我國核二廠的PSA二階模式,於民國八十八年由原能會、核能研究所以及台灣電力公司共同合作完成,由於當時SAG尚未完成,因此核二廠的PSA二階評估內容中並未包含SAG的各項考量。SAG主要的考量為盡可能的確保圍阻體在嚴重事故下的完整性,以防止放射性物質外釋至環境。在SAG中提出了許多指引與建議,均是用來減緩嚴重事故對於圍阻體完整性的衝擊,與控制放射性物質的外釋量。為此,本論文也將深入探討有關核二廠SAG中,各項指引建議以及救援行動的適切性。 經由本論文的研究,有關SAG對於核二廠Level 2 PSA的各項影響與改變均已被明確的提出;原本PSA二階的人為誤失量化亦在本論文中重新作了計算;在研究的過程中,對於SAG所提及的核電廠嚴重事故下之救援策略,我們也以程式模擬來分析其適用性與正、負面效應。為評估SAG納入PSA二階分析後的影響,本論文也作了靈敏度分析以驗證結果及趨勢是否與我們預期的相同。除了評估SAG對PSA二階分析的影響外,本論文亦針對許多電廠可能發生的嚴重事故進行模擬分析,對於這些現象發生時序作探討,可供日後SAG執行效果的驗證作參考。
Probability Safety Assessment (PSA) is a systematic approach to estimate the risk of nuclear power plants (NPPs). PSA has been widely utilized by nuclear utilities, nuclear industry, and nuclear regulators to enhance the safety of NPPs. Over the past few years, Severe Accident Guidelines (SAGs), which delineate the mitigation actions of core meltdown accidents of NPP, are developed to support operators and staffs in the Technical Support Center (TSC) during the emergency responses of core melt accidents. The proper executions of SAGs could decrease the failure probability of containment and reduce the amount of radionuclide released to the environment during the accident. It can be expected that the implementation of SAGs will reduce the risk of the operation of NPPs. However, SAGs are not available when the conventional Level-2 PSA analyses are performed. In this study the mitigation actions of SAGs are incorporated into the Level-2 PSA of a General Electric designed Boiling Water Reactor (BWR) with Mark III containment. The plant analyzed is Kuosheng Nuclear Power Plant of Taiwan Power Company (TPC). The purposes of the study are to assess the impact of SAGs on the risk of NPP and to identify the importance measure of these mitigation actions. MAAP code calculations are performed to verify and validate the mitigation actions specified in SAGs. In the conclusion of this thesis, we find that the percentage of intact containment is increased, and the percentage of other contentment failure modes are decreased. We could say SAGs bring positive effect and reduce the damage when the severe accident occurs.