U–Mo alloy fuel for TRU-burning advanced fast reactors

The use of U–Mo instead of U–Zr as the base alloy fuel for transuranics (TRU)-burning advanced fast reactors is assessed in several aspects. While the replacement of Zr with Mo involves no significant differences in terms of neutron physics (core design), U–TRU–Mo does provide advantages. U–TRU–Mo has lower TRU migration to cladding because of its simpler phase diagram, is advantageous in safety margin due to its higher thermal conductivity and better fuel-cladding-chemical-interaction resistance. High fuel swelling data, obtained at low temperatures, available in the literature are not directly applicable to the TRU-burning advanced fast reactors. The potential high swelling can also be controlled when strong cladding and degassing are used as are adopted for typical U–Pu–Zr fuel. Results and detailed analysis are presented in this paper, indicating the benefits of U–Mo base alloy fuel in TRU-burning advanced fast reactors.