Effects of Internal Leakage Pathwayon Main Control Room Habitable Dose in Accident Condition of Nuclear Power Plants

In order to fully consider the effects of internal leakage pathway on the radiation safety of the operators in the main control room habitable area during potential accident condition, a radioactive material migration model is established and compartment model is modified considering internal leakage pathways in this paper. The radioactivity in the main control room habitable area and the surrounding non-habitable area is analyzed, and the habitable doses of the operators in the main control room of a nuclear power plant in China are assessed in this paper. At the same time, the sensitivity analysis for the leakage rate of the penetrations is also performed. The results show that: the effective dose and the thyroid equivalent dose of the operators in the habitable area of the main control room calculated by considering the internal leakage pathways method are 8.704 times and 120.749 times of the calculation results without considering the internal leakage pathways. The effective dose increase and the thyroid equivalent dose increase caused by the inhalation pathway are particularly significant. The effective dose is 0.628 mSv and the thyroid equivalent dose is 6.32 mSv which are lower than the limits in HAD 002/01-2019. The sensitivity analysis shows that in the potential accident condition, the effective dose and thyroid equivalent dose of the operators in the main control room habitable area show a clear linear proportional relationship with the penetration rate of penetrations. The research results in this paper provide suggestions for the improvement of the radiation protection design of the main control room and penetrations of nuclear power plants in China. © 2020, Editorial Board of Journal of Nuclear Power Engineering. All right reserved.