Susquehanna: Manual Reactor Scram Due to an Unisolable Extraction Steam System Leak

Event Number: 46569
Event Date: 01/25/2011
Facility: SUSQUEHANNA

MANUAL REACTOR SCRAM DUE TO AN UNISOLABLE EXTRACTION STEAM SYSTEM LEAK

"At 0610 EST hours on January 25, 2011, Susquehanna Steam Electric Station Unit 1 reactor was manually scrammed due to an unisolable extraction steam system leak in the 1C Feed Water Heater Bay area.

"At 0517 EST reactor operators commenced lowering reactor power from 98.4% to 65%. Attempts to isolate the source of the leakage were unsuccessful. Based on continued indications of unisolated steam leakage, operations decided to shut down the plant. The reactor operator placed the mode switch in shutdown. All control rods inserted. Reactor water level lowered to -31 inches causing Level 3 (+ 13 inches) isolation and RCIC initiation. The operations crew subsequently maintained reactor water level at the normal operating band using FW [feedwater]. No steam relief valves opened. All safety systems operated as expected. RCIC automatically initiated on a -30 inch level signal and was manually secured.

"The reactor is currently stable in Mode 3. Investigation into the cause of the extraction steam system leakage is underway.

"The NRC Resident Inspector was notified. A voluntary notification to PEMA and press release will occur."

The steam leak was isolated after the turbine was tripped. The plant is stable at normal temperature and pressure. Decay heat is being removed via the condenser steam dumps to the main condenser. The electrical lineup is in a normal configuration. Estimated time to restart is not known.