Neutron environment in the fusion materials irradiation test facility

A method has been developed to generate detailed three-dimensional flux maps within test modules for FMIT. A Monte Carlo calculation is used to determine fluxes averaged over small surface segments. These data are utilized by an auxiliary program to rapidly generate energy dependent neutron fluxes at space points of interest. In the test problem considered, 1,200,000 neutron histories were sampled on a CDC-7600 computer in 28 minutes. The auxiliary computer program determines the energy dependent flux at about 1,700 spatial points per minute within a test module where the total flux can change by an order of magnitude within a few centimeters. This rapid retrieval enables the generation of damage contours and other engineering studies at a minimum of cost without sacrificing accuracy