Matrix Swelling Rate and Cavity Volume Balance of UO2 Fuels at High Burn-Up

The low temperature matrix swelling of UO2-fuels was analysed as a function of burn-up, taking into account changes in the fuel density, porosity and retained Xe-concentration as measured by EPMA. The combined evaluation of these data leads to the conclusion that at average pellet burn-ups ≥ 60 GWd/tM the total matrix swelling rate is gradually reduced from ~1 %/10 GWd/tM to ~0.3 %/10 GWd/tM; the latter value being reached at an average burn-up above 110 GWd/tM. The decrease in the swelling rate is due to the progressive depletion of fission gas in the fuel matrix by thermal and athermal processes, such that at very high burn-up the matrix swelling becomes dominated by the precipitation of solid fission products. Owing to volume conservation, the volume occupied by the depleted gas is replaced by porosity.

SPINO Jose Luis;  WALKER Clive;  REST J.;  GOLL W.; 

2006-01-17

ELSEVIER SCIENCE BV

JRC30230

https://publications.jrc.ec.europa.eu/repository/handle/JRC30230,   

10.1016/j.jnucmat.2005.06.015,