Shielding design of reactor core region in fusion experimental reactor

Shielding properties for SCM and biological shields are investigated for ITER core structure. From these investigations, we obtained following results. In TFC, copper radiation damage and insulator dose considering safety factor 3 do not satisfy the shielding design limits in 3 MWa/m2 first wall neutron fluence. In order to satisfy the limits, inboard shield thickness must be added by 8 cm. Dose rates in center solenoid coils are 2-3 orders larger than biological design limit of 25 μSv/h at one day after shutdown. Therefore, it is impossible for workers to access directly the coils. While, dose rate just outside the cryostat is much smaller than the limit. Therefore, workers can enter into the reactor room. Two dimensional calculation can express passing neutron around the vacant space between outboard shield and cryostat. Two dimensional calculation is indispensable to shielding investigation, when this effect is large. It can be seen that homogenizing voids makes shielding properties overestimated. Support structures free from voids should be devised in reactor core design. In the present report, shielding properties were investigated on reactor core structure excluded various penetrations, such as ducts and ports, etc. The effects of these penetrations on the shielding properties will be presented in another report. These results obtained can also be applied to the domestic next facility of FER. (author)