The objective of this paper is to provide information for nuclear field specialists and decision makers on opportunities for minimizing radioactive wastes arising from the decontamination ＆ decommissioning of a CANDU...The objective of this paper is to provide information for nuclear field specialists and decision makers on opportunities for minimizing radioactive wastes arising from the decontamination ＆ decommissioning of a CANDU-6 NPP. The paper proposes a method for selection of appropriate decontamination techniques which may be used at Cernavoda NPP decommissioning, equipped with CANDU heavy water reactors, based on the simulation with ProVision software. The paper has a singular focus on physical decontamination techniques and does not address other aspects of decommissioning. The physical decontamination techniques which are the best for certain areas of the CANDU-6 NPP from point of view of effectiveness and cost were determined. A unit cost for each decontamination technique was determined by relating the total cost to the average surface to be decontaminated. In conclusion, physical techniques will apply more efficiently to concrete surfaces. The chemical decontamination methods, in comparison with physical decontamination methods are. more suitable for non-porous surfaces respectively metal and are less recommended for concrete surfaces.展开更多
Evaluation of soil erosion in agricultural fields is valuable to develop conservation practices for reducing agricultural nonpoint source pollution. Soil erosion rates were quantified using the fallout radionuclide tr...Evaluation of soil erosion in agricultural fields is valuable to develop conservation practices for reducing agricultural nonpoint source pollution. Soil erosion rates were quantified using the fallout radionuclide tracer technique in Mojiagou Basin located on the outskirts of Changchun in Northeast China. The calculated soft erosion rates in the study area were 1.99 and 1.85 mm year-1 using 137Cs and excess 210pb （210Pbex） measurements, respectively. Both fallout radionuclides showed a similar tendency at downslope sites. All measured sites have experienced net erosion during the past 50 to 100 years. 137Cs and 210Pbex measurements were useful to quantify soil erosion rates on field and small basin scales. At this rate of erosion, the current fertile topsoil layer would be entirely removed within 70 years.展开更多
A nuclear accident involving the leaking of radioactive pollutants occurred at the Fukushima Nuclear Power Plant in Japan, following an earthquake and subsequent tsunami on March 11,2011. Using official Japanese data ...A nuclear accident involving the leaking of radioactive pollutants occurred at the Fukushima Nuclear Power Plant in Japan, following an earthquake and subsequent tsunami on March 11,2011. Using official Japanese data on pollutant emissions during the accident, this study simulates the dispersion of nuclear pollutants. The source term of the nuclear leakage of radioactive material is designed using PM2.5 as the tracer of radioactive pollutants, and the study considers dry and wet deposition processes. A coupled-model system is constructed from the air-quality model Models-3/CMAQ and the Weather Research and Forecasting atmospheric model. The transport path and distribution of radioactive pollutants over long and short distances are simulated with different model horizontal resolutions of 30 and 4 km respectively. The long-distance simulation shows that, following the Fukushima nuclear accident, under the effect of westerly winds, radioactive pollutants are transported generally towards the eastern Pacific and reach the American continent after 5 days, but their concentration is only about 10-7 times the concentration near the Fukushima Nuclear Power Plant. The time required for pollutants to reach the United States is basically consistent with measurements made in California on March 18. Because the upper westerly wind is faster than the lower westerly wind, the distribution of pollutants tilts eastward in terms of its vertical structure. The short-distance （local） highresolution simulation indicates that strong winds and precipitation associated with a cyclone can accelerate the deposition, dif- fusion and transport of pollutions, and local cyclonic circulation can change the transport path of pollutants, even resulting in repeated effects of pollution in some areas. Pollutants disperse to southeastern Honshu, Japan, on March 14, 2011, agreeing well with the timing of local observations of increases in the absorbed dose rate. Results also show that radioactive pollutants from the Fukushima nuclear accident are mainly transported and diffuse eastward, resulting in a relatively short-term impact on the Japanese mainland even under the influence of the cyclone system. Therefore, in terms of atmospheric conditions, the location of the Fukusbima Nuclear Power Plant is appropriate and could serve as a reference to site selection and protection of other nuclear facilities.展开更多
文摘The objective of this paper is to provide information for nuclear field specialists and decision makers on opportunities for minimizing radioactive wastes arising from the decontamination ＆ decommissioning of a CANDU-6 NPP. The paper proposes a method for selection of appropriate decontamination techniques which may be used at Cernavoda NPP decommissioning, equipped with CANDU heavy water reactors, based on the simulation with ProVision software. The paper has a singular focus on physical decontamination techniques and does not address other aspects of decommissioning. The physical decontamination techniques which are the best for certain areas of the CANDU-6 NPP from point of view of effectiveness and cost were determined. A unit cost for each decontamination technique was determined by relating the total cost to the average surface to be decontaminated. In conclusion, physical techniques will apply more efficiently to concrete surfaces. The chemical decontamination methods, in comparison with physical decontamination methods are. more suitable for non-porous surfaces respectively metal and are less recommended for concrete surfaces.
