Reducing Uncertainties Affecting the Assessment of the Long-Term Corrosion Behavior of Spent Nuclear Fuel

Reducing the uncertainties associated with the extrapolation to very long term of corrosion data and findings obtainable from laboratory tests on relatively young spent fuel is a formidable challenge. In a geologic repository, spent nuclear fuel may become in contact with water tens or hundred thousand years after repository closure. The corrosion behaviour will depend on the fuel properties and on the conditions characterizing the near-field surrounding the spent fuel at the time of water contact. This paper summarizes the main conclusions drawn from multi-year experimental campaigns performed at JRC-ITU to study corrosion behaviour and radionuclide release from spent light water reactor fuel. The radionuclide release from the central region of a fuel pellet is higher than that from the radial periphery, in spite of the higher burnup and the corresponding structural modifications occurring at the pellet rim during irradiation. Studies on extent and time boundaries of the radiolytic enhancement of the spent fuel corrosion rate indicate that after tens or hundred thousand years have elapsed very small or no contribution to enhanced corrosion rate has to be expected from alpha-radiolysis. A clear beneficial effect inhibiting spent fuel corrosion due to the hydrogen overpressure generated in the near field by iron corrosion was confirmed. The results obtained so far point towards a benign picture describing spent fuel corrosion in a deep geologic repository. More work is ongoing to further reduce uncertainties and to obtain a full description of the expected corrosion behaviour of spent fuel and other waste forms.

FANGHAENEL Thomas;  RONDINELLA Vincenzo;  GLATZ Jean-Paul;  WISS Thierry;  WEGEN Detlef;  GOUDER Thomas;  CARBOL Paul;  SERRANO PURROY Daniel;  PAPAIOANNOU Dimitrios; 

2013-07-30

AMER CHEMICAL SOC

JRC74292

0020-1669,   

pubs.acs.org/IC,    https://publications.jrc.ec.europa.eu/repository/handle/JRC74292,   

10.1021/ic302012c,