METHOD

RELATED APPLICATIONS

This application claims benefit of and priority to U.S. Provisional Application Serial No. 62/590,795 filed November 27, 2017, under 35 U.S.C. §§119, 120, 363, 365, and 37 C.F.R. §1.55 and §1.78, which is incorporated herein by this reference.

FIELD OF THE INVENTION

This subject invention relates to nuclear power plant steam generators.

BACKGROUND OF THE INVENTION

Foreign objects within the tube bundle of a steam generator can cause damage to the heat exchanger tubes and leak primary, radioactive water to the secondary side. It is imperative that such objects be located and if possible, removed.

This invention addresses a problem that is presented by the CE-80, OPR-1000, APR-1400 type steam generators and others where their unique geometry requires use of this invention to exceed performance of existing and proven foreign object search and retrieve (FOSAR) technologies. Almost ail other steam generator designs employed in nuclear power plants to this day have an accessible via the No Tube Lane running from one handhole to the other through the center and provide means for deploying conventional FOSAR equipment to perform foreign object search and retrieval operations. Attempts have been made by previous inventions to address this problem by deploying remotely operated equipment, that either ride on the tubesheet or crawl on the internal diameter surface of the steam generator shell, but their success has been limited. The prior technologies do not provide a fixed, safe rail that a robot can travel on, predictably and precisely around the steam generator annulus region and access all areas of the tube bundle. These design deficiencies of existing designs result in getting the retrieving equipment stuck inside the tube bundle, at great expense through lost productivity and endangering the heat exchanger tubes. Another problem with the crawling robots is that they are prone falling from the shell surface to the annulus tubesheet and causing damage. See, for example, U.S. Patent Nos. 5,286,154; 4,702,878; and 6,814,169 incorporated herein by this reference.

BRIEF SUMMARY OF THE INVENTION

Unique features of this invention include its curved rail design, its ability to pivot (using the azimuth rotation module) the robot vehicle's lance/tilt module that transports and drives the segmented FOS AR lance, the approach of a foreign object from an angle which is provided by the position of the rail above the tubesheet and the angled direction of the retrieving tool. The rail design may be fixed by magnets against the shell surface, by pneumatic bladders pushing the rail against the shell surface, and/or by kickstands that hold the rail high above the tubesheet.

The curved rail design in this invention provides a unique platform to drive (locomote) the robot around the annulus safely, predictably, and precisely thus making possible the positioning of the lance carrying robot in front of a targeted for inspection/retrieval tube bundle lane, and avoiding misalignments that cause the lance to either get stuck inside a tube bundle, or make it impossible to enter the lane. The robot pivoting (azimuth rotation) is a unique feature that allows the operator to position die FOSAR lance such, that entry into a lane is certain, driving of the lance is easy because the lance advances parallel to the tube lane, getting the lance stuck is avoided and object retrieval is made easier.

Object retrieval is also made easier by the height of the robot above the tubesheet which provides the FOSAR lance a proven angle of approach to a foreign object for good vision and retrievability.

Another unique feature is the combination of a lance drive and tilt drive in a single module. This feature when combined with azimuth rotation allows lance lane entry at multiple locations around the annulus.

Featured is a steam generator foreign object search and retrieval system comprising a curved rail configured to be deployed from a handhole of the steam generator into and around an outer annulus inside the steam generator shell about a tube bundle of the steam generator. A robot is drivable on the rail around the outer annulus and includes a lance drive. A flexible lance with a lance head is driven by the robot lance drive to position the flexible lance head between tubes of the tube bundle. One or more tools are associated with the flexible lance head for viewing, pushing, and/or grasping a foreign object between the tubes of die tube bundle.

The rail may include interlocking rail sections and may be attached to the handhole. Preferably, the rail includes one or more wheeled kick stands engaging a steam generator tube sheet to support the rail in the annulus. The rail may include one or more expandable bladders engaging tubes of the tube bundle and/or one or more magnets with riding wheels engaging the steam generator shell. A locomotion drive tape may be connected to the robot for pushing and pulling the robot along the rail.

