427 Role of Radiolysis in Spent Nuclear Fuel Alteration in Repository Conditions

Friday, November 6, 2009: 4:40 PM
Hereford (Camino Real Hotel)
Jean-Francois Lucchini , Ees-12, Los Alamos National Laboratory, Carlsbad, NM
The dissolution kinetics of the uranium dioxide (UO2) and the rates of radionuclide release are the most important parameters to determine in the performance assessment of a spent nuclear fuel underground repository.

Because of the radiation fields coming from the spent nuclear fuel, it is generally acknowledged that over time, the main factor influencing the stability of the spent nuclear fuel under repository conditions will be the radiolytic generation of oxidants in the water that may surround the spent fuel. Water radiolysis within spent fuel canister can significantly affect the chemistry of the spent fuel/water interface.

Experimental studies on spent fuel leaching have been going on since the late 1970s, using a variety experimental conditions and solution compositions. None of these studies could determine a clear effect of water radiolysis on spent nuclear fuel alteration, whereas some specific studies on UO2 dissolution in the presence of radiation showed an impact.

This bibliographic work will present the current status of knowledge and the most recent experimental works on the possible effect of water radiolysis on spent nuclear fuel alteration in underground repository conditions. We will especially focus on the strength and limitations of laboratory testing on UO2 alteration behavior with the respect to the interpretation of long-term spent nuclear fuel alteration.