SAFETY PROTECTION FACILITY OF PRESSURIZED WATER NUCLEAR POWER PLANT

摘要

PURPOSE:To prevent a primary coolant from being released into the outside to safely and effectively make possible cooling by providing a cooling water tank at a higher position than the set position of a steam generator to cool the steam of a secondary coolant so as to circulate in the steam generator. CONSTITUTION:When small heat exchanger tubes 13 of a steam generator 2 are damaged and a primary coolant is leaked in a secondary coolant, the steam of the secondary coolant also has radioactivity, which is measured by a radiation counter 18. And when a measured value exceeds an allowable value, a controller 19 is allowed to operate to close a main steam separation valve 11 while a drain valve 17 of a cooling water tank 14 is opened to allow the steam of the secondary coolant of the steam generator to pass a guide tube 15 so as to enter the cooling water tank 14. When the steam passes heat exchanger tubes 20, it is cooled to be condensed water to pass circulation tubes 16 so as to circulate in the steam generator 2. Furthermore, a water holding quantity of the coolant of the steam generator 2 after separation by the circulation of the condensed water is held constant and cooling is performed effectively. Furthermore, inflow for a secondary system of the steam which has high radioactivity is checked at a minimum and contamination of secondary system devices of a turbine 6 and the like can be prevented.