05000321/LER-2015-002, Regarding 1A Plant Service Water Pump Misalignment Results in a Condition Prohibited by Tech Specs
| ML15246A537 | |
| Person / Time | |
|---|---|
| Site: | Hatch  |
| Issue date: | 09/03/2015 |
| From: | Pierce C Southern Nuclear Company, Southern Nuclear Operating Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NL-15-1642 LER 15-002-00 | |
| Download: ML15246A537 (6) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 3212015002R00 - NRC Website | |
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Charles R. Pierce Regulatory Affairs Director SEP 0 3 2015 Docket Nos.: 50-321 Southern Nuclear Operating Company, Inc.
40 Inverness Center Parkway Post Office Box 1295 Birmingham, AL 35242 Tel 205.992.7872 Fax 205.992.7601 U. S. Nuclear Regulatory Commission A TIN: Document Control Desk Washington, D. C. 20555-0001 Edwin I. Hatch Nuclear Plant Unit 1 Licensee Event Report 2015-002-00 SOUTHERN<<\\
NUCLEAR A SOUTHERN COMPANY NL-15-1642 1 A Plant Service Water Pump Misalignment Results in a Condition Prohibited by Tech Specs Ladies and Gentlemen:
In accordance with the requirements of 10 CFR 50.73(a)(2)(i)(B), Southern Nuclear Operating Company hereby submits the enclosed Licensee Event Report.
This letter contains no NRC commitments. If you have any questions, please contact Greg Johnson at {912) 537-5874.
C. R. Pierce Regulatory Affairs Director CRP/jcm Enclosure: LER 2015-002-00
U.S. Nuclear Regulatory Commission NL-15-1642 Page 2 cc:
Southern Nuclear Operating Company Mr. S. E. Kuczynski, Chairman, President & CEO Mr. D. G. Bost, Executive Vice President & Chief Nuclear Officer Mr. D. R. Vineyard, Vice President-Hatch Mr. M. D. Meier, Vice President-Regulatory Affairs Mr. D. R. Madison, Vice President-Fleet Operations Mr. B. J. Adams, Vice President-Engineering Mr. G. L. Johnson, Regulatory Affairs Manager-Hatch Mr. M. A. Dowd, Operating Experience Coordinator-Hatch RTYPE: CHA02.004 U. S. Nuclear Regulatory Commission Mr. V. M. McCree, Regional Administrator Mr. R. E. Martin, NRR Senior Project Manager-Hatch Mr. D. H. Hardage, Senior Resident Inspector-Hatch
Edwin I. Hatch Nuclear Plant Unit 1 1 A Plant Service Water Pump Misalignment Results in a Condition Prohibited by Tech Specs Licensee Event Report 2015-002-00 1 A Plant Service Water Pump Misalignment Results in a Condition Prohibited by Tech Specs
X NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 01/31/2017 (02*2014)
, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
YEAR 2015
- 6. LER NUMBER I
SEQUENTIAL 1 NUMBER 002 REV NO.
00 2
- 3. PAGE OF 3
Energy Industry Identification System codes appear in the text as (EllS Code XX)
DESCRIPTION OF EVENT
On January 20, 2015 at 2304 with Unit 1 at approximately 7 percent thermal power due to a scheduled outage for SRV maintenance, it was observed that the 1A Plant Service Water (PSW) pump (EllS Code P) was exhibiting unusually high vibrations. Vibration readings were taken at the upper and lower motor bearing areas on the pump. The data compared to reference data showed a significant change from normal vibration levels.
Additionally, vibration data was taken along the pump suction column in the area near the upper and lower seismic restraints. The 1 A PSW pump was declared inoperable and the 1 C PSW pump was placed in service.
On January 22, 2015 at 1515 the upper restraint strap was found broken and the strap bolt was galled on the west side. Two bolts of the lower restraint strap were also found sheared. It was determined that the restraints were weakened over time due to fatigue from the vibrating pump. Therefore, when the restraints broke, the pump began to exhibit unusually high vibrations.
On January 26, 2015 at 0245 with Unit 1 at approximately 100 percent thermal power, the 1 A PSW pump was replaced. The pump was then declared operable and returned to service.
