Stress Generation Mechanism of Elbow Pipes Due to Thermal Stratification
In nuclear power plants, the structural components that are in contact with coolant are susceptible to thermal loads due to the change in the fluid temperature. If the heating and cooling processes are cyclic, the structure will endure thermal fatigue that may lead to failure. Thermal stratification is one of the main loads that can lead to high cycle thermal fatigue damage. The Japan Society of Mechanical Engineers, (JSME) have published the evaluation guideline for high cycle thermal fatigue. It treats branch pipe due to thermal stratification, however, it does not contain an analysis method for stress evaluation. To develop its analysis method, finite element analyses were conducted for an elbow pipe to clarify the stress generation mechanism due to thermal stratification load.