Patent Number: 047818832
Section: abstract

A spent fuel storage cask for long-term storage of spent nuclear fuel following short-term storage in a pool of water. The cask includes a grid basket assembly, resembling a matrix of pigeonholes, for accommodating cells which in turn accommodate spent fuel assemblies. The grid basket assembly is formed by metal plates which transmit heat to channel sections affixed to the interior walls of the cask. The edges of the plates movably fit into the channel sections in order to permit radial movement of the grid basket assembly with respect to the walls of the cask as temperature changes. During storage the cask can be flooded with helium, which readily transmits heat through narrow gaps between the edges of the plates and the walls of the channel sections. Several embodiments of cells having material for moderating neutrons emitted from spent fuel assemblies are also enclosed, some of these embodiments permitting easy conversion of the cask for storing consolidated fuel rather than intact fuel assemblies.