Activation analyses for the different options considered in the U.S. ITER blanket trade-off study

Since the beginning of the Engineering Design Activity (EDA) of ITER a variety of blanket design options have been proposed. A blanket option trade-off study has been conducted by the U.S. ITER home team to examine some of these options. As part of this study detailed activation analyses have been performed for three of the different blanket design options considered. 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 (VV) made of a double wall Inconel 625 and water cooled 316 SS balls is used with all options. The analyses have been performed for the normal case with 3 GW fusion power and average neutron wall loading of 2 MW/m2. Total activity decay heat and integrated decay heat have been determined for the blanket and vacuum vessel. Dose rate calculations have been performed at different locations inside the reactor containment. The activation results have also been utilized in radwaste classification and off-site dose calculations. The waste disposal ratings (WDR) for the blanket and vacuum vessel have been determined using the US NRC 10CFR61 waste disposal concentration limits. The off site doses are produced by the accidental release of the radioactive inventory from the reactor containment building assuming worst case weather conditions and 100% release