基金Supported by the National Basic Research Program(973 Program)of China(No.2007CB407205)the Knowledge Innovation Program of the Chinese Academy of Sciences(No.KSCX1-YW-09-13)+1 种基金the National Key Technology R&D Program of China during the 12th Five-Year Plan Period(No.2011BAD31B00)the National Major Science and Technology Program of China for Water Pollution Control and Treatment(No.009ZX07106-03-01)
文摘Evaluation of soil erosion in agricultural fields is valuable to develop conservation practices for reducing agricultural nonpoint source pollution. Soil erosion rates were quantified using the fallout radionuclide tracer technique in Mojiagou Basin located on the outskirts of Changchun in Northeast China. The calculated soft erosion rates in the study area were 1.99 and 1.85 mm year-1 using 137Cs and excess 210pb （210Pbex） measurements, respectively. Both fallout radionuclides showed a similar tendency at downslope sites. All measured sites have experienced net erosion during the past 50 to 100 years. 137Cs and 210Pbex measurements were useful to quantify soil erosion rates on field and small basin scales. At this rate of erosion, the current fertile topsoil layer would be entirely removed within 70 years.
基金supported by the Special Funds of Public Welfare of China (Grant No. GYHY201306061)the National Natural Science Foundation of China (Grant Nos. 41230421, 41105065 & 41275128)
文摘A nuclear accident involving the leaking of radioactive pollutants occurred at the Fukushima Nuclear Power Plant in Japan, following an earthquake and subsequent tsunami on March 11,2011. Using official Japanese data on pollutant emissions during the accident, this study simulates the dispersion of nuclear pollutants. The source term of the nuclear leakage of radioactive material is designed using PM2.5 as the tracer of radioactive pollutants, and the study considers dry and wet deposition processes. A coupled-model system is constructed from the air-quality model Models-3/CMAQ and the Weather Research and Forecasting atmospheric model. The transport path and distribution of radioactive pollutants over long and short distances are simulated with different model horizontal resolutions of 30 and 4 km respectively. The long-distance simulation shows that, following the Fukushima nuclear accident, under the effect of westerly winds, radioactive pollutants are transported generally towards the eastern Pacific and reach the American continent after 5 days, but their concentration is only about 10-7 times the concentration near the Fukushima Nuclear Power Plant. The time required for pollutants to reach the United States is basically consistent with measurements made in California on March 18. Because the upper westerly wind is faster than the lower westerly wind, the distribution of pollutants tilts eastward in terms of its vertical structure. The short-distance （local） highresolution simulation indicates that strong winds and precipitation associated with a cyclone can accelerate the deposition, dif- fusion and transport of pollutions, and local cyclonic circulation can change the transport path of pollutants, even resulting in repeated effects of pollution in some areas. Pollutants disperse to southeastern Honshu, Japan, on March 14, 2011, agreeing well with the timing of local observations of increases in the absorbed dose rate. Results also show that radioactive pollutants from the Fukushima nuclear accident are mainly transported and diffuse eastward, resulting in a relatively short-term impact on the Japanese mainland even under the influence of the cyclone system. Therefore, in terms of atmospheric conditions, the location of the Fukusbima Nuclear Power Plant is appropriate and could serve as a reference to site selection and protection of other nuclear facilities.
