Dissolution Behavior of Irradiated Mixed-oxide Fuels with Different Plutonium Contents

The effects of Pu content on the dissolution rate and the mass of the insoluble residue of irradiated mixed oxide fuel were studied. On the basis of the kinetic analysis assuming the surface-area model, the dissolution rate was found to decrease exponentially with an increase of the Pu content, but those were estimated to be up to 103 times larger than non-irradiated fuels. The mass of the insoluble residue tended to increase with an increase of the Pu content, possibly due to the promotion of fission product formation and an increase of refractory Pu enriched zone.