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《Journal of Nuclear Science and Technology》2013,50(5):632-640
The new version of WSPEEDI (Worldwide version of System for Prediction of Environmental Emergency Dose Information) is developed by introducing the combination of models, the atmospheric dynamic model MM5 and the Lagrangian particle dispersion model GEARN-new to improve the prediction capability of atmospheric dispersion of radionuclides discharged during nuclear emergency. The major improvements are (1) the forecasts of meteorological conditions with high resolution in time and space, (2) the simultaneous calculations for local and regional areas and (3) the consideration of detailed physical processes (e.g. wet deposition, vertical diffusion in atmospheric boundary layer). The performance of new models is evaluated by air sampling data on 137Cs over Europe during the Chernobyl accident. The calculated surface air concentrations showed good agreement with measurements. 相似文献
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Takuya Kobayashi Hideyuki Kawamura Katsuji Fujii Yuki Kamidaira 《Journal of Nuclear Science and Technology》2017,54(5):609-616
The Japan Atomic Energy Agency (JAEA) has, for many years, been developing a radionuclide dispersion model for the ocean, and has validated the model through application in many sea areas using oceanic flow fields calculated by the oceanic circulation model. The Fukushima Dai-ichi Nuclear Power Station accident caused marine pollution by artificial radioactive materials to the North Pacific, especially to coastal waters northeast of mainland Japan. In order to investigate the migration of radionuclides in the ocean caused by this severe accident, studies using marine dispersion simulations have been carried out by JAEA. Based on these as well as the previous studies, JAEA has developed the Short-Term Emergency Assessment system of Marine Environmental Radioactivity (STEAMER) to immediately predict the radionuclide concentration around Japan in case of a nuclear accident. Coupling the STEAMER with the emergency atmospheric dispersion prediction system, such as Worldwide version of System for Prediction of Environmental Emergency Dose Information version II (WSPEEDI-II), enables comprehensive environmental pollution prediction both in air and the ocean. 相似文献
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针对内陆核电选址中小风、静风频率较高的厂址,分别采用美国核管会(NRC)导则推荐方法和运用三维客观诊断风场与Lagrangian烟团模型模拟整年8 760小时逐时排放方法,计算了湖南桃花江厂址事故工况下的大气扩散因子,探讨复杂条件下大气扩散模型的适宜性。研究表明:在非居住区边界概率论方法计算的最大小时事故扩散因子较烟团模型计算方法保守;Lagrangian烟团模型计算的小时事故扩散因子在某些方位大于概率论方法结果,某些远距离子区的扩散因子大于近距离子区;对于释放时间相对较长的情形,导则方法估算结果仍偏小。由此可见,导则推荐方法得到的扩散因子存在不保守的情形,建议在计算复杂地形、小静风频率较高的内陆厂址事故扩散因子时慎重选择扩散模型。 相似文献
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针对原苏联切尔诺贝利核事故在核应急区人群中产生的心理影响,提出了一个心理学范畴的概念——“切尔诺贝利阴影”,分析了其成因及“阴影”下应急区内社会心理环境的特点,讨论了核应急区内居民和谐心理环境建设的工作重点,为我国地方核电发展创建一个科学、和谐的心理环境提供参考。 相似文献
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卡尔曼滤波反演核设施核事故中核素释放率的研究 总被引:1,自引:1,他引:0
为能在核设施发生核事故时快速连续反演核素释放率,本文结合高斯多烟团大气扩散模型,模拟固定区域的连续监测数据,设计并实现了核设施核事故核素释放率的卡尔曼滤波实时跟踪反演。研究结果表明:与高斯多烟团大气扩散模型结合的卡尔曼滤波器,在约10次滤波后,跟踪到虚设的稳定、线性及非线性变化的释放率真值,反演值标准差随真值的增大而增大;在扩展卡尔曼滤波反演释放高度时,由于截断误差过大,滤波结果不收敛。利用环境监测数据,通过与高斯多烟团大气扩散模型结合的卡尔曼滤波器可用于固定高度和位置、短时连续排放的核事故核素释放率参数反演,是核设施核事故应急可选择的源项反演手段。 相似文献
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《Annals of Nuclear Energy》1987,14(6):295-315
As in the case of the TMI accident public concern around the world over nuclear safety has been aroused by the Chernobyl nuclear accident. Because of its severity and enormous impact on public opinion, it is important to study the accident and its implications carefully and to provide accurate information to the public.Since this was the first nuclear accident with large offsite releases of radionuclides, valuable insights are to be gained especially, for example, from Soviet actions to terminate the accident and mitigate its consequences, emergency preparedness and evacuation measures, medical treatment, protection against contaminated food and water supplies, and a variety of post-accident recovery measures.With the perspective of a year since the accident and a recent visit by the Author to Chernobyl with a U.S. nuclear safety delegation this paper reviews a number of new studies to draw conclusions about the causes of the Chernobyl accident, its health and environmental consequences and some of the implications for regulation of the safety of U.S. nuclear power plants. 相似文献
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《核技术(英文版)》2015,(3)
