Nuclear Waste Disposal with Thermally Engineered Bentonite Backfill

Abstract:

This modeling study demonstrates the feasibility of disposal of very large sized nuclear waste canisters in bentonite-backfilled tunnels by the use of backfill engineered for high heat conduction. The high heat conduction backfill material can efficiently transfer decay heat from the waste into the surrounding host rock and thereby reduce the backfill temperature to acceptable levels, even for very large nuclear waste canisters. On the other hand, the use of high heat conduction backfill will not reduce the far field rock peak temperature that can occur several thousand years after closure of the repository. This longer term host rock peak temperature generates thermal-poro-elastic stress and geomechanical changes that must be considered in the thermal management and design of a repository.