ML19338C536
| ML19338C536 | |
| Person / Time | |
|---|---|
| Site: | Callaway  |
| Issue date: | 07/31/1980 |
| From: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Bryan J UNION ELECTRIC CO. |
| References | |
| NUDOCS 8008180097 | |
| Download: ML19338C536 (1) | |
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UNITED STATES g
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NUCLEAR REGULATORY COMMISSION e
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GLEN ELLYN. ILLINOIS 60137 o
Docket No. 50-483 Docket No. 50-486 Union Electric Company ATTN:
Mr. John K. Bryan Vice President - Nuclear P. O. Box 149 St. Louis, MO 63166 Gentlemen:
Enclosed is IE Bulletin No. 80-20 which requires action by you with regard to your nuclear power facility.
In order to assist the NRC in evaluating the value/ impact of each bulletin on licensees, it would be helpful if you would provide an estimate of the manpower expended in conduct of the review and preparation of the reports required by the bulletin.
Please estimate separately the manpower associated with corrective actions necessary following identification of problems through the bulletin.
Should you have any questions regarding this bulletin or the actions required by you, please contact this office.
Sincerely, hJamesG.Keppler Director
Enclosure:
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Mr. W. H. Weber, Manager, Nuclear Construction Central Files Director, NRR/DPM Director, NRR/ DOR PDR Local PDR NSIC TIC Region I & IV Ms. K. Drey Mr. Ronald Fluegge, Utility j
Division, Missouri Public I
Service Commission 1
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8008180097 b
SSINS No.: 6820 5-UNITED STATES Accession No.:
8006190043 A'T NUCLEAR REGULATORY COMMISSION
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,,g July 31, 1980 IE Bulletin No. 80-20 FAILURES OF WESTINGHOUSE TYPE W-2 SPRING RETURN TO NEUTRAL CONTROL SWITCHES By letter dated June 18, 1980, Commonwealth Edison Company submitted Licensee Event Report No. LER 50-295/80-24 to the NRC describing a malfunction of a Westinghouse Type W-2 control switch at the Zion Generating Station, Unit 1.
The malfunctioning switch is a three position spring return to neutral switch.
Although the switch was in its procar neutral position when it malfunctioned, its neutral contacts failed to clase properly thereby preventing the automatic
%t. art of 1A Service Water Pump.
Subsequent tests conducted on the mlfunctioning switch revealed that contact closure was intermittent with the, witch in the neutral (or " Auto Start")
position.
Other tests conducted on identical switches from spares and from Unit 2 equipment disclosed two additional switches with a tendency for inter-mittent contact closure.
A review of this matter by Westinghouse led to the issuance of NSD Technical Bulletin No. NSD-TB-80-9 to the utility owners of all Westinghouse operating plants.
The recommendations contained in the Westinghouse technical bulletin include: (i) testing the neutral position contacts of the subject W-2 switches.
for continuity, and (ii) rewiring of the indicating light circuit to permit the early detection of a neutral contact failure as shown in Figure 1.
Depending on how the indicating light circuit is wired, loss of continuity thru the neutral position contact of a W-2 switch could remain undetected until the equipment associated with the switch were called upon to operate.
Since such a failure would be equivalent to by passing the system associated with the switch, consideration should be given to rewiring the switches used in safety-related applications as shown in Figure 1.
Such rewiring would provide an acceptable means for detecting contact failure, provided the indicating light is in the control room and readily visible by the operator.
If the indicating light is not so located, consideration should be given to annunciating the neutral position contact failures at the control room to alert the operator of the inoperable status of a safety-related system.
In addition, consideration should be given to adding redundant contacts to the W-2 switches or to replacing the W-2 switches with others having a more posi-tive contact wiping action.
ACTIONS TO BE TAKEN BY LICENSEES AND HOLDERS OF CONSTRUCTION PERMITS:
1.
Determine whether Westinghouse Type W-2 control switches with spring return to neutral position are used in safety-related applications at i
l your facility.
