NUCLEAR POWER GENERATION SYSTEM

Abstract

Disclosed is a nuclear power generation system comprising a reactor vessel comprising a body defining a cavity housing a reactor core, and an integrated head package having a closure head for closing an opening to the cavity. The system also comprises a containment structure having a working floor surrounding and substantially vertically aligned with the opening to the cavity.

Claims

1. A nuclear power generation system comprising: a reactor vessel comprising a body defining a cavity housing a reactor core, and a closure head for closing an opening to the cavity; and a containment structure having a working floor surrounding and substantially vertically aligned with the opening to the cavity.

2. The nuclear power generation system according to claim 1 comprising a pathway extending from a deployment location adjacent the reactor vessel to a first storage location remote from the reactor vessel, the deployment location being substantially vertically aligned with the opening to the cavity.

3. The nuclear power generation system according to claim 2 wherein the pathway comprises one or more tracks or rails supported on the working floor.

4. The nuclear power generation system according to claim 3, wherein the one or more tracks or rails comprises a pair of parallel tracks or rails spaced either side of the reactor vessel at the deployment location.

5. The nuclear power generation system according to claim 2, wherein the pathway extends from the deployment location to a second storage location, and wherein the deployment location is between the first and second storage locations.

6. The nuclear power generation system according to claim comprising an annex structure separated from the containment structure by at least one separating wall, the annex structure comprising the first storage location.

7. The nuclear power generation system according to claim 6 comprising a hatch in the at least one separating wall, the hatch moveable between a closed position in which the containment and annex structures are sealed from one another, and an open position in which access is provided between the containment and annex structures, and wherein the pathway extends through the hatch.

8. The nuclear power generation system according to claim 6 or 7 comprising one or more maintenance devices, each comprising wheels for movement along the pathway between the containment and annex structures.

9. The nuclear power generation system according to claim 8, wherein the one or more maintenance devices comprises one or more of: a stud tensioner/detensioner device, a closure head lifting device, a reactor internals cask, and a reactor refuelling device.

10. The nuclear power generation system according to claim 9, wherein at least one of the one or more maintenance devices is movable between a collapsed configuration and an expanded configuration.

11. The nuclear power generation system according to claim 9 comprising a fuel storage structure separated from the annex structure by at least one separating wall, the pathway extending between the annex and fuel storage structures, and wherein the fuel storage structure comprises a fuel pool for storage of spent fuel.

12. The nuclear power generation system according to claim 1 comprising a base structure supporting the working floor, the base structure defining a cavity having an upper opening formed in the working floor for receipt of the reactor vessel.

13. The nuclear power generation system according to claim 1 comprising a plurality of steam generators circumferentially spaced about the reactor vessel, the portion of the one or more rails extending from the deployment location to the storage location passing between first and second steam generators of the plurality of steam generators.

14. The nuclear power generation system according to claim 1, wherein the reactor vessel forms part of a pressurised water reactor system.

15. A method for maintaining a nuclear power generation system according to claim 2, the method comprising: supporting a maintenance device on the working floor of the containment structure; moving the maintenance device to the deployment location; and operating the maintenance device to perform a maintenance operation on the reactor vessel of the nuclear power generation system.

16. The method according to claim 15, wherein the maintenance device is a closure head lifting device and the maintenance operation comprises lifting the closure head of the reactor vessel above the body of the reactor vessel.

17. The method according to claim 16 comprising moving the head closure lifting device, whilst supporting the head closure, along the pathway to a storage location.

18. The method according to claim 17 comprising moving an internals cask along the pathway from a storage location to the deployment location, operating the internals cask to withdraw the reactor internals from the body, then subsequently moving the internals cask along the pathway to a storage location.

19. The method according to claim 18 comprising moving a refuelling device along the pathway from a storage location to the deployment location and withdrawing and replacing fuel assemblies in the body of the reactor vessel using the refuelling device.

20. The method according to claim 19 comprising moving the refuelling device from the deployment location, once the fuel assemblies have been withdrawn and replaced, and depositing the withdrawn fuel assemblies in a fuel pool at the deployment location.

Description

SUMMARY OF THE FIGURES

[0070] Embodiments will now be described by way of example only, with reference to the Figures, in which:

[0071] FIG. 1A is a perspective view of a containment structure of a nuclear power generation system; and

[0072] FIG. 1B is a schematic view of the power generation system shown in FIG. 1A.

DETAILED DESCRIPTION

[0073] Aspects and embodiments of the present disclosure will now be discussed with reference to the accompanying figures. Further aspects and embodiments will be apparent to those skilled in the art.

