Japanese contributions to ITER shielding neutronics design

Shielding design for superconducting magnets and personal exposure were performed in ITER nuclear design on the basis of reports presented to the 1990 winter and summer ITER specialist meetings. Inboard shield benchmark calculation, bulk inboard shielding analysis, inboard heterogeneity effect on shielding property analysis, gap streaming analysis were discussed on shielding properties for superconducting magnets. In addition to these, transport and Monte Carlo analyses in neutral beam injector duct for biological shielding were investigated with relation to the concept of cryostat. Further biological shielding were investigated in reactor room and site boundary during the maintenance when one activated module was extracted and hanged from the ceiling. As the results of these studies, ITER shielding characteristics were evaluated and problem areas and directions for future works were shown. (author)