Radiological Safety Assessment of the Ghana Research Reactor-1 at Shutdown using Atmospheric Dispersion Model

Abstract

A radiological safety assessment of the GHARR-1 was evaluated by calculating approximately the TEDE of radionuclides release from the reactor at shutdown using atmospheric dispersion model before the commencement of the core conversion from HEU to LEU fuel. A condition essentially needed for safety and environmental impact assessment to obtain the core conversion (removal) program license. In doing so, a source term estimation and radiological safety assessment were initially performed. Radionuclide inventory of the HEU core was first determined by depleting the core using isotope depletion code ORIGEN-S. After the source term estimation and radiological safety assessment of the MNSR, atmospheric dispersion modeling was undertaken for a hypothetical severe accident scenario of the HEU core. Addressing the hypothetical accident scenario. Hotspot code which is based on Gaussians plume model was employed. The code was used to simulate the atmospheric dispersion of the released radionuclide and TEDE estimation as a function of distance downwind. The assumed methodological analysis was based on predominant site-specific meteorological condition statistics and dispersion modeling theories. Some radionuclides which are assumed to have health implications were selected among the estimated core inventories and doses estimated. Radiological health effect to on-site personnel and the public were assessed through dose estimation. The maximum TEDE was found to be 1.9E-01 mSv while the maximum ground deposition was also found to be 4.9E+00 kBq/m2at a distance of 200m, respectively. The values obtained were far far less than the regulatory recommended threshold of the 50 mSv for the on-site workers and 1mSv for the public.