Internal structure lifting device

Abstract

The present disclosure provides a lifting and transport apparatus for lifting upper internals from a nuclear power system core at a deployment location and transporting them to a storage location. The lifting / transport apparatus includes an apparatus body formed of a radioactive shielding material, the apparatus body defining a storage chamber having an open base. The apparatus further includes a movable sealing plate formed of a radioactive shielding material, the sealing plate being movable between an open position in which the storage chamber is open and a closed position in which the storage chamber is sealed. There is also a lifting system mounted within the storage chamber, the lifting system having a lifting rig for releasably connecting to the upper internals and configured to raise the upper internals into the storage chamber when the apparatus is at the deployment location and the plate is in the open position. The apparatus includes wheels for guiding movement of the lifting / transport apparatus between the deployment location and the storage location.

Description

Technical Field

[0001] The present disclosure relates to an apparatus and method for removing upper internal structures from a reactor core in a nuclear power generation system during maintenance and refueling operations.

Background Art

[0002] A nuclear power plant converts thermal energy from the nuclear decay of fissionable materials contained in fuel assemblies within the reactor core into electrical energy. A water-cooled nuclear power plant such as a pressurized water reactor (PWR) plant includes a reactor pressure vessel (RPV) containing the reactor core / fuel assemblies, and a turbine for generating electricity from steam generated by heat from the fuel assemblies.

[0003] A PWR plant has a pressurized primary coolant circuit that flows through the RPV and transfers thermal energy to one or more steam generators (heat exchangers) within the secondary circuit. The (low-pressure) secondary circuit includes a steam turbine that drives a generator for power generation. These components of a nuclear power plant are conventionally housed in an airtight containment building, which can be in the form of a concrete structure.

[0004] The RPV typically includes a body that defines a cavity for housing the reactor core / fuel assemblies, and a closure head for closing the upper opening to the cavity. The closure head can further form part of an integral head package (IHP) (or integral head assembly) that includes control rod drive mechanisms contained within a shroud. The control rod drive mechanisms include drive rods that pass through the closure head and are connected to control rods contained within the reactor core. The control rods are provided to absorb neutron radiation within the reactor core and control the nuclear reaction within the reactor core. The drive rods within the control rod drive mechanisms are powered by an electrical source and translate vertically to raise and lower the control rods within the reactor core.

[0005] The reactor core further includes guide columns for the control rods, which together with the associated electronics are commonly referred to as the "upper internal structures."

[0006] Maintenance and refueling are critical parts of the operation of nuclear power systems. For example, regular maintenance is required to replace old and / or damaged parts of the system. Refueling is required periodically (e.g., every 18 to 24 months) to replace spent fuel rods within fuel rod assemblies.

[0007] When performing core maintenance / refueling, it is necessary to remove the IHP from the RPV, thereby exposing the core. Once the core is exposed, the upper internal structures are removed from the core to access the fuel rod assemblies.

[0008] In nuclear power plants, overhead crane systems, such as polar gantry cranes with circular runways, are typically installed within the system's containment structure to perform maintenance and refueling operations. Because they enable the lifting of heavy components of nuclear power plants, polar cranes are inherently large and heavy structures. This makes their installation expensive.

[0009] During refueling, the polar crane typically lifts the IHP vertically upward from the RPV body, moves it horizontally away from the RPV body, and then lowers it onto a storage stand on the work platform inside the containment building. The polar crane is then used to lift the radioactive upper internal structure, which typically weighs about 15 to 50 tons. The polar crane raises the internal structure vertically and then horizontally before lowering it into a water storage pool. This is to provide gamma shielding around the internal structure during refueling.

[0010] To provide a refueling cavity above the exposed core within the reactor vessel, the reactor vessel is typically positioned at a considerable distance below the work platform of the containment structure. During the removal of IHP from the reactor vessel, the drive rods remain connected to the control rods and protrude from the reactor vessel cavity into a refueling cavity filled with water to contain any radioactive release from the drive rods.

