Apparatus and method for removing the upper internals from a nuclear reactor pressurized vessel

Patent metadata

Field	Value
Publication number	US-9318227-B2
Application number	US-201313741737-A
Country	US
Kind code	B2
Filing date	Jan 15, 2013
Priority date	Jan 15, 2013
Publication date	Apr 19, 2016
Grant date	Apr 19, 2016

Abstract

A lifting fixture for removing the upper internals from a nuclear reactor to provide access to the core during a refueling that does not require flooding of a refueling canal. A shield plate is integral to a lifting rig used to remove the upper internals. The shield plate is sized to be supported on the reactor vessel upper flange and to cover the reactor vessel opening with the closure head removed. The shield plate has openings that are in-line with the control rod assembly drive rod travel housings. Control rod assembly drive rods can be accessed through the openings. The lifting rig allows personnel to decouple the drive rods from the rod cluster control assemblies. The lifting fixture enables the decoupled drive rods to be lifted from the core with the upper internals while shielding maintenance personnel without use of flooding the area above the reactor.

First claim

What is claimed is:

1. An upper internals package lifting fixture for refueling a reactor having a reactor vessel with an upper flange surrounding an opening in the reactor vessel that is sealed by a mating flange on a closure head, the reactor vessel enclosing an upper internals package that seats above a plurality of fuel assemblies within a core of the reactor, the upper internals package including control rod assembly drive rod travel housings in which control rod assembly drive rods are housed and through which the drive rods travel along a vertical path that is enclosed entirely within the reactor vessel and closure head, the upper internals package lifting fixture comprising:
a shield plate sized to cover the opening in the reactor vessel when supported on the reactor vessel upper flange with the closure head removed from the upper flange, with openings through the shield plate in-line with the control rod assembly drive rod travel housings through which the control rod assembly drive rods can be accessed, the shield plate being formed from a material that lessens the radiation exposure of workers working above the shield plate covering the reactor vessel opening;
a lifting rig formed integral with and extending above the shield plate; and
an attachment mechanism for attaching the shield plate directly to the upper internals package.

2. The upper internals package lifting fixture of claim 1 wherein the openings to access the control rod assembly drive rods respectively include a tubular penetration through the shield plate that align and mate with the rod travel housings in the upper internals package.

3. The upper internals package lifting fixture of claim 2 wherein the tubular penetrations respectively include a conical guide that engages the corresponding rod travel housing.

4. The upper internals package lifting fixture of claim 2 wherein a number of the tubular penetrations include a drive rod latching tool that is reciprocally moveable within the tubular penetrations and is configured to couple with one or more of the drive rods and disconnect the respective drive rods from a corresponding control rod assembly.

5. The upper internals package lifting fixture of claim 4 including a retainer that maintains a position of the drive rod latching tool in the tubular penetration.

6. The upper internals package lifting fixture of claim 4 including a hoist configured to raise and lower the drive rod latching tool wherein the hoist has sufficient power to do so with the drive rod, decoupled from the control rod assembly, attached to the drive rod latching tool.

7. The upper internals package lifting fixture of claim 6 wherein the hoist is an integral part of the lifting fixture.

8. The upper internals package lifting fixture of claim 1 wherein the shield plate includes a ventilation and filtration system configured to draw air from below the shield plate, filter the air so drawn to remove radioactive contaminants and exhaust the drawn air above the shield plate.

9. An upper internals package lifting fixture for refueling a reactor having a reactor vessel with an upper flange surrounding an opening in the reactor vessel that is sealed by a mating flange on a closure head, the reactor vessel enclosing an upper internals package that seats above a plurality of fuel assemblies within a core of the reactor, the upper internals package including control rod assembly drive rod travel housings in which control rod assembly drive rods are housed and through which the drive rods travel along a vertical path, the upper internals package lifting fixture comprising:
a shield plate sized to cover the opening in the reactor vessel when supported on the reactor vessel upper flange, the shield plate being formed from a material that lessens the radiation exposure of workers working above the shield plate covering the reactor vessel opening;
a lifting rig formed integral with and extending above the shield plate; and
means for attaching the shield plate to the upper internals package through a connection to at least some of the control rod assembly drive rod travel housings wherein the rod travel housings extend above the upper flange and the shield plate is formed in a top hat configuration to span the reactor vessel opening above the rod travel housings and has a radially outwardly extending brim that is supported on the upper flange of the reactor vessel.

10. The upper internals package lifting fixture of claim 9 including a shielded cylinder having an inner diameter that is larger than an outer diameter of the shield plate, a narrowed opening in an upper end that has a smaller diameter than the outer diameter of the shield plate and a length that is substantially equal to or longer than the upper internals package.

11. The upper internals package lifting fixture of claim 10 wherein the shielded cylinder is slidably positioned over the shield plate.

12. The upper internals package lifting fixture of claim 11 wherein the lifting rig has an outer diameter that is smaller than the narrowed opening in the upper end of the shielded cylinder.

13. The upper internals package lifting fixture of claim 1 including a shielded cylinder having an inner diameter, below an upper radially inwardly extending annular lip that forms a narrowed upper opening in the shielded cylinder, wherein the inner diameter below the narrowed upper opening in the shielded cylinder is larger than an outer diameter of an upper portion of the shield plate so that at least a lower portion of the shielded cylinder can slide over the shield plate and a radially outward annular portion of the shield plate engages the upper radially inwardly extending annular lip on the shielded cylinder during lifting of the upper internals package to prevent the shielded cylinder from sliding off of the shield plate.

Assignees

• Westinghouse Electric Corp

Inventors

• Harkness Alexander W

Classifications

• G21C1/32

  Integral reactors, i.e. reactors wherein parts functionally associated with the reactor but not essential to the reaction, e.g. heat exchangers, are disposed inside the enclosure with the core (G21C1/02 - G21C1/30 take precedence) · CPC title

• G21C19/02 Primary

  Details of handling arrangements · CPC title

• G21C19/207

  Assembling, maintenance or repair of reactor components (G21C3/334 takes precedence) · CPC title

• G21C19/10

  Lifting devices or pulling devices adapted for co-operation with fuel elements or with control elements (manipulators B25J) · CPC title

• G21C19/20

  Arrangements for introducing objects into the pressure vessel; Arrangements for handling objects within the pressure vessel; Arrangements for removing objects from the pressure vessel · CPC title