Improved shielding design with an accelerated Monte Carlo simulation for a neutron generator at Missouri S&T

Currently, Missouri University of Science and Technology (Missouri S&T) has a neutron generator that is limited in its operational time per year by regulatory limits. Previous work has identified key areas that require additional shielding and made recommendations; accordingly, this study was conducted to optimize the additional shielding design for the neutron generator at Missouri S&T to enable long-term usage. Dose analysis was performed using Monte Carlo simulation. Moreover, an automatic weight window generator - ADVANTG was employed to reduce the necessary computation time of the Monte Carlo simulation. The effectiveness of the proposed design is compared with previous work. Additional shielding offered significant dose reductions to 1.018, 1.127, 0.680, 1.243, and 1.400 mRem/h representing a decrease of 55.7%, 48.5%, 59.0%, 90.8%, and 70.5% for the north, south, west, east, and floor, respectively compared to similar values reported in previous studies. Additional shielding, from 5 cm to 20 cm in thickness, was suggested, depending on the current shielding. The neutron generator is projected to maintain a 300-hour operation time per year with the suggested shielding design.