APPARATUS AND METHOD FOR REMOVING THE UPPER INTERNALS FROM A NUCLEAR REACTOR PRESSURIZED VESSEL

摘要

A lifting fixture for removing the upper internals from a reactor to provide access to the core for refueling that does not require flooding of a refueling canal. The invention provides a means of shielding and ventilation that is integral to a lifting rig used to remove the upper internals. The lifting rig provides a means for personnel to decouple the drive rods from the rod cluster control assemblies so the drive rods can be lifted from the core with the upper internals while shielding maintenance personnel without flooding the area above the reactor.

主权项

1. A method of removing an upper internals package from a nuclear 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 the upper internals package that seats above a plurality of fuel assemblies within a core of the reactor, the upper internals package including a plurality of rod travel housings in which control rod assembly drive rods are housed and through which the drive rods travel along a vertical path, the method comprising the steps of:
removing the closure head from the reactor vessel; lowering a shield plate over the opening in the reactor vessel, the shield plate being sized to cover the opening when supported on the reactor vessel upper flange and being formed from a material that lessens the radiation exposure of workers working above the shield plate covering the reactor vessel opening, the shield plate including an integral lifting rig extending above an upper surface thereof; attaching the shield plate to the upper internals package; and raising the shield plate to withdraw the upper internals package out of the reactor.