Neutron and photon flux spectra in a mock-up of the ITER shielding system

A neutronics mock-up of the ITER inboard shielding system including first wall, shield-blanket, vacuum vessel and magnetic field coils, was investigated in order to validate calculational tools used for the ITER design and to verify the nuclear performance of the shield by measuring neutron and photon flux spectra at two positions inside the bulk assembly. The measured spectra are compared with results from calculations using the Monte Carlo code MCNP-4A and the data library FENDL-1. Integral values such as neutron-induced reaction rates and gamma-heating are calculated on the basis of the experimentally obtained flux spectra, and are compared with independent measurements of these data. Helium and hydrogen production rates, as well as the radiation damage rate, are determined again by using the measured flux spectra. (orig.)