In atmospheric dispersion models of nuclear accident, the dispersion coefficients were usually obtained by tracer experiment, which are constant in different atmospheric stability classifications. In fact, the atmospheric wind field is complex and unstable. The dispersion coefficients change even in the same atmospheric stability,hence the great errors brought in. According to the regulation, the air concentration of nuclides around nuclear power plant should be monitored during an accident. The monitoring data can be used to correct dispersion coefficients dynamically. The error can be minimized by correcting the coefficients. This reverse problem is nonlinear and sensitive to initial value. The property of searching the optimal solution of Genetic Algorithm(GA) is suitable for complex high-dimensional situation. In this paper, coupling with Lagrange dispersion model, GA is used to estimate the coefficients. The simulation results show that GA scheme performs well when the error is big. When the correcting process is used in the experiment data, the GA-estimated results are numerical instable. The success rate of estimation is 5% lower than the one without correction. Taking into account the continuity of the dispersion coefficient, Savitzky-Golay filter is used to smooth the estimated parameters. The success rate of estimation increases to 75.86%. This method can improve the accuracy of atmospheric dispersion simulation. 相似文献
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分段烟羽模型和烟团模型在核事故应急中的应用比较 总被引:2,自引:0,他引:2
为了研究分段烟羽模型和烟团模型在核事故应急中的适用性 ,对不同流场条件下分段高斯烟羽模型和烟团模型的模拟结果进行了比较。在均匀稳定流场中 ,两种模型的模拟结果相近 ;而在非均匀稳定的流场中 ,分段烟羽模型的模拟结果呈现明显的不连续性。而且对于瞬时释放 ,烟团模型比分段烟羽模型更接近实际情况。通过对模型性能的对比 ,并考虑应急决策支持的要求和我国核电站的厂址条件 ,推荐采用烟团模型 相似文献
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利用福岛第一核电厂事故期间环境监测资料反推事故释放源项 总被引:3,自引:0,他引:3
2011年3月11日,日本福岛核事故导致放射性物质向大气环境的大规模释放。本工作利用大气数值预报模式WRFV2.2.1和大气弥散模式CALPUFF,对事故期间放射性物质的大气输运和弥散进行了模拟。应用大气释放源项的逆推算方法,结合单位释放率条件下的大气弥散模拟结果和环境监测数据,对福岛第一核电厂1到3号机组向大气环境释放的放射性核素总量进行了评估,推算的131I和137 Cs气载释放量分别为8.6×1016 Bq和8.6×1015 Bq。 相似文献
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This study integrated the nuclear power plant simulation software, PCTRAN, with an atmospheric diffusion model to efficiently evaluate a nuclear power plant accident and its off-site dose consequences. PCTRAN, with its user-friendly interface, provides a fast simulation scheme that can simulate many kinds of nuclear power plant accidents. Once accident initiation events are activated in the software, the plant parameters are calculated and displayed via animations on the user interface. Based on the simulated plant conditions, the radioactive materials considered in the software may be released from the plant to the environment. In this study, a dispersion algorithm, including a modified atmospheric diffusion model and its programming method, is proposed such that PCTRAN satisfies the application requirements to be used to plan nuclear emergency responses. First, the modified atmospheric diffusion model handles the variations of meteorological conditions (wind direction, wind velocity, and stability category) during a nuclear power plant accident simulation. Furthermore, the proposed programming method promotes calculation capability and efficiency by reducing the computational burden. For demonstration purposes, a postulated accident event was simulated for the Maanshan Nuclear Power Plant in Taiwan. The overall accident evolution, whole plant response, and off-site dose consequences could be predicted much earlier than what actually occurs. The thyroid and whole body dose rates (and their accumulations) as a function of accident time are displayed on the map within the emergency planning zone (EPZ). The influence of the accident on the off-site area can thus be estimated earlier, and the emergency classification can be determined by referring to the emergency action levels (EALs) for a quick nuclear emergency response. 相似文献
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Yu. V. Sivintsev 《Atomic Energy》2003,94(6):421-427
The 1985 reactivity accident on a submarine in bukhta Chazhma was accompanied by a substantial emission of fission products and activational radionuclides whose total activity reached 5 MCi. Some specialists have compared this emission to the emission resulting from the 1986 accident in Chernobyl, neglecting the large difference in the radionuclide composition: short-lived products of prompt fission of uranium (with an admixture of activational 60Co) in Chazhma and long-lived fission products accumulated over the run of the power reactor with an admixture of short-lived nuclides from the spontaneous excursion of the RBMK-1000 reactor in the Chernobyl nuclear power plant. It is shown that the emission of long-lived radioecologically significant radionuclides in Chazhma was approximately 0.79 Ci, while in the Chernobyl accident this emission was 90 MCi.A quantitative comparison is presented of the activity and radionuclide composition between the accidents in Chazhma and Chernobyl taking account of the fraction of long-lived radionuclides and neglecting the radioactive inert gases. These quantitative estimates are used to show that the Chazhma accident is not analogous to the 1986 accident in Chernobyl. 相似文献
