Evolution of the Uranium Concentration in Dissolution Experiments with Cr-(Pu) Doped UO2 in Reducing Conditions at SCK CEN

Cr-doped UO 2 -based model materials were prepared at SCK CEN, mimicking modern LWR fuels, to understand the influence of Cr doping on the spent fuel dissolution behaviour in geological repository conditions. Tests were carried out with four model materials: depleted UO 2 , Cr-doped depleted UO 2 , Pu-doped UO 2 and Pu-Cr-doped UO 2 . Static dissolution experiments have been performed up to 4 months in autoclaves under 10 bar H 2 pressure with a Pt/Pd catalyst in media at pH 13.5 and at pH 9. The Cr-doping appeared to reduce the U concentrations by a factor 6 at pH 13.5, but it had no or not much effect at pH 9. Graphic abstract