Simulating Radiation Shielding Effectiveness Against Three Neutron Sources

Abstract

Laboratories and Universities regularly apply for approval from the United States Nuclear Regulatory Commission (NRC) to use neutron generators for experimental research. To comply with the regulations set by the NRC, adequate shielding is necessary to ensure that the radiation dose rates experienced by an operator, and outside the walls of any containment buildings, are below the prescribed levels. Typically, the neutron source needs to be shielded such that the radiation dose rate experienced by any user is less than 0.25 mRem/hr (500mrem/2000-hour work-year). To address this requirement, we investigate the effectiveness of boronated concrete, boronated water, and light water shielding materials and their applicability to three neutron sources. We present our findings on the radiation shielding design and calculations for three neutron sources situated inside shielding layers. Our modeling utilized the Monte Carlo n-Particle transport codes (MCNP6.2) to simulate neutron attenuation of the shielding. The simulation results reveal that a light water shielding can sufficiently reduce the dose rate for an individual located as close as two meters from the source. Therefore, this shield design can effectively decrease the radiation dose below the maximum recommended limit.