A probabilistic model for estimating the life expectancy of used nuclear fuel containers in a Canadian geological repository: Baseline model

Abstract

Placement of encapsulated used nuclear fuel in a deep geological repository is recognised internationally as the leading option to achieve containment and isolation from the environment and the public. In Canada, containment and isolation are proposed through an engineered barrier system, which comprises a copper-coated, welded carbon-steel container to encapsulate used fuel, highly compacted bentonite clay buffer, and the geosphere. Critical to regulatory approval and public confidence is the robustness of the engineered barrier system to perturbations capable of affecting the survival of used fuel containers over time scales of interest. However, uncertainty in the evolving conditions of a repository adds to the challenge of used fuel container life predictions. A new probabilistic container survival model is presented, featuring a simple, multi-level Monte Carlo technique to account in part for the unique constraints posed by a deep geological repository layout and an engineered barrier system on lifetime predictions.