[0011] The upper internal structure must pass through the vertical height of the drive rod / fueling cavity and then be moved horizontally to descend into the storage pool; therefore, the vertical range of the protruding drive rod and fueling cavity is driven by the polar crane to the required lifting height of the upper internal structure.

[0012] The required lifting height of the polar crane determines the height of the containment structure (and therefore the cost / time associated with constructing the containment structure). The risks associated with dropping the upper internal structure onto the reactor core from a considerable vertical height are extremely high. [Overview of the project] [Problems that the invention aims to solve]

[0013] There is a need for improved nuclear power systems that mitigate at least some of the problems associated with known systems. [Means for solving the problem]

[0014] In the first embodiment, a lifting and transporting device is provided for lifting the upper internal structure of a nuclear power plant core at a deployment site and transporting it to a storage location, the lifting / transporting device is A device body formed of radioactive shielding material, defining a storage chamber having an open base, A movable sealing plate made of a radioactive shielding material, which is movable between an open position in which the storage chamber is open and a closed position in which the storage chamber is sealed, A lifting system mounted within a storage chamber, having a lifting rig for releasably connecting to an upper internal structure, and configured to raise the upper internal structure into the storage chamber when the device is in the deployed position and the plate is in the open position, Wheels for guiding the movement of the lifting / transporting device between the deployment area and the storage area, Includes.

[0015] By providing a device having a body and sealing plate formed of radioactive shielding material, the upper internal structure can be housed within the device (and stored in a storage location) after removal from the core, thus eliminating the need for a storage pool. When the storage chamber is open (i.e., the sealing plate is in its open position and the device is in the deployment location), the upper internal structure can be pulled from the core into the storage chamber using a lifting rig. This eliminates the need for a polar crane to lift the upper internal structure vertically, thus reducing the height and construction cost / time of the containment structure. Wheels allow for the movement of the device (and therefore the upper internal structure) between the deployment location and the storage location (e.g., on the work platform of the containment structure) (e.g., horizontal movement). This horizontal movement would have previously been performed by a polar crane.

[0016] Herein, optional features of the present disclosure are described. These can be applied individually or in any combination with any aspect of the present disclosure. In some embodiments, the body may be formed of steel. It may have a top (substantially horizontal) wall. It may have four (substantially vertical) side walls forming a rectangular storage cavity. Alternatively, it may have cylindrical walls forming a cylindrical storage cavity. These walls may each have a thickness between 100 and 200 mm, for example between 120 and 180 mm or between 140 and 160 mm, for example, about 150 mm. Steel walls with a thickness of 150 mm provide radiation shielding equivalent to a water depth of 1 m in a storage pool. These walls may be lined with lead.

[0017] The sealing plate, when in its closed position, forms the base of the storage cavity. In its closed position, it forms a liquid-tight seal with the body, preventing any radioactive liquid from penetrating from the device. The sealing plate can be made of steel. It can have a thickness between 100 and 200 mm, for example between 120 and 180 mm or between 140 and 160 mm, for example, about 150 mm. The sealing plate can be slidably moved between its open and closed positions.

[0018] The sealing plate can be moved between its open and closed positions (for example, slidably) by an actuator that can be operated by a control system located remotely from the device.

[0019] In some embodiments, the lifting system includes one or more winches / hoists. These can be mounted on the inner surface of the upper (substantially horizontal) wall within the storage cavity. The lifting system can be operated by a control system located remotely from the device.

[0020] The lifting system may further include a gripper element for connecting to an upper internal structure. For example, the gripper element may be a servo-operated gripper / clamping element for grasping / clamping a handle provided on the upper internal structure. The lifting system may include one or more sensors (e.g., load sensors) for detecting an effective connection (e.g., of the gripper element) to the upper internal structure (e.g., to a handle on the upper internal structure).

[0021] The device may further include an opening frame for supporting the main body. Wheels can be attached to the opening frame. In these embodiments, the opening in the frame is aligned with the opening base of the storage chamber so that the upper internal structure can be lifted through the opening and opening base using a lifting system when the sealing plate is in its open position (and the device is in its deployed position).

