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Influence of the Evolution of the Surface Area Value on the Spent Nuclear Fuel Dissolution Rate for Performance Assessment Studies

Published online by Cambridge University Press:  01 February 2011

Javier Quiñones ,
Eduardo Iglesias ,
Nieves Rodriguez  and
Juan Manuel Nieto
Javier Quiñones
Affiliation:
javier.quinones@ciemat.es, CIEMAT, Energy, Madrid, Spain
Eduardo Iglesias
Affiliation:
eduardo.iglesias@ciemat.es, CIEMAT, Energy, Madrid, Spain
Nieves Rodriguez
Affiliation:
nieves.rodriguez@ciemat.es, CIEMAT, Energy, Madrid, Spain
Juan Manuel Nieto
Affiliation:
juan.nieto@ciemat.es, CIEMAT, Energy, Madrid, Spain
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Abstract

This paper focuses on how to extrapolate current knowledge of spent fuel matrix alteration processes from laboratory to repository conditions, i.e., the influence of changes in both the initial surface oxidation level and the evolution of the specific surface area during the alteration process. Therefore, a spent fuel matrix alteration model allowing the alteration rate evolution to be predicted as a function of both the host rock considered and evaluation time scale of interest is described. At present, the model assumes that alteration of the spent fuel will start when the groundwater reaches the solid surface and that only the radiolytic species of the groundwater (oxidants generated by a-radiation of spent fuel) will produce the surface oxidation process and subsequent matrix dissolution; O2, H2O2 and OH are the species that react with UO2(s) for oxidation of the pellet surface. The dissolution process of the surface sites that are oxidized is modelled in two steps: first, a surface co-ordination of the oxidized layer with aqueous ligands and, second, detachment (dissolution) of the product species. Taking this mechanism into account, the model gives the evolution of the spent fuel matrix alteration rate over periods as long as 1,000,000 years. In this work is focussed on input the experimental results obtained of UO2 surface area behaviour (presented in previous MRS conference), on the MAM model. The matrix alteration rate results obtained, with MAM model, for repository granitic environment will be presented and compared to those performed for SFS project. Furthermore, a sensitivity analysis study has been performed on the influence of the following variables: Influence of the initial power size distribution and the initial oxidation state

Keywords

waste managementsurface reactioncorrosion
Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 1124: Symposium Q – Scientific Basis for Nuclear Waste Management XXXII , 2008 , 1124-Q02-02
Copyright
Copyright © Materials Research Society 2009

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References

REFERENCES

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