ML19331D479
| ML19331D479 | |
| Person / Time | |
|---|---|
| Site: | Hope Creek  |
| Issue date: | 08/15/1980 |
| From: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | Martin T Public Service Enterprise Group |
| References | |
| NUDOCS 8009030060 | |
| Download: ML19331D479 (1) | |
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UNITED STATES 85)y NUCLEAR REGULATORY COMMISSION
- j REGION t 4
631 PARK AVENUE
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KING OF PRUSSIA PEN YL l
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Docket Nos. 50-354 50-355 Public Service Electric and Gas Company ATTN.
Mr. T. J. Martin Vice President Engineering and Construction 80 Park Place Newark, New Jersey 07101 Gentlemen:
Enclosed is Revision I to IE Bulletin No. 80-15.
The revision merely clarifies the areas of concern; therefore, thE actions, including dates of reports required from you with respect to your nuclear power facility, are not changed.
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 corrective actions necessary following identification of problems through the Bulletin.
Should you have any questions regarding the Bulletin or actions required by you, please contact this office.
Sincerely,
.M B y e H. Grier Director
Enclosures:
1.
IE Bulletin No. 80-19, Revision 1 2.
List of Recently Issued IE Bulletins l
CONTACT:
D. L. Caphton (215-337-5266) cc w/encls:
E. N. Schwalje, Manager - Quality Assurance, Engineering and Construction Department 8009030oroO Q
e s
SSINS No.: 6820 UNITED STATES Accession No.:
NUCLEAR REGULATORY COMMISSION 8006190052 0FFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C.
20555 August 15, 1980 IE Bulletin No. 80-19 1
Revision 1 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 (RPS) of nuclear power pla
-wetted relays used in the logic matrix of the reactor protective system iesigned 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 RPS.
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 relays 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-cr2 (31) failures of mercury-wetted relays used in the logic matrix of the RPS.
l Most of the reported failures were " failed-closed" type (i.e., the typ that could inhibit a reactor trip), and four of the reported evens 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-clcsed" 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 t
concerns. (1) the total number of failures yields a much higher random failure 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 l
Data for Nuclear Power Generating Stations", IEEE, New York; and (3) NUREG/
CR-0942, " Nuclear Plant iteliability Data System, 1978 Annual Reports of l
Cumulative System and Component Reliability", NRC.
p IE Bulatin No. 80-19, Revision 1 August 15, 1980 Page 2 of 2 multiple failures detected suggests the presence of a common-mode failure mechanism.
Such a common-mode failure mechanism could result in the build-up of specific " failed-closed" failures which, in turn, could result in antici-patedtransientswithoutscram(ATWS). Thus, the relatively high random failure rate and the suggested common-mode failure mechanism, indicate that plants using mercury-wetted matrix relays in the RPS are more susceptible to scram failures than predicted in other studies.
ACTIONS TO BE TAKEN BY HOLDERS OF CONSTRUCTION PERMITS OR OPERATING LICENSES FOR NUCLEAR POWER FACILITIES:
1.
Review your facility to determine whether C.P. Clare Model HG2y-1011 RE mercury-wetted relays are used in the logic matrix of the RPS.
If Rll no such relays are used, you should submit a negative declaration to this effect end you need not respond to the remaining items in this bulletin. Your negative declaration shall be submitted to the appropriate NRC regional office within thirty (30) days of the date of this bulletin and a sopy forwarded to the Director, Division of Reactor Operations Inspection, Office of Inspe tion and Enforcement, NRC, Washington, D. C. 20555-2.
Licensees of operating facilities using the above relays in the logic RR matrix of the RPS should increase the frequency of their surveillance R3 tests. Until further notice, or until the mercury-wetted relays have been replaced with qualified relays of a different dedgn, surveillance testing of the relays shall be initiated within ten (10) days of the date of this bulletin and repeated at intervals not exceeding ten (10) days thereafter. The additional surveillance testing applies when operability R2 of the RPS is required by the Technical Specification. Upon detecting a RT failed relay, the failed unit shall be replaced with a qualified dry-contact relay or a new mercury-wetted relay.
(The removed relay shall not be reused in the RPS.)
3.
Nuclear power facilities which are using or whose design includes the use of the above relays in the logic matrix of the RPS shall submit either RT their plans and schedules for replacing the mercury-wetted relays with qualified relays of a different design, or justification for using the mercury-wetted relays. Res?onses to this item shall be submitted to the offices listed in Item 1, above, within ninety (90) days of the date of the original version of this bulletin, July 30, 1980.
RS Approved by GAO, B180225 (R0072); clearance expires July 31, 1980.
(Application for renewal pending before GA0.) Approval was given under a blanket clearance specifically for identified generic problems.
l IE Bulletin No. 80-19, Revision 1 August 15, 1980 RECENTLY ISSUED IE BULLETINS Bulletin Subject Date Issued Issued To No.
80-20 Failures of Westinghouse 7/31/80 All holders of a Type W-2 Spring Return power reactor OL or to Neutral Control Switches CP 80-19 Failures of Mercury-7/31/80 All holders of a Wetted Matrix Relays power reactor OL in Reactor Protective or CP Systems of Operating Nuclear Power Plants Designed by Combus-tion Engineering 80-18 Maintenance of Adequate 7/24/80 All holders of a Minimum Flow Thru PWR power reactor Centrifugal Charging Pumps OL or CP Following Secondary Side High Energy Line Rupture Supplement 2 Failures Revealed by 7/22/80 All holders of a BWR to 80-17 Testing Subsequent to power reactor OL Failure of Control Rods or CP to Insert During a Scram at a BWR Supplement 1 Failure of Control Rods 7/18/80 All holders of a to 80-17 to Insert During a Scram BWR power reactor at a GWR OL or CP 80-17 Failure of Control Rods 7/3/80 All holders of a to Insert During a Scram BWR power reactor at a BWR OL or CP 80-16 Potential Misapplication of 6/27/80 All holders of a Rosemount lnc., Models 1151 power reactor and 1152 Pressure Transmitters OL or CP with Either "A" or "D" Output Codes 80-15 Possible Loss Of Hotline 6/18/80 All holders of a With Loss of Off-Site Power power reactor or fuel facility OL connected to the Emergency Notification System 80-14 Degradation of Scram 6/12/80 All holders of a Discharge Volume Capability BWR power reactor OL or CP
.