Improvements of Radiation Shielding Designs on Advanced Liquid Blankets for Fusion Reactor FFHR

Improvements of radiation shielding designs for the Flibe-cooled and Li-cooled blanket systems have been performed in the design activity of the helical-type fusion reactor FFHR2 based on 3-D Monte Carlo neutronics calculations. Evaluations of the fast neutron fluxes with a simple torus calculation model indicate that the Flibe-cooled blanket systems would achieve adequate shielding abilities within the blanket space of similar to 100 cm by adjusting the ratios of JLF-I (Reduced Activation Ferritic Steel) and B4C in the radiation shield. For the Li-cooled blanket system, enhancement with a heavy density material such as WC would be needed for reducing the blanket space to similar to 100 cm. Nuclear heating in the superconducting magnet regions was lower than the allowable level for all the blanket systems. In the optimization of the shielding configuration with a 3-D reactor geometry, neutron streaming through the divertor pumping areas and neutron reflection are the issues to be improved by further design modification.