[0074] FIG. 1A shows the interior of a containment structure 10 of a nuclear power generation system. Whist not apparent from the figures, the containment structure 10 is a containment building of a nuclear power generation system. So that the various components enclosed within the containment structure 10 can be seen, the walls of the containment structure 10 are not illustrated.

[0075] The system comprises a reactor vessel 12 comprising a body 14 defining a cavity for accommodating a nuclear reactor and an IHP 16 for closing an opening to the cavity. In FIG. 1A, the IHP 16 is shown in a position in which it has been removed, and moved away from, the body 14. The system further comprises a first pathway in the form of a first pair of spaced parallel tracks 18 that extend from a deployment location 20 laterally adjacent to the reactor vessel 12 to a first storage location 22 (shown in FIG. 1B). The deployment location 20 (and thus the reactor vessel 12) is centrally located within the containment structure 10, whilst the storage location 22 is located externally to the containment structure 10. In some embodiments, one or more of the storage locations may be external to the containment structure.

[0076] The first pair of tracks 18 extend along a substantially horizontal and linear pathway between the deployment 20 and storage 22 locations. At the deployment location 20, the first pair of tracks 18 are spaced either side of the reactor vessel 12 (i.e. such that the reactor vessel 12 is located between the first pair of tracks 18 at the deployment location 20). The first pair of tracks 18 also extend beyond the reactor vessel 12, along the linear path, to a second storage location 24 (i.e. the deployment location 20 being between the first 22 and second 24 storage locations). In FIG. 1A, the IHP 16 of the reactor vessel 12 is positioned at this second storage location 24. The IHP comprises a closure head which cooperates with the reactor body

[0077] Each of the body 14 and IHP 16 of the reactor vessel 12 comprises an attachment portion in the form of an outwardly extending circumferential flange 26. These flanges 26 comprise circumferentially spaced apertures for receipt of closure studs to secure the IHP 16 to the body 14.

[0078] The containment structure 10 comprises a base structure 28 formed of reinforced concrete, which defines a reactor vessel cavity 30 into which the reactor vessel 12 is received. Whilst not shown in FIG. 1A, it should be appreciated that, when the IHP 16 is secured to the body 14, the IHP 16 projects from an upper opening of the cavity 30. The base structure 28 supports a substantially planar and circular working floor 32 (which extends across the top of the base structure 28). The opening to the reactor vessel cavity 30 is formed in the working floor 32. The working floor 32 is vertically aligned (i.e. at the same height) as the opening to the cavity of the body 12, so as to be generally aligned with the flanges 26 of the reactor vessel 12.

[0079] The first pair of tracks 18, which are formed of steel, are set into the working floor 32. Thus, the tracks 18, like the working floor 32, are vertically aligned with the opening of the body 12 of the reactor vessel 12.

[0080] The containment structure 10 further contains three steam generators 36 that are circumferentially spaced about (and radially from) the reactor vessel 12. The steam generators 36 are in fluid connection with the reactor vessel 12 by way of a plurality of pipes. These pipes extend through openings and passages formed in the base structure 28. The working floor 32 comprises three steam generator openings 38 that the steam generators 36 project through so as to be disposed substantially above the working floor. The first pair of tracks 18 extend between these steam generator openings 38 and thus between the steam generators 36.

[0081] A second pair of tracks 40 also extends between the steam generator openings 36 (and the steam generators 38). This second pair of tracks 40 is also formed into the working floor 32 and extend from a peripheral region (i.e. a third storage location 42) of the working floor 32 to the reactor vessel 12. In particular, the second pair of tracks 40 extend generally perpendicularly (when viewed from above) to the first pair of tracks 18. Like the first pair of tracks 18, the second pair of tracks 40 are parallel and spaced either side of the reactor vessel 12 (i.e. at the deployment location 20). However, unlike the first pair of tracks 18, the second pair of tracks 40 do not extend beyond the reactor vessel 12.

[0082] As is apparent from FIG. 1B, the system comprises an annex structure 44 that is adjacent to the containment structure 10. The annex structure 44 houses a plurality of maintenance devices that are used to maintain the reactor vessel 12 (and other components of the system). In particular, three devices are housed in the annex structure 44. These devices are a stud tensioner/detensioner device 46, an IHP lifting device 48, and a reactor vessel internals cask 50. The stud tensioner/detensioner device 46 is configured to tension/detension studs securing the IHP 16 of the reactor vessel 12 to the body 14 (e.g. to allow removal or securing of the IHP 16). The IHP lifting device 46 is configured to lift the IHP 16 above the body 14 and can move the IHP 16 laterally away from the body 14. The internals cask 50 is configured to remove reactor internals from the body 14 of the reactor vessel 12 and to store the internals.

