Neutron beam design for neutron radiography at the Musashi reactor

Studies were carried out for the design of a thermal, an epithermal, and a fast neutron beam for neutron radiography (NRG) in the horizontal beam port or in the thermalizing column at the Musashi reactor (TRIGA-II, 100 kW). Thermal, epithermal and fast neutron energy ranges were selected as <0.4 eV, 0.4 eV-10 keV, and >10 keV, respectively. To produce a good neutron beam in terms of intensity and quality, several materials (bismuth (Bi), silicon (Si) and alumina (Al2O3)) were examined as neutron filters. The MCNP (Monte Carlo Neutron Photon) computations showed that a thermal, an epithermal, and a fast neutron beam could be produced using single-crystal Si, Al2O3 and Bi filters, respectively. Such neutron beams, if built into the Musashi reactor, could increase extensive application of NRG in Japan. (orig.)