Experimental investigation of neutron and photon penetration and streaming through iron assemblies

Nuclear shield parameters of fusion reactors such as ITER are determined by the neutron and photon fluxes within and behind the shield. Iron is the main element of shields.In order to verify calculational tools for the blanket design a solid Fe slab of dimensions 100cm x 100cm x 30cm in thickness was irradiated with 14MeV neutrons, and the neutron and photon fluxes penetrating the assembly were measured in wide energy ranges. They are compared with calculated fluxes using the three-dimensional Monte Carlo code MCNP and nuclear data of the European Fusion File EFF-1. The calculation underestimates the neutron flux at low and at high energies. It is discussed in connection with the underestimated photon flux. The investigation was extended to Fe assemblies with a gap at several positions. (orig.)