RADIATION DOSE OF AIRBORNE RADIOACTIVE MATERIAL IN NUCLEAR POWER PLANT CONVENTIONAL OPERATING CONDITIONS

摘要

In this paper, air-immersion, ground deposition, ingestion and inhalation of airborne radioactive effluent released from nuclear power plant under normal operating conditions is studied according to the atmospheric diffusion and ground deposition patterns and parameters that are suitable for the environmental characteristics of the nuclear power plant site, and the public living habits and food chain parameters around the site. Based on the Gaussian plume model, with a radius of 80 kilometers we divide 1, 2, 3, 5, 10, 20, 30, 40,50,60,70,80 km concentric circles around the nuclear power plant site. The 16 compass azimuth axial are the sector center-line, forming a total of 192 sub-regions, atmospheric diffusion of radionuclides is simulated in the assessment area of the region. The annual average atmospheric dispersion factor is calculate by using hourly observation data of wind direction, rainfall and atmospheric stability of the meteorological tower and the ground station, taking into account the ground reflection during transmission, the decay of the radionuclide, and the loss brought by the wet and dry settling that caused by gravity and rain washing. The airborne radioactive effluent is deposited on the ground or plant surface by dry settling and wet settling in the process of atmospheric environment changing and diffusion. Radioactivity of per unit area brought about by dry settling and rain fall settling is described by the deposition coefficient and deposition speed. The long-term ground deposition factor and ground annual concentration in the evaluation area were calculated under the situation of airborne radioactive effluents in the nuclear power station mixing emission, and the calculated result of radionuclide concentration in the air and soil was compared with the natural background value and the actual monitoring value. Based on the radionuclide deposited on the ground and air through the terrestrial food radioactive transfer mode, together with a large number of environmental surveys data on the population distribution, agriculture, farming, animal husbandry and people's living and eating habits in the 80km around nuclear station, combing with the actual situation of nuclear power station, the calculation model is amended accordingly. Using reasonable dose mode to calculate the maximum individual and entire public effective dose of the residents in the assessment area, and the results will be compared with other human activities. By comparing the calculated results of radionuclide concentration and radiation dose, it provide quantitative reference information for us understanding the influence of nuclear power station on the surrounding radiation environment, and to meet the requirements of nuclear power plant influence on surrounding environment and people under normal operating conditions.