[0083] A fuel storage structure 52 (which may define a fourth storage location) is located adjacent to the annex structure 44, such that the annex structure 44 is disposed between the fuel storage 52 and containment 10 structures. The fuel storage structure 52 comprises a fuel storage pool 54 and a refuelling device 56 that is configured to remove and replace spent fuel from the reactor vessel 12 and deliver the spent fuel to the fuel storage pool 54.

[0084] The annex structure 44 is separated from the containment structure 10 by a first separating wall 58, and from the fuel storage structure 52 by a second separating wall 60. Each of the first 58 and second 60 separating walls comprise openings that are sealed by corresponding hatches 62. As will be discussed further below, these hatches 62 are openable to allow access between the structures 10, 44, 52.

[0085] The first pair of tracks 18 extend from the containment structure 10, through the hatches 62 and to the fuel storage structure 52 (i.e. via the annex structure 44). The annex structure 44 comprises branches (branching from the first pair of tracks 18) in the form of pairs of cross tracks 64 that extend transversely across the second enclosure 44 so as to be perpendicular to the first pair of tracks 18 (and parallel to the second pair of tracks 40). Each of the stud tensioner/detensioner device 46, IHP lifting device 48 and internals cask 50 is supported on a pair of these cross tracks 64. The cross tracks 64 are operatively connected to the first pair of tracks 18 by turntables 66. The turntables 66 can be rotated to align with the first pair of tracks 18 or the cross tracks 64, such that a device can be moved onto the turntable 66 from a first pair of tracks and then rotated so as to be able to move another pair of tracks. As should be appreciated from FIG. 1B, this allows the devices 46, 48, 50 housed in the annex structure 44 to move from the annex structure 44 to the reactor vessel 12 in the containment structure 10 (through the hatch 62). As will be described below, this allows the devices 46, 48, 50 to be used to maintain (e.g. refuel) the reactor vessel 12.

[0086] As an example, the devices 46, 48, 50 in the annex structure 44, and the refuelling device 56 may be used to refuel the reactor vessel 12. An exemplary method for performing this will now be described. First, the reactor vessel 12 is de-pressurised and cooled down before the refuelling process can begin. The hatch 62 connecting the annex structure 44 with the containment structure 10 is opened and the stud tensioner/detensioner device 46 is moved from the annex structure 44 to the containment structure 10 so as to be adjacent the reactor vessel 12. The stud tensioner/detensioner device 46 disconnects the closure studs which attach the IHP 16 the body 14. Once disconnected, the stud tensioner/detensioner device 46 is returned to its storage position in the annex structure 44. The lifting device 48 is then moved so as to be adjacent the reactor vessel 12. The lifting device 48 lifts the IHP 16 above the body 14 and moves the IHP 16 further along the first pair of tracks 18 towards the second storage location 24.

[0087] Subsequently, the internals cask 50 is moved so as to be positioned immediately above the body 14 (i.e. where the closure head 16 was previously located). The internals cask 50 seals around the reactor cavity opening 30 and extracts the reactor upper internals from the cavity of the body 14. These internals are removed to allow fuel assemblies to be removed from the body 14. The internals cask 50 is configured to shield radiation from the extracted internals. Once the internals are extracted, the internals cast 50 is returned the annex structure 44.

[0088] The hatch 62 connecting the annex 44 and fuel storage 52 structures is then opened, and the refuelling device 56 is moved from the fuel storage structure 52 to the reactor vessel 12. In particular, the refuelling device 56 is positioned immediately above the reactor vessel 12. The refuelling device 56 comprises a dual-axis (i.e. X-Y axis) movement mechanism to allow it to access specific fuel assemblies in the nuclear core. This may allow the refuelling device 56 to reposition one or more fuel assemblies within the nuclear core. The refuelling device 56 also comprises a shielded lifting device which extracts fuel assemblies vertically from the body 14.

[0089] Once the fuel assemblies are extracted, the refuelling device 56 delivers the extracted fuel assemblies from the reactor vessel 12 to the fuel storage structure 52 and deposits the fuel in the pool 54. The refuelling device 56 may subsequently deliver fuel (e.g. new fuel) from the pool 54 to the reactor vessel by retrieving the fuel from the pool 54 and returning to the reactor vessel 12.

[0090] Once the fuel is removed and/or any repositioning and replacement of fuel is performed, the internals are replaced by the internals cask 50, the IHP 16 is be moved back onto the body 14 (by the closure head lifting device 48), and the closure studs are engaged with the reactor vessel 12 and tensioned by the stud tensioner/detensioner device 46. The hatches 62 are then be closed in order to seal the enclosures 10, 44, 52.

[0091] 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.