Radiation streaming analysis through narrow gaps in Fusion Experimental Reactor. (FER)

Abstract

Many void gaps originated from assembly/disassembly concept of reactor structures exist in a tokamak reactor. Radiation streaming through these gaps causes hot spots in terms of irradiation of in-vessel components and of biological dose rate in personnel access area. For two-dimensional analysis of streaming through such a narrow gap, the discrete ordinates (S N) method suffers from ray effects. In this paper, therefore, necessary conditions for angular quadrature were fist investigated by comparing the S N results with the line-of-sight results and the Monte Carlo results. As a result, it was found that the biased 166 angular quadrature (131 forward angles) gave results with practically sufficient accuracy for shielding design with some correction for the ray-effect. Also, local peaking factors due to the gap streaming were obtained as a function of gap width and shield thickness, and they are useful for future shielding design. Based on these preliminary investigations, the design calculation for the FE...