Stress and Seismic Calculation of HTR-10 Primary Loop Pressure Relief System

Generator (SG) heat transfer tubes of 10MW High Temperature Gas Cooled Reactor (HTR10) are protective screens between the primary loop of helium and the secondary loop of water and steam. Water and steam will enter into the primary loop from the secondary loop if SG heat transfer tubes rupture, which is one of reasons leading to increase of the primary loop pressure. Function of the primary loop pressure relief system (PLPRS) is to reduce pressure of the primary loop so that the pressure not to exceed the designed maximum pressure value and to guarantee the integrity of pressure boundaries by discharging part of helium. PLPRS is connected to the lower head of SG pressure vessel. The piping part between the PLPRS nozzle of SG and the safety relief valves constitutes one of the primary loop pressure boundaries. If the pipe of PLPRS ruptures, helium of the primary loop will lose. This might cause unplanned reactor shut down. So it is important to guarantee the integrity of PLPRS. This paper presents stress and seismic calculation and analysis of PLPRS. Results show that stress distributions satisfy the requirements of ASME codes for C