Transient thermal stress analysis for module feedwater pipe of SMART steam generator

A transient thermal stress analysis for the module feedwater pipe of the SMART steam generator was performed. An analytic equation to calculate the thermal transient stress was derived on the basis of Green function concept. The thermal transient stress of the module feedwater pipe subjected to an arbitrary change of the coolant temperature was obtained from the Duhamel integration for the product of the coolant temperature and the Green function. A transient finite element analysis was also carried out for the methodological justification and the quantitative comparison with the Green function method. The results of the linear transient finite element analysis have shown a good agreement with those of the Green function method. The results of transient finite analysis using temperature dependent nonlinear material properties have shown 20% difference with those by using constant material properties. During the start up of the integral reactor SMART, maximum thermal stress has reached up to 10% of the yield stress of the titanium alloy