MANUAL REACTOR TRIP DUE TO RISING STEAM GENERATOR LEVEL
"On 08/17/20 at 2113 EDT, with Unit 3 in Mode 1 at approximately 92% [Rated Thermal Power] RTP, the reactor was manually tripped. This was due to a turbine runback caused by CV-3-2011, Low Pressure Feedwater Heater Bypass Control Valve, failing open, followed by rising Steam Generator (S/G) levels. Unit 3 reactor was tripped manually when the 3C S/G Level reached 78% narrow range. Unit 3 Main Steam Isolation Valves were closed manually in accordance with Emergency Operating Procedure (EOP) network due to 38 MSR Main Steam Stop valve position indication lost. All other systems operated normally. Auxiliary Feedwater initiated as designed to provide S/G water level control. EOPs have been exited and General Operating Procedures (GOPs) were entered. Unit 3 is stable in Mode 3 at normal operating temperature and pressure.
"This event is being reported pursuant to 10 CFR 50.72(b)(2)(iv)(B) and 10 CFR 50.72(b)(3)(iv)(A).
"The NRC Resident Inspector has been notified."
All rods are inserted, decay heat is being removed via S/G through normal secondary systems. The plant is in normal electrical line up. Lightning strike is believed to be the initial cause of the runback. |