Minor actinides (MA) and lanthanides (LA) migration to the cladding in fast reactor metallic fuel was a concern because of their reaction with the cladding material. MA and LA migration test results were analyzed and reactions with the cladding were characterized. Remedies for reducing MA and LA migration and reaction with cladding were reviewed. A possible method was proposed that includes the addition of a compound forming element such as indium or thallium in fuel. These elements preferentially form stable compounds with MA and LA and should therefore reduce migration of MA and LA. As an intrinsic solution to the issue, the feasibility of the use of U–Pu–Mo alloy as fuel was studied. Unlike U–Pu–Zr, U–Pu–Mo consists of a single phase at typical fuel operation temperatures, and should have negligible fuel constituent redistribution and reduce MA and LA migration.

Migration of Minor Actinides and Lanthanides in Fast Reactor Metallic Fuel. Y.S.Kim, G.L.Hofman, A.M.Yacout: Journal of Nuclear Materials, 2009, 392[2], 164-70