16:03 Jun 7, 2013
At approximately 1203 [EDT] on June 7, 2013, Susquehanna Steam Electric Station Unit One reactor was manually scrammed during reactor startup. Pressure setpoint was being adjusted to the normal operating setpoint, from 750 psig to 934 psig, when all turbine bypass valves unexpectedly opened. Reactor Feed Pumps, Main Turbine, HPCI and RCIC tripped on the high level setpoint Level 8 (+54 inches) due to the resultant reactor level swell. The reactor operator then inserted a manual scram.
All control rods inserted. Reactor water level lowered to approximately -10 inches causing Level 3 (+13 inches) isolations. There were no automatic emergency core cooling system initiations. No steam relief valves opened during the event. All safety systems operated as expected. The cause of the Turbine Bypass valve opening is under investigation.
Unit 2 was unaffected.The licensee notified the NRC Resident Inspector and will notify the Pennsylvania Emergency Management Agency.
Pennsylvania (NRC Region 1)
|10 CFR 50.72(b)(2)(iv)(B), RPS Actuation|
10 CFR 50.72(b)(3)(iv)(A), ECCS Actuation
|Time - Person (Reporting Time:+-2.22 h-0.0925 days <br />-0.0132 weeks <br />-0.00304 months <br />)|
13:50 Jun 7, 2013
|NRC Officer:||Vince Klco|
|Last Updated:||Jun 7, 2013|
|49099 - NRC Website|