摘要
依據美國聯邦法規10CFR50.46(Acceptance Criteria for Emergency Core Cooling System for Light Water Reactors)規定，冷卻水流失事故分析方法分為保守性與真實興兩種模式。本研究論文採用保守型模式，以清華大學熱水流動態模擬實驗室所發展的核二廠RELAP5-3D穩態模式為基礎，使用RELAP5-3DK保守估算程式為計算工具，建立核二廠RELAP5-3DK冷卻水流失事故輸入數據檔，執行冷卻水流失事故分析測試。
核二廠冷卻水流失事故輸入數據檔之建立程序如下，將核二廠RELAP5-3D穩態模式數據檔進行Appendix K 模式轉換與冷卻水流失事故相關時程設定。為使本模式分析能符合真實情況下電廠各系統的運作，安全系統跳脫邏輯設定參考核二廠提供的最新資料進行設定，而緊急爐心冷卻系統設定、電廠初始狀態，以及冷卻水流失事故分析案例特性如:破口大小、位置等，皆參考廠家報告之設定。
本分析案例特性為:(1)雙頭斷管大破口位於再循環管路汲水側(2)初始狀態104.2%額定功率、75%額定爐心流量(3)燃料軸向功率分布為Top-peak(4)緊急爐心冷卻系統單一失效(ECCS single failure)為HPCS失效。完成參考輸入數據檔(reference case)建立後，接續進行模式靈敏度分析與電廠狀態靈敏度分析，得到的最保守的燃料棒護套最高溫(Peak Cladding Temperature, PCT)為1844℉，並加入了電廠狀態不準度分析，其組合為反應爐高壓力、低爐心流量、反應爐低水位(L-3)、低飼水溫度。研究結果顯示本模式可提供很大的保守性，因其PCT高於廠家報告之分析，且低於法規限值2200℉，可用於未來核二廠相關安全分析之基礎。

Abstract
As specified in the 10 CFR 50.46 of U.S Nuclear Regulatory Commission, lisensing calculations of Loss of Coolant Accident (LOCA) of Light Water Reactor can be performed by the conservative method or the realistic method. In the present study, the conservative method is adopted to analyze the large break LOCA accident of Kuosheng Nuclear Power Plant of Taiwan Power Company. The plant emolys a Boiling Water Reactor (BWR VI) designed by General Electric.. Based on RELAP5-3D input deck of the plant analyzed, a LOCA Evaluation Model input deck for RELAP5-3DK is developed. The results of the analyses are compared with the results of the fuel supplier of the plant.
The major chracteristics of LOCA alalyses of the present study are:(1) double-ended large break at recirculation suction side, (2) 104.2% rated thermal power & 75% core flow, (3) top-peak axial power distribution, (4) failure of high pressure spray system is chosen as the single failure of emergency core cooling system. Sensitivity study of initial condition is also performed. The combination used in the analysis is high reactor vessel pressure、low reactor vessel water level at L-3、low feedwater temperature. It has been identified the most conservative estimation of the peak cladding temperature (PCT) is 1844 ℉。

參考資料
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10 CFR 50附錄 K中之緊急爐心冷卻系統分析評估模式(ECCS Evaluation Model,EM Model)
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