A Study of AP1000 Nuclear Power Plant SGTR Event Processing Strategy

Abstract

As a key equipment in nuclear power plant, steam generator (SG) serves for both primary and secondary systems. As the pressure boundary of primary system during plant operation, when SG tubes experience rupture (SGTR), primary coolant could flow into secondary system, causing loss of coolant in primary system and radioactive materials enter into second system. If loss of offsite power happens or turbine condenser steam dump is unavailable during the accident, radioactive materials may release to atmosphere through steam relief valve or safety valve. Therefore, when dealing with SGTR, loss of primary coolant should be stopped in a timely manner, radioactivity release should be prevented as well. As the third generation advanced nuclear power plant, Passive Pressurized Water Reactors (PPWR) adopts a series of measures in design to fully satisfy the utility’ requirements (URD) when face of SGTR. This paper compares the differences in regard to SGTR management between M310 and PPWR, and performs simulation verification using the latter’s full-scope simulator on conditions that with/without intervention from operators, it turns out that PPWR units can mitigate radioactive consequences of SGTR effectively; its management of SGTR reflects features of advanced nuclear power plants defined by the U.S. NRC.