Neutron and gamma ray streaming calculations for the ETF neutral beam injectors

Two-dimensional radiation transport methods have been used to estimate the effects of neutron and gamma ray streaming on the performance of the Engineering Test Facility (ETF) neutral beam injectors. The calculations take into account the spatial, angular, and spectral distributions of the radiation entering the injector duct. The instantaneous nuclear heating rate averaged over the length of the cryopumping panel in the injector is 7.5 x 10-3 MW/m3 which implies a total heat load of 2.2 x 10-4 MW. The instantaneous dose rate to the ion gun insulators was estimated to be 3200 rad/s. The radial dependence of the instantaneous dose equivalent rate in the neutral beam injector duct shield was also calculated