Enhanced nuclear safety of spent fuel

Criticality safety analysis of highly enriched nuclear fuels requires sophisticated calculation techniques like burnup credit in order to show that fuel reactivity is below legislative limits. However, new fuel types are continuously introduced and the increase of the boron concentration in the absorbing tubes of spent fuel pool racks or spent fuel casks is necessary. Borated steel or aluminum alloys may not be economically reasonable and other types of absorber components can be feasible. Absorber tubes with neutron traps between them are very effective from the neutronics point of view; the only better solution is to place absorbers directly within the fuel assembly. This study shows a concept for enhanced nuclear safety of spent fuel. The analysis is dedicated to the selection and optimization of the most suitable materials for this concept. (author)