ML20082E747
| ML20082E747 | |
| Person / Time | |
|---|---|
| Site: | Vogtle  |
| Issue date: | 11/09/1983 |
| From: | Conway R GEORGIA POWER CO. |
| To: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| REF-PT21-83 10CFR-050.55E, 10CFR-50.55E, GN-280, NUDOCS 8311280303 | |
| Download: ML20082E747 (6) | |
Text
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h t'": mt:*.:m, m3rc wtan R.E.Conway kn.or V< e Freent November 9,1983 United States Nuclear Regulatory Commission File: X78G03 Office af Inspection and Enforcement Log:
GN-280 Region II-Suite 3100 101 Marietta Street Atlanta, Georgia 30303
Reference:
Vogtlr Electric Generating Plant-Units 1 and 2 504/24)50-425; Westinghouse Gate Valve Position Indication, GN-257, dated September 19, 1983 Attention: Mr. James P. O'Reilly Gentlemen:
In our previous correspondence on this subject, Georgia Power Company indicated that a final report could be expected on November 4, 1983. Georgia Power Company has completed its investigation into the reportability of this concern and has concluded that a substantial safety hazard and significant deficiency do exist. Based upon guidance from the NRC in NUREG-0302, Revision 1, and other NRC letters, Georgia Power Company is reporting this concern as a significant deficiency pursuant to the requirements of Part 10 CFR 50.55(e). Enclosed is a copy of our evaluation.
This response contains no sr.prietary information and may be placed in the NRC Public Document Room upon receipt.
Yours truly, R. E. Conway ]
REC /REF/cc enclosure xc:
U. S. P.egulatory Commission Document Control Desk Washington, D. C.
20555 xc:
R. J. Kelly R. H. Pinson E. D. Groover D. O. Foster B. M. Guthrie L. T. Gucwa G. F. Head R. A. Thomas M. Malcom J. T. Beckham, Jr.
J. A. Bailey G. Bockhold D. N. MacLemore
- 0. Batum P. D. Rice D. E. Dutton H. H. Gregory, III J. L. Vota W. F. Sanders C. W. Hayes d,r;yn 7
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8311280303 831109
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EVALUATION FOR A SUBSTANTIAL SAFETY HAZARD EVALUATION FOR A SIGNIFICANT DEFICIENCY Westinghouse Gate Valve Position Indication Initial' Report:
On August 17, 1983, Mr..C. W. Hayes' of Georgia Power Company notified the NRC of a potential. deficiency concerning the possibility of inaccurate Westinghouse gate valve position indication.
In a-subsequent. letter, Georgia Power Company informed the NRC that,a final report could be expected by November 4,.1983.
Background:
' Westinghouse Electric Corporation infermed Georgia Power Company of a potential safety concern-involving valve position indication for certain Westinghouse-
. manufactured gate valves. The concern involves the possibility o_f supplying a false valve position indication to plant operators, depending upon which rotor
.on the motor operator was used to indicate a closed position. Georgia Power
- Company. requested that Bechtel Power Corporation, the A/E for the Vogtle '
Electric Generating Plant, perform an engineering review to determine if this problem could exist in other valve applications. Bechtel concluded that this concern only. existed for the valves supplied by Westinghouse Electric and notified Georgia Power Company that a potential deficiency could exist. Sub-sequently, Georgia Power Company notified the NRC that a potential deficiency could exist.
4
- The Limitorque motor operators, supplied on the Westinghouse valves, provide four adjustable limit switch rotors with four switches per rotor. Rotors 1 and 2 are set by the valve manufacturer per Westinghouse requirements to ensure proper valve operation. Rotor,1 is set at the open travel limit. Rotor 2 is set to provide a bypass of the open torque switch, so that the-valve is partially
.open when the rotor is actuated. This setting is constrained by the valve design to ensure that the open torque switch does not terminate the opening ~of the valve due to the unseating torque. Depending on the valve size, the valve disc will
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be 1.25 inches to 3.0' inches off the main seat'when the rotor is actuated. This is as indicated in Westinghouse Instruction Book 5710-99 and in Bechtel Log 1/2XGAA-06-451. The other two rotors are spares for customer use (see Figure 1).
4 Engineering Evaluation:
The actuation setpoint of the rotor is used for remote indication lights and inter-locks that-operate at the fully closed valve position. Limitorque Type SMB Instruction and Maintenance Manual SMBI-170 indicates that-both fully closed and fully open limit switch rotors should be set to operate slightly before the valve
- reaches the full travel position. Some valve travel between closed limit switch operation.and operation of the closing torque switch to stop valve motion must exist, but should be >kept to a minimum to accurately indicate that valves are essentially closed. Westinghouse has defined that the indication set point for their valves is a maximum of 0.35 inches (0.75 inches for 12-inch and 14-inch Class 1500 valves) from the main seat.
In some cases, as specified by the T
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Westingh_ouse Gate Valve Position Indication Page 2 Evaluation for a~ Substantial Safety Hazard Evaluation for a Significant Deficiency Westinghouse electrical wiring diagrams, the gate valves have been engineered
'with the close indication wired to a limit switch on rotor 2.