[0022] In some embodiments, the apparatus further includes a liquid (e.g., water) supply system installed within the storage chamber to maintain moisture levels in the upper internal structures stored within the apparatus, so as to prevent radioactive vapor from forming and diffusing throughout the containment structure. The supply system may include one or more liquid spray nozzles. The liquid supply system may include a recirculation pump, which may include a liquid storage tank. In these embodiments with a liquid supply system, the apparatus may further include a discharge system for discharging the liquid from the apparatus.

[0023] In some embodiments, the device further includes a motor for driving wheels to move the device from deployment to storage. The motor can be operated by a control system located remotely from the device. The wheels can be flanged, i.e., wheels having a reduced diameter portion sandwiched axially between two flanges. Thus, the wheels can be configured to be driven along rails / tracks.

[0024] This device can be made foldable. That is, this device can be configured to be movable between a folded configuration and an extended configuration. This can be facilitated, for example, by the structure of the device including nested, pivoting or hinged components. This device can include an actuator for moving the device between its folded and extended configurations. In the folded configuration, the height and / or width of the device can be made less than in the extended configuration. This device can be made movable (e.g., drivable) in the folded configuration. Thus, when it is required for the device to move through an opening, for example, to enter or exit a storage structure, the size of the opening (i.e., for accommodating the device) can be minimized. Accordingly, this device can be transported in the folded configuration and maintenance operations (e.g., removing an upper internal structure) can be performed in the extended configuration.

[0025] In a second aspect, there is provided a nuclear power generation system including a device according to the first aspect and a nuclear reactor vessel comprising a nuclear reactor vessel body defining a cavity for accommodating a reactor core including a control rod assembly and an upper internal structure for guiding the control rod assembly, a closure head configured to seal against the nuclear reactor vessel body to close an opening to the cavity, and a nuclear reactor vessel having the same.

[0026] This nuclear power generation system can be a pressurized water reactor system.

[0027] The reactor vessel may include an integrated head package (IHP) which includes a closure head and a control rod drive mechanism housed within a shroud. The control rod drive mechanism includes at least one drive rod (and preferably more drive rods) extending through the closure head, and each of its drive rods has a coupling element (e.g., a pneumatic coupling element) for releasably coupling to a control rod assembly in the core. At least one drive rod is movable to a maintenance / refueling position in which at least one drive rod is detached from the control rod assembly and retracted at least partially (preferably completely) into the IHP (e.g., into the shroud). The IHP further includes at least one locking element for locking at least one drive rod in the maintenance / refueling position.

[0028] This IHP (Injection Heat Pump) makes it possible to remove the drive rods from the reactor core along with the IHP. In this way, the radioactive drive rods will no longer remain protruding from the reactor core, eliminating the need to flood the refueling cavity.

[0029] Therefore, in some embodiments, the system includes a storage structure, the working floor of which surrounds the opening to the cavity and is substantially aligned with it.

[0030] Given the scale of nuclear power generation systems, the term "substantially vertically aligned" means that the vertical distance between the work platform and the opening to the cavity (defined by the upper edge of the reactor vessel body) is less than 2 meters, for example, 1 meter or 0.5 meters above the opening to the cavity within the reactor vessel body.

[0031] In some embodiments, the work platform includes at least one path extending from the vicinity of the reactor vessel to a (remote) storage location, the at least one path being substantially perpendicular to the opening of the reactor vessel body to the cavity. The remote storage location may be located outside the containment structure, for example, in a shielded detachment.

[0032] In some embodiments, at least one path may be a linear path extending between the reactor vessel body and the storage area. In some embodiments, at least one path may be a substantially horizontal path.

[0033] In some embodiments, at least one path may include a track or rail extending from between the reactor vessel body and the storage area, and the wheels of the equipment are mounted on the track / rail. The track / rail can be aligned substantially vertically with the opening to the cavity within the reactor vessel body. The use of a track / rail can facilitate the automation of the movement of maintenance / refueling equipment along at least one path, thereby reducing the number of workers required to perform maintenance / refueling (which reduces the safety risks associated with these processes).