The robo ts preferably rotatable relative to the rail long axis and also tillable.

The system may further include a tool manual control for the lance. Preferably, the lance includes at least one of a retrieval grappler, a pusher tool, one or more fiberscopes and a purge nozzle for each fiberscope. The tool control is configured to extend and retract the retractable grappler tool and to open and close the grappler tool. The tool control is preferably further configured to extend and retract the pusher tool.

Also featured is a method of searching for and retrieving foreign objects in a steam generator. The method comprises installing a rail into and around an outer annulus inside the steam generator about the tube bundle of the steam generator; driving a robot along the rail, and driving a flexible lance relative to the robot positioning a head of the flexible lance between tubes of the tube bundle to view, push, and/or grasp a foreign object between the tubes of the tube bundle.

Installing the rail may include interlocking multiple rail sections to each other, attaching the rail to a handhole of the steam generator, supporting the rail above a tube sheet of the steam generator, expanding bladders between the rail and the tubes of the tube bundle and/or magnetically attaching the rail to the interior of the steam generator shell. Installing the rail may include rolling the rail against the steam generator shell.

Driving the robot along the rail preferably includes connecting a drive tape to the robot and pushing and pulling the drive tape. The method may further include rotating and/or pivoting the robot relative to the rail. The method preferably further includes driving the flexible lance to grasp or push a foreign object between the tubes of the tube bundle.

One steam generator foreign object search and retrieval system comprises a rail configured to be deployed from a handhole of the steam generator into and around an outer annulus inside the steam generator shell about a tube bundle of the steam generator, means for supporting the rail in the annulus, a robot drivable on the rail around the outer annulus and including a lance drive, a flexible lance with a lance head and driven by the robot lance drive to position the flexible lance head between tubes of the tube bundle, and one or more tools associated with the flexible lance head for viewing, pushing, and/or grasping a foreign object between the tubes of the tube bundle. The means for supporting the rail preferably includes one or more rail kick stands engaging a steam generator tube sheet, one or more expandable bladders between the rail and tubes of the tube bundle, and/or one or more magnets on the rail.

Also featured is a method of seaidiing for aiid retrieving

generator comprising installing a rail into and around an outer annulus inside the steam generator about the tube bundle of the steam generator; supporting the rail in the annulus, driving a robot along the rail, and driving a flexible lance relative to the robot positioning a head of the flexible lance between tubes of the tube bundle to view, push, and/or grasp a foreign object between the tubes of the tube bundle.

The subject invention, however, in other embodiments, need not achieve all these objectives and the claims hereof should not be limited to structures or methods capable of achieving these objectives.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Other objects, features and advantages will occur to those skilled in the art from the following description of a preferred embodiment and the accompanying drawings, in which:

Fig, 1 is a schematic view showing a preferred rail configured to be deployed from a steam generator handhole and into and around the outer annul us inside the steam generator shell about the steam generator tube bundle;

Fig.2A-2F are schematic views showing the installation of a rail section;

Fig. 3 is a schematic three dimensional view showing the rail now installed inside the steam generator outer annulus;

Fig.4 is a schematic view showing an example of a robot drivable on the rail;

Fig.5 is another schematic view showing the robot drivable on the rail and deploying a flexible lance;

Fig.6 is a schematic view showing how the robot can be rotated via an azimuth motor;

Fig. 7 is a schematic view showing an example of the flexible lance head;

Fig. 8 is a schematic view showing an example of a manual controls for the FOSAR lance retrieval tools;

Figs.9-11 are schematic views showing additional details of the FOSAR lance retrieval tools;

Fig. 12 is a view of the steam generator foreign object search and retrieval system manual control unit; and

Fig. 13 is a block diagram depicting the primary components associated with a preferred steam generator foreign object search and retrieval system.

