Criticality safety of spent nuclear fuel assemblies from the transmutation of minor actinides in fast reactors

Criticality safety concerning the packaging of spent nuclear fuel assemblies from the transmutation of 237Np and 241Am in a fast reactor are investigated and compared to cases of spent fuels from commercial nuclear power stations. The investigation is based on the neutron multiplication factor calculated using the fresh and spent fuel compositions. Fuels based on a fresh composition with high amount of fissile material and low amounts of 237Np and 241Am resemble the fast reactor fuel, with the multiplication factor decreasing when calculated using the spent fuel compositions. However, the multiplication factor increases for targets based on a fresh composition without fissile content and high amounts of 237Np and 241Am, although it remains below 1 for up to 90 GWd/t burnup.