Materials selection for reduced activation of fusion reactors

The induced activity of thirty elements which are assumed to compose the fusion reactor first wall and shield has been calculated as a function of the neutron fluence. The evaluation of the radioactivity was made to criteria for surface dose rate and waste disposal. The potential materials for a low activation first wall are strictly limited to light elements found in ceramics and composites, based on rapid access for maintenance after long-term operation. Al is a promising low activation material for neutron fluences of <1 MW.y.m-2. Mo is not favorable for the first wall material because of the production of long lived radioactive nuclides. However, the activity decay of Mo is very fast if Mo is used as the shield material and the fluence does not exceed 1 MW.y.m-2. (orig.)