核能級地震模擬技術於近震源地震危害度分析之應用

核心技術名稱: 核能級地震危害度分析

主持人:  承辦人:林柏伸  02-87919198#317

摘  要

 

       本研究引進國際最新之地震模擬技術,完成「特定孕震斷層之地震強震動模擬方法準則(Recipe) 」的本土化工作,其內容涵蓋強地動模擬方法的構成要素:震源特性、地下構造模型、強地動計算、預測結果的驗證方法及有關震源特性參數設定時的建議。以台灣地區的地震資料建立本土化地震模擬參數經驗式,透過客觀的數學模式,採自我相關函數(autocorrelation function)推估其主要有效震源參數,包含斷層長(fault length),斷層寬(fault width)及平均滑移量(mean slip),探討地震矩規模介於4.6至8.9地震之震源尺度關係及檢驗地震自我相似性(self-similarity)。為了核能機組之地震安全評估,本研究針對可能影響既有核能電廠的重大歷史地震事件,蒐集早期儀器所記錄的波形資料進行處理,以便掌握這些歷史地震的震源參數,未來進行歷史地震的境況模擬。過去地震危害度分析中所使用的強地動衰減式在近場資料的部份都是缺乏的,本研究透過蒐集全世界的近場強震資料進行分析處理,除了透過對既有資料的分析外,未來希望透過地震模擬的方式,增加近場強震特性分析,輔助進行近場強地動衰減式的建立。如此能有效提昇核能電廠的地震安全評估精度,維持核能電廠的安全運轉。

 

關鍵詞:地震波模擬、近震源、歷史地震、強地動衰減式

摘要
地震危害度分析為核能電廠決定設計地震的技術,此一技術包括震源-路徑-廠址之波傳考量,與地震發生頻率之統計,實踐此技術需有極高的科學背景資料,並要進行各種學說的整合,方能對未來可能的地震災害形成共識。國內地調所公布之斷層圖,其中山腳斷層與恆春斷層鄰近於核電廠,新增機組之規劃與溝通,勢必會被列為必要考量的項目。日本柏崎刈羽核能電廠之中越沖事件,其觸發斷層於建廠時期也納入評估,但因採用之衰減模式欠缺近震資料而造成預估失準。
本計畫則希望運用地震模擬之技術建立科學資料,進行核能電廠地震模擬,並建立近斷層震源的地振動模擬資料,回饋於強地動衰減模式,以供地震危害度分析使用。此方法將為國內首次使用,並將影響未來地震危害度分析發展。地震模擬目前已納入日本核能耐震指針與 IAEA NS-G-3.3 中,美國 NRC 於 2008~2011 之四年地震研究計畫已有著墨,並贊助美國太平洋地震工程研究中心(PEER)深入研究,目的應是希望及時追上日本的腳步;日本於中越沖事件後大量宣傳此一技術,相信下次 NRC 的法規重點應在此處,故可藉此計畫積極準備未來需面對之要求。目前國內既有核電之地震危害度分析技術已不符 NRC RG 1.208 相關規定,為增進地震引致之核能電廠廠址強地動值評估之精確性,並研發日本與美國之地震模擬技術,以運用於進行特定震源之地震動情境模擬。
本計畫擬將國際間最新之地震危害度評估技術與理論,結合台灣的地震與地質最新研究成果,建立一套適合我國核電廠址地質構造條件,且符合國際核能標準的地震模擬技術與程序,作為後續新建核能機組地震安全評估之參考方式,並落實評估技術的本土化與自我執行率。故本子項計畫之工作項目如下:
(1)影響核能電廠之歷史災害地震資料調查與模擬,
(2)建立地震波傳實境模擬之震源參數設定方針,
(3)混合法(Hybrid)地震模擬技術研究,
(4)核能級地震模擬程式建立,
(5)近震源之地震動衰減律模式建立。
Abstract
Seismic hazard analysis is the technique for the determination of design earthquake in nuclear power plant, this technique including the consideration of earthquake source, wave propagation, site response and the statistics of earthquake occurrence rate. The practice of this technique needs highly scientific background information and integration of all kinds of theory in order to form a consensus in future seismic hazard. The fault map published by Central Geological Survey indicate that Sanchiao fault and Hengchun fault are close to the nuclear power plant, this will be the necessary consideration of the planning and communication of adding new unit in the power plant. The Chūetsu earthquake in Kashiwazaki-Kariwa nuclear power plant was trigger by an fault that already consider in construction period, because of the lack of near source data in attenuation relationship, the estimation of ground-motion is inaccurate.
This project is trying the implement the ground-motion simulation technique to create scientific data and near source ground-motion data for ground-motion attenuation relationship in seismic hazard analysis. This will be the first time in Taiwan and will affect the future development of seismic hazard analysis. The ground-motion simulation has already included in Japan’s nuclear power plant seismic guide, IAEA NS-G-3.3, US NRC also include ground-motion simulation in their 2008~2011 four years seismic research and sponsor PEER for more research on it, their purpose should be keep up with Japan. Because Japan propagated the simulation technique after the Chūetsu earthquake, it is believe that NRC will put the ground-motion simulation in next version of Regulatory Guides, this project could be the preparation of the future needs. Current seismic hazard analysis technique for nuclear power plant in Taiwan couldn’t fit the needs of NRC RG 1.208, in order to increase the accuracy of seismic hazard assessment and research for ground-motion simulation technique to do the scenario simulation for specific earthquake source this project is needed.
This project intends to implement the newest international seismic hazard analysis technique and theory combine with Taiwan’s newest research result on seismology and geology to establish a technique and procedure conform to international nuclear standard and suitable for our nuclear power plant’s site geological condition, follow-up for the seismic safety assessment of new installation unit and for the localization and self execution rate. The work items are as follows:
1. The investigation and simulation of historical earthquake that will affect nuclear power plant.
2. To establish the guidelines for earthquake source parameter in ground-motion simulation of scenario earthquake.
3. Studies of hybrid method of ground-motion simulation technique.
4. The establishment of nuclear level ground-motion simulation program.
5. The establishment of near source ground-motion attenuation relationship.