Clarification of fission gas release behaviour of LWR MOX fuels by means of out-of-pile annealing tests and microstructure observations

For the efficient operation of LWR MOX fuels, burnup extension of MOX fuels up to the same burnup level of UO2 fuels would be advantageous. Previous studies reported that the release of fraction of fission gas (FG) from MOX fuels tends to be slightly larger than that of UO2; therefore, the burnup of MOX fuels has been restricted to lower levels that for UO2. In order to implement a burnup extension for MOX fuels, full clarification of the fission gas release behaviour is needed. To understand the fission gas release mechanisms, out-of-pile annealing tests were performed in JRC-ITU on irradiated MOX using a shielded Knudsen cell connected to a mass spectrometer. The correlation between fission gas release and fuel microstructure changes was investigated by adopting a stepwise annealing schedule combined with morphology examination after each temperature step by scanning electron microscopy (SEM). In this study, samples from periphery, intermediate and central region of the same MOX fuel pellet (44 GWd/tM) were analyzed.

SONODA T.;  SASAHARA A.;  KITAJIMA S.;  RONDINELLA Vincenzo;  PAPAIOANNOU Dimitrios;  COLLE Jean-Yves;  WISS Thierry;  BENES Ondrej; 

2013-06-07

Elsevier

JRC73072

www.nuclearmaterialsconference.com,    https://publications.jrc.ec.europa.eu/repository/handle/JRC73072,