Atmospheric dispersion assessment of radioactive materials during severe accident conditions for Bushehr nuclear power plant using HYSPLIT code

In nuclear power plants and nuclear research reactors, radioactive material release into the environment and the dose received by individuals are the main concerns during a severe accident. Thus, calculation of expected dose at reactor perimeters and surrounding area in the event of an accident is a basic requirement for the safety of these facilities. This study uses the HYSPLIT code to simulate the consequences of the worst hypothetical accident scenario of Station Blackout (SBO) and Large Break Loss-of-Coolant Accident (LBLOCA) in Bushehr nuclear power plant unit-1 (BNPP-1). The concentration of released radioactive material and external effective doses received by populations within 30 km radius of facility are computed. Dispersion of radioactive materials is simulated using of Global Data Assimilation System (GDAS) meteorological data. Particle behavior in different stages of dispersion and annual dispersion along each of the 16 geographic directions are obtained from trajectory calculations. The concentration of different radionuclides is determined and the resulting annual external effective dose at different locations are computed as well. All calculations are performed for four different release time durations including 4, 12, 24 and 48 h. Given the distribution of population around the NPP facility, the highest doses are expected at 3 km north and 4 km northwest of the reactor location. The maximum dose for 4, 12, 24, and 48-h long emission at different points of Bushehr city is calculated and compared with the allowable dose limits.