DETAILED DESCRIPTION OF THE INVENTION

Aside from the preferred embodiment or embodiments disclosed below, this invention is capable of other embodiments and of being practiced or being carried out in various ways. Thus, it is to be understood that the invention is not limited in its application to the details of construction and the arrangements of components set forth in the following description or illustrated in the drawings. If only one embodiment is described herein, the claims hereof are not to be limited to that embodiment Moreover, the claims hereof are not to be read restrictively unless there is clear and convincing evidence manifesting a certain exclusion, restriction, or disclaimer.

Fig. 1 shows a curved rail 10 installed via a steam generator handhole 12 into and around outer annulus 14 inside steam generator 15 shell 16 and about tube bundle 18 of the steam generator 15 including individual tubes 20. Each rail segment may be of length that allows ease of installation. The purpose of the rail is to allow a robot to travel along the rail which itself drives a flexible lance between individual tubes 20 of the tube bundle 18.

Rail 10 may include magnets 22 attached to the interior of steam generator shell 16 and/or inflatable bladders 24 engaging the tubes 20 of the tube bundle 18 in order to support the rail in place in annulus 14. Each magnet may include one or more wheels bearing against the generator shell.

Figs.2A 2F show how rail segment 10b is coupled to rail segment 10a using a positive engagement system and secured with high strength pins 11.

Fig. 3 shows kickstands 30 with wheels 31 which engage the steam generator tube sheet below the rail to further support the rail in the annulus. Fig.3 also shows rail section 10c attached to handhole 12.

Robot 40, Figs.4-6 engages rail 10 and is drivable along the rail in the steam generator annulus. In one example, tape drive 42 includes tape 44 (e.g., stainless steel) connected to robot frame portion 46 and extending along the rail between opposing tape guide roller sets 48 and driven by motorized tape drives sprocket SO. Also, robot frame 46 includes rollers 52 riding in rail slots on each side of the rail. In this way, tape 44 pushes and pulls robot 40 along the rail.

Fig.5 shows flexible lance 60 driven by a robot lance drive sprocket itself driven by lance drive motor 64 which extends and retracts the lance head into and out of the steam generator tube lane. Tilt drive motor 66 and robot azimuth drive motor 68 rotate the robot 40 around its horizontal and vertical axes respectively allowing the lance always to enter a lane parallel to the tubes for more reliable tube gap entry and manual lance removal. Lance 60 may be protected from damage in the annulus using a lance management sleeve. Fig. 5 also shows foreign object tray 63 which travels with robot 40 and is attached to frame member 46. Fig.6 further shows how the azimuth motor rotates the robot so the lance enters a tube lane at 90°.

Fig. 7 shows lance 60 head 70 with tools such as extendible and retractable grasper 72 for grasping foreign objects and placing them into foreign object tray 63, Fig. 5 or for removing the foreign object from the steam generator. Lance head 70 may further include extendible and retractable pusher tool 74 for pushing a foreign object to dislodge it from between two adjacent steam generator tubes. Fiberscopes 76 provide viewing foreign objects and the steam generator tubes. A gas (e.g., nitrogen) purge hose 78 may terminate in a nozzle.

Fig. 8 shows manual controls 90 for the FOSAR retrieval tools of the lance 60 with tool driver 92 which extends and retracts the grappler tool, tool driver 94 which opens and closes the jaws of the grappler, and tool driver 96 which extends and retracts the pusher tool. See also Figs. 9-11.

Fig. 12 shows manual control unit 100 which includes locomotion and lance joysticks, tilt and azimuth rotation switches and a computer display screen that provides the operator visual and data feedback from the robot and lance. Fig. 13 is a block diagram showing the primary components associated with a preferred system.

The In-Bundle FOSAR system for steam generators such as the CE-80, OPR- 1000, APR- 1400 preferably includes the following subsystems: 1) an in-bundle FOSAR flexible lance for inspecting/removing loose foreign objects from all in-bundle accessible lanes, 2) an annulus rail, 3) a robot module deployed in the annulus region, 4) a robot and lance control box, and 5) a handhole support equipment .

