ML19331D589
| ML19331D589 | |
| Person / Time | |
|---|---|
| Site: | River Bend  |
| Issue date: | 08/15/1980 |
| From: | Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | Draper E GULF STATES UTILITIES CO. |
| References | |
| NUDOCS 8009030271 | |
| Download: ML19331D589 (1) | |
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AR LINGToN, T EXAS 76012 August 15, 1980 In Reply Refer To:
RIV Docket Noa.
50-458/IE Eulletin No. 80-19, Revision 1 50-459/IE Bulletin No. 80-19, Revision 1 Gulf States Utilities Atta:
Dr. E. Linn Draper, Jr.
Vice President - Technology Post Office Box 2951 Beaumont, Texas 77704 Gentlemen:
SUBJECT:
IE BULLETIN NO. 80-19, REVISION 1 - FAILURES OF MERCURY-WETTED MATRIX RELAYS IN REACTOR PROTECTIVE SYSTEMS OF OPERATING NUCLEAR POWER PLANTS DESIGNED BY COMBUSTION ENGINEERING Enclosed is Revision 1 to IE Bulletin No. 80-19.
The revision merely clarifies the areas of concern; therefore, the actions including dates of reports required by you with respect to your nuclear power facility are not changed.
In order to assist the NRC in evaluating the valite/ 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 problems through the Bulletin.
Should you have any questions regarding the revised Bulletin or actions required by you, please contact this office.
Sincerely,
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K. V. Seyfrit Director
Enclosures:
1.
IE Bulletin No. 80-19, Revision 1 2.
List of Recently Issued IE Bulletins
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UNITED STATES Accession No.:
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g 40 av es ao IE Bulletin No. 80-19 Revision 1 Date: August 15, 1980 Page 1 of 2 FAILURES OF MERCURY-WETTED MATRIX RELAYS IN REACTOR PROTECTIVE SYSTEMS OF OPERATING NUCLEAR POWER PLANTS DESIGNED BY COMBUSTION ENGINEERING BACKGROUND:
This bulletin addresses the failures of mercury-wetted relays used in the logic matrix of the reactor protective system (RPS) of nuclear power plants designed by Combustion Engineering (C-E).
Except for Arkansas Nuclear One Unit 2 and Palisades, both of which use dry-contact matrix relays, the NRC understands that all other operating C-E plants use C.P. Clare Model HG2X-1011 mercury-wetted matrix relays in the R2S.
Mercury-wetted matrix relays manufactured by the Adams and Westlake Company were initially used in the Palisades plant; however, because of repeated failures of these relays, they were subsequently replaced with celays having dry-contacts.
GTE, the manufacturer of these dry-contact relays, however, has since discontinued their production.
Thus, although the dry-contact relays used at Palisades have performed without a failure since they were installed, they are not available for the other operating nuclear power plants designed by C-E.
OPERATING EXPERIENCES AND EVALUATION:
To date, operating nuclear power plants designed by C-E have reported thirty-one (31) failures of mercury-wetted relays used in the logic matrix of the RPS.
Most of the reported failures were " failed-closed" type (i.e., the type that could inhibit a reactor trip), and four of the reported events involved multi-ple failures (i.e., three relay failures were detected during two tests; two other failures were detected during two different tests).
Because of the re-dundancy within the RPS, no reported event would have prevented a reactor trip; however, the build-up of coincident " failed-closed" failures of certain sets of relays could result in trip failures for off-normal events.
The number of single and multiple relay failures reported gives rise to two (1) the total number of failures yields a much higher random failure concerns:
rate than that used in other relay failure estimates *, and (2) the number of
- Other relay failure estimates include (1) WASH-1400, " Reactor Safety Study",
NRC, October 1975; (2) IEEE Std 500-1977,"IEEE Guide to the Collection and Presentation of Electrical, Electronic, and Sensing Component Reliability Data for Nuclear Power Generating Stations", IEEE, New York; and (3) NUREG/
CR-0942, " Nuclear Plant Reliability Data System, 1978 Annual Reports of Cumulative System and Component Reliability", NRC.
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IE Bulletin No. 80-19 July 31, 1980 RECENTLY ISSUED IE BULLETINS Bulletin Subject Date Issued Issued To No.
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) 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 80-19 Failures of Mercury-Wetted 7/31/80 All nuclear power Matrix Relays in Reactor facilities having Protective Systems of either an Operating Operating Nuclear Power License (OL) or a Plants Designed by Combus-Construction Permit (CP) tion Engineering 80-20 Failures of Westinghouse 7/31/80 To each nuclear Type W-2 Spring Return power facility in to Neutral Control your region having Switches an Operating License (OL) or a Construction Permit (CP)
Enclosure
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