INTERNALS LIFTING DEVICE

Abstract

The present disclosure provides a lifting and transport device for lifting upper internals from a reactor core of a nuclear power generation system in a deployment location and transporting them to a storage location. The lifting/transport device comprises a device body formed of radioactive shielding material, the device body defining a storage chamber having an open base. The device further comprises a movable sealing plate formed of 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 having a lifting rig for releasable connection to the upper internals and configured to raise the upper internals to within the storage chamber when the device is in the deployment location and the plate is in the open position. The device comprises wheels for guiding movement of the lifting/transport device between the deployment location and the storage location.

Claims

1. A lifting and transport device for lifting upper internals from a reactor core of a nuclear power generation system in a deployment location and transporting them to a storage location, the lifting and transport device comprising: a device body formed of radioactive shielding material, the device body defining a storage chamber having an open base; a movable sealing plate formed of 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; a lifting system mounted within the storage chamber having a lifting rig for releasable connection to the upper internals and configured to raise the upper internals to within the storage chamber when the device is in the deployment location and the plate is in the open position; and wheels for guiding movement of the lifting/transport device between the deployment location and the storage location.

2. The lifting and transport device of claim 1, wherein the sealing plate is movable between its open and closed positions by an actuator that is actuable by a control system located remotely from the device.

3. The lifting and transport device of claim 1 further comprising a liquid supply system mounted within the storage chamber.

4. The lifting and transport device of claim 1 further comprising a motor for driving the wheels to effect movement of the device from the deployment to the storage location.

5. A nuclear power generation system comprising: a lifting and transport device comprising: a device body formed of radioactive shielding material, the device body defining a storage chamber having an open base; a movable sealing plate formed of 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; a lifting system mounted within the storage chamber having a lifting rig for releasable connection to the upper internals and configured to raise the upper internals to within the storage chamber when the device is in the deployment location and the plate is in the open position; and wheels for guiding movement of the lifting/transport device between the deployment location and the storage location; and a reactor vessel comprising: a reactor vessel body defining a cavity housing a reactor core containing a control rod assembly and upper internals for guiding the control rod assembly; and a closure head configured to seal against the reactor vessel body to close an opening to the cavity.

6. The nuclear power generation system according to claim 5, wherein the reactor vessel comprises an integrated head package comprising the closure head, and a control rod drive mechanism housed within a shroud, the control rod drive mechanism comprising 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 within the reactor core, the at least one drive rod being movable to a maintenance/refuelling position in which the at least one drive rod is uncoupled from the control rod assembly and at least partially retracted into the integrated head package, the integrated head package further comprising at least one locking element for locking the at least one drive rod in the maintenance/refuelling position.

7. The nuclear power generation system according to claim 5 further comprising a containment structure wherein a working floor of the containment structure surrounds and is substantially vertically aligned with the opening to the cavity.

8. The nuclear power generation system according to claim 7, wherein the working floor comprises at least one pathway extending from adjacent the reactor vessel to the storage location, the at least one pathway being substantially vertically aligned with the opening to the cavity in the reactor vessel body, wherein the at least one pathway comprises tracks or rails extending from between the reactor vessel body and the storage location, the wheels of the device being mounted on the tracks/rails.

9. The nuclear power generation system according to claim 8, wherein the tracks/rails comprise a removable/temporary portion that extends vertically above the reactor vessel body.

10. The nuclear power generation system according to claim 5 further comprising a control system for sending control signals for actuation of the slidable sealing plate and/or the lifting system and/or for driving the wheels.

11. A method of removing upper internals from an exposed reactor core within a nuclear power generation system comprising: removing the closure head from the reactor vessel body, moving the device to the deployment location vertically above the reactor vessel body with the sealing plate in its open position; lowering the lifting rig and connecting it to the upper internals; raising the upper internals vertically to within the storage chamber using the lifting system; sealing the storage chamber by moving the sealing plate to its closed position; and moving the device to the storage location.

12. The method according to claim 11 further comprising returning the upper internals to the exposed reactor core by: moving the device to the deployment location; opening the storage chamber by moving the sealing plate to its open position; lowering the upper internals vertically into the reactor core using the lifting system; disconnecting the lifting rig from the upper internals; raising the lifting rig from within the reactor core to within the storage chamber; and moving the device away from the deployment location.

13. The method according to claim 11 further comprising spraying a liquid onto the upper internals within the storage chamber.

14. The method according to claim 11 comprising moving the device between the deployment and storage locations along a working floor of the containment structure that is substantially vertically aligned with the opening to the cavity.

15. The method according to claim 14 comprising driving wheels of the device along tracks or rails extending between the deployment location and the storage location, the wheels of the device being mounted on the tracks/rails.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0081] Embodiments will now be described by way of example only with reference to the accompanying drawings in which:

[0082] FIG. 1 shows a schematic cross-sectional view through the lifting/transporting device; and

[0083] FIG. 2 shows a schematic of the device in the deployment location within a nuclear power generation system.

DETAILED DESCRIPTION AND FURTHER OPTIONAL FEATURES

[0084] FIG. 1 shows a lifting and transport device 1 comprising a device body 2 having a horizontal upper wall 3 and vertical side walls 4. The walls are formed of 150 mm thick steel. The walls 3, 4 define a cuboid storage chamber 5 having an open base. The device body 2 is seated on an apertured frame 6 which has a plurality of flanged wheels 7. The aperture (not shown) in the wheeled apertured frame 6 is aligned with the open base of the device body 2.

