Development of Nondestructive Examination Acceptance Criteria for Shallow Partial Penetration Welds in a Conceptual Used Nuclear Fuel Container

Abstract The used fuel container (UFC) is a metal container for long-term management (i.e., disposal) of used nuclear fuel in a deep geological repository. The UFC employs a nonstandard closure weld joint with a shallow partial penetration. The container was constructed following the principles of ASME Boiler and Pressure Vessel Code (BPVC) Section III, Division 3, and the weld is inspected by surface and volumetric nondestructive examination (NDE) methods, i.e., eddy current testing (ET) and ultrasonic testing (UT). NDE acceptance criteria for this customized weld joint are developed based on the effect of porosity and its interaction with the partial penetration weld geometry. The safety margin of the proposed acceptance criteria is verified through tensile tests of welded specimens containing artificial defects of bounding geometry. The effectiveness of the acceptance criteria is further demonstrated in full-scale prototype manufacturing and external pressure tests.