Numerical Analysis of Thermal Stratification in Pressurizer Surge Line

The thermal stratification is generic to un-isolable piping system in pressurized water reactor (PWR), which is not considered in original design. This effect can finally threaten the integrity of the piping system. The pressurizer surge line is affected by thermal stratification during reactor heat up and shutdown processes particularly. It’s important to investigate and mitigate thermal stratification in the surge line to meet safety requirements. In this paper, the thermal hydraulic analysis and the mechanical analysis using numerical simulation method were conducted to evaluate the impact of thermal stratification in the surge line during reactor heat up processes. The results give the three-dimensional temperature distribution and stress status of the surge line. It indicates that thermal stratification can cause stress concentration in the displacement restricts. The mitigation of thermal stratification was also studied. The numerical simulation of pressurizer surge line can put forward thermal stratification analysis.