METHOD OF BRINGING FUEL AGGREGATE TO STATE IN WHICH IT CAN BE RECONSTITUTED AND MOUNTING STRUCTURE OF UPPER NOZZLE THEREOF

摘要

An improved arrangement for attaching and reattaching a top nozzle of a reconstitutable fuel assembly includes a sleeve member associated with each guide thimble of the fuel assembly and complementary elements for attaching the sleeve member and the upper end portion of the guide thimble together. The sleeve member includes an inner tubular alignment sleeve portion which receives the guide thimble upper end portion and extends between the upper hold-down and lower adapter plates of the top nozzle. The sleeve member also includes an outer tubular shroud portion having a lower annular flange which underlies a coil spring surrounding the sleeve portion and interconnects the shroud portion and the sleeve portion. The outer shroud portion extends upwardly about a portion of the coil spring for protecting the spring from damage by coolant cross flow from adjacent fuel assemblies. The complementary elements include upper primary and lower secondary interior spaced annular grooves formed on the alignment sleeve portion and a primary exterior bulge formed on the guide thimble upper end portion. The primary bulge extends into the primary annular groove to connect the sleeve portion to the guide thimble. The secondary groove is adapted to receive a secondary exterior bulge, being formed on the guide thimble upper end portion after an initial severance of an upper segment of the upper end portion, for reconnection of the alignment sleeve portion and the severed guide thimble together.