由於爐心噴灑管嘴對熱疲勞非常的敏感，所以在核反應爐中視為關鍵的組件，本研究主旨在計算核反應爐內爐心噴灑管嘴在不同狀態下之熱應力分佈及疲勞壽命。疲勞壽命計算方法之一是使用多軸向應力疲勞分析，其疲勞壽命的計算方式係考慮六個應力分量的變化，與ASME NB-3200規範所述一致，而另一疲勞壽命計算方式則採用多軸疲勞之臨界平面法，並藉由商用軟體FE-SAFE加以分析，進一步比較兩種不同方法的分析結果，並選擇合適的疲勞壽命評估模式。分析結果顯示，使用ASME規範計算，發現有六個分析位置點顯示有限的壽命，而使用商用軟體FE-SAFE時，則有四個分析位置點顯示有限的壽命，進而得知ASME規範的多軸向應力疲勞分析較商用軟體FE-SAFE的臨界平面法保守。因此對核反應爐中的爐心噴灑管嘴而言， ASME規範的疲勞壽命計算方式是較為保守的評估模式。One of the critical components or locations in a nuclear reactor is the core spray nozzle because it is very sensitive to thermal fatigue. The fatigue life of a core spray nozzle is calculated using a new multiaxial stress-based fatigue (SBF) analysis module during transient events. Fatigue calculation considers all six components of stress in accordance with ASME Subarticle 3200 involving modified stress cycle pairing method. The fatigue life is also calculated using a critical plane approach by means of a multiaxial fatigue software, FE-SAFE. The comparison between these two approaches provides some insight into selection of a suitable fatigue life assessment model for the core spray nozzle in a nuclear power plant. The investigated points in the core spray nozzle using ASME code shows finite life at six points, while the FE-SAFE results show four points of finite life. The ASME code gives more conservative results than does the critical plane approach in the FE-SAFE. ASME code is suitable for fatigue life assessment of the core spray nozzle in a nuclear power plant for a more conservative consideration.