The purpose of the FOSAR system design is to provide capability to inspect the in-bundle area of any of these steam generators and to identify/remove loose foreign objects.

The preferred in-bundle FOSAR system includes a flexible lance assembly, driven in and out of the tube-sheet lanes using a robotic transport vehicle. The robot is based on CECIL® waterlancing robot, using a proven rugged and reliable design. It may be controlled using a computerized and/or manually-operated remote control box. In- bundle FOSAR operations are manual and are performed by operators located at the handhole. The flexible lance assembly consists of the lance head, the lance main body, retrieval tools, fiberscope/camera, light-pipe, and retrieval tools manual control.

Preferred FOSAR system equipment attributes include safe installation and removal, minimum use of hand tools, visual feedback, easy change out of grappler tools, procedures to maintain cleanliness throughout operations, easy decontamination and operation and troubleshooting procedures.

The in-bundle FOSAR is designed to operate within the tube bundle of a steam generator in all accessible lanes from the steam generator's annulus region. The annulus area should be free and clear of any obstructions from the tubesheet to 403 mm (TYP) above it The in-bundle FOSAR lance accesses the tube bundle from the annulus region. It is driven in and out of the tube lanes by a robot that travels on a temporary rail deployed in the annulus region of the steam generator. The lance and robot movement are controlled using the computerized and/or manually operated remote control box. Foreign object retrieval operations are conducted by technicians positioned at the handhole area. Typical flexible FOSAR lance components include a FOSAR lance head (stainless steel), a foreign object retrieval grappler (high strength hardened steel), a pusher tool (stainless steel and rare earth magnet), a camera (or fiberscope) with light bundle, Air (or nitrogen) purge, primary and secondary hosebars (high strength stainless steel and plastic), tensioning /safety cables (aircraft quality multi-strand stainless steel), a mid-lance transition /tensioning block (stainless steel), and a manual FOSAR Control Box (anodized aluminum).

The lance head is designed to house both a straight and side view fiberscope.. The lance head as shown in Fig. 7 has both a pusher tool and a grappler assembly. The pusher tool assists in determining if an object is loose or fixed to the tube sheet It can also reposition an object for ease of grappling it Once an object is secured in the grappler jaws, the lance head will be withdrawn to the annulus and can either release the object in a catch container that travels with the robot or transport the object out of the steam generator for release. At the end of operations for a given steam generator quadrant, the robot is driven to the handhole area where the objects are removed from the catch container. A major feature in the design of the FOSAR lance head is that it is angled, and the grappler can approach a foreign object from above in all areas of the bundle. The grappler holding strength ensures safe transport of the objects to the catch container and safe transport outside the steam generator.

The in-bundle FOSAR is capable of picking up loose foreign objects and removing them from within the tube bundle. This assumes that the overall width of the object, plus the thickness of the grapple fingers, do not exceed the inter-tube gap width.

The FOSAR tool control box (Fig.8) located at the end of the lance provides the user with the ability to manipulate the flexible lance functions for retrieving an object. These functions include the ability to extend/retract the grappler, extend/retract the pusher tool, and open/close the grappler for capturing and releasing an object

The rail assembly preferably includes short segments of a length that allows ease of installation from the steam generator handhole, The short segments are assembled at the handhole, and then pushed in and around the annulus. A pair of unique rail section transition the rail from the annulus, through the handhole, and out of the handhole. The rail sections interlock with each other, and for additional safety, a rail pins are used to hold them in place. Assembly of the rail section is performed at the handhole by a technician. During mating of two rail sections, a pair of pre-installed Rail Insertion Devices (RIDs) may be attached to the handhole flange, to provide a level surface for the sections to rest on and to help the technician maintain control of them at all times. The rail spans one full quadrant of the steam generator and is firmly attached to the handhole. It is supported with kickstand(s) which ride on the tubesheet and expandable rubber bladders against the tubes providing stability during FOSAR operation.

