Additive Manufacturing and Regulatory Testing of Canisters for Spent Nuclear Fuel Management

Abstract

Abstract The back end of the nuclear fuel cycle focuses on the interim storage, transportation, and final disposition of the spent nuclear fuel (SNF) from reactors. Commercial light-water nuclear power stations across the United States operate with fuel assemblies that are irradiated for up to 6 years (planned) in the reactor pressure vessel. After their planned irradiation, the fuel assemblies are moved to a spent fuel pool within the facility complex. After the SNF is removed from the fuel pool, it is typically inserted into a welded metal canister that can be transferred between overpacks for storage, transportation, and possibly disposal. Most dry storage systems used in industry today use dual-purpose canisters (DPCs), which designed for use in storage and transportation overpacks but are not specifically designed for disposal. Triple-purpose canisters, designed for disposal in addition to storage and transportation, have also been researched. Traditional manufacturing methods for spent fuel canisters involve fusion welding along the length or circumference of the canister, resulting in high-tensile residual stresses in the joint weld zone (WZ) and heat-affected zone (HAZ). This paper documents work in which spent fuel canister designs were printed by wire arc additive manufacturing (AM) using the 316L SS welding wire to demonstrate (1) the feasibility of SNF canister fabrication using this advanced manufacturing method and (2) the dynamic response of the AM canister design when subjected to the federally mandated Normal Conditions of Transport (NCT) and Hypothetical Accident Conditions (HAC) physical tests for Type B packages. This paper focuses on the canister printing design and structural tests. The AM 3D-printed design, regulatory testing, and post-test evaluation of the canister tested to the 10 CFR 71.71 and 10 CFR 71.73 requirements are presented herein. One AM canister design was subjected to the penetration, free drop, and puncture test. Before and after the dynamic structural tests, the AM canister design was scanned with a handheld scanner to capture a 3D CAD geometry to compare to the 3D-printed canister design in the deformed shape. The scanned geometry was sectioned in areas with deformation, and the cross section profile was measured to determine accurate and repeated results of the deformed shape of the AM canister design.