Aspects of Postclosure Safety of the Mark II Engineered Barrier System for a Used Fuel Repository

Abstract

The Nuclear Waste Management Organization is responsible for the implementation of Adaptive Phased Management, the federally-approved plan for the safe long-term management of Canada’s used nuclear fuel. Under this plan, used nuclear fuel will ultimately be placed within a deep geological repository in a suitable host rock formation.Before specific sites have been identified for detailed examination, generic studies are used to illustrate the long-term performance and safety of the multi-barrier repository system within various geological settings. The 6^th and 7^th Case Studies consider the postclosure safety of a repository that uses the Mark II engineered barrier system (EBS).To be effective, the safety assessment must be robust and have an appropriate balance of model simplicity without excess conservatism. This paper considers how to approach a postclosure safety assessment of the Mark II EBS, with focus on the container failure model. Models representing the Normal Evolution Scenario are presented, including calculations and results.