ML17296A941
| ML17296A941 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 08/15/1980 |
| From: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | Van Brunt E ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR |
| References | |
| NUDOCS 8009030276 | |
| Download: ML17296A941 (8) | |
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UNITED STATES NUCLEAR REGULATORY COMMISSION REGION V 1990 N. CALIFORNIA8OULEVARD SUITE 202, WALNUTCREEK PLAZA WALNUTCREEK, CALIFORNIA94596 August 15, 1980 Docket Hos. 50-528, 50-529, 50-530 Arizona Public Service Company P. 0.
Box 21666
- Phoenix, Arizona 85036 Attention:
Mr. E.
E.
Van Brunt, Jr.
Vice President, iVuclear Projects Gentlemen:
SUBJECT:
IE BULLETIN HO. 80-19, REVISION 1 - FAILURES OF MERCURY-METTED MATRIX RELAYS IH REACTOR PROTECTIVE SYSTEMS OF OPERATI'lG NUCLEAR
,POI(lER PLANTS DESIGNED BY COMBUSTION ENGINEERIIVG Enclosed is Revision 1 to IE Bulletin I'lo. 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 HRC in evaluating the valve/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 revised Bulletin or actions required by you, please contact this office.
Sincerely, R
,H.
cg elken Director
Enclosures:
1.
IE Bulletin Ho. 80-19 Revision 1
2.
List of Recently Issued IE Bulletins cc w/enclosures:
F.
M. Hartley, APS
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UHITED STATES NUCLEAR REGULATORY COMMISS ION OFFICE OF IHSPECTION AND ENFORCEMENT WASHINGTON, D.C.
20555 August ]5, 1980 SSINS No.: 6820 Accession No.:
8006190052 IE Bulletin Ho. 80-19 Revision 1
FAILURES OF MERCURY-WETTED MATRIX RELAYS IN REACTOR PROTECTIVE SYSTEMS OF OPERATING NUCLEAR POWER PLANTS DESIGNED BY COMBUSTION ENGINEERIHG 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 RPS.
Mercury-wetted matrix relays manufactured by the Adams and Westlake Company were initially used in the Palisades plant; however, because of repeated fai lures 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 AHD 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 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 ther re 8y ai ure estimates include (1) WASH-1400, "Reactor Safety Study",
HRC, 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, Hew York; and (3)
HUREG/
CR-0942, "Nuclear Plant Reliability Data System, 1978 Annual Reports of Cumulative System and Component Reliability", NRC.
I l
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IE Bulletin No. 80-19, Revision 1
August 15, 1980 Page 2 of 2 multiple ailures 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 whi'ch, in turn, could result in antici-pated transients without scram (ATWS).
- Thus, the relatively high random failure rate and the suggested corrmon-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 HG2X-1011 mercury-wetted relays are used in the logic matrix of the RPS.
If no such relays are used, you should submit a negative declaration to this effect and you need not resoond to the remaining items in this bulletin.
Your negative declaration shall be submitted to the appropriate NRC r gional office within thirty (30) days of the date of this bulletin and a copy forwarded to the Director, Division of Reactor Operations Inspection, Office of Inspection and Enforcement,,
NRC, Washington, 0,
C.
20555.
Rl Rl 2.
Licensees of operating facilities using 'the above relays in the logic matrix of the RPS should increase the frequency of their surveillance tests.
Until further notice, or until the mercury-wetted relays have been replaced with qualified relays of a different design, 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 Rl of the RPS is required by the Technical Specification.
Upon detecting a
R1 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 R1 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.
Responses to this item shall be submitted to the of ices listed in Item 1, above, within ninety (90) days of the date of the original version of.his bulletin, July 30, 1980.
R1 Approved by GAO, B180225 (R0072); clearance expires July 31, 1980.
(Application for renewal pending before GAO.)
Approval was given under a blanket clearance specifically for identified generic problems.
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IE Bulletin No. 80-19, Revision 1
August 1$
1980 RECENTLY ISSUED IE BULLETINS Encl osure Bul 1 etin No.
80-20 Subject Failures of Westinghouse Type M-2 Spring Return to Neutral Control Switches 7/31/80 To each nuclear power facility in your region having an OL or a CP Date Issued Issued To 80-19 80-18 Supplement 2
to 80-17 Supplement 1
to 80-17 80-17 Failures of Mercury-Metted Matrix Relays in Reactor Protective Systems of Ooerating Nuclear Power Plants Designed by Combus-tion Engineering Haintenance of Adequate Minimum Flow Thru Centrifugal Charging Pumps Following Secondary Side High Energy Line Ruoture Failures Revealed by Testing Subsequent to Failure of Control Rods to Insert During a Scram at a
BMR Failure of Control Rods to Insert During a Scram at a
BMR Failure of Control Rods to Insert During a Scram at'a BMR 7/31/80 7/24/80 7/22/80 7/18/80 7/3/80 All nuclear power
".acilities having either an OL or a CP All PMR power reactor aci lities holding OLs and to those PMRs nearing licensing A'il BMR power reactor facilities holding OLs All BWR power reactor facilities holding OLs All BMR power reactor facilities holding OLs 80-16 Potential t1i sappl ication of 6/27/80 Rosemount Inc., Models 1151 and 1152 Pressure Transmitters with Either "A" or "D" Output Codes All Power Reactor Facilities with an OLor a CP 80-15 80-14 Possible Loss Of Hotline With Loss Of Off-Site Power Degradation of Scram Discharge Volume Capability 6/18/80 6/12/80 All nuclear acilities holding OLs All BWR's with an OL
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