The effect of eccentric loading in spent fuel pool criticality safety analyses

Eccentric fuel loading is one of the studies performed in a spent nuclear fuel criticality safety analysis. The study normally considers fuel assemblies placed at one side or corner in the rack cell. The purpose of this work is to study the effect of random placement of fuel assemblies on reactivity. MCNP was used to model the high density spent fuel pool and the depleted PLUS7 fuel. A total of 1400 cases with randomly displaced fuel assemblies in the rack cells, with and without neutron absorbers, were prepared. The results showed that none of the k-effective values from the random displacement cases exceed that of the base case where the fuel assemblies were centered in the rack cell. This suggests that eccentric fuel loading studies may not be needed in all criticality safety analyses with randomly displaced fuel assemblies.