Neutron Streaming Through Gaps in Fusion Reactor Shielding

Calculations have been performed using the Monte Carlo code, MORSE-CG, to determine the neutron streaming through various straight and stepped gaps between radiation shield sectors in the conceptual tokamak fusion power plant design STARFIRE. This design calls for “pie-shaped” radiation shields with gaps between segments. It is apparent that some type of offset, or stepped gap, configuration will be necessary to reduce neutron streaming through these gaps. To evaluate this streaming problem, a MORSE-to-MORSE coupling technique was used, consisting of two separate transport calculations, which together defined the entire transport problem. The results define the effectiveness of various gap configurations to eliminate radiation streaming.