The Use of Numerical Simulations to Establish Copper Coating Bond Acceptance Criteria in Used Fuel Containers for Nuclear Waste Disposal

Abstract

The Adaptive Phased Management program is Canada’s solution for the long-term management of its used nuclear fuel. The end point of this program is to contain and isolate the used fuel in a centralized Deep Geological Repository (DGR) equipped with a multiple barrier system, which includes a suitable rock formation and several engineered barriers. The Used Fuel Container (UFC) is a key engineered barrier that provides the containment function for a significant period. NWMO’s current Reference Design for the UFC is comprised of a carbon steel vessel and an integrally bonded copper coating. The steel vessel is designed to provide structural strength, while the copper coating is designed as a corrosion barrier to provide long-term corrosion protection.

Two different coating technologies (electrodeposition and cold spray) are used to apply the copper corrosion barrier to the exterior surface of the UFC. Non-destructive examination (ultrasonic testing) is used to inspect and characterize the copper-steel interface for bond integrity and provide feedback for further coating process development. In the absence of applicable codes and standards for this first-of-a-kind application, the acceptance criteria for disbond indications are being developed at the NWMO through experimental testing and computer modeling. The work includes adhesion strength testing, benchmarking simulations of the tests, and stress analysis of the UFC under its design basis loads. This paper presents the current progress of the above work.