Actinide-Only Burnup Credit for Spent Fuel Transport

A conservative methodology is described that would allow taking credit for burnup in the criticality safety analysis of spent nuclear fuel packages. Requirements for its implementation include isotopic and criticality validation, generation of package loading criteria using limiting parameters, and assembly burnup verification by measurement. The method allows credit for the changes in the 234U, 235U, 236U, 238U, 238Pu,239Pu,240Pu,241Pu,242Pu,and 241Am concentrations with burnup. No credit for fission product neutron absorbers is taken. Analyses are included regarding the methodology's financial benefits and conservative margin. It is estimated that the proposed actinide-only burnup credit methodology would save 20% of the transport costs. Nevertheless, the methodology includes a substantial margin. Conservatism due to the isotopic correction factors, limiting modelling parameters, limiting axial profiles and exclusion of the fission products ranges from 10 to 25% k.