抄録
This paper deals with the high cycle thermal fatigue phenomenon at a T-junction. The case of the phenomenon is a turbulent mixing at a T-junction, where hot and cold temperature fluids are mixed, in a plant piping system. The current guideline for high cycle thermal fatigue at pipes published by the Japan Society of Mechanical Engineers does not provide any procedure to measure actual safety margins, although both design and maintenance of nuclear plants need quantification of safety margins. Therefore, this paper proposes a new reliability assessment method for thermal fatigue in piping which considers loading and strength uncertainties to quantify safety margin. Since the procedure of the method should be concise for practical use, the proposed method uses the new concept "equivalent stress amplitude" which makes the complicated loading easy to deal with. Due to its conciseness and low calculation cost, the proposed method can contribute to introducing reliability assessment to the guideline for thermal fatigue evaluation.