ECN publication
10 DPA 600 K fracture toughness of 316L(N) ERHII plate material: ITER Task T214, NET deliverables GB5 ECN-4 and GB6 ECN-4
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ECN report number: Document type:
ECN-C--98-032 ECN publication
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The fracture toughness properties of unirradiated and neutron irradiatedtype 316L(N)-SPH stainless steel plate have been measured. Compact tension specimens with a thickness of 2.5 mm of the European Reference Heat 11 (ERH11) were irradiated in the High Flux Reactor (HFR) in Petten, The Netherlands, simulating the first wall conditions by a combination of high displacement damage with proportional amounts of helium. Helium contents are up to 80 appm for 10 dpa dose level. The irradiation conditions were 1 and 10 displacements per atom (dpa) at 600K. The report contains the experimental conditions and summarises the results, which are given in terms of J-resistance curve fits. The main conclusions are that the 1 dpa, 600K irradiation gives a considerable reduction in J-toughness in the plate materials. The increase of the dose up to 10 dpa does give a further significant decrease in fracture toughness. Fractography supports these measurements. As these fracture toughness measurements have been obtained by using small CT-specimens with a thickness of 2.5 mm, and as unirradiated austenitic stainless steel has a very high toughness, the values presented do not qualify as a size independent material property. However, the fracture toughness is reduced significantly after 10 dpa irradiation, approaching the validity criteria. Further it is shown that the fracture toughness results for reference and 1 dpa irradiated material presented here are conservative compared to results of 10 mm thick CT fracture toughness experiments. This conservatism is probably less present for the 10 dpa irradiated specimens because of the amount of embrittlement. Further work is continuing, investigating the fracture toughness of 600K 10 dpa irradiated 316L(N) TIG deposit and 316L(N) Electron beam welds. 14 refs.

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