Regional Basic Professional Training Course in Korea

❙ 1171 ❙
Introduction Of e‐FAST and Exercise
rapidly due to the reactor trip. The SBCS (Steam Bypass Control System) operates
automatically to control the main steam pressure. As a result, the pressure of steam
generator is maintained as the pressure of Hot‐standby operational mode and is higher
than that of steam generator in full power.
4) Operational Strategy for SGTR
First, operator should cool down the RCS using both steam generators(defected & sound)
until RCS hot leg temperature becomes less than 550℉(287.8℃). Before isolating the
defected steam generator, the initial cooling is necessary to reduce the possibility of
MSSV(Main Steam Safety Valve) open.
Second, the defected steam generator should be found & isolated to stop the release of
radioactive materials from the defected steam generator to the secondary system & the
environment.
Third, the pressure difference between the RCS & the isolated steam generator should be
maintained to keep within the range of ±50 psid(±3.5kg/cm2) to reduce & control the
leak rate from RCS to steam generator.
Fourth, the forced circulation or natural circulation cooling should be used for the
cooldown of RCS before the connection of shutdown cooling system. In this case, the
sound steam generator should be used for decay heat removal. The defected steam
generator shall be depressurized or cooled down according to the RCS condition.
5) Steam Generator Tube Rupture (SGTR) Exercise
(Malfunction 20.1)
At 100% reactor power, carry out the exercise to control the plant in a stable state after
SGTR accident as following procedure;