Irradiation behaviour of MOX fuel : Results of an EPMA investigation
The redistribution of Pu and the behaviour of Xe and Cs were investigated in three sections of irradiated MOX fuel produced by the AUPuC process. Two of the fuels had been irradiated under steady-state conditions to burn-ups of 23.2 and 38.8 GWd/t; the third had been transient tested to 42 kW/m at a burn-up of 26.2 GWd/t. The MOX agglomerates became highly porous in the course of irradiation. This porosity is attributed to vacancy supersaturation caused by the locally high fission density. Little U/Pu diffusion had occurred in the fuels irradiated under steady-state conditions. In the central region of the transient-tested fuel, as a consequence of fast interdiffusion, the MOX agglomerates had dissolved completely in the UO(2) matrix. Release of Xe and Cs from the MOX agglomerates is considered to involve two steps. First, Xe and Cs atoms are transferred to the UO(2) matrix by recoil or thermal diffusion or both, depending on the fuel temperature. Second, 5% of the Cs inventory is released from the UO(2) matrix in the fuels irradiated under steady-state conditions. In the transient-tested fuel, release figures of 50% for Xe and 35% for Cs were obtained.
Bibliographic Reference: Article: Nuclear Engineering and Design, Vol. 131 (1991) pp. 1-16
Record Number: 199210203 / Last updated on: 1994-12-02
Original language: en
Available languages: en