Atmosphere Dispersion Research Of Accident Source Terms In Nuclear Power Plant On CALPUFF

When uncontrollable radioactivity accidents take place, radioactive materials can make a large-scale impact by way of atmospheric dispersion at short notice. So in progress of real time environment consequence estimate and making emergency decisions, the transport,diffusion estimate and forecast of radioactivity nuclides must be considerate during atmospheric dispersion process, all these are foundation and premise of a series of emergency measures. But the abruptness of accident conditions,timeliness of accident emergencies and the complexity of local actual geography and atmosphere conditions present various kinds of especial requests for practical atmospheric dispersion model. CALPUFF is an air quality dispersion model which is recommended by EPA of USA and developed by Sigma Research Corporation. It can be used to research atmospheric dispersion of different scales. It is in common use of atmospheric dispersion model on condition of complex geography, and it is used extensively in atmospheric dispersion sector. But CALPUFF model has not been used in atmospheric dispersion during normal or accidental conditions actually in nuclear power plant interiorly. This paper introduce CALPUFF atmosphere dispersion model, and make quantitative compare with RIMPUFF model and ATSTEP model, which are two different atmospheric dispersion models in RODOS system, then compare the differences among three atmospheric dispersion models. The differences between three different are acceptable. At the same time, on the background of Daya bay nuclear power plant, research atmospheric dispersion of one severe accident Source terms in nuclear power plant, to simulate dispersion process of characteristic pollutant (131I was used) on the condition of different seasons to analysis seasonal dispersion laws. Meanwhile, classifying weather data in of one year to research atmospheric dispersion on the ultimate conditions,?to analysis and forecast the distribution condition of radioactive nuclides on the extreme average conditions.Along with accelerating urbanization progress, change of land use around the nuclear power plant can take place extensively, these changes can change the energy balance of these area, then cause the change of atmosphere flow field and onflow characteristics, then change the law of pollutant diffusion,transform and accumulation within the sector. Following the establishment of inland nuclear power plant, the atmospheric dispersion research on the conditions of inland underlying surface has made important sense, and is important for site selection of nuclear power plant and accident environment evaluation. So this article applied CALPUFF atmospheric dispersion model to simulate and forecast the influence on characteristic pollutant distribution and diffusion process of land cover change. Three different single underlying surfaces conditions are Urban and built-up land,agriculture land and Water body. The results showed that the affect of different land uses depended on the meteorologic conditions, the laws were complicated.