Storage of spent nuclear fuel.

摘要

A rack for storing spent-fuel assemblies in spent-fuel storage locations (29) in a minimum space. The rack has these locations (29) each formed by bending a stainless steel sheet into a hollow body (42) of the generally rectangular cross section and with each side shaped so that the apices of the body (42) project outwardly. Except for bodies (42) along the outer periphery of the rack, the apex of each body is contiguous to the apex of an adjacent body (42). These contiguous apices are joined by welds which are spaced so as to maximize the resistance of the rack to seismic acceleration. Additional storage locations are formed between adjacent body locations. Pockets receiving neutron-absorbing material are arranged between, and common to, adjacent locations. Preferably, the fuel storage pool where the rack is installed is divided into two regions. Region 1 is in a checkerboard pattern with locations corresponding to one set of squares capped. In Region 2, all cells are uncapped. Initially spent assemblies are deposited in Region 1. After fuel burn-up is checked, the fuel in Region 1 which has undergone at least a predetermined minimum burn-up is transferred to Region 2. The capped cells are provided to prevent the fuel in Region 1 of the rack from going critical.