PHITS modeling and simulation of a D-D neutron generator facility for radiation safety assessment

Abstract

A deuterium-deuterium (DD) neutron generator (NG) is a promising alternative neutron source for various applications. A detailed understanding of dose rate distribution and shielding of a radiation facility is necessary to ensure the radiological protection of the personnel involved. This study aims to develop a simulation model to evaluate the radiological safety of the future DD NG facility in the Philippines and ensure compliance with prescribed dose limits. The Monte Carlo-based Particle Heavy Ion Transport Code System (PHITS) was used to model a DD NG facility with a 2.48 MeV source and 10⁸ n/s yield. The ambient dose equivalent rates around the NG were calculated using the ICRP 74 flux-to-dose conversion factors. Optimal radiation protection was determined by analyzing different high-density polyethylene (HDPE) moderator configurations. From this, the west-oriented, fully shielded NG yielded the lowest doses, making it the optimal configuration. Results indicate that workers can safely operate the NG even with full operating time in a year. Establishing safety boundaries near the source and defining controlled areas are recommended. This study provides a reference for the radiation safety assessment of the DD NG facility that is being established in the DOST Philippine Nuclear Research Institute.