Compatibility test between beryllium and ferritic stainless steel(F82H)

In a fusion blanket, beryllium has been identified for use as neutron multiplier, where it will be in contact with the structural material. Austenitic stainless steel, 316SS has been considered as the structural material. However, from some studies, it is reported that beryllium reacts with 316SS above 600 °C. In our investigations, we found that the reaction product between beryllium and nickel, BeNi was formed on 316SS side at 600 °C. Therefore, the compatibility between beryllium and ferritic stainless steel without nickel, F82H(Fe — 8%Cr — 2%W — 0.2%V) as the new structural material in JAERI was investigated to determine if it was more compatible with beryllium. In this study, for clarifying the chemical interaction between beryllium and F82H, the out-of-pile compatibility test has been carried out with diffusion couples of beryllium and F82H which were inserted in the capsule filled with high purity helium gas. Annealing temperatures was 400, 600 and 800 °C, and annealing periods was 100, 300 and 1000 h, respectively. From the results of this test, it is obvious that the thickness of reaction layer in F82H is 23 of that in 316SS in the case of annealing at 800 °C for 1000 h.