This means that
- the CLOSE indication is received prior to' the disc fully isolating flow.' If the.valvestalls(or. binds)following/he'prematdreindicationbeinggiven,
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- the operator would h' ave'an< inaccurate indicatio~n of true valve position. 'If the
' valve has not isolated. flow:as, intended, the potential exists for the unit to be.in an unanalyzed condition. JAdditionally, these. incorrect signals could mislead the. operator into takingLinappropriate-actions.
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- Westinghouse had identified-the following gate valves in which the-position r
indication deficiency
- exists'and could ' impact-plant safety:
8802A, B.- Reactor-Coolant System (RCS) Hot Leg Header Isolation (ISO) Valves 8809A, B - Residual Heat Removal (RHR) to Safety Injection System (SIS) Cold Leg 150 Valve 8835
- SIS Cold Leg loop Inlet Hea' der ISO Valve 8840
- RHR Hot Leg Injection Crossover ISO. Valve In addition, Westinghouse has identified the'following valves that require accurate indication to provide safety in the event of multiple failures:
8105, 8106 -~ Charging (Chg.) Pump'to RCS ISO Valve 800A, B
- Pressurizer Pressure Relief Valves 8146, 8147 - Chg. to RCS ISO Valve 8807A~, B
- Safety-Injection (SI) Pump Suction Header Valve 1
8924"
- Chg. Pump Header to SIS Pump 1 Inlet Valve 8821A, B~
- SI Pump to RCS Cold Leg ISO Valve 8801A,'B-
- Boron Injection Tank Discharge and Inlet ISO Valves 8803A, B' 8485A,~B
- Chg. Pump' Discharge Valves 8438
>8923A, B
- SI Pump-Inlet Valve 8471A, B
- Chg. Pump Suction Valve LCV-1120. E-Refueling Water Storage Tank to Chg. Pump Valves 8806
- SI Pump Suction ISO Valve 8716A, B
- RHR Hot Leg 150 Valve
r Westinghouse Gate Valve Position Indication Page 3 Evaluation for a Substantial Safety Hazard Evaluation for a Significant' Deficiency 8808A, B,
- Accumulator ISO Valve C, D 8701A, B
- RHR Inlet ISO Valve 8702A, B
-Other valves with the same design have been identified by Westinghouse and are listed below..Their premature indication will not affect the safety of the plant, but nevertheless will be corrected.
8994A,B
- Spray-Additive Tank Outlet Isolation Valve FV-610,611
- Residual Heat Removal (RHR) Pump Miniflow Control Valve LV-1128,C
- Volume Control Tank Outlet Isolation Valve 8804A
- RHR Heat Exchanger to Charging Pump Suction Isolation Valve 8804B
- RHR Heat Exchanger to Safety Injection Pump Suction Train 'B' Isolation Valve
-9001A, B
- Containment Spray (CS) Pump to Spray Header Valve 9017A, B
- CS Pump Reactor Water Storage Tank (RWST) Inlet Valve 9003A, B
- CS Pump Emergency Sump Suction Valve (Containment Isolation) 9002A, B
- CS Pump Emergency Sump Suction Valve (Containment Isolation) 8812A, B
- RHR Pump RWST Inlet Valve 8811A, B-
- Containment Sump RHR Pump Suction. Isolation Valve The gate valves procurred by Bechtel and located in balance-of-plant (B0P) applications were also reviewed to-determine whether this concern exists and if it impacts the safety of the plant. 'The following' criteria were used to determine whether safety of the plant is impacted:
The condition causes reduction in Emergency Core Cooling Systems
-(ECCS) performance, or
- The condition causes a reduction in Engineered Safety Feature (ESF)
Systems performance, or Th'e condition impacts containment isolation.
Based upon the review, it was found that this concern does not exist in any 80P
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motor-operated gate valves.
==
Conclusion:==
It can be concluded that incorrect position indication of safety-related valves represents a reportable concern since the open path resulting from the valves not
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Westinghous' Gate Valve Position Indication Page 4 e
Evaluation for a substantial Safety Hazard Evaluation for a Significant Deficiency being closed could affect the safe operation of the Vogtle Electric Generating Plant. fThis represents a deficiency in the final design as approved and released
-_for. construction.such that the design does not conform to the criteria and bases in the safety analysis report.
It has also been concluded that-this con-
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- cern represents a defect.in a. basic component and is therefore reportable under Part 10 CFR 21 since a substantial safety hazard could be' created.
Corrective Action:
Westinghouse has submitted the generic wiring changes required to move the indication from bypass rotor 2 to' rotor 4, which is set to-operate at the valve
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closed position, and thus provides more accurate indication. The associated Westinghouse ele' trical wiring diagranis will be revised to. formally document this c
change.-
Field. modifications will be performed at the site and it is expected that all wiring; changes will be. completed by December 31, 1984.
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