[0085] The device further comprises a sealing plate 8 which is slidable between an 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 (in a liquid tight manner) with the sealing plate 8 covering the open base and sealed against the device body 2.

[0086] The sealing plate 8 is also formed of 150 mm thick steel and is associated with an actuator (not shown) for driving it between its open and closed positons. The actuator is connected to a control system located remotely from the device. In FIG. 1, the sealing plate 8 is shown mid-way between the closed and open positions.

[0087] A lifting system 9 is mounted within the storage chamber 5 and has a lifting rig (not shown) for releasable connection to the upper internals. The lifting rig is connected to two hoists (not shown) for raising and lowering the lifting rig. The lifting system 9 is connected to the remote control system.

[0088] The device 1 further comprises a liquid (e.g. water) supply system 20 mounted within the storage chamber 5 for maintaining the moisture levels of the upper internals stored within the device 1 to prevent radioactive vapour from forming and dispersing throughout the containment structure. The liquid supply system may comprise a recirculation pump and a liquid storage tank. In these embodiments with a liquid supply system, the device may further comprise a drainage system for draining the liquid from the device.

[0089] Also not shown, there is a motor for driving the wheels 7. The motor may be actuable by the control system located remotely from the device 1. The wheels 7 may be flanged wheels having a reduced diameter portion axially sandwiched between two flanges. The wheels 7 may be arranged in two aligned rows.

[0090] This device is provided to facilitate the removal (and subsequent replacement) of the upper internals from the reactor core within a nuclear power generation system which is shown in FIG. 2. The system comprises a reactor vessel having a reactor vessel body (not shown) defining a cavity housing the reactor core containing upper internals. The reactor vessel also comprises an integrated head package (IHP) 10 comprising a closure head 11 configured to seal against the reactor vessel body to close an opening to the cavity. The IHP also comprises a control rod drive mechanism 12 housed within a shroud 13. The control rod drive mechanism 12 comprises a plurality of drive rods 14 extending through the closure head 11, the drive rods 14 each having a pneumatic coupling element (not shown) for releasably coupling to a control rod assembly within the reactor core.

[0091] The system further comprises a plurality of steam reactors 17, 17 and a pressuriser 18.

[0092] In order to expose the reactor core (to allow removal of the upper internals), the IHP 10 must be removed from the reactor vessel body. This is achieved by moving the drive rods 14 to a maintenance/refuelling position in which they uncoupled from the control rod assembly and fully retracted into the shroud 13. The drive rods 14 are locked within the shroud 13 in the maintenance/refuelling position. The IHP 1 is then raised vertically away from the reactor vessel body and moved horizontally out of alignment with the reactor vessel body to an IHP storage location (as shown in FIG. 2).

[0093] Next the lifting/transport device 1 is moved from a storage location (e.g. in a shielded annex outside the containment structure) to a deployment location vertically over the reactor vessel body (as shown in FIG. 2). The lifting/transport device 1 is moved to the deployment location along rails/tracks 15 extending along a linear pathway on the containment working floor 16. The liquid supply system may comprise one or a plurality of nozzles. The working floor 16 and rails/tracks 15 are substantially vertically aligned with the opening to the cavity in the reactor vessel body. The tracks/rails 15 allow the positioning of the lifting/transporting device 1 directly over the reactor vessel body/reactor core.

[0094] Once in the deployment location, the sealing plate 8 is moved (using a remotely operated actuated e.g. actuated by a user input at the remote user interface forming part of the remote control system) to its open position where the storage chamber 5 is open through its open base. The lifting system 9 lowers the lifting rig into the reactor core through the open base and the aperture in the frame 6. Again, this may be effected automatically from a remote location (e.g. by input of a user input at a user interface at a remote control system).

[0095] The lifting rig is (automatically) connected to the upper internals and then the lifting system 9 hoists the lifting rig and the connected upper internals vertically upwards into the storage chamber 5 (through the apertured frame 6 and the open base). Once the upper internals are fully contained within the storage chamber 5, the sealing plate 8 can be (automatically) moved to its closed position where it forms a liquid tight seal with the device body 2.

[0096] The lifting/transport device 1 can then be moved (horizontally) away from the deployment location by driving the wheels 7 along the rails/tracks 15. During transport away from the deployment location and/or during storage of the upper internals in the storage location, the liquid supply system may be used to maintain moisture levels of the upper internals.

[0097] When refuelling is complete, the device 1 is moved back along the rails/tracks 15 to the deployment location by driving the wheels 7 of the device 1. The storage chamber 5 is opened by moving the sealing plate 8 to its open position. The upper internals are lowered vertically into the reactor core using the lifting system 9 where they are disconnected (automatically). Next the lifting rig is raised from within the reactor core to within the storage chamber 5 using the lifting system 9 and the sealing plate 8 is moved to its closed position. Finally, the device 1 is moved away from the deployment location back to the storage location by driving the wheels 7 of the device 1 along the tracks/rails 15.

[0098] It will be understood that the disclosure is not limited to the embodiments above-described and various modifications and improvements can be made without departing from the concepts described herein. Except where mutually exclusive, any of the features may be employed separately or in combination with any other features and the disclosure extends to and includes all combinations and sub-combinations of one or more features described herein.