Monte Carlo Calculations of a Fusion Reactor Shielding Experiment

A modern continuous energy-angle Monte Carlo program has been used to perform neutron shielding calculations for a fusion shield. The SAM-CE Monte Carlo program developed by the Mathematical Applications Group has been used for a demonstration calculation of an Oak Ridge National Laboratory fusion shield benchmark with a deuterium-tritium neutron source. Calculations were made for three shielding configurations. They were compared with experiment and also with previous calculations using S_n with first- and last-flight modifications. Agreement with experiment was found to be good at high (>14-MeV) and low (<5-MeV) energies. At intermediate energies where the fluxes are much lower, the agreement was less accurate differing by as much as factors of 2 or 3 in extreme cases. An improved resolution broadening function for the NE-213 detectors helped reduce some of these differences.