05000366/LER-2006-002, Re Unit Scram on Turbine Control Valve Fast Closure
| ML061590539 | |
| Person / Time | |
|---|---|
| Site: | Hatch  |
| Issue date: | 05/26/2006 |
| From: | Sumner H Southern Nuclear Operating Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NL-06-1089 LER 06-002-00 | |
| Download: ML061590539 (6) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(iv)(A), System Actuation |
| 3662006002R00 - NRC Website | |
text
H. L Sumner, Jr.
Vice President Hatch Project Southern Nuclear Operating Company, Inc.
Post Office Box 1295 Birmingham, Alabama 35201 Tel 205.992.7279 May 26, 2006 4Ir SOUTHERN AM COMPANY Energy to Serve Your World*
NL-06-1089 Docket No.:
50-366 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D. C. 20555-0001 Edwin I. Hatch Nuclear Plant - Unit 2 Licensee Event Report Inadequate Procedure Results in Automatic Reactor Scram Ladies and Gentlemen:
In accordance with the requirements of 10 CFR 50.73(a)(2)(iv)(A), Southern Nuclear is submitting the enclosed Licensee Event Report concerning an inadequate procedure which resulted in an automatic reactor scram on turbine control fast closure.
This letter contains no NRC commitments. If you have any questions, please advise.
Sincerely, H. L. Sumner, Jr.
HLS/OCV/daj Enclosure: LER 2-2006-002 cc:
Southern Nuclear Operating Company Mr. J. T. Gasser, Executive Vice President Mr. D. R. Madison, General Manager - Plant Hatch RTYPE: CHA02.004 U. S. Nuclear Regulatory Commission Dr. W. D. Travers, Regional Administrator Mr. C. Gratton, NRR Project Manager - Hatch Mr. D. S. Simpkins, Senior Resident Inspector - Hatch
Abstract
On 4/5/2006 at 00:16 EDT, Unit 2 was in the Run mode at a power level of 2804 CMWT (100 percent rated thermal power). At that time a power-load unbalance was sensed resulting in a turbine control valve fast closure. The sensed power-load unbalance was a false indication introduced by performance of a calibration procedure. Reactor pressure spiked to approximately 1125 psig, which resulted in an additional trip signal due to high reactor pressure. All control rods fully inserted. Eight of the eleven Safety Relief Valves opened as designed to mitigate the pressure transient. Pressure did not reach the nominal actuation set points for the remaining three Safety Relief Valves. Reactor water level initially decreased due to void collapse and then increased to a maximum value of approximately 60 inches due to swell after both Recirculation Pumps tripped automatically on End of Cycle-Recirculation Pump Trip per design and eight SRVs opened. Reactor water level subsequently decreased when the reactor feed pumps automatically tripped on high reactor water level per design. The minimum reactor water level decreased to approximately seven inches and was recovered with manual initiation of the Reactor Core Isolation Cooling and High Pressure Coolant Injection systems.
This event was caused by a power-load unbalance created during the calibration of the KVR Generator and Main Transformer Protection Recorder. The calibration procedure was found to be inadequate in that it allowed this calibration to be performed with the main turbine on-line and at greater than 40 percent rated thermal power. The calibration procedure was revised.
NRC FORM 366 (6-2004)
(If more space Is required, use additional copies of (If more space Is required, use additional copies of (If more space is required, use additional copies of (If more space is required, use additional copies of NRC Form 366A)
This event was due to an inadequate procedure. There were no equipment failures that caused this event.
Failed Components Information
None Commitment Information: This report does not create any permanent licensing commitments.
Previous Similar Events in the last two years in which the reactor scrammed automatically while critical were reported in the following Licensee Event Reports:
1-2005-002, dated 12-21-2005 Previous Similar Events in the last two years in which an ECCS system has actuated either automatically of manually:
1-2004-004, dated 5-5-2004 1
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