URANINITE AND UO2 IN SPENT NUCLEAR-FUEL - A COMPARISON

Similarities and differences between uraninite and uranium dioxide in spent nuclear fuel are discussed in detail. Uraninite and its morpholo gical variety, pitchblende, display structural and chemical properties and features that can be considered analogous to UO2 in spent nuclear fuel, despite the different thermal histories and irradiation conditi ons. The similarities include topologically identical structures, high resistance to radiation damage, solid solutions with ThO2, CaO, and R E(2)O(3), similar behavior during oxidation, and presence of fission p roducts in uraninite from natural fission reactors in Gabon. The behav ior of fission product residues during alteration of uraninite to coff inite in natural fission reactors may aid in estimation of the long-te rm behavior of fission products from spent fuels under repository disp osal conditions.