Structure Reliability Analysis of the Safety Valve Body Based on Thermal-structure Coupling Effect

To ensure the reliability of the safety valve for nuclear power system,a three-dimensional model for steady thermal-structure coupling was developed by considering the heat exchange of valve body with internal medium and environment.Based on the model,the thermal-structure coupling effect of valve body was analyzed by employing the multi-physics field method of the ANSYS software with proper gridding density.Further,the structure reliability analysis of valve body was carried out by using the probabilistic design system of the ANSYS software and Monte-Carlo simulation method.The results show that the structure reliability of the valve body is enough under working circumstance,but the reliability allowance seems too high for reliable operation of the safety valve.Sensitivity of the random variables on maximum stress was also researched.It is shown that the width dimension L of the valve is the most significant variable on reliability and the reliability allowance of body structure can be adjusted by changing the parameter L.The example calculation for a real dimension of safety valve shows that,considering the effects of threaded holes,the valve can work with 100% reliability even though L reduces to 290mm,making the valve volume decrease by 17.9%.