Abstract For interfacing system loss of coolant accident (ISLOCA) and multiple steam generator tube rupture (MSGTR) sequences, which are reactor building (RB) bypass accidents in CANDU-6 type reactors, off-site consequence analyses were performed based on an optimization method for the WinMACCS input model that reflects CANDU-6 nuclear power plant design-specific and nearby site-specific features, with related sensitivity analyses performed for important variables. As a result of assessment, it was confirmed that there is exceedingly low early fatality risk in the unmitigated case from MSGTR and ISLOCA accidents. For cancer fatality risk, it was confirmed that the averaged risk from the RB bypass accidents in CANDU-6 plants sufficiently satisfies NSSC safety goal (1.0E−6/year). Sensitivity analyses found surface roughness to be the most influential parameter in the MSGTR accident, with other parameters confirmed to be insignificant considering uncertainty in the off-site consequence analysis. Through the sensitivity analyses, long-term improvement items related to surface roughness, dry deposition velocities, initial radioactive clouds, the domestic public protection measures model, and dose conversion factors were derived for future off-site consequence analyses. The proposed long-term improvements for the best-estimate analysis of off-site consequence are applicable to all similar CANDU plants and can provide valuable insights into Level 3 PSA.

中文翻译：

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使用 WinMACCS 代码对 CANDU-6 工厂的 ISLOCA 和 MSGTR 严重事故进行场外后果分析

摘要 针对 CANDU-6 型反应堆中反应堆建造 (RB) 旁路事故的接口系统冷却剂损失事故 (ISLOCA) 和多蒸汽发生器管破裂 (MSGTR) 序列，基于优化方法进行了场外后果分析。用于反映 CANDU-6 核电站设计特定和附近站点特定特征的 WinMACCS 输入模型，并对重要变量进行相关敏感性分析。评估结果证实，MSGTR 和 ISLOCA 事故的未缓解案例的早期死亡风险极低。对于癌症死亡风险，确认 CANDU-6 工厂 RB 旁路事故的平均风险足以满足 NSSC 安全目标（1.0E-6/年）。敏感性分析发现，表面粗糙度是 MSGTR 事故中影响最大的参数，考虑到场外后果分析中的不确定性，其他参数被证实无关紧要。通过敏感性分析，推导出地表粗糙度、干沉降速度、初始放射性云、国内公共防护措施模型、剂量换算系数等长期改善项目，用于未来场外后果分析。提出的对厂外后果的最佳估计分析的长期改进适用于所有类似的 CANDU 工厂，并且可以提供对 3 级 PSA 的宝贵见解。通过敏感性分析，推导出地表粗糙度、干沉降速度、初始放射性云、国内公共防护措施模型、剂量换算系数等长期改善项目，用于未来场外后果分析。提出的对厂外后果的最佳估计分析的长期改进适用于所有类似的 CANDU 工厂，并且可以提供对 3 级 PSA 的宝贵见解。通过敏感性分析，推导出地表粗糙度、干沉降速度、初始放射性云、国内公共防护措施模型、剂量换算系数等长期改善项目，用于未来场外后果分析。提出的对厂外后果的最佳估计分析的长期改进适用于所有类似的 CANDU 工厂，并且可以提供对 3 级 PSA 的宝贵见解。