On July 8, 2015, in consultation with the pump vendor and engineering, it was determined that the 1 A PSW pump would not have been able to meet its 30 day mission time based on the broken seismic restraints and the excessive vibration levels found on January 20, 2015. Although the pump accumulated 30,000 hours0 days <br />0 hours <br />0 weeks <br />0 months <br /> of run time prior to being declared inoperable on January 20, 2015, if a seismic event would have occurred such that the seismic restraints on the pump would have broken, this would have left the 1 A PSW pump unsupported. It was then concluded that the pump would have not been able to operate at elevated vibrations for more than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. This assessment is based in the amount of wear that was found on the shaft after the pump was disassembled. Shaft degradation indicated that with continued operation after 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, the pump would not have been able to meet rated flow and pressure.
CAUSE OF EVENT
The cause of the 1 A PSW pump high vibrations was due to pump shaft misalignment as a result of inadequate procedural guidance. It was identified that the 1 A PSW pump seismic restraints were installed offset from the centerline of the pump. The upper restraint was installed 1/4 inch offset to the east, while the lower restraint was installed 3/4 inch offset to the west and a 5/8 inch offset that extended from the wall. These seismic restraints were installed in 201 0. The pump column had to be pressed and bridged over in order to appropriately fit in the restraints. In this configuration, considerable loads were applied to both the upper and lower restraints and the pump shaft. The upper and lower supports eventually failed due to the applied stress resulting in the unusually high vibrations seen from the 1 A PSW pump.
REPORT ABILITY AND SAFETY ASSESSMENT This event is reportable per 10 CFR 50.73(a)(2)(i)(B) due to being in a condition prohibited by Technical Specifications. As a result of the misalignment of the seismic restraints, it was determined that if a design basis seismic event would have occurred, the 1 A PSW pump would not have been able to meet its 30 day mission (02*2014)
U.S. NUCLEAR REGULATORY COMMISSION LICENSEE EVENT REPORT (LER)
CONTINUATION SHEET
- 1. FACILITY NAME
- 2. DOCKET
- 6. LEA NUMBER
- 3. PAGE OF YEAR I SEQUENTIAL I REV NUMBER NO.
Edwin I. Hatch Nuclear Plant Unit 1 05000 321 3
2015 002 00 time. This conclusion is based on the elevated vibrations found on the pump after the failure of the seismic restraints.
3 The plant service water system is designed to provide screened cooling water to the plant during normal operation and shutdown conditions. Each system consists of four, one-third capacity service water pumps.
Each pump is capable of delivering their rated capacity of 8500 gallons per minute. In the event of a shutdown or emergency shutdown, only one PSW pump delivering 4428 gallons per minute is required. Therefore, the loss of one PSW pump does not pose a significant impact to provide reliable cooling to equipment required for accident conditions. Based on this information, this condition was determined to have very low safety significance.
CORRECTIVE ACTIONS
The 1 A PSW pump was refurbished and replaced. The misaligned pump seismic restraints were also corrected and set in an appropriate configuration. The plant service water pump and motor disassembly, inspection, and re-assembly procedure was also revised to ensure that the restraints are maintained in the proper configuration if maintenance is performed that replaces or adjusts the pump saddle restraints.
Preventive maintenance work orders were also modified to obtain monthly measurements of the vibration levels near the pump seismic restraints should high vibrations be encountered at the motor.
As part of the extent of condition review, all of the seismic restraints on the remaining 7 PSW pumps were inspected and found to be in their proper alignment. The 1 A PSW pump was the only pump found to have increased vibration levels.
ADDITIONAL INFORMATION
Other Systems Affected: None.
Failed Components Information
Master Parts List Number: 1 P41 C001 A Manufacturer: Sulzer Model Number: GC-2751/54 Type: 24EC 3 Stage Vertical Pump Manufacturer Code: S450 EllS System Code: 81 Reportable to EPIX: Y Root Cause Code: 8 EllS Component Code: P Commitment Information: This report does not created any new licensing commitments.
Previous Similar Events
None.