Towards higher temperatures in nuclear waste repositories

Recently, there is a tendency to explore the possibility of increasing the maximum design temperature in deep geological repositories for high-level nuclear waste and spent fuel. In the paper, a number of issues related to the use of higher temperatures are reviewed. Both bentonite barriers and argillaceous host rocks are addressed. An application involving the modelling of a large-scale field test conducted at a maximum temperature of 140ºC is presented. It is shown that currently available theoretical formulations and computer codes are capable to deal with temperatures above 100ºC and to reproduce satisfactorily the thermally-induced overpressures in the rock.