Preliminary neutronics analysis and maintenance approach for final optical devices of fast ignition ICF reactor FALCON-D

The final optics system of a fast ignition laser reactor concept with a Dry first-wall and a high repetition laser (FALCON-D) is discussed. A cartridge module is proposed for the final optics system. Preliminary neutronics analysis for the final optics systems concept is carried out with the three-dimensional Monte Carlo N-particle transport code MCNP-4C. The total neutron and gamma-ray fluxes attenuate by 4-5 orders of magnitude between inlet and outlet of the duct in the final optics system for FALCON-D. Both of the total neutron and gamma-ray fluxes at the outlet in the final optics system are less then 1.0 × 10⁸ cm^-2 s^-1, which are about 10 times less than that of the total neutron gamma-ray fluxes at the position just after the shield blanket of the tokamak reactor concepts. Hence, we can qualitatively get the prospect that the cask and hot-cell maintenance, which are proposed for blanket replacement in the tokamak reactor concepts, are also applicable to FALCON-D. The maintenance approach of the final optics system is also proposed. The cartridge module built in the wall of the reactor room can be replaced from the outside of the reactor room. This built-in style cartridge module probably leads an efficient replacement method for the high plant availability.