Evaluation of radioactive contamination caused by the core accident of the Bushehr nuclear reactor over the time

Nuclear accidents are sometimes unavoidable, but the risks can be significantly reduced with preparedness and prudence. Therefore one must have a proper assessment of the consequences of the accident. In this research, a three-dimensional simulation of the reactor core has been used to estimate the leakage rate of radioisotopes in case of the worst accident in the Bushehr nuclear power plant. The main parameters of the Bushehr reactor core simulation were benchmarked with the FSAR. Then the time-dependent activity and the isotopes are assumed as the source term for the accident, and the incident of complete melting of the reactor core and the entry of all pollutants into the environment was calculated. Activity changes over time were calculated for 18 years after the accident.Furthermore, by examining more than a hundred radioisotopes, the most active ones were figured out. Results were calculated for these isotopes' source terms over time up to 18 years after the accident. Finally, specific activity caused by each of the important isotopes was presented in order to prioritize the elimination of contaminants. Calculations were done using the MCNPX2.7.E code and considering the Burn card.