Electron Microscopy of Barrier Coatings on Uranium-Molybdenum Fuel Irradiated to Burnup 60%

Abstract

Two directions of modification for increasing the stability of dispersion fuel U–Mo/Al under reactor conditions are examined. The first direction is to introduce Zr, Ti, and Si into the fuel alloy and Si, Mg into the aluminum matrix. The second direction is to create barrier coatings on the surface of fuel particles. Reactor tests of mini-fuel-elements with barrier coatings comprised of Nb, the alloy Zr–1%Nb, and UO₂ around the fuel particles were performed in the IVV-2M reactor. These tests showed a positive effect on the reduction of the swelling of mini-fuel-elements and growth rate of the (U, Mo)Al_x layer. The results of electron-microscopy and the distributions of U, Mo, Zr, Nb, Si, Al, Xe, Kr, and Nd in the components of the fuel compositions U–Mo/Al and U–Mo/Al–12%Si with barrier coatings comprised of niobium and the alloy Zr–1%Nb and UO₂ around fuel particles and without coatings irradiated to burnup 60% are presented.