MITgcm-RN v1.0: Modeling the Transport and Fate of Radionuclides Released from Nuclear Power Plants Wastewater in the Global Ocean Using MITgcm_c65i with the Radionuclide Module

Nuclear energy plays an important role in global energy supply and mitigates greenhouse gas emissions. Potential environmental and human health risks are associated with the generated radioactive isotopes in the wastewater, especially the accidental release during natural disasters. However, the long-term transport and fate of these radionuclides remain uncertain. Here we employ a state-of-the-art ocean tracer model (MITgcm) to simulate the transport and fate of tritium, carbon-14, and other seven typical radionuclides in the twenty-first-century ocean. We use the discharge of radioactive wastewater from the Fukushima Daiichi Nuclear Power Station, both during the March 2011 earthquake and tsunami and from the subsequent release of stored wastewater, as a case study. The model indicates that the Kuroshio and North Pacific Current will spread the radionuclides over the whole North Pacific basin after three years. The enduring transport of long-term discharge in the Pacific will expand to other ocean basins by 2050. Accumulation of particle-reactive radionuclides in the sediments will mostly be centered in the northwest Pacific till 2050. This study demonstrates the effectiveness of our modeling tool, which can be broadly applied to assess the transport and fate of other types of radionuclides and other nuclear discharges worldwide.