ML19331C317
| ML19331C317 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 07/31/1980 |
| From: | Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | Gary R TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC) |
| References | |
| NUDOCS 8008140544 | |
| Download: ML19331C317 (1) | |
Text
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9 UNITED STATES
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NUCLEAR REGULATORY COMMISSION PDR
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.I REGloN IV c
611 RYAN PLAZA ORIVE, SUITE 1000 LPDR i
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f ARLINGTON, TEXAS 76o12 TIC V 3
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NSIC July 31, 1980 CENTRAL FILES In Reply Refer To:
RIV Docket Nos. 50-445/IE Bulletin No. 80-20 50-446/IE Bulletin No. 80-20 Texas Utilities Generating Company ATTN:
Mr. R. J. Gary, Executive Vice President and General Manager 2001 Bryan Tower Dallas, Texas 75201 Gentlemen:
Enclosed is IE Bulletin No. 00-20 which requires action by you with regard to your nuclear power facilities.
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 report (s) required by the Bulletin. Please estimate separately the manpower associated with correc-tive actions necessary following identification of probleme through the Bulletin.
Should you have any questions regarding this Bulletin or the actions required by you, please contact this office.
Sincerely,
?V
/
H f.f s c I
& Karl V. Seyfrit f
8 Director
Enclosures:
1 1.
2.
List of Recently Issued IE Bulletins i
8008140 5 9
SSINS No.: 6820 UNITED STATES Accession No.:
NUCLEAR REGULATORY COMMISSION 8006190023 0FFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C.
20555 IE Bulletin No. 80-20 Date: July 31, 1980 Page 1 of 2 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 proper neutral position when it malfunctioned, its neutral contacts failed to close properly thereby preventing the automatic start of 1A Service Water Pump.
Subsequent tests cenducted on the malfunctioning switch revealed that contact closure was intermietent with the switch 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-j mittent contact closure.
A review of this matter by Westinghouse led to the issuance of NSD Technical t
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 V-2 control switches with spring return to neutral position are used in safety-related applications at your facility.
If so, identify the safety-relateo systems using these
IE Bulletin No. 80-20 Date: July 31, 1980 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.
2.
Licensees of operating plants using Type W-2 spring return to neutral 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) days of the date of this bulletin.
In addition, this continuity test 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.
3.
Licensees of operating plants and holders of construction permits shall 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 Figure 1 provided the light is readily visible to the control room operator.
If 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 office within forty-five (45) days of the date of this bulletin. A copy of 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 probleus.
Enclosure:
Figure 1
EXISTING INDICATING LIGHT CIRCUIT (TYPICAL)
NEUTRAL 4
SWITCH CONTACT N"
INDICATING LIGHT d,,
M SAFETY
(-)
SIGNAL
(+)
PROPOSED REWIRING OF INDICATING LIGHT CIRCUIT (TYPICAL)
[
NEUTRAL SWITCH
-[
CONTACT 7 INDICATING A
LIGHT Y,
SAFETY w = SIGNAL
%/
N/
l C+)
l
(-)
FIGURE 1 l'
REVIRING OF INDICATING LIGHT CIRCUIT OF W-2 SWITCHES AS RECCit*iENDED BY WESTINGHCUSE TECHNICAL SULLETIN NSE-TB-80-9 l
IE Bulletin No. 80-20 July 31, 1980 RECENTLY ISSUED IE BULLETINS Bulletin Subject Date Issued Issued To No.
80-14 Degradation of Scram 6/12/80 All BWRs with an Discharge Volume Operating License (OL)
Capability or Construction Permit (CP) 80-15 Possible Loss of Emergency 6/18/80 All nuclear facilities Notification System (ENS) holding Operating Licenses with Loss of Offsite Power (OLs) 80-16 Potential Misapplication 6/27/80 All Power Reactor of Rosemount Int., Models Facilities with an 1151 and 1152 P:: essure Operating License (0L)
Transmitters with Either or a Construction Permit "A" or "D" Output Codes (CP) 80-17 Failure of 76 of 185 7/3/80 All BWR power reactor Control Rods to Fully facilities holding Insert During a Scram Operating Licenses (OLs) at a BWR or Construction Permit (CP)
Sup. 1 Failure of Control Rods 7/18/80 All BWR power reactor to 80-17 to Insert During a Scram facilities holding Operating at a BWR Licenses (OLs) or Con-struction Permits (cps)
Sup. 2 Failures Revealed by 7/22/80 All BWR power reactor to 80-17 Testing Subsequent to facilities holding Failure of Control Rods Operating Licenses (OLs) to Insert During a Scram or Construction Permits at a BWR (cps) l 80-18 Maintenance of Adequate 7/24/80 All PWR power reactor l
Minimum Flow Thru Centrifugal facilities holding OLs Charging Pumps Following and to those PWRs Secondary Side High Energy nearing licensing Line Rupture 80-19 Failures of Mercury-7/31/80 All nuclear power facilities l
Wetted Matrix Relays in having either an Operating Reactor Protective Systems License (OL) or Construction of Operating Nuclear Power Permit (CP)
Plants Designed by Combus-tion Engineering i
Enclosure 1
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