Irradiation testing of type 316L(N)- ERH plate and its EB and TIG welds. Report on sub-task T214 GB6-ECN-4. Fracture toughness after irradiations to 1 and 10 dpa at 325C

This report contains the results of an investigation into the fracture toughness reduction due to neutron irradiation of Type 316L(N)-IG steel, its electron beam welds, and a TIG deposit. The experimental work comprised upper shelf fracture resistance testing of unirradiated and 1 and 10 dpa irradiated steel. Small, 2.5 mm thick, compact tension specimens were irradiated in the reactor core of the HFR in Petten, The Netherlands, at a target temperature of 325C. They were subsequently tested at 80C and 325C. The results are tabulated and visualised in J-curves graphs and discussed. The main conclusions are that there is a reduction in fracture toughness when a neutron irradiation dose level is applied up to 10 dpa at 325C. Also, at 325C testing temperature, the j-toughness is lower than at 80C testing temperature. These conclusions apply for all materials considered in this report. Furthermore, it is found that EB welding is a good means of joining Type 316L(N)-ERH steel for these material and irradiation conditions, since the joint possesses almost the same fracture toughness properties as the mother material. The TIG weld is, though lower in fracture toughness than ERHII to begin with, not degraded as severely as ERHII. The tearing resistance at 10 dpa dose level at an irradiation temperature of 325C reduces the tearing resistance of all materials tested at the irradiation temperature to fairly low values. 22 refs