Fracture toughness evaluation for thin-shell stainless steel weldment

Abstract

Integrity of spent nuclear fuel (SNF) interim storage canisters are very important to the safety of the back-end nuclear fuel cycle. Stress corrosion cracking (SCC) potential of interim storage canister has been considered as a high priority. Because no post-weld heat treatment was required for forming these canisters, the high tensile residual stress existed within these canister welds. This can change the fracture resistance capacity significantly as well as increase SCC potential. Due to relative thin shell thickness of a canister weldment, the spiral notch torsion test (SNTT) method of small specimen approach was used to estimate the canister weldment fracture toughness. Most SNTT weldment samples fracture initiation sites are at heat-affected zone (HAZ) regions. The estimated fracture toughness JQ’ for the baseline SS304 steel is at 283 kJ/m2. The estimated JQ’ for the SS304/308 weld from HAZ and weld specimens are 126 kJ/m2 and 148.9 kJ/m2, respectively.