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標題: | 核能電廠再循環管路之老化與可靠度評估 Aging and Reliability Assessment of Recirculation Piping in Nuclear Power Plants |
作者: | Yu-Liang Cheng 鄭宇良 |
指導教授: | 吳文方 |
關鍵字: | 再循環管路,失效機率,機率破壞力學, recirculation piping,failure probability,probabilistic fracture mechanics, |
出版年 : | 2008 |
學位: | 碩士 |
摘要: | 核能發電具有發電成本低及二氧化碳排放量少等優點,在面臨全球能源危機及溫室效應等問題下,核能電廠延役在國外已成為發展趨勢,而在電廠延役前,進行各組件老化評估為首要任務。本文以再循環管路為老化評估對象,其為核能電廠管路系統中極為重要的組件之一,在電廠長期運轉後,會面臨各種老化問題,進而影響電廠安全。因此,本文將以機率破壞力學軟體PRAISE (Piping Reliability Analysis Including Seismic Events),及國內核一廠之應力資料,針對再循環管路各焊道因疲勞裂縫成長所導致之洩漏問題,進行失效機率估算。研究結果顯示,各焊道於電廠運轉六十年時之失效機率,大致介於 至 之間,其與電廠運轉四十年之失效機率相較,增加之幅度有限,說明此組件具良好之安全性,可提供電廠延役之老化評估參考。除此之外,本研究以機率破壞力學觀點為根基,利用可靠度相關理論,自行建立一套簡易的老化評估模式,除可進行機率式的分析外,另可以定論式分析流程評估單一裂縫成長之情形。分析結果顯示,若同樣以機率式分析流程進行評估,各焊道於電廠運轉六十年時之失效機率,大致介於 至 之間,與PRAISE軟體所計算之結果大致符合,由於其趨於保守,在無完善的套裝軟體可供進行評估之情形下,此分析流程亦不失為一方便且快速的方法,可提供相關人員參考。 Nowadays, we are facing problems of global energy crisis and the greenhouse effect. The advantage of low cost and small amount of discharge of makes life extension of existed nuclear power plants an important research topic. The first task of life extension of a power plant is the aging assessment of its components. And one of the most important components of a nuclear power plant is its piping systems. Therefore, in the present study, the aging assessment of reactor recirculation system of an existed nuclear power plant is assessed. In general, after a long period of operation, piping of a reactor recirculation system faces various aging problems that affect the safety of the plant. In the first half of the study, in consideration of fatigue crack growth, probabilistic fracture mechanics software PRAISE (Piping Reliability Analysis Including Seismic Events) is applied to find failure probabilities of welds of the system based on stress data of a BWR (Boiling Water Reactor) plant. The result shows that failure probabilities of welds range from to , and the difference is not significant when evaluated, respectively, after 40-year and 60-year of operation. It indicates that life extension of the system can be considered. In the second half of the study, a rather simple and convenient aging assessment model for the fatigue crack growth problem of nuclear piping is proposed. Like PRAISE, it is also based on the deterministic fatigue crack growth model and can be used to evaluate failure probabilities of piping welds through a probabilistic analysis. The calculated result indicates that failure probabilities of those studied welds are between and . They are compatible with but more conservative than those obtained by PRAISE. Therefore, if PRAISE is not available, the proposed method can be used for the aging assessment and failure probability estimation of a piping system. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/40258 |
全文授權: | 有償授權 |
顯示於系所單位: | 機械工程學系 |
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