Radiation shielding analysis of a large helical device

Radiation shielding analysis of a large helical device (LHD) has been performed to provide information on a radiation environment needed for equipment design and operation planning. First, the applicability of the JENDL-3 library which was applied to the shielding calculations of the LHD was tested by means of a benchmark experiment on the shielding efficiency of ordinary concrete carried out at the fusion neutronics source facility at JAERI. Benchmark analysis was carried out with the MCNP continuous energy Monte Carlo code to test the JENDL-3 library itself. The same benchmark calculation was carried out with the DOT3.5 code to examine the groupwise cross-section library of fusion-40 processed from JENDL-3. Secondly, the evaluation of the following items with the DOT3.5 code was revised, using fusion-40 instead of the formerly used GICX-40 library: (1) dose distribution inside and outside the LHD building; (2) dose distribution inside the cellar of the LHD building resulting from steamed radiations; (3) Environmental dose distribution resulting from sky-shine effect; (4) activity and dose rate levels of vacuum vessel and superconducting magnet.