Evaluation of weldment sensitization on Type 304 and 304L stainless steel spent-fuel canisters

Sensitization was evaluated on welded Type 304 and 304L stainless steel canisters produced for the Commercial Waste Spent Fuel Packaging Program (CWSFPP) and the Nevada Nuclear Waste Storage Program (NNWSP). The canister weldments which were made under conditions having the greatest potential for causing sensitization were examined using metallographic and corrosion test practices described in Specification ASTM A-262, and also by exposure to hypothetical conditions simulating continuous boiling water immersion at the storage sites. When tested to ASTM A-262, the Type 304 weldments displayed classical evidence of sensitization; i.e., loss of corrosion resistance at heat affected zones, but no evidence of sensitizations was uncovered on the Type 304L weldments. Both the Type 304 and 304L weldments were totally unaffected by exposure for 1500 hours under conditions of continuous boiling water immersion, indicating that the CWSFPP and NNWSP canisters have adequate corrosion resistance for the intended applications