Influence of low temperature air oxidation on the dissolution behaviour of UO(2) and MOX spent fuel
The dissolution behaviour of pre-oxidized light water reactor (LWR) UO(2) and mixed oxide (MOX) spent fuel was studied by means of semi-dynamic leaching tests. The fuels, irradiated to burnups of 53 GWd/t and 39 GWd/t respectively, were thermally treated at 250 C in air for various times, up to different oxygen/metal (O/M) ratios. The leaching tests performed in deionized water at ambient temperature revealed, for both UO(2) and MOX, an instantaneous release step strongly dependent on the oxidation degree. After this initial stage, a very low leaching rate, almost independent of the O/M-ratio, was measured. For both fuel types, the fission products considered showed a fractional release normalized to uranium higher than 1. In contrast to fission products, the fractional release of Pu from the UO(2) fuel was not affected by the oxidation level of the fuel and was one order of magnitude lower than the release of U. For MOX fuel, the heterogeneity of the material due to the fabrication process with Pu as fissile element being concentrated in agglomerates leads to a stronger release of this element relative to the matrix U for the non-oxidized sample. After oxidation the instantaneous release rate of Pu is again significantly lower in comparison to U.
Bibliographic Reference: Paper presented: Actinides '97, Baden-Baden (DE), 21-26 September 1997
Availability: Available from (1) as Paper EN 41110 ORA
Record Number: 199810232 / Last updated on: 1998-03-09
Original language: en
Available languages: en