[0034] The tracks / rails may include removable / temporary portions that extend vertically above the reactor vessel body so that the lifting / transporting equipment can be positioned directly above the reactor vessel body / core. Alternatively, the tracks / rails may be spaced apart from each other by a distance greater than the width of the opening to the cavity in the reactor vessel so that the lifting / transporting equipment can be positioned directly above the reactor vessel body / core.

[0035] In some embodiments, the lifting device is deployed vertically above the reactor vessel body. Thus, when the sealing plate is in its open position, the lifting system can extend into the core to engage the upper internal structure and lift it vertically upward.

[0036] In some embodiments, the system includes a control system for sending control signals to actuate a sliding sealing plate and / or a lifting system, and / or drive wheels. The control system (and any associated user interface) can be remote from the reactor vessel.

[0037] In some embodiments, the system includes drainage conduits extending from the device's drainage system (if provided) to the system's primary cooling circuit.

[0038] In a third embodiment, a method is provided for removing upper internal structures from an exposed reactor core in a nuclear power plant system according to a second embodiment, using the apparatus according to a first embodiment (for example, for maintenance / refueling).

[0039] In some embodiments, this method is The steps include removing the closure head (e.g., an integrated head package) from the reactor vessel body, With the sealing plate in its open position, the step of moving the device to a deployment location vertically above the reactor vessel body (for example, by driving the device's wheels along a path or track / rail), The steps include lowering the lifting rig (for example, using at least one winch / hoist) and connecting it to the upper internal structure, The steps include raising the upper internal structure vertically into the storage chamber using a lifting system (for example, by lifting it with at least one winch / hoist), The steps include sealing the storage chamber by moving the sealing plate to its closed position, The steps include moving the device to a storage location (for example, by driving the device's wheels along a path or track / rail), Includes.

[0040] In some embodiments, this method is The steps include moving the device to the deployment location (for example, by driving the device's wheels along a path or track / rail), The steps include opening the storage chamber by moving the sealing plate to its open position, The steps include lowering the upper internal structure vertically into the reactor core using a lifting system (for example, using at least one winch / hoist), Steps include: separating the lifting rig from the upper internal structure, The steps include raising the lifting rig from inside the reactor core into the storage chamber (for example, by lifting it with at least one winch / hoist), A step of moving the sealing plate to the closed position, The steps include moving the device away from its deployment location (for example, to a storage location) (for example, by driving the device's wheels along a path or track / rail), This further includes the step of returning the upper internal structures to the exposed core (for example, after maintenance / refueling).

[0041] In some embodiments, this method may include the step of sliding a sealing plate between its open and closed positions. This method may include remote operation of the movable sealing plate by a control system located remotely from the apparatus, i.e., this method may include the step of sending an output signal from the control system to an actuator associated with the sealing plate (e.g., by input at the user interface of the remote control system) to move (e.g., slide) the sealing plate.

[0042] This method may include remote operation of the lifting system by a control system located remotely from the device. Thus, this method may include the step of sending an output signal from the control system to the lifting system (for example, by input at the user interface of the remote control system) to lower the lifting rig for connection to the superstructure. This method may also include the step of sending an output signal from the control system to the lifting system (for example, by input at the user interface of the remote control system) to raise the lifting rig after connection to the superstructure.

[0043] After refueling / maintenance, this method may include the step of sending an output signal from the control system to the lifting system (for example, via input at the user interface of the remote control system) to lower the lifting rig and superstructure into the reactor core. This method may also include the step of sending an output signal from the control system to the lifting system (for example, via input at the user interface of the remote control system) to raise the lifting rig after it has been separated from the superstructure.

[0044] In some embodiments, the method further includes the step of spraying a liquid (e.g., water) onto an upper internal structure within a storage chamber. In these embodiments, the method includes the step of discharging the liquid from the apparatus, for example, into the system's primary cooling circuit.

[0045] In some embodiments, this method includes the step of moving the device between deployment and storage locations along a working floor of a storage structure (e.g., along a linear horizontal path) which is substantially vertically aligned with an opening to a cavity.

