PAVAN在核燃料循环设施事故后果评价中的讨论

The Discussion on the Application of PAVAN in the Evaluation of Accident Consequences of Nuclear Fuel Cycle Acilities

设计基准事故后果评价,是核燃料循环设施(转化、浓缩、元件制造)环境影响评价的重要内容。PAVAN程序包是根据美国核管会导则1.145的要求,由美国太平洋西北实验开发的事故短期弥散因子计算程序包。该程序包广泛应用于核燃料循环前端设施的设计基准事故后果评价。PAVAN程序包在使用过程中,风速组的划分对事故后果评价具有相当重要的影响。低风速组的细分提高PAVAN程序包计算结果的保守性。核燃料循环前端设施设计基准事故的高架源释放情景下,PAVAN程序包计算的弥散因子出现了下风向双极大值的现象。双极大值现象要求在进行事故后果评估时,不仅仅需要评估厂址边界的事故后果,还需要进一步分析厂址外最大浓度处的事故后果。

Design reference accident consequence assessment is an important part of environmental impact assessment of nuclear fuel cycle facilities(conversion,enrichment,component manufacturing).PAVAN package is an accident short-term dispersion factor package developed by Pacific Northwest Laboratory in accordance with the requirements of Nuclear Regulatory Commission Guideline 1.145.This package is widely used in the evaluation of accident consequences based on design criteria of nuclear fuel cycle front-end facilities.In the process of using PAVAN package,the division of wind speed group has a very important influence on the evaluation of accident consequences.The subdivision of the low wind speed group improves the conservatism of the calculation results of the PAVAN package.In the overhead source release scenario of the nuclear fuel cycle front-end facility design reference accident,the dispersion factor calculated by PAVAN package appears the phenomenon of downwind double maximum.The double maximum phenomenon requires that the accident consequences should be evaluated not only at the site boundary,but also at the maximum concentration outside the site.