05000499/LER-2003-001, For South Texas Unit 2 Regarding, Inoperable Residual Heat Removal Train
| ML031150024 | |
| Person / Time | |
|---|---|
| Site: | South Texas  |
| Issue date: | 04/18/2003 |
| From: | Halpin E South Texas |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NOC-AE-03001499, STI 31580649 LER 03-001-00 | |
| Download: ML031150024 (6) | |
| Event date: | |
|---|---|
| Report date: | |
| 4992003001R00 - NRC Website | |
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Nuclear Operating Company South Tus Pro/cd Ekclbc GCnefangStauon IPO
&x2839 Wdsmorth, rn 77483 April 18, 2003 NOC-AE-03001499 STI 31580649 10CFR50.73 U. S. Nuclear Regulatory Commission Attention: Document Control Desk One White Flint North 11555 Rockville Pike Rockville, MD 20852 South Texas Project Unit 2 Docket No. STN 50-499 Licensee Event Report 03-001 Inoperable Residual Heat Removal Train Pursuant to 10CFR50.73, South Texas Project submits the attached Unit 2 Licensee Event Report 03-001 regarding Train C Residual Heat Removal (RHR) operations not permitted by Technical Specifications 3.0.4 and 3.4.5.6. This event did not have an adverse effect on the health and safety of the public.
If there are any questions on this submittal, please contact S. M. Head at (361) 972-7136 or me at (361) 972-7849.
E. D. Halpin Plant General Manager awh Attachment: LER 03-001 (South Texas, Unit 2)
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NOC-AE-03001499 Page 2 of 2 cc:
(paper copy)
(electronic copy)
Ellis W. Merschoff Regional Administrator, Region IV U.S. Nuclear Regulatory Commission 611 Ryan Plaza Drive, Suite 400 Arlington, Texas 76011-8064 U. S. Nuclear Regulatory Commission Attention: Document Control Desk One White Flint North 11555 Rockville Pike Rockville, MD 20852 Richard A. Ratliff Bureau of Radiation Control Texas Department of Health 1100 West 49th Street Austin, TX 78756-3189 Cornelius F. O'Keefe U. S. Nuclear Regulatory Commission P. O. Box 289, Mail Code: MN116 Wadsworth, TX 77483 A. H. Gutterman, Esquire Morgan, Lewis & Bockius LLP L. D. Blaylock/W. C. Gunst City Public Service Mohan C. Thadani U. S. Nuclear Regulatory Commission R. L. Balcom Texas Genco, LP A. Ramirez City of Austin C. A. Johnson/A. C. Bakken III AEP - Central Power and Light Company Jon C. Wood Matthews & Branscomb C. M. Canady City of Austin Electric Utility Department 721 Barton Springs Road Austin, TX 78704
Abstract
On January 25, 2003 with Unit 2 in MODE 5, 2-RH-MOV-0060C, Loop C RHR pump suction valve, failed to open. 2-RH-MOV-0060C failed when the motor stalled and overheated causing the breaker to trip. This motor failure was caused by the motor pinion gear sliding down the motor shaft and contacting the de-clutching mechanism resulting in increased frictional loading. The motor pinion set-screw was not installed correctly in the drilled recess on the shaft. Consequently, when the motor was energized the pinion gear was thrust into the declutching mechanism. Coincident with this condition, the pinion key was also observed to be partially disengaged from the motor shaft keyway; however, this discrepancy was determined not to have contributed to the failure.
Corrective actions include rework of MOV-0060C, inspection and repair as required of all potentially affected Unit 1 and Unit 2 motor operated valves (MOVs), and confirmation that the maintenance procedures for MOVs is adequate to assure proper installation of the setscrews.
This event resulted in no personnel injuries, offsite radiological releases or damage to safety related equipment other than MOV-0060C.
NRC FORM 366 (7-2001)
(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) (17)
ADDITIONAL INFORMATION
Results of STPNOC inspections:
Of the 327 MOVs inspected (in addition to MOV-0060C), 24 MOVs had deficiencies that required an engineering evaluation. Any deficiencies found in the 327 MOVs were repaired and the MOV returned to service.
An operability/reportability review was conducted on the 24 MOVs that required an evaluation and documented in the Corrective Action Program. Except for Unit 2 RHR MOV-0060C (the subject of this LER), all the MOVs were determined to have been operable and capable of performing their design function.
The results of the inspections are consistent with the investigation and the causes described above.
Industry History:
There is a substantial amount of industry operating experience information spanning a number of years regarding Limitorque operators, including experience with motor pinions and key placement. As this information has become known, STP has incorporated it into station procedures and practices.
Requirements for spot drilling for setscrew seating and staking for setscrews and keys were among those added to STP maintenance procedures.