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Effect of Spent Fuel Burnup and Composition on Alteration of the U(Pu)O2 Matrix

Published online by Cambridge University Press:  21 March 2011

C. Jégou ,
S. Peuget ,
J.F. Lucchini ,
C. Corbel ,
V. Broudic  and
J.M. Bart
C. Jégou
Affiliation:
Commissariat à l'Énergie Atomique (CEA), Rhô Valley Research Center, DRRV/SCD, BP 171, 30207 Bagnols-sur-Cèze Cedex, France
S. Peuget
Affiliation:
Commissariat à l'Énergie Atomique (CEA), Rhô Valley Research Center, DRRV/SCD, BP 171, 30207 Bagnols-sur-Cèze Cedex, France
J.F. Lucchini
Affiliation:
Commissariat à l'Énergie Atomique (CEA), Rhô Valley Research Center, DRRV/SCD, BP 171, 30207 Bagnols-sur-Cèze Cedex, France
C. Corbel
Affiliation:
Commissariat à l'Énergie Atomique (CEA Saclay), DSM/DRECAM/SCM Laboratoire de radiolyse, 91191 Gif sur Yvette Cedex, France
V. Broudic
Affiliation:
Commissariat à l'Énergie Atomique (CEA), Rhô Valley Research Center, DRRV/SCD, BP 171, 30207 Bagnols-sur-Cèze Cedex, France
J.M. Bart
Affiliation:
Commissariat à l'Énergie Atomique (CEA), Rhô Valley Research Center, DRRV/SCD, BP 171, 30207 Bagnols-sur-Cèze Cedex, France
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Abstract

For a potential performance assessment of direct disposal of spent fuel in a nuclear waste repository, the chemical reactions between the fuel and possible intruding water must be understood and the resulting radionuclide release must be quantified.

Leaching experiments were performed with five spent fuel samples from French power reactors (four UO2 fuel samples with burnup ratings of 22, 37, 47 and 60 GWd·tHM−1 and a MOX fuel sample irradiated to 47 GWd·tHM−1) to determine the release kinetics of the matrix containing most (over 95%) of the radionuclides. The experiments were carried out with granitic groundwater on previously leached sections of clad fuel rods in static mode, in an aerated medium at room temperature (25°C) in a hot cell.

After 1000 or 2000 days of leaching, the Sr/U congruence ratios for all the UO2 fuel samples ranged from 1 to 2; allowing for the experimental uncertainty, strontium can thus be considered as a satisfactory matrix alteration tracer. No significant burnup effect was observed on the alteration of the UO2 fuel matrix. The daily strontium release factor was approximately 1 à 10−7 d−1 for UO2 fuel, and five to six times higher for MOX fuel. Several alteration mechanisms (radiolysis, solubility, precipitation/clogging) are examined to account for the experimental findings.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 663: Symposium – Scientific Basis for Nuclear Waste management XXIV , 2000 , 399
Copyright
Copyright © Materials Research Society 2001

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References

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