| dc.description.abstract | The construction of new nuclear power plants in the Middle East region calls for an estimate of the radiation dose to the general members of public in the region due to an accidental radiological release, even though it is a highly unlikely scenario. The main objective of this thesis research is to perform radiation dose assessments for the Kingdom of Bahrain and the countries of the Arabian Gulf region for the case of a large radioactive material release due to a hypothetical accident in a regional nuclear power plant. This objective was accomplished by computing the radioactive source term by performing nuclear reactor core physics and fuel burnup simulations using Monte Carlo radiation transport code, MCNP. MCNP code was used to prepare the model of a fuel assembly used in one of the nuclear reactor cores in the Middle East region. The MCNP model was used to perform fuel burnup simulations for estimating the concentration of radionuclides in the burned nuclear fuel. Subsequently, the estimation of location-dependent radiation dose rates was carried out by using a material dispersion code, HOTSPOT. For fuel assembly and the corresponding burnup simulations, a model of the advanced pressurized water reactor (APWR) was used. A mixture of radioactive isotopes from the estimated source term was used to perform material dispersion simulation based on the Gaussian dispersion model. The atmospheric dispersion simulation of radioactive materials and the corresponding radiation dose rate estimates gave useful insights on the potential areas that will be affected, which should help in emergency planning and preparedness. The most probable dose rate was recorded at a wind speed of 6.8 m/s and ranged between 0.0085 mSv for atmospheric stability A and 4.3 mSv for atmospheric stability D, while the highest radiation dose recorded was 41 mSv in the Kingdom of Bahrain for the worst-case scenario studied, which involved the hypothetical accidental release of 10% of the core inventory and atmospheric conditions at a wind speed of 3 m/s and atmospheric stability F.
For the most probable scenario with a 10% of the nuclear source term activity released, for atmospheric stability classes from A, C, and D the radiation dose rates to the members of the public were calculated. The higher the letter, the more stable the situation. Before the fuel elements were cooled, the estimated TED ranged from 0.0085 mSv to 4.30 mSv. The maximum TED in this case is more than four times the permissible dose limit for public exposure, which is 1 mSv per year.
The highest estimated TED in the Kingdom of Bahrain was 41 mSv/year at 10% source term activity released when atmospheric stability was at its peak (Stability F). That is 41 times higher than the permissible dose limit for public exposure of 1 mSv/year, and nearly double the permissible dose limit for radiation workers per year, 20 mSv averaged over five years for a total of 100 mSv. An annual dose of 1000 mSv (1 Sv) may cause radiation sickness symptoms such as nausea and vomiting. A dose of 7000-10000 mSv (7-10 Sv), on the other hand, may result in death.
To obtain 41 mSv/year, I used a very conservative approach in the calculations in which all fuel pins are at maximum irradiation time, but in reality, the source term is predicted to be approximately 66% at any point in time, implying about 27 mSv/year, which is still higher than the public dose limit for a year (1 mSv). However, to bring this dose rate value to perspective, if 10000 members of the public received this amount of dose one in that group may develop cancer according to the radiation risk studies found in literature. | |
