ML20115C178
| ML20115C178 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 10/13/1992 |
| From: | William Cahill, Walker R TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC) |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| SDAR-CP-92-016, SDAR-CP-92-16, TXX-92471, NUDOCS 9210190200 | |
| Download: ML20115C178 (3) | |
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C File # 10110 (CP-92 016)
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903.9 7UELECTRIC Ref.
- 10CFR50.55(e) u ima.n J. cohm. Jr.
October 13, 1992 Group Vke l'rrshicer V. S. Nuclear Regulatory Commission Attn:
Document Control Desk Washington, DC 20555
SUBJECT:
COMANCHE PEAK STEAM ELECTRIC STATION (CPSES) - UNIT 2 DOCKET NO. 50-446 BORG-WARNER 3' HANUALLY OPERATED GATE VALVES SDAR-CP-92-016 (INTERIM REPORT)
Gentlemen:
On September 11. 1992, via facsimile, TV Electric notified the NRC of a reportab'e defect concerning two manually-operated 3' gate valves.
The stems had separated from the-dists.
The disks remained tightly wedged in the seats.
Attached is the written report which satisfies the reporting requirements of 10CFR50.55(e).
The report has been formatted in a manner that corresponds to the specific information requested by subparts (i) 1.hrough (viii ) of paragraph 10CFR50.55(e)(E) of the regulations.
This is er.clusive of that portion of subpart (viii) regarding advice that has been or iill be given to other entities outsice of TV Electric.
Such aavice would be dependent upon the entities' specific use and operating /ri,aintenance history of the suicet.t components.
Sincerely, Y
William J. Cahill, Jr.
By:_
M Roger 'O Walker Manager of Regulatory Af fairs for NE0 JTC/tg Attachmont c-Mr. J. L. Milhoan, Region IV Mr. T.
A.
Bergman, NRR Mr. B. E. Holian, NRR Resident Inspectors. CPSES (2)
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, Attachment to TXX-92471 Page 1 of 2
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10CFR50,55(e) REPORTABLE DEFECT CONCERNING BORG WARNER 3" GATE VALVES (i)
Individual Informing the NRC William J. Cahill, Jr.
TV Electric 400 North Olive Street, L.B.' 81 vallas, Texas 75201 (ii)
Basic Component Which Contains a Defect The basic components are 3" manually-coerated gate valves.
(iii)
Firm Supplying the Basic Component Borg-Warner supplied the valves in accordance with CPSES Specific:t'cr-2323-MS-20B.I.
(iv)
Nature of Defect and. Safety Hazard During disassembly of two manually-operated 3" rising stem gate valves, it was d'.scovered that the stems had been pulled through the attaching ears of the valve disks.
Apparently-as a result of j
previous valve operations, the disks were wedged tightly in the seats.
As the valves were opened, sufficient-force was exerted on g^
the stems-to pull them out of the disks and the stems continued to travel in the upward direction, One valve was located in the minimum flow recirculation line:for the Turbine Driven Auxiliary Feedwater Pump (TDAFWP) and the other was in the discharge from the TDAFWP to Steam Generator #4.
5 Two similar valves are located in the discharge from the TDAFWP to each of the four steam generatort.
The normal position of the valves is "open".
If the valves were closed and 'then _ reopened and the same phenomenon described above were to occur, the valve stems would indicate that the valves were open, but the disks-would in fact be sected.
Although these valves are not "ective" and are rarely operated, they are required to be in their normal position for.the TDAFWP to perform its safety function.
Therefore, this could have created a substantial safety hazard, The cause of this condition appears to a design error (oversized handwheels) combined-with excessive force being applied during valve operation.
(v)
Date the Information was Obtained This defect-was identified on July 6,1992.
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Attuchment to'TXXa924)1 r
Page 2 of_2' (vi)
Number and Location of all Defective Components in Use-There are twenty-two of these valves located :in the Auxiliary
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Feedwater, Feedwater, and Main Steam systems.
(vil)
Corrective Action I
The internals of the two valves have been replaced.
The size of the handwheel will be reduced on each of the twenty-two -valves of this type to reduce the force with which the valve can be closed.
Further corrective actions are being evaluated and a supplemental letter will be provided within sixty days.
t' (viii) a6."-* Given to Othe'r Entities A corrective action document has been' issued to-address these-l velves-in.CPSES' Unit 1.
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