Assessment of radiological consequences from a hypothetical nuclear reactor accident at a proposed site in Sierra Leone

This study presents a hypothetical radiological impact assessment of a proposed nuclear research reactor site as part of an Environmental Impact Assessment (EIA) to support regulatory review. The study evaluates the potential radiological consequences of a postulated Loss of Coolant Accident (LOCA), where failure of the cooling system may lead to fuel overheating, core damage, and the release of radioactive materials into the environment. The HotSpot 3.2.1 atmospheric dispersion and health physics code was used to simulate the spread of radionuclides and estimate their impact. The analysis focuses on the Total Effective Dose (TED) to on-site workers and the surrounding public, as well as on ground deposition of selected radionuclides, such as 137 Cs, 90 Sr, and 85 Kr, due to their radiological importance and relatively long half-lives. The results show that 90 Sr contributes the highest TED of 3.32E−08 Sv, while the combined source term from the damaged core produces a TED of 4.92E−06 Sv at 0.21 km from the release point. In terms of environmental impact, 137 Cs records the highest ground deposition of 3.00E−03 kBq/m 2 at 0.20 km, with a peak total deposition of 2.00E+02 kBq/m 2 for the overall source term at the same distance. The dispersion pattern indicates that radionuclides are mainly transported in the northwest direction. All estimated dose and deposition values are below the regulatory limits set by the International Atomic Energy Agency General Safety Requirements (GSR) Part 3. These findings suggest that, even under conservative accident conditions, the proposed reactor site meets international radiological safety standards and is unlikely to pose significant risks to public health or the environment.