[0046] This method may include the step of moving the device to a storage location outside the storage structure, for example, in a shielded detached area, and from there.

[0047] In some embodiments, the method includes the step of driving the frame wheels of a refueling device along a track or rail extending between a deployment location and a storage location, the wheels of the device being mounted on the track / rail. The track / rail can be aligned substantially vertically with an opening to a cavity within the reactor vessel body.

[0048] This method may include the step of moving the device vertically to the deployment location on the reactor vessel body.

[0049] The present invention includes, is configured as part of, or can be used in conjunction with, a nuclear reactor power plant (hereinafter referred to as a reactor). In particular, the present invention may relate to a pressurized water reactor. The nuclear reactor power plant may have an output between 250 and 600 MW, or between 300 and 550 MW.

[0050] A nuclear reactor power plant can be a modular reactor. A modular reactor can be considered a reactor composed of numerous modules manufactured off-site (for example, in a factory), which are then assembled on-site into a nuclear reactor power plant by connecting them together. The primary, secondary, and / or tertiary circuits can all be formed using a modular structure.

[0051] A nuclear reactor may include a primary circuit comprising a reactor pressure vessel, one or more steam generators, and one or more pressurizers. The primary circuit circulates a medium (e.g., water) through the reactor pressure vessel to extract heat generated by nuclear fission in the core, which is then delivered to the steam generators and transferred to the secondary circuit. The primary circuit may include steam generators between 1 and 6, or between 2 and 4, or three steam generators, or any range of the aforementioned numbers. The primary circuit may include one, two, or more than two pressurizers. The primary circuit may include circuits extending from the reactor pressure vessel to each of the steam generators, the circuits capable of carrying a high-temperature medium from the reactor pressure vessel to the steam generators and returning a cooling medium from the steam generators to the reactor pressure vessel. The medium may be circulated by one or more pumps. In some embodiments, the primary circuit may include one or two pumps for each steam generator in the primary circuit.

[0052] In some embodiments, the circulating medium in the primary circuit may include water. In some embodiments, the medium may include neutron-absorbing materials (e.g., boron, gadolinium) added to the medium. In some embodiments, the pressure in the primary circuit may be at least 50, 80, 100, or 150 bar during full-power operation, and the pressure may reach 80, 100, 150, or 180 bar during full-power operation. In some embodiments, when water is the medium in the primary circuit, the heated water temperature of the water leaving the reactor pressure vessel may be between 540 and 670 K, or between 560 and 650 K, or between 580 and 630 K during full-power operation. In some embodiments, when water is the medium in the primary circuit, the cooled water temperature of the water returning to the reactor pressure vessel may be between 510 and 600 K, or between 530 and 580 K during full-power operation.

[0053] A nuclear reactor may include a secondary circuit that includes a water circulation loop in a steam generator that extracts heat from the primary circuit, converts water into steam, and drives a turbine. In an embodiment, the secondary loop may include one or two high-pressure turbines and one or two low-pressure turbines.

[0054] The secondary circuit may include a heat exchanger that condenses the steam into water when it is returned to the steam generator. The heat exchanger may be connected to a tertiary loop that can include a large body of water that acts as a heat sink.

[0055] The reactor vessel may include a steel pressure vessel, which is 5 to 15 m high or 9.5 to 11.5 m high and has a diameter between 2 and 7 m, or between 3 and 6 m, or between 4 and 5 m. The pressure vessel may include the reactor body and a reactor head positioned vertically above the reactor body. The reactor head may be connected to the reactor body by a series of studs passing through flanges on the reactor head and corresponding flanges on the reactor body.

[0056] The reactor head may include an integrated head assembly that can integrate numerous elements of the reactor structure into a single element. These integrated elements may include the pressure vessel head, cooling shroud, control rod drive mechanism, missile shield, lifting rig, hoist assembly, and cable tray assembly.