If so, identify the safety-related systems using these l
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i July 31, 1980 IE Bulletin No. 80-20 Page 2 of 2 switches and the total number of switches so used.
If no such switches are used in your facility, you should indicate that this is the case and ignore the remaining questions.
Licensees of operating plants using Type W-2 spring return to neutral 2.
control switches in safety-related applications shall perform continuity tests on all such switches.
These tests shall be performed with the switch operator in the neutral position and completed within ten (10)
In addition, this continuity test days of the date of this bulletin.
shall be repeated at least every thirty-one (31) days after the initial test and after each manipulation of the switch from its neutral position.
These continuity tests may be discontinued subsequent to implementing the longer term corrective measures described below.
Licensees of operating plants and holders of construction permits shall 3.
describe the longer term corrective measures planned and the date by which such measures will be implemented by actual installation or by design change, as appropriate.
As a minimum, the longer term corrective measures should include rewiring the indicating light as shown in FigureIf 1 provided the light is readily visible to the control room operator.
not, failures of the neutral position contacts should be annunicated in the control room.
A report addressing the above matters, including the number of failures detected during the first series of tests and the safety-related systems involved, shall be submitted to the director of the appropriate NRC regional A copy of office within forty-five (45) days of the date of this bulletin.
the report shall be forwarded to the Director, Division of Reactor Operations Inspection, Office of Inspection and Enforcement, Nuclear Regulatory Commission, Washington, D. C. 20555.
Approved by GAO, B180225 (R0072); clearance expires 7/31/80.
Approval was given under a blanket clearance specifically for identified generic problems.
Enclosure:
Figure 1
EXISTING INDICATING lichi CIRCUIT (TYPICAL) s NEUTRAL SWITCH CONTACT INDICATIN3 LIGHT Y
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(-)
SAFETY SIGNAL
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PROFDSED REWIRING OF INDICATING LIGHT CIRCUIT (TYPICA NEUTRAL SWITCH M
CONTACT. 7 Yj INDICATING A
LIGHT mai
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SAFETY SIGNAL
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FIGURE 1:
REWIRING OF INDICATING LIGHT' CIRCUIT OF W-2 SWITCHES AS REC 0"'. ENDED BY WESTINGHOUSE TECHNICAL BULLETIN NSD-T
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I' IE Bulletin No. 80-20 Enclosure July 31, 1980 RECENTLY ISSUED IE BULLETINS Bulletin Subject Date Issued Issued To No.
80-19 Failures of Mercury-7/31/80 All nuclear power Wetted Matrix Relays in facilities having Reactor Protective Systems either an OL or a CP of Operating Nuclear Power Plants Designed by Combus-tion Engineering 80-18 Maintenance of Adequate 7/24/80 All PWR power reactor Minimum Flow Thru Centrifugal facilities holding OLs Charging Pumps Following and to those PWRs Secondary Side High Energy nearing licensing Line Rupture Supplement 2 Failures Revealed by 7/22/80 All BWR power reactor to 80-17 Testing Subsequent to facilities holding OLs Failure of Control Rods to Insert During a Scram at a BWR Supplement 1 Failare of Control Rods 7/18/80 All BWR power reactor to 80-17 to Insert During a Scram facilities holding OLs at a BWR 80-17 Failure of Control Rods 7/3/80 All BWR power reactor to Insert During a Scram facilities holding OLs at a BWR 80-16 Potential Misapplication of 6/27/80 All Power Reactor Rosemount Inc., Models 1151 Facilities with an and 1152 Pressure Transmitters OL or a CP with Either "A" or "D" Output Codes 80-15 Possible Loss Of Hotline 6/18/80 All nuclear facilities With Loss Of Off-Site Power holding OLs 80-14 Degradation of Scram 6/12/80 All BWR's with an Discharge Volume Capability OL 80-13 Cracking In Core Spray 5/12/80 All BWR's with an Spargers OL I
80-12 Decay Heat Removal System 5/9/80 Each PWR with an OL Operability
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