核电厂核事故应急情况下某些操作干预水平默认值

SOME DEFAULTS OF OILs UNDER EMERGENCY CONDITIONS IN NUCLEAR POWER PLANT

本文根据IAEA-TECDOC-955给出的核电厂核事故应急情况下操作干预水平(OIL)的计算公式和InterRAS1.3计算程序,分别计算了压水堆核电厂两种假想严重事故(堆芯熔化/安全壳完整性丧失或泄漏事故、蒸汽发生器完整性严重丧失事故)烟羽照射期间撤离和服用碘片的操作干预水平OIL1和OIL2;讨论了相关时间(例如预期烟羽照射时间、放射性开始向环境释放时间)、气象条件(风速、混合层高度、稳定度和降雨)、距事故源距离和释放方式(低架和高架释放)等对OIL1和OIL2计算值的影响。在此计算和讨论的基础上,对所假想的严重事故推荐了相应的OIL1和OIL2默认值;强调指出了OIL1和OIL2依赖于事故类型及事故放射性在释放到环境之前是否被去除减少等因素,其默认值须按照不同事故类型及事故放射性被去除减少的特征分别给出。

Based oa the formulae presented in IAEA-TECDOC-955 for operational intervention levels （OILs） under emergency conditions in nuclear power plant（NPP） and by InterRAS1.3 computer cede, this paper calculates OIL1 and OIL2 for two kinds of postulated severe accidents（ core meh/containment integrity failure or leakage accident and SG integrity severe failure accident）of PWR NPP respectively. OIL1 and OIL2 are used to recommend for public evacuation and taking iodine-blocking agent during the period of plume exposure resulted from the above postulated severe accidents. The effects on OIL1 and OIL2 calculation results of related times （e. g. expected plume exposure time, beginning time of the radioactivity released into the environment）, weather conditions （wind speed, height of mixing layer, stability, and rainfall）, distance from release source and release patterns （release at low elevation and high elevation） are also discussed. On the basis of the calculation and discussion, this paper presents the relevant recommended defaults of OIL 1 and OIL2 for above-mentioned postulated severe accidents, and also points out that OIL1 and OIL2 not only depend on the specific type of accidents, but also on the factors such as whether radioactivity are reduced before being released into the environment, so the defaults shall be presented for different accident types and specific conditions under which radioactivity are how reduced.