[0057] A nuclear reactor core can consist of numerous fuel assemblies, each containing fuel rods. Fuel rods can be formed from pellets of fissile material. A fuel assembly can also contain space for control rods. For example, a fuel assembly can provide housing for 17x17 grid rods, i.e., a total of 289 spaces. Of these 289 spaces, 24 can be reserved for control rods for the reactor, each of which can be formed by 24 control rods connected to the main arms, and one can be reserved for instrumentation tubes. Control rods are movable in and out of the core to control the fission process the fuel undergoes by absorbing neutrons released during fission. A reactor core can contain between 100 and 300 fuel assemblies. Fully inserting control rods usually leads to a subcritical state where the reactor shuts down. Up to 100% of the fuel assemblies in the core can contain control rods.

[0058] The control rod drive mechanism can control the movement of the control rods. The control rod drive mechanism can command and power actuators to lower and raise the control rods inside and outside the fuel assembly, and to maintain the position of the control rods relative to the core. The control rod drive mechanism can rapidly insert the control rods to quickly shut down (i.e., scram) the reactor.

[0059] The primary circuit can be housed within a containment structure that holds steam from the primary circuit in the event of an accident. The containment vessel can have a diameter between 15 and 60 m, or between 30 and 50 m. The containment structure can be formed from steel or concrete, or concrete lined with steel. The containment vessel can house or support externally water tanks for emergency cooling of the reactor. The containment vessel may include equipment and facilities that enable refueling of the reactor, storage of fuel assemblies, and transport of fuel assemblies between the inside and outside of the containment vessel.

[0060] The power plant may include one or more civil structures to protect the reactor elements from external hazards (e.g., missile attacks) and natural disasters (e.g., tsunamis). The civil structures may be made of steel, concrete, or a combination of both.

[0061] Here, an embodiment will be described as merely an example with reference to the attached drawings. [Brief explanation of the drawing]

[0062] [Figure 1] A schematic cross-sectional view is shown, passing through the lifting / transporting device. [Figure 2] This shows a schematic diagram of the equipment at its deployment location within the nuclear power generation system. [Modes for carrying out the invention]

[0063] Figure 1 shows a lifting and transporting device 1 including a device body 2 having a horizontal top wall 3 and vertical side walls 4. The walls are made of 150 mm thick steel. Walls 3 and 4 define a rectangular storage chamber 5 having an open base. The device body 2 is mounted on an opening frame 6 having a plurality of flanged wheels 7. An opening (not shown) in the wheeled opening frame 6 is aligned with the open base of the device body 2.

[0064] The apparatus further includes a sealing plate 8 that is slidable between a position in which the storage chamber 5 is open (through its open base) and a closed position in which the storage chamber 5 is sealed (liquid-tightly) by a sealing plate 8 covering the opening base and sealed to the apparatus body 2.

[0065] The sealing plate 8 is also made of 150 mm thick steel and is associated with an actuator (not shown) for driving it between its open and closed positions. The actuator is operably connected to a control system located remotely from the device. In Figure 1, the sealing plate 8 is shown in an intermediate position between the closed and open positions.

[0066] The lifting system 9 is installed inside the storage chamber 5 and has a lifting rig (not shown) for releasably connecting to the upper internal structure. The lifting rig is connected to two hoists (not shown) for raising and lowering the lifting rig. The lifting system 9 is connected to a remote control system.

[0067] Apparatus 1 further includes a liquid (e.g., water) supply system 20 installed within the storage chamber 5 to maintain moisture levels in the upper internal structures stored within Apparatus 1, so as to prevent radioactive vapor from forming and diffusing throughout the containment structure. The liquid supply system may include a recirculation pump and a liquid storage tank. In these embodiments with the liquid supply system, the apparatus may further include a discharge system for discharging the liquid from the apparatus.

[0068] Although not shown in the diagram, there is also a motor for driving the wheel 7. The motor can be operated by a control system located remotely from the device 1. The wheel 7 can be a flanged wheel having a small diameter portion sandwiched axially between two flanges. The wheels 7 can be arranged in two parallel rows.

