Activation analyses for the different options considered in the US ITER blanket trade-off study

Detailed activation analyses were performed for the different blanket design options considered in the ITER blanket option trade-off study. The options considered included a self-cooled Li/V option, a helium-cooled Li/V option and a water-cooled 316 SS non-breeding shield option. A vacuum vessel made of double-wall Inconel 625 and water-cooled 316 SS balls was used with all options. The He-cooled blanket activity is higher than that of the self-cooled blanket due to the larger structure content. Meanwhile, the vacuum vessel activity is lower for the He-cooled blanket option due to the larger neutron attenuation in the blanket. The shield activity and decay heat of the 316 SS/H2O option are higher than those of the Li/V blankets due to the large amount (80%) of 316 SS used. In both Li/V options the blanket qualifies as class C low-level waste. On the other hand, the 316 SS/H2O shield does not qualify for disposal as low- level waste. The 316 SS/H2O option produces the highest off-site doses in the case of accidental release of 100% of its radioactive inventory. Only remote maintenance would be allowed for all options. (orig.)