In addition, magnets and riding wheels are incorporated on the rail side against the steam generator shell to hold the rail firmly against it during installation and operations. The magnets combined with the bladders have sufficient force to provide for a secure operation. The riding wheels allow the rail to glide easily into the annulus. The rail provides the means for robot locomotion in the annulus region and allows the lance to align with each tube lane. The FOSAR system rail design is unique and is adaptable to all three steam generator types: CE-80, OPR-1000, APR- 1400. The robot assembly preferably includes a housing which supports the necessary functions for the safe In-bundle FOSAR operations. There are preferably four axes provided for the robot module: robot locomotion via a tape drive, robot tilt, robot azimuth rotation, and lance extend-retracL

The robot locomotion drive moves the robot on the rail in and out of the steam generator annulus. The locomotion drive motor assembly is located outside of the handhole. It is attached to the outside rail section. A perforated stainless steel drive tape securely attached to the robot is driven back and forth by the drive assembly sprocket located in the tape drive housing. The tape pushes and pulls the robot in and out of the steam generator using proportional control at the manual control box, and allows the operator to position the robot in front of a target tube lane for entry. In the event the drive motor malfunctions, the drive can be easily disengaged at the handhole. This allows required repairs to be performed on the drive. If needed, the robot can be pulled out of the steam generator by simply pulling the tape.

The robot tilt rotates the robot so that the lance exits at a desired angle with respect to the steam generator tubesheet. During initial lance entry into a lane, the lance needs to be nearly parallel to the tubesheet to prevent lance sticking and buckling. During operations, the robot is tilted so that the lance sees the tubesheet at an angle. This enables the operators to inspect the tubesheet from a short standoff distance and makes it possible to attempt retrieval of an object from above rather than approaching it with a parallel to the tubesheet motion.

There is preferably no scenario where a robot tilt drive malfunction can prevent equipment removal from the steam generator. If the tilt motor malfunctions it is not necessary to have a provision for drive disengagement

The lance rotational position (azimuth) is changed using a DC motor drive proportionally controlled from the robot control box using an observation camera mounted to the robot module for guidance. The camera provides visual feedback to ensure the operator positions the lance head parallel and fully aligned to a tube lane before the lance is driven in. The azimuth movement is necessary in order to compensate for the steam generator curvature and thus allows proper lance lane entry. The specially designed proportional lance head movement that is provided with this system gives the lance the ability to move smoothly back and forth in each tube lane and minimizes the risk of the lance sticking and buckling. In the event an azimuth motor malfunction takes place, pulling on the cable at the handhole disengages the drive gear from the motor gear. The cable is attached to the detente drive gear assembly and its back end is fully accessible at the handhole. When disengagement takes place the robot-lance assembly can safely be removed from the steam generator.

The lance drive is housed inside the robot and includes, a DC motor

proportionally controlled from the control box, and a sprocket assembly that provides positive engagement with the lance hosebars. The sprocket pitch matches the hosebar pitch, providing lance motion forward and reverse in a rack and pinion fashion. Using the proportional control and the operator's skill, the lance can be precisely positioned at a desired location for either lane inspection, or foreign object retrieval. The sprocket assembly is mounted on a movable detente sled that enables lance-sprocket disengagement. For the disengagement, the design provides a cable that is attached to the sprocket sled detente and its back end is accessible at the handhole. Pulling on the cable disengages the lance-sprocket in the event the lance motor malfunctions and the lance can be pulled to its home position for sale equipment removal.

All drives, including locomotion, robot tilt, lance extend/retract and azimuth, will be proportionally controlled utilizing DC motors activated manually from the robot control box. All motors include encoders providing position feedback to the operator via the system computer display monitor. In addition, current and voltage limits are imposed to these drives to ensure the forces and drive speeds remain within safe values to prevent damaging any of the three steam generators: CE-80, OPR-1000, APR- 1400 FOSAR equipment or the steam generator tubes.

