燃料操作区域气载放射性浓度分析

Study of airborne radioactivity concentration in fuel handling area

本文建立了燃料操作区域气载放射性浓度计算模型,对典型核素气载放射性浓度的变化趋势进行了分析。利用该模型研究了核素类型、通风流量等因素对燃料操作区域气载放射性浓度的影响,最后分析了燃料操作区域气载放射性的主要来源。结果表明,不同核素达到气载放射性浓度最大值的时刻不同,应取各核素燃料操作期间气载放射性浓度最大值作为设计值;燃料操作区域排风量与其净空间体积比值λ_h与气载放射性浓度成反比,反应堆冷却剂中放射性活度是气载放射性的主要来源,可以通过调节排风量、降低冷却剂放射性活度、降低蒸发量将气载放射性控制在一定水平。

Background： Currently, the computational model used to airborne radioactive source terms is too simple to applying to all cases. Purpose： The aim is to build a computational model for airborne radioactive concentration in fuel handling area and to study the influence factor of airborne radioactive source term thus to decrease occupational exposure dose. Methods： This paper constructed a computational model of airborne radioactive concentration in fuel handling area. Variations of typical radionuclide were analyzed. Then, we studied the effluences of radionuclide types, ventilation flow on airborne radioactive concentration and the main sources of radioactivity. Results： The maximum values of airborne radioactive concentration for all radionuclides during refueling should be treated as design values instead of the values at a certain moment or at the end of refueling. There is an inverse relation between the ratio of ventilation flow to net volume of fuel handling area ~h and airborne radioactivity concentration, the radioactivity in reactor coolant is the main source of airborne radioactivity. Conclusion： Adjusting ventilation flow, reducing radioactivity in coolant and decreasing evaporation are the main ways to reduce airborne radioactivity.