ependence of the specific surface area of the nuclear fuel with the matrix oxidation

Abstract

This paper is focused on the study of the changes in the specific surface area measured using BET techniques. The objective is to obtain a relation between this parameter and the change in the matrix stoichiometry (i.e., oxidation increase). None of the actual models used for extrapolating the behaviour of the spent fuel matrix under repository conditions have included this dependence yet. In this work the specific surface area of different uranium oxide were measured using N{sub 2}(g) and Kr(g). The starting material was UO{sub 2+x}(s) with a size powder distribution lower than 20 {mu}m. The results included in this paper shown a strong dependence on specific surface area with the matrix stoichiometry, i.e., and increase of more than one order of magnitude (SUO{sub 2} = 6 m{sup 2}*g{sup -1} and SU{sub 3}O{sub 8} = 16.07 m{sup 2}*g{sup -1}). Furthermore, the particle size distribution measured as a function of the thermal treatment done shows changes on the powder size related to the changes observed in the uranium oxide stoichiometry.