[0069] This device is provided to facilitate the removal (and subsequent replacement) of the upper internal structure from the core in a nuclear power generation system shown in Figure 2. Such a system includes a reactor vessel having a reactor vessel body (not shown) that defines a cavity housing the core, including the upper internal structure. The reactor vessel also includes an integrated head package (IHP) 10, which includes a closure head 11 configured to seal to the reactor vessel body and close the opening to the cavity. The IHP also includes a control rod drive mechanism 12 housed within a shroud 13. The control rod drive mechanism 12 includes a plurality of drive rods 14 extending through the closure head 11, each drive rod 14 having a pneumatic coupling element (not shown) for releasably coupling to a control rod assembly in the core.

[0070] This system further includes multiple steam reactors 17, 17' and a pressurizer 18.

[0071] To expose the reactor core (allowing the removal of the upper internal structure), the IHP 10 must be removed from the reactor vessel. This is achieved by moving the drive rods 14 to a maintenance / refueling position where they are detached from the control rod assembly and fully retracted into the shroud 13. The drive rods 14 are locked into the shroud 13 at the maintenance / refueling position. The IHP 10 is then raised vertically from the reactor vessel and moved horizontally to the IHP storage location so as to be out of alignment with the reactor vessel (as shown in Figure 2).

[0072] Next, the lifting / transport device 1 is moved from its storage location (for example, in a shielded detachment outside the containment structure) to a vertical deployment location on the reactor vessel body (as shown in Figure 2). The lifting / transport device 1 is moved to the deployment location along rails / tracks 15 that extend along a linear path on the work platform 16 of the containment vessel. The liquid supply system may include one or more nozzles. The work platform 16 and rails / tracks 15 are aligned substantially vertically with the opening to the cavity within the reactor vessel body. The tracks / rails 15 allow the lifting / transport device 1 to be positioned directly above the reactor vessel body / core.

[0073] Upon reaching the deployment location, the storage chamber 5 moves the sealing plate 8 to its open position through its open base (using a remotely operated actuator, for example, activated by user input in a remote user interface that forms part of a remote control system). The lifting system 9 lowers the lifting rig into the reactor core through the openings in the open base and frame 6. This can also be done automatically from a remote location (for example, by user input in a user interface of a remote control system).

[0074] The lifting rig is automatically connected to the upper internal structure, and the lifting system 9 then lifts the lifting rig and the connected upper internal structure vertically upward (through the opening frame 6 and open base) into the storage chamber 5. Once the upper internal structure is fully housed in the storage chamber 5, the sealing plate 8 can be automatically moved to its closed position, which forms a liquid-tight seal with the device body 2.

[0075] Next, the lifting / transporting device 1 can be moved (horizontally) away from the deployment site by driving the wheels 7 along the rails / tracks 15. During transport from the deployment site and / or during storage of the superstructure in the storage area, a liquid supply system can be used to maintain the moisture level of the superstructure.

[0076] Once refueling is complete, the wheels 7 of the device 1 are driven to return the device 1 to its deployment location along the rails / tracks 15. The storage chamber 5 is opened by moving the sealing plate 8 to its open position. The upper internal structure is lowered vertically into the core using the lifting system 9, where it is (automatically) separated. Next, the lifting system 9 is used to raise the lifting rig from the core into the storage chamber 5, moving the sealing plate 8 to its closed position. Finally, the wheels 7 of the device 1 are driven along the rails / tracks 15 to move the device 1 away from its deployment location and back to its storage location.

[0077] This disclosure is not limited to the embodiments described above, and it will be understood that various modifications and improvements can be made without departing from the concepts described herein. Any of these features may be used individually or in combination with any other features, except where they are mutually exclusive, and this disclosure covers and includes all combinations and partial combinations of one or more features described herein. [Explanation of Symbols]

[0078] 1. Lifting and transport equipment 2. Main unit of the device 3 Upper wall 4 side wall 5 Chambers 6. Opening frame 7 wheels 8. Sealing plate 9. Lifting System 10. Integrated head package 11 closure heads 12 Control rod drive mechanism 13 Shroud 14 Drive rod 15 Tracks / Rails 16 Work platform 17. Steam reactor 17' Steam reactor 18 Pressurizer 20 Liquid supply systems

Claims

1. A lifting and transporting device for lifting the upper internal structure of a nuclear power plant core at a deployment site and transporting it to a storage location, A device body formed of radioactive shielding material, defining a storage chamber having an open base, A movable sealing plate made of a radioactive shielding material, which is movable between an open position in which the storage chamber is open and a closed position in which the storage chamber is sealed, A lifting system installed in the storage chamber, having a lifting rig for releasably connecting to the upper internal structure, and configured to raise the upper internal structure into the storage chamber when the device is in the deployment location and the plate is in the open position, Wheels for guiding the movement of the lifting / transporting device between the deployment area and the storage area, Lifting and transporting equipment, including.

