Evaluation of the Effectiveness of Light-Element Shielding Materials in Complex Radiation Fields

Abstract

MCNPX and Multi-Purpose Particle and Heavy Ion Transport code System (PHITS) simulations were carried out to investigate the secondary neutron and photon dose arising from 30-100 MeV incident protons on polyethylene, 5/10 wt % borated polyethylene, LiBH₄ , ⁶Li¹⁰BH₄, LiH, and ⁶LiH. Shield thicknesses were calculated using SRIM for each material at each incident proton energy. Both MCNPX and PHITS results showed that the secondary neutron dose was highest in LiH and LiBH and lowest in polyethylene. The neutron dose from ⁶Li¹⁰BH₄ and ⁶LiH was significantly lower than their natural counterparts. The secondary photon dose was comparable in all materials except for ⁶Li¹⁰BH which offered a marginal improvement.