It is one of the foci for nuclear safety research after Fukushima accident whether equipment can perform its designed function under severe accidents with reasonable assurance (equipment survivability). One of the foundations for equipment survivability research is screening and analysis environmental conditions under severe accidents. The maintenance floor where much severe accident mitigation measure is assigned aside was taken as an instance for an approach to study compartment environmental conditions comprehensively. According to CAP1400 design features,conditions that can happen in the maintenance floor are screened out. The MAAP code is used to develop thermal hydraulic results for several sequences in each condition,thus representative result was achieved. Meanwhile PSA analysis is used to develop frequency for these conditions. By combining the two aspects information,deep insights were attained for environmental conditions of the maintenance floor. The results shows that under most circumstances environmental conditions for the maintenance floor are not very limiting , which provides useful guidance for subsequent analysis and demonstration of equipment survivability.%设备是否能以合理的可信度在严重事故下执行预期功能(设备可用性)是福岛事故后核安全研究的重点之一,而严重事故环境条件的筛选和分析是设备可用性研究的基础.本文以布置着大量严重事故缓解措施的维修平台为例,提出一种对环境条件全面系统的研究方法.根据CAP1400 的设计特性,分析得出维修平台可能出现的各类工况.运用 MAAP 程序分别对这几类工况中的多条序列做了分析,得出典型的环境条件.同时运用概率安全分析(PSA)工具,给出了每类工况发生的频率.通过结合这两方面的信息,获得对维修平台环境条件全面系统的理解.研究表明,在绝大部分情况下,维修平台的环境条件并不恶劣,为后续维修平台设备可用性的分析和验证提供有力的指导.
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