Effect of Inhomogeneity on the Level of Fission Gas and Caesium Release from OCOM MOX Fuel during Irradiation
Two sections of OCOM fuel were investigated by electron probe microanalysis (EPMA). In one fuel the MOX agglomerates contained 18 wt% fissile plutonium, and had a low volume fraction of 0.17; in the other the agglomerates contained 9 wt% fissile plutonium, and had a high volume fraction of 0.34. Both fuels had been irradiated to a burn-up of approximately 44 GWd/t. It was found that the concentration of plutonium in the MOX agglomerates had decreased by about 50% as a result of fission, whereas the plutonium content of the UO(2) matrix had increased 10-fold to approximately 2 wt%, due to neutron capture. More than 80% of the fission gas had been released from the oxide lattice of the MOX agglomerates. A very high fraction of this gas precipitated and remained in the pore structure of the agglomerates. Consequently, for both fuels the percentage of gas related to the rod free volume increased from less than 0.5% at 10 GWd/t to a maximum of 3.5% at 45 GWd/t. Caesium showed near complete retention in both the MOX agglomerates and the UO(2) matrix.
Bibliographic Reference: Article: Journal of Nuclear Materials (1995)
Record Number: 199610078 / Last updated on: 1996-02-16
Original language: en
Available languages: en