Neutron streaming analysis for helical geometry system, heliotron-H fusion power reactor.

Abstract

Nuclear analysis was carried out for the Heliotron-H reactor. Due to the helical geometry of the system, 14 MeV neutron streaming inherent in the reactor exists; some of source neutrons generated in the plasma region can see the coil shield surface in a direct line-of-sight manner and stream through blanket regions without collisions. With an appropriate coordinate transformation from the helical geometry, analysis on the neutron streaming was made possible by a method coupling the three-dimensional Monte Carlo code and two-dimensional discrete-ordinates transport code. For each radiation response parameter in the helical magnet, the streaming neutrons contribute 40–50%. This fact strongly suggests the need of taking account of the contribution from the streaming neutrons to provide an adequate shielding for the helical magnet.