ML20081M712

Forwards LERs 83-101/01T-0 & 83-064/99T-0

ML20081M712
Person / Time
Site:	McGuire, Mcguire
Issue date:	11/07/1983
From:	Tucker H DUKE POWER CO.
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML20081M713	List: ML20081M712 ML20081M753
References
NUDOCS 8311170345
Download: ML20081M712 (3)

Text

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1 DUKE POWER GOMPANY P.O. ISOX 33189

- CifARLOTTE, N.C. 28242 IIALH. TUCKER 1 . r) 9 retzenome vm .. em e Lb- (704) 373-4538 m m. ,-m g3 N0gl {&\ b.. vember 7, 1983 f

.Mr. James P. O'Reilly, Regional Administrator U. 5. Nuclear Ragulatory Commission Region II j 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30303 )

Subject:

.McGuire Nuclear Station Units 1 and 2 Docket Nos. 50-369 and 50-370 LER/RO-369/83-101 and 370/83-64

Dear Mr.'O'Reilly:

. Please find attached Reportable Occurrence Reports R0-369/83-101 (Unit 1) and 370/83-64 (Unit 2). These reports concern a potential problem with Westinghouse sal differential relays which is reportable per Technical Specification 6.9.1.10(e),

" Failure or malfunction of one or more components which prevents or could prevent, by itself, the fulfillment of the functional requirements of systems used to cope with accidents analyzed in the SAR". This situation was considered to be of no significance with respect to the health and safety of the public.

Very truly yours,

5. W //h/

Hal B. Tucker WHM/php Attachment cc: Document. Control Desk U. S. Nuclear Regulatory Commission Washington, D. C. 20555 INPO Records Center Suite 1500 1100 Circle 75 Parkway Atlanta, Georgia 30339 Mr. W. T. Orders

'NRC Resident Inspector McGuire Nuclear Station B311170345 831107 DR ADOCK 05000 , g ,egi L7_. -

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. JP0/HBT/WHM Novzmbsr 7, 1983 Duke Power Company g McGuire Nuclear Station

-Reportable Occurrence Report Nos. 369/83-101 and 370/83-64

, Report Date: -November 7, 1983 Facility: McGuire Units 1 and'2,~Cornelius, North Carolina Identification: : Potential Problem with Westinghouse SA1 Differential Relays

Description:

_ Duke Power was notified of a potential problem with Westinghouse sal differential relays containing tantalum capacitors .that are subject to electrolyte leakage. Also reported was a possibility that some SA1 relays may contain defective silicon controlled rectifiers.. These problems were brought

'to Duke Power's attention through letters from Westinghouse dated September 12 and October 5 describing the potential problems with one sal relay at McGuire.

Subsequent' conversations with. Westinghouse confirmed that the potential problems are generic in nature and therefore could exist on all of the McGuire sal relays.

Evaluation: _ W estinghouse has discovered that given tantalum capacitors used internal to their sal relays are subject to electrolyte leakage which could cause component corrosion, possible capacitor failure, and possible false trip output on the relay itself.

Westinghouse has also noted that sal relays which contain silicon controlled rectifiers (SCR) manufactured by ST Semicon are subject to false tripping. Note that due:to manufacturing. dates, it is believed that only one of the relays at McGuire contains this SCR.'

At McGuire, the SA1 relay is used to protect the Class lE diesel generators (emergency AC on-site _ power sources) against short circuits. Each of_the four diesel generators is protected by its own respective relay. If a given sal relay produces a trip output, the affected diesel generator's main circuit 1breake'r will trip. A shutdown of the engine and generator will also occur.

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' Corrective Action: Westinghouse intends to make available to Duke Power Company replacement capacitors that are hermetically sealed as well as new silicon controlled rectifiers, if required. McGuire Nuclear Station will remove the sal' relays from service, replace the capacitors, inspect the -SCR, and replace it if-necessary, bi August 1,1984.

' Safety Analysis:. If a situation were to occur at McGuire Nuclear Station in which all off-site power was lost, the two Class lE diesel generators per unit (Train A and Train B) would provide the required on-site AC power. In the event thatra false trip of an sal relay were to take place during the above event, one of the on-site AC sources would be lost. In order to restore power.to the affected train, the lockout relay tripped by the sal relay would have to first be reset._ The affected diesel generator would then have to be restarted and loaded.

-8 v..,

JPO/HBT/WHM November 8, 1983

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In this described. situation, there would be no effect on the health and safety of theLpublic. ?The AC. power needed to shut down the unit would be provided

'by the unaffected diesel generator.

Duke Power has employed the Westinghouse sal relays _in various applications-both for Class IE and non-Class lE service. No-false trips of these relays have ever been reported attributable to either capacitor leakage or silicon controlled rectifier failures. 'Furthermore, allsof these relays on the Duke system are-inspected and tested on a regular basis (12-24 month cycle depending

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upon location). No capacitor electrolyte leakage has ever been observed. The probability of a false ~ trip due to the deficiencies described in this report is, therefore, judged extremely remote. Thus, continued operation of McGuire

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is justified until corrective action is taken.

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