ML20207G812
| ML20207G812 | |
| Person / Time | |
|---|---|
| Site: | Summer  |
| Issue date: | 01/05/1987 |
| From: | Nauman D SOUTH CAROLINA ELECTRIC & GAS CO. |
| To: | Harold Denton Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8701070403 | |
| Download: ML20207G812 (2) | |
Text
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Co u b 29218 Nuclesr Operations SCE&G January 5,1987 Mr. Harold R. Denton, Director, Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, D.C. 20555
Subject:
Virgil C. Summer Nuclear Station Docket No. 50/395 Operating License NPF-12 Main Feedwater RegulatingValve and Operator NPRDS Trends and Pattern Analysis
Dear Mr.Denton:
In a letter from Mr. J. B. Hopkins to Mr. D. A. Nauman dated October 30,1986, South Carolina Electric and Gas Co. (SCE&G) was requested to perform a review and provide conclusions regarding the Virpl C. Summer operating experience of the main feedwater regu ating valves. T he Maintenance Services Department has reviewed the maintenance history file of the main feedwater regulating valves with respect to the referenced NRC letter.
The Virgil C. Summer Nuclear Station has three air operated main feedwater regulating valves which have 16 inch forged bodies. A maintenance history review of these valves revealed that during the 1982-85 time frame, the majority ofvalve problems occurred during 1984. A frequent symptom ofvalve problems was the j allure to meet stroke time test requirements. The cause of the problems was attributed to malfunctions in the valve operators. Corrective actions which have been takeninclude:
Performing a design change on the pneumatic components (valve a.
positioner and volume booster). This change eliminated the need for a separate volume booster.
b.
Establishing a preventive maintenance task to replace the valve operator diaphragm at each refueling outage.
c.
Establishing a preventive maintenance task to repack the valve at each refueling outage.
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A Mr. H. R. Denton Main Feedwater Regulating Valve and Operator NPRDS Trends and Pattern Analysis Page 2 January 5,1987 Corrective maintenance tasks were reduced by a factor of 9 from 27 to 3 from 1984 to 1985. In 1986, SCE&G replaced the valve positioner manifolds with metal reinforced manifolds due to cracks developing in the plastic connections. In addition, one valve required repacking. Currently, corrective maintenance rates appear to be about the same as those in 1985.
As outlined above, the SCE&G review supports the NRC conclusion of a peak number of failures in 1984. Since the three valves are of the same design and operate under the same conditions, it is difficult to draw any other conclusions.
SCE&G agrees with the conclusion drawn in the fourth paragraph of the enclosure to the NRC letter, in that units with "high failure rates" have " low mean times to failure."
In response to the request for comment on the NRC approach of disseminating results directly for review and discussion, SCE&G believes it could be more useful if new and significant problems or trends are identified. The INPO SER/SOER program provides such information.
If SCE&G could be of any further assistance, please notify Mr. David Malkmus of my staff at(803) 345-5209 ext. 4322.
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1 an DBM: DAN:bjh c:
O. W. Dixon, Jr.fr. C. Nichols, Jr.
C. A. Price i
E. C. Roberts C. L. Ligon (NSRC)
O. S. Bradham R. M. Campbell, Jr.
J. C. Connelly K. E. Nodland D. R. Moore R. A.Stough l
W. A. Williams,Jr.
G. O. Percival J. N. Grace R. L. Prevatte Group Managera J. B. Knotts, Jr.
W. R. Baehr NPCF File 4
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