2. The apparatus according to claim 1, wherein the sealing plate is movable between its open and closed positions by an actuator that can be operated by a control system located remotely from the apparatus.

3. The apparatus according to claim 1 or 2, further comprising a liquid supply system installed within the storage chamber.

4. The apparatus according to any one of claims 1 to 3, further comprising a motor for driving the wheels to move the apparatus from the deployment location to the storage location.

5. The apparatus according to any one of claims 1 to 4, A reactor vessel, A reactor vessel body defining a cavity that houses the core including the control rod assemblies and the upper internal structures for guiding the control rod assemblies, A closure head configured to seal the reactor vessel body and close the opening to the cavity, A reactor vessel having, A nuclear power generation system that includes nuclear power.

6. The system according to claim 5, wherein the reactor vessel includes a closure head and an integrated head package including a control rod drive mechanism housed within a shroud, the control rod drive mechanism including at least one drive rod extending through the closure head, the or each drive rod having a coupling element for releasably coupling to a control rod assembly in the core, the at least one drive rod being movable to a maintenance / refueling position in which the at least one drive rod is detached from the control rod assembly and retracted at least partially into the integrated head package, and the integrated head package further includes at least one locking element for locking the at least one drive rod in the maintenance / refueling position.

7. The system according to claim 5 or 6, comprising a storage structure, wherein the working floor of the storage structure surrounds the opening to the cavity and is substantially aligned with it.

8. The system according to claim 7, wherein the work platform includes at least one path extending from the vicinity of the reactor vessel to the storage area, the at least one path being substantially perpendicular to the opening to the cavity in the reactor vessel body, the at least one path including a track or rail extending from between the reactor vessel body and the storage area, and the wheels of the device being mounted on the track / rail.

9. The system according to claim 8, wherein the track / rail includes a removable / temporary portion extending vertically above the reactor vessel body.

10. The system according to any one of claims 5 to 9, further comprising a control system for sending control signals to operate the movable sealing plate and / or the lifting system and / or to drive the wheels.

11. A method for removing an upper internal structure from an exposed reactor core in a nuclear power generation system according to any one of claims 5 to 10, The steps include removing the closure head from the reactor vessel body, The steps include: driving the wheels to move the device to the deployment location vertically above the reactor vessel body with the sealing plate in its open position; The steps include lowering the lifting rig and connecting it to the upper internal structure, The steps include raising the upper internal structure vertically into the storage chamber using the lifting system, The steps include sealing the storage chamber by moving the sealing plate to its closed position, The steps include moving the device to the storage location by driving the wheels, Methods that include...

12. The steps include moving the device to the deployment location, The steps include opening the storage chamber by moving the sealing plate to its open position, The steps include lowering the upper internal structure vertically into the reactor core using the lifting system, The steps include: separating the lifting rig from the upper internal structure, The steps include raising the lifting rig from the reactor core into the storage chamber, The steps include moving the device away from the deployment location, The method according to claim 11, further comprising the step of returning the upper internal structure to the exposed core.

13. The method according to claim 11 or 12, further comprising the step of spraying a liquid onto the upper internal structure within the storage chamber.

14. The method according to any one of claims 11 to 13, comprising the step of moving the device between the deployment and storage locations along a work floor of the storage structure which is substantially vertically aligned with the opening to the cavity.

15. The method according to claim 14, comprising the step of driving the wheels of the device along a track or rail extending between the deployment location and the storage location, wherein the wheels of the device are mounted on the track / rail.

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