Methodological Study On Radiological Impact Assessment Of Ta-Nb Metallurgy

As the rare metals, Tantalum （Ta） and Niobium （Nb） are widely used in the field ofnational defense industry and advanced science and technology due to the excellentperformance. However, most Ta-Nb ores with a little high nuclides, radionuclide will possiblybe enriched during the process, which leads to impact on the surrounding environment.Recently, efforts to limit the radioactive pollution caused by mineral exploration, mining,mineral processing and metallurgy have been strengthened by Chinese government. In orderto contribute to supervise mineral with radionuclides exploitation in management of radiationenvironment, facing the realistic lack of methods for assessing the radiation of mineral withradionuclides exploitation, it is extraordinarily significant to conduct researches onmethodology for does assessment and put forward feasible methodology in order to protectenvironment and the public.Based on understanding of the existing environmental laws and assessment system, aswell as combined with radiological environmental impact assessment of the Ta-Nb metallurgy,the author firstly put forward Raw Ores Induced Radiological Impact Assessment （abbr.ROIRIA）. The method consists of raw ores analysis, nuclides behavior analysis; and Dosecalculation. Raw ores analysis is composed of mineral metallurgy and nuclides phase analysis;nuclides behavior analysis includes nuclides migration in products, effluent in the process,and nuclides features in tailings; dose calculation consists of sources items analysis andcalculation, nuclides diffusion, and dose calculation for the workers and the public. ROIRIAand its application could play an active role in the environment protection and ensure thepublic safety.During the dissertation, based on the literature retrieval of²²⁰Rn and its daughter, theauthor used the Fick’s first law and1-Dimension model to describe the migration of²²⁰Rn, theinstant concentration estimation model of²²⁰Rn is put forward, which was applied into thedose assessment of environment impact assessment of “Raw Ores Induced Radiological Impact Assessment”.The result is checked by comparing with the measured data, the resultshows that this model is possible applicable for²²⁰Rn dose assessment of similar projects.Simultaneously, the requirements and the measures to minimize the radioactive impact arepresented.