Environmental Exposure Assessment for Emergency Response in a Nuclear Power Plant Using an Integrated Source Term and 3D Numerical Model

Nuclear power plants are normally assumed to be safe when their radiation impact in all operational states is kept at a reasonably low level. However, accidentally released radioactive substances and ionizing radiation may lead to a situation that cannot maintain the regulatory prescribed dose limits for internal and external exposure of the personnel and population. Nuclear emergency preparedness and response in nuclear or radiological events have been of concern recently in international communities. Nuclear power plants may need to provide essential information regarding possible scenarios of accidental releases that might have short-term detrimental effects and long-term risks in nearby populated regions. This paper presents a synergistic integration of a source term model and a three-dimensional, time-dependent, numerical model (i.e., HOTMAC/RAPTAD), which was applied to simulate a specific scenario in which a vapor cloud was accidentally released from Maanshan (i.e., the third nuclear power plant) in South Taiwan. It aims at dealing with middle-range risk assessment for nuclear emergency preparedness and response. The solutions of such an integrated modeling platform can be found with numerical analyses that describe the processes of radionuclide generation, transport, decay, and deposition, giving the final risk assessment in a neighboring coastal city—Kaohsiung, South Taiwan. In addition, sensitivity analyses were performed to evaluate the internal consistency of model parameters, which further support the application potentials. Such a modeling technique is valuable because it can characterize the fate and transport of radioactive nuclides over the long term. The case study in South Taiwan uniquely demonstrates the feasibility and significance of such model integration.