A Preliminary Study on the Transport of Critical Radionuclide Polonium in the Marine Environment After Source Term Release

Abstract Regional Ocean Modeling System (ROMS) was employed to model the transport of radionuclide Po-210 in the ocean over a one-week period, simulating the scenario of a hypothetical nuclear accident. The simulation incorporated considerations for the radioactive decay of Po-210, various release modes, and the combined impact of fifteen tidal constituents. The initial release concentration of Po-210 was set at 10000 unit/m3, with the release point situated near a coastal nuclear power plant in Guangdong Province, China. The concentration distribution analysis revealed that, driven by ocean currents, Po-210 initially moved towards the northwest coast from the release point. Subsequently, it followed a southwesterly trajectory along the coast, impacting the entire coastal region of western Guangdong Province. Five days postrelease, the influence of Po-210 extended to the South China Sea. Analyzing the concentration distribution and results from three coastal concentration detection stations revealed consistently high concentration values in coastal waters, indicating a significant impact of polonium on the coastal environment. Notably, high Po-210 concentrations in the waters surrounding Port X (the estuary) in Guangdong Province suggested a potential impact on inland rivers, directly affecting nearby residents. Cross-sectional analysis unveiled that Po-210 exhibited rapid vertical mixing, a phenomenon closely associated with tidal influences and water depth. Comparing simulation results with and without tidal effects demonstrates that that the rising tides exerted an inhibitory effect on Po-210 transport, while ebbing tides had a promoting effect.