The Manual Cintrol Unit of Fig. 12 is located either near the handhole or up to 50 meters away from it at a remote location.. The operator can perform the following functions using rotational and joystick devices: drive the robot along the rail, extend the lance in and out of the tube bundle, tilt the lance, and/or adjust the lance rotational (azimuth) position.

To assist the operator during the above operations, the design provides feedback from the drive motor encoder and displays either robot locomotion length into the annulus (mm), lance extend length into a lane (mm), robot tilt rotation (degrees) and azimuth rotation (degrees).

The handhole equipment preferably includes a handhole adaptor plate, a lance management system (as required and maybe different for each steam generator type), a robot umbilical, a manual control unit cable interconnection box, a pneumatic box, a handhole and control monitors, a recording device, a rail insertion device, a camera box, and camera light sources.

The handhole adaptor is an interface plate that is bolted onto the steam generator handhole flange. It is used to attach the outside rail section, the RID during rail installation and removal, the lance management equipment and any other special tools that may be needed for safe equipment installation and removal. The lance management system provides lance support and maintains proper lance tension during operations. The cable interconnection box houses electrical terminal blocks and converters to enhance the encoder feedback for transmission to the manual control unit The pneumatic box houses pressure regulators and on-off switches to control the camera purge and rail bladder control functions. The design provides two monitors that display images from the lance fiberscope and the robot camera. One monitor will be used by the FOSAR tool control operator and the other by the manual control unit operator. A recording device is provided to record the images received from the fiberscope and the robot camera. The Rail Insertion Device (RID) includes multiple platforms (fixed and adjustable) that are installed into the steam generator annulus to the left and right side of the handhole and attached to the interface plate. When two rail sections are inserted into the steam generator, the technician uses the RID to support the sections and perform the interlock and fastening functions.

The camera box houses the accessory components for bom, the fiberscope and the robot camera. Outside the camera box, there are two light sources to provide camera and fiberscope lighting independently. Several special tools may include manual removal tools, installation/removal tools and/or special system maintenance tools.

A robust and reliable FOSAR is a major component of the system design. The FOSAR equipment is intended for in-generator use and has the following characteristics: 1) capable of withstanding typical steam generator conditions as expected during an outage. These conditions are: Temperature 60 degrees C; Humidity 100°o;

Radiation Level = 0.01 Sv/hr. 2) constructed of materials in accordance with the requirements of steam generator manufacturer's technical specification, 3) designed to enter/exit the access handhole area smoothly without damaging the FOSAR system or steam generator components.

The components entering or attaching to the steam generator are designed, to the maximum extent practical, with provisions for adjustments in order to accommodate steam generator access hole dimensional irregularities within agreed tolerances.

The robot module will have provisions for manual removal of the flexible lance and the robot from within the steam generator by disengagement of locomotion tape drive, lance drive and azimuth mechanisms, even in the case of loss of electrical power.

Robot components and the support rail are designed for ease of decontamination to the maximum extent practical.

The robot and support equipment are designed for rapid installation in confined spaces at the steam generator handhole platforms with physical obstructions as close as 1 ½ meters away from the steam generator access opening.

Installation of the robot, support rail, and support equipment is facilitated by minimizing the number of tools necessary for installation. The installation tools provided for use at the steam generator access holes will be attached with lanyards to prevent loss.

Although specific features of the invention are shown in some drawings and not in others, this is for convenience only as each feature may be combined with any or all of the other features in accordance with the invention. The words "including",

"comprising", "having", and "with" as used herein are to be interpreted broadly and comprehensively and are not limited to any physical interconnection. Moreover, any embodiments disclosed in the subject application are not to be taken as the only possible embodiments. Other embodiments will occur to those skilled in the art.

What is claimed is: