Criticality safety methodology for CASTOR spent fuel transport and storage casks

CASTOR casks are designed for the transport and dry storage of spent light water reactor fuel or nuclear waste, like for instance vitrified waste. The subcriticality of CASTOR V casks is mainly assured by: the limitation of the fissile content of the fuel, the geometrical positioning of the fuel assemblies within a basket, and the neutron absorbing structures. Using the example of CASTOR V type casks, an outline of the methodology of criticality analyses for CASTOR casks is presented. The development of models for normal and accidental conditions of transport is presented. The criticality safety analyses are performed with the KENO codes and with the SCALE 238-group ENDF/B-V cross section library. This methodology has been developed over the last 15 years and has been successfully applied to various licensing procedures