Induced activity of first wall materials of fusion reactors

Induced radioactivity, surface dose rate of γ-ray, biological hazard potential, and decay heat of 30 element at the first wall position of a fusion reactor were calculated as a function of neutron fluence using Induced Radioactivity Calculation (IRAC) code. Based on the criteria such as safe surface dose rate, natural uranium activity level, and land disposal limits of NRC, the classification of materials was made. Among elements, Co, Ni, Cu, Nb, and Mo are not preferable elements as first wall component materials. The production of long-lived γ-emitter nuclides, 26Al, from Al and Si was expected. The radioactivity of 26Al from Al can not be ignored for long term operation of ≥10MW.y.m-2. It is necessary to carefully evaluate the radioactivity of 10Be and 14C with long half-lives, respectively, formed from B and N, although these nuclides are not γ-emitters. (author)