压水堆严重事故下裂变产物迁移与释放研究

Study on the Migration and Release of Fission Products under Severe Accident for PWR

严重事故情况下大量放射性裂变产物释放到环境中,直接对人体造成危害。本文采用MELCOR程序,研究了DVI管小破口始发严重事故下,Cs I在一回路系统和安全壳中的存在形态,以及Cs I和惰性气体向安全壳、环境的迁移和释放行为。结果表明:Cs I主要以气溶胶形式释放出来,滞留在一回路系统中的Cs I几乎全部沉积在热构件上,约70%的Cs I以气溶胶的形式迁移到安全壳中,并不断沉积在安全壳热构件或溶于水中,极少量释放到环境中。事故后绝大部分惰性气体迁移到安全壳中,只有少部分滞留在反应堆其他系统中,在安全壳正常泄漏率下,释放到环境的惰性气体质量很少,仅为0.11%。

A large number of radioactive fission products are released into the environment and cause harm to the human directly in the case of severe accidents. In this paper,the MELCOR program was used to study the existence form of Cs I in the primary coolant system and containment,as well as the migration and release behavior of Cs I and inert gas to the containment and environment. The results showed that Cs I was mainly released in the form of aerosol. Most of the Cs I retaining in the primary coolant system was deposited on the heat structures. About 70% of the Cs I migrated into the containment in the form of aerosols and continuously deposited in the containment or dissolved in the water,a small amount of Cs I released to the environment. Most of the inert gas migrated into the containment after the accident and only a small portion remained in other reactor systems. Only 0. 11% of inert gas released to the environment under normal containment leakage rate.