Influence of the Specific Surface Area Value on Spent Nuclear Fuel Dissolution Rates

Abstract

This paper focuses on the influence of the evolution of the specific surface area during the alteration process of the spent nuclear fuel. We describe results of a spent fuel Matrix Alteration Model (MAM) that allows the alteration rate evolution to be predicted as a function of the host rock considered and evaluation time scale of interest.

The changes produced by the value of the UO2 specific surface area on the MAM model (presented in a previous MRS conference) are here analyzed. The matrix alteration rates obtained with the MAM model (for granitic environment) are presented and compared to those performed for Spent Fuel Stability project (SFS). 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.

A strong dependence of the alteration rates of the spent fuel on the specific surface area is found. These results are presented for a specific scenario, but they could be extrapolated to different environments depending on the input file.