ML20205F470
| ML20205F470 | |
| Person / Time | |
|---|---|
| Site: | Catawba  |
| Issue date: | 10/18/1985 |
| From: | Tucker H DUKE POWER CO. |
| To: | Grace J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| REF-PT21-85-490-000 PT21-85-490, PT21-85-490-000, SD-414-85-05, SD-414-85-5, NUDOCS 8511120085 | |
| Download: ML20205F470 (3) | |
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-DuxE POWER GOMPANY P.O. HOK 33180 CHAMLOTTE. N.C. 28242 HA1. B. TUCKER -
retzenown vuos eneseswv (704) GTN831 wecs.saa enom a rson co October 18,1985 ao H
Dr. J. Nelson Grace, Regional Administrator U. S. Nuclear Reglatory Commission
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Region II CD 101 Marietta Street, NW, Suite 2900
-Atlanta, Georgia 30323 y
Re: Catawba Nuclear Station Docket No. 50-414 Significant Deficiency No 414/85-05
Dear Dr. Grace:
Please find attached a final report on the subject deficiency which describes the resolution of and the proposed corrective action for this item.
Very truly yours, lh Hal B. Tucker LTP/hrp Attachment cc: Director INPO Records Center Office of Inspection and Enforcement Suite 1500 U. S. Nuclear Regulatory. commission.
1100 Circle 75 Parkway Washington, D. C. 20555
, Atlanta, Georgia 30339 Mr. Jesse L. Riley Dr. K. Jabbour Carolina Environmental' Study Group 0ffice of Nuclear Reactor Regulation 854 Henley Place U. S. Nuclear Regulatory Commission Charlotte, North Carolina 28207 Washinton D. C. 20555 Robert Guild, Esq.
-P.O. Box 12097 Charleston, South Carolina 29412 Palmetto Alliance 1235 Devine Street Columbia, South Carolina 29205 i
l NRC Resident Inspector Catawba Nuclear Station 8511120005 851018 a
r PDR ADOCK 05000414 I I 8
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Report Number: SD 414/85-05 Report Date:
October 18, 1985 Identification of Deficiency:
A potential problem may exist with the starting air check valves in the on-engine mounted starting air piping.
At another utility, a piece of the check valve broke of f and passed through the air start valve, and was found on top of a piston crown. A second check valve was inspected and found to be cracked.
Initial Report:
On April 19, 1985, Mr. Hugh Dance of the NRC, Region 11, Atlanta, Georgia office was notified of this potential deficiency by Mr. L. M. Coggins, Mr. N. A. Rutherford, Mr. R. O. Sharpe, Mr. T. L. Utterback, and Mr. 3. M. Lines of Duke Power Company, Charlotte. North Carolina 28242.
Supplier and/or component:
Transamerica Delaval Inc. of Oakland, California supplied the four diesel generators, designated I A, IB, 2A and 2B, utilized at the Catawba Nuclear Station.
The Claw Corporation of Oskaloose, Iowa manufactured the valves.
Description of Deficiency:
A potential problem may exist with the starting air check valves in the on-engine mounted starting air piping. There are four of these valves on each Catawba diesel.
At another utility, a piece of the check valve (3/8" dia. x 7/8" length) broke of f and passed through the air start check valve, and was found on top of a piston crown. A second check valve was inspected, and found to be cracked.
The third and forth valves were inspected, and no other indications were found.
Analysis of Safety implication:
If the check valves are damaged, it could compromise the operability of the diesels.
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Corrective Action:
Based on the investigation, performed by Dominion Engineering, into the causes of the check valve failures at Grand Gulf and Shoreham, the failures resulted from high cycle fatigue at approximately 1600-2000 hours of engine operation.
Additionally, disc misalignnient (Grand Gulf) and improper disc seating (Shoreham) may have contributed to the check valve failures.
The original disc asse mbly material used in the check valves was cast 304 stainless steel.
The corrective action to be taken by Duke Power Company, based on the investigation results, is to install new' modified disc assemblies manufactured from 17-4 PH stainless steel, which is not subject to the high cycle fatigue failures that were experienced with the cast 304 stainless steel assemblies.
In addition, dimensional controls will allow the disc to be properly seated in the valve body so that potential cracking of the valve body should not occur.
Since the hours of operation on the Unit 2 diesels are approximately 200, Duke Power expects to replace each Unit 2 check valve disc ass 'mbly with the modified disc assembly by the end of the first refueling outage.