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截断总体最小二乘变分核事故源项反演数值研究 总被引:1,自引:0,他引:1
放射性释放源项是核事故应急与事故后果评价的基础。核事故源项反演方法利用事故期间辐射环境监测数据估计事故释放源项。由于其不依赖电厂状态参数,在福岛核事故后被广泛重视。变分核事故源项反演模型(VAR)对释放源项的求解为全局最优,但受大气扩散模型误差的影响较大。为降低大气扩散模型误差对源项估计结果的影响,建立了截断总体最小二乘变分核事故源项反演数值计算模型(TTLS-VAR)。该模型可对扩散模型算子与监测向量进行修正,以提高源项反演的准确性。基于风洞实验数据对TTLS-VAR模型进行验证,结果显示:TTLS-VAR模型对释放源项估计结果的准确性较VAR模型有所提高。 相似文献
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《Journal of Nuclear Science and Technology》2013,50(8):835-846
It is advantageous for an emergency response system to have a forecast function to provide a time margin for countermeasures in case of a nuclear accident. We propose to apply an atmospheric dynamic model PHYSIC (Prognostic Hydrostatic model Including turbulence Closure model) as a meteorological forecast model in the emergency system. The model uses GPV data which are the output of the numerical weather forecast model of Japan Meteorological Agency as the initial and boundary conditions. The roles of PHYSIC are the interface between GPV data and the emergency response system and the forecast of local atmospheric phenomena within the model domain. This paper presents a scheme to use PHYSIC to forecast local wind and its performance. Horizontal grid number of PHYSIC is fixed to 50 x 50, whereas the mesh and domain sizes are determined in consideration of topography causing local winds at an objective area. The model performance was examined for the introduction of GPV data through initial and boundary conditions and the predictability of local wind field and atmospheric stability. The model performance was on an acceptable level as the forecast model. It was also recognized that improvement of cloud calculation was necessary in simulating atmospheric stability. 相似文献
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Shigekazu Hirao Hiromi Yamazawa Takuya Nagae 《Journal of Nuclear Science and Technology》2013,50(2):139-147
The atmospheric release rates of I-131 and Cs-137 from the Fukushima Daiichi nuclear power plant in March 2011 were estimated by comparing environmental monitoring data of air concentration and deposition rate on a regional scale with calculated values from an atmospheric dispersion model. Although the release rates were not estimated for all days after 11 March, because of lack of monitoring data, temporal changes in the release rates were reasonably estimated with estimated uncertainties in a factor of 3.3 and 2.9 for I-131 and Cs-137, respectively. A large release was estimated from the night of 14 March to at least the afternoon of 15 March, with maximum values of 7.2 × 1015 Bq h?1 for I-131 and 1.5 × 1014 Bq h?1 for Cs-137. The release rates during other periods were estimated at one- to two-orders of magnitude smaller than the largest release rate on 15 March. Uncertainty in the estimated release rate for 15 and 20 March was larger than for other periods. The significant release during 14 and 15 March and the trend of the release rate by the end of March were consistent with previous reports. This agreement, despite using different datasets, shows robustness of the temporal changes estimated in the studies. 相似文献
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Accident sequences which lead to severe core damage and to possible radioactive fission products into the environment have a very low probability. However, the interest in this area increased significantly due to the occurrence of the small break loss-of-coolant accident at TM1–2 which led to partial core damage, and of the Chernobyl accident in the former USSR which led to extensive core disassembly and significant release of fission products over several countries. In particular, the latter accident raised the international concern over the potential consequences of severe accidents in nuclear reactor systems. One of the significant shortcomings in the analyses of severe accidents is the lack of well-established and reliable scaling criteria for various multiphase flow phenomena. However, the scaling criteria are essential to the severe accident, because the full scale tests are basically impossible to perform. They are required for (1) designing scaled down or simulation experiments, (2) evaluating data and extrapolating the data to prototypic conditions, and (3) developing correctly scaled physical models and correlations. In view of this, a new scaling method is developed for the analysis of severe accidents. Its approach is quite different from the conventional methods. In order to demonstrate its applicability, this new stepwise integral scaling method has been applied to the analysis of the corium dispersion problem in the direct containment heating. 相似文献