ENS 45930
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ENS Event | |
|---|---|
03:01 May 15, 2010 | |
| Title | Manual Reactor Scram Due To Increasing Reactor Water Level |
| Event Description | At approximately 2301 hours0.0266 days <br />0.639 hours <br />0.0038 weeks <br />8.755305e-4 months <br /> EDT on May 14, 2010, Susquehanna Steam Electric Station Unit One reactor scrammed while performing a condensate pump trip test. The reactor operator placed the mode switch in shutdown when reactor water level reached +51 inches and rising. The main turbine tripped due to high reactor water level. All control rods inserted and both reactor recirculation pumps tripped. Reactor water level lowered to -30 inches causing Level 3 (+13 inches) isolations. The Operations crew restored reactor water level to the normal operating band using RCIC [Reactor Core Isolation Cooling] and subsequently the feedwater system. All isolations at this level occurred as expected. No steam relief valves opened. Pressure was controlled via turbine bypass valve operation. All safety systems operated as expected.
The reactor is currently stable in Mode 3. An investigation into the cause of the shutdown is underway. Unit Two continued power operation. The NRC Resident Inspectors were notified. A press release will occur. The licensee was performing testing on the digital feedwater control system which was installed during their recent refueling outage when the loss of level control occurred. It appears that the control system did not respond fast enough to control water level. This resulted in the reactor operator inserting a manual scram at +51 inches prior to reaching the reactor automatic scram setpoint of +54 inches for water level. Currently, the plant is removing decay heat via main steam line drains to the condenser. The plant is in its normal shutdown electrical lineup with all safety equipment available. The licensee has notified the Pennsylvania Emergency Management Agency. |
| Where | |
|---|---|
Susquehanna  Pennsylvania (NRC Region 1) | |
| Reporting | |
| 10 CFR 50.72(b)(2)(iv)(B), RPS Actuation 10 CFR 50.72(b)(3)(iv)(A), System Actuation | |
| LER: | 05000387/LER-2010-002 |
| Time - Person (Reporting Time:+-1.73 h-0.0721 days <br />-0.0103 weeks <br />-0.00237 months <br />) | |
| Opened: | Todd Creasy 01:17 May 15, 2010 |
| NRC Officer: | Howie Crouch |
| Last Updated: | May 15, 2010 |
| 45930 - NRC Website
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Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | Yes, Manual Scram |
| Before | Power Operation (94 %) |
| After | Hot Shutdown (0 %) |
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