Primary coolant circuit

Purpose: To enable response to the requirements of abrupt load follow-up characteristics for an atomic power plant by avoiding severe thermal stress occurring in a reactor cooling system when a pump abnormally tripped. Constitution: A reactor container and a steam generator of a PWR type reactor power plant are connected via a primary coolant low temperature pipe circuit. The pipe is provided by connecting a primary main circulation pump having a large inertial efficiency in series with a primary main circulation pump having a small inertial efficiency. Further, a bypass tube and a bypass valve are added to the primary main circulation pump having a small inertial efficiency. Thus, the prescribed purpose can be performed. (Yoshihara, H.)