【摘要】 严重事故工况下,可能会导致安全壳失效,使大量裂变产物释入环境。本文以百万千瓦级核电厂为对象,利用一体化程序研究不同破口事故叠加全厂断电事故下裂变产物CsI在一回路和安全壳内的质量以及裂变产物向环境释放的源项,并分析安全壳喷淋措施对控制裂变产物向外释放的影响。分析结果表明,小破口事故、中破口事故和大破口事故下释放到环境的裂变产物质量差别较小,主要为向环境释放时间上的差异。开启安全壳喷淋时能够有效控制裂变产物向环境的释放,其中小破口事故下产生的气溶胶质量高于其他两种事故,且气溶胶主要以扩散电泳的方式沉积在安全壳内。开启堆腔注水措施能够保证压力容器的完整性,降低了进入安全壳的裂变产物的质量,能够有效控制非挥发性裂变产物向环境的释放。本文计算结果可以为事故条件下应急措施的制定和厂外源项后果评价提供参考。更多还原

【Abstract】 Under severe accident conditions,it may cause the containment to fail and release a large amount of fission products into the environment.This paper uses integrated code to study the quality of fission product Cs I in the primary system and the containment and the source term of the fission product released to the environment under the superposition of different break accidents with the total loss of electric power supply.The paper also considers the effectiveness of containment spray in controlling the outward release of fission products.The results show that there is little difference in the quality of fission products released into the environment under small break,medium break and large break accidents.The main difference is the failure time of containment.The release of fission products to the environment can be effectively controlled when the containment spray is turned on.The quality of the aerosol produced in the small breach accident is higher than the other two accidents,and the aerosol is mainly deposited in the containment by diffusion electrophoresis.Opening the cavity injection system can ensure the integrity of the vessel,reduce the quality of fission products entering the containment, and effectively control the release of non-volatile fission products to the environment.The results of this paper can provide reference for the formulation of emergency measures and the evaluation of the consequences of external sources.更多还原