Background The operation of a D-T neutron generator produces neutron radiation and air induced radioactivity, creating potential hazards of radiation leakage that may jeopardize the radiation safety of experimental personnel and the public in severe cases. Therefore, radiation-safety analysis must be carried out to ensure the safe operation of the equipment.

Purpose A set of evaluation criteria balancing conservatism and accuracy is established for the radiation protection design of the D-T neutron generator room to verify the safety and rationality of shielding and ventilation designs, mitigate operational radiation risks, and ensure radiation safety for personnel and the public.

Methods A refined shielding calculation model for the D-T neutron generator room is developed using the FLUKA Monte-Carlo code. Radiation shielding calculations are implemented through numerical simulation, and the labyrinth and shielding door are optimally designed based on the analysis of radiation source terms. Meanwhile, a systematic analysis is conducted on the airborne radioactivity generated during operation.

Results When the surrounding concrete walls of the D-T neutron generator room are 150-160 cm thick and the roof thickness reaches 120 cm, the direct penetrating radiation and neutron "sky-shine" effect can be effectively suppressed, and the outdoor dose rate can be strictly controlled within the set limit values. Further air-activation analysis shows that for a two-hour air-change cycle, the activity concentrations of major induced radionuclides are well below the exemption levels specified in GB 18871-2002, demonstrating an adequate safety margin for the ventilation design.

Conclusions The current radiation-protection design for the D-T neutron generator room is safe and reliable. The integrated evaluation framework of “physical shielding-sky-shine-air activation” established in this paper can provide references for the shielding design and environmental impact assessment of similar neutron-source facilities.