ML20028F051
| ML20028F051 | |
| Person / Time | |
|---|---|
| Site: | South Texas  |
| Issue date: | 01/18/1983 |
| From: | Oprea G HOUSTON LIGHTING & POWER CO. |
| To: | Jay Collins NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| References | |
| 10CFR-050.55E, 10CFR-50.55E, ST-HL-AE-923, NUDOCS 8301310064 | |
| Download: ML20028F051 (4) | |
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The Light comPuy llouston 1.ighting & l'ower PO.11ox 1700 llouston Texas 77001 (713)22833211 January 18, 1983 ST-HL-AE-923 File Number: G12.136 Mr. John T. Collins l' . h 5[
Regional Administrator, Region IV ]
Nuclear Regulatory Commission 611 Ryan Plaza Dr., Suite 1000
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l 1 Arlington, Texas 76012 '
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Dear Mr. Collins:
SOUTH TEXAS PROJECT Units 1 & 2
, Docket Nos. STN 50-498, STN 50-499 j Final Report Concerning Westinghouse Gate Valve Limit Switches On December 23, 1982 Houston Lighting & Power Company (HL&P), pursuant to 10CFRSO.55(e), notified your office of an item concerning limit switches used for certain Westinghouse gate valves. Attached is our final report concerning this item.
If you should have any questions concerning this item, please contact Mr. Michael E. Powell at (713) 877-3281.
Very tr ly yours,
. ./ pY7 r.
Executive ce President LJK/mg Attachment r301310064 830118 PDR ADOCK 05000498 s PUR
llouston 1.ighting & Power Compan)
January 18, 1983 cc: G. W. Oprea, Jr. ST-HL-AE-923 J. H. Goldberg File Number: G12.136 J. G. Dewease Page 2 J. D. Parsons D. G. Barker M. R. Wisenburg R. A. Frazar J. W. Williams R. J. Maroni J. E. Geiger H. A. Walker S. M. Dew J. T. Collins (NRC H. E. Schierling NRC W. M. Hill, Jr. NRC M. D. Schwarz Baker &Botts)
R. Gordon Gooch Baker & Botts)
J. R. Newman -(Lowenstein, Newman, Reis, & Axelrad)
STP RMS Director, Office of Inspection & Enforcement Nuclear Regulatory Commission Washington, D. C. 20555 G. W. Muench/R. L. Range Charles Bechhoefer, Esquire Central Power & Light Company Chairman, Atomic Safety & Licensing Board i
P. O. Box 2121 U. S. Nuclear Regulatory Commission Corpus Christi, Texas 78403 Washington, D. C. 20555 H. L. Peterson/G. Pokorny Dr. James C. Lamb, III City of Austin 313 Woodhaven Road P. O. Box 1088 Chapel Hill, North Carolina 27514 Austin, Texas 78767 J. B. Poston/A. vonRosenberg Mr. Ernest E. Hill City Public Service Board Lawrence Livermore Laboratory P. O. Box 1771 University of California San Antonio, Texas 78296 P. O. Box 808, L-46 Livermore, California 94550 Brian E. Berwick, Esquire William S. Jordan, III Assistant Attorney General Harmon & Weiss 4 for the State of Texas 1725 I Street, N. W.
P. O. Box 12548 Suite 506 Capitol Station Washington, D. C. 20006 Austin, Texas 78711 Lanny Sinkin Citizens for Equitable Utilities, Inc.
Citizens Concerned About Nuclear Power c/o Ms. Peggy Buchorn 5106 Casa Oro Route 1, Box 1684 San Antonio, Texas 78233 Brazoria, Texas 77422 Jay Gutierrez, Esquire Hearing Attorney Office of the Executive Legal Director U. S. Nuclear Regulatory Commission Washington, D. C. 20555 Revision Date 12-20-82
Final Report Concerning -
Westinghouse Gate Valve Limit Switches I. Summary On December 22, 1982, HL&P was notified by telephone that the Westinghouse Safety Review Board had identified an item which Westinghouse recommended should be evaluated pursuant to 10CFR50.55(e). The item concerned the design of the internal limit switches used for gate valves supplied by Westinghouse for the High-Head and Low-Head Safety Injection Systems. The potential exists for the control room to receive a FULLY-CLOSED position indication when the valve is stuck partially open.
II. Description On motor-operated valves with Limitorque motor operators the torque bypass switch and the STILL-0 PEN limit switch are both taken from the same rotor of the operator. The limit switch rotor is set to provide an electrical bypass of the OPEN torque switch at the beginning of the opening stroke. On a closing stroke, this switch changes state before the flow path is completely blocked. As a result, the monitor and/or indicator lights also operated by that rotor can indicate valve closure slightly before the flow path is completely shut off. If the valve were to stop between this setpoint and the full shut off position, a flow path throuah the valve could exist even though a CLOSED indication had been achieved. For a potential deficiency to exist all of the following criteria must be met:
- 1) The valve must be in a safety-related system and application.
- 2) The valve must either be closed already for an accident situation or be expected to close at some point following the accident.
- 3) The valve must perform this closure function without the benefit of a backup or redundant valve.
- 4) The condition must impact the safety analysis of the event as a result of being partially open.
- 5) Incorrect valve position indication could delay correct operator action to overcome the problem.
For the Westinghouse scope of supply the hot and cold leg safety injection isolation valves have been identified as meeting the above criteria. A review of P&ID's has determined that the above criteria are not met for any valves within the Bechtel scope of supply.
III. Corrective Action The corrective action is to move the STILL-0 PEN limit switch to a different rotor whose setpoint could be established at the FULLY CLOSED position. Currently the rotor setpoint is established for the torque bypass, not the position indication.
Final Report Concerning Westinghouse Gate Valve Limit Switches IV. Recurrence Control i This deficiency occurred due to a unique circumstance resulting from the design of the valve motor operators. Therefore, a formal recurrence control is not applicable in this instance.
V. Safety Evaluation A detailed safety evaluation has not been performed for this item.
The situation described could result in the creation of an unanalyzed condition. The corrective action outlined in Section III will be implemented for the identified valves, prior to the completion of the effected systems, in accordance with our construction schedules. This will eliminate the safety hazard resulting from the unanalyzed condition should one exist.
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