本研究係針對台灣電力公司核四廠 ─ 進步型沸水式核能電廠 ─ 的圍阻體系統，進行設計基準事故下熱水流動態現象的模式建立與計算分析。研究工作之特點與重要性，在於根據理論基礎，建立一套獨立之核能電廠圍阻體系統熱流分析程式，用來分析在暫態及事故發生情況下，圍阻體內熱流性質與流體參數時變數值，進一步更可提供在結構體造成之水動力負載計算方面所需之邊界條件。
而依流動及熱傳現象來區分，整個模式可分成：乾井系統、濕井系統、導管內水清除系統及導管排流系統。在乾井與濕井系統部分，可由熱力學之質量與能量守恆方程式來進行分析探討；導管內水清除系統及導管排流系統則是需探討動量方程式，來計算清除速度與流體排放量。

本研究之分析模式主要針對（1）飼水管路雙頭截斷大破口冷卻水流失事故，及（2）主蒸汽管路雙頭截斷大破口冷卻水流失事故，來探討不同斷管條件下，圍阻體系統所受之影響，並將分析結果針對乾、濕井內的熱力性質與核四廠之PSAR數據，進行分析比對，以確立分析程式之正確性與合理性；然後將計算所得之導管內清除之流體數據，包括水清除速率與流體排放流量等，予以整理以提供給下游濕井中抑壓池及氣體空間水動力負載計算之邊界條件用。

This study is aimed directly to the containment system of the Lungmen nuclear power station, which is an advanced boiling water reactor, constructed and operated by the Taipower company. A two-phase, multi-component, air-water-steam flowing model simulating different dynamic phenomena of containment system, during design basis accidents, is established. Importances and characteristics of this study are to establish an independent fluid thermohydraulic computer code, which is based on the fundamental theories, for the containment system of the Lungmen nuclear power station. It can analyze the thermodynamic properties and parameters of fluids in the containment during accidents or transients. Then we can provide the time-varying system response data as the boundary conditions for the detail analysis of hydrodynamic loading inside wetwell. Based on fluid dynamics and heat transfer processes, the model can be divided into several submodels, which includes drywell, water clearing, air clearing and wetwell. The mass and energy conservation of thermodynamics can be used to analyze the drywell and wetwell submodels. By adding the momentum equation to water clearing and air clearing submodels, the clearing velocity and parameters of flowing fluids can be calculated.
In this investigation, two LOCAs of desian basis accidents are the targets to be analyzed and compared. One is the Feedwater line LBLOCA, and the other is the Main-Steam line LBLOCA. By analyzing two LBLOCAs, we can understand different effects created by these two DBAs. The thermodynamic porperties in the drywell or in the wetwell can compare with PSAR results of the Lungmen nuclear power station, to assure that the established computer program is correct and precious. Then the data of fluids flowing in the vents can act as the boundary conditions, which includes velocity of water clearing and mass of the fluid flowing, to enable the calculations of hydrodynamic loading on the structures submerged or above the suppression pool.

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