Neutronics analysis of the ITER NB system Nuclear responses of the components and shutdown dose around the NB injector

Neutronics of the neutral beam (NB) injector for international thermonuclear experimental reactors (ITER) was analyzed by two- and three-dimension (3-D) codes, and their results were then compared. The neutron flux on the beam line axis obtained by the 2-D code agrees with that by the 3-D code within 30%. The shutdown dose rate around the NB injector was estimated by the 2-D model developed by taking into consideration both the plasma operation pattern and the scenario. The dose rate at 106 s after the shutdown around the NB injector was estimated to be 40 μSv/h, which allows for hands-on maintenance during the shutdown period