ML20082P172
| ML20082P172 | |
| Person / Time | |
|---|---|
| Site: | Catawba  |
| Issue date: | 10/31/1983 |
| From: | Tucker H DUKE POWER CO. |
| To: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| REF-PT21-83, REF-PT21-83-089-000 PT21-83-089-000, PT21-83-89, NUDOCS 8312080119 | |
| Download: ML20082P172 (3) | |
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DUKE POWER GOMPMY P.O. BOX 33180 CHARLOTTE, N.C. 28242 HAL B. "It'CKER TELEPHONE Ngyfg (704)373 453 Octo6er31,1983 2*gg Mr. James P. O'Reilly, Regional Administrator U. S. Nuclear Regulatory Commission Region II 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30303 Re: Catawba Nuclear Station Units 1 and 2 Docket Nos. 50-413 and 50-414
Dear Mr. O'Reilly:
Pursuant to 10 CFR 21, please find attached Significant Deficiency Report SD 413-414/83-15.
Very truly yours, 1
$8./% L gj a
j Hal B. Tucker LTP/php Attachment cc: Director INP0 Records Center Office of Inspection and Enforcement Suite 1500 U. S. Nuclear Regulatory Commission 1100 Circle 75 Parkway 4
Washington, D. C. 20555 Atlanta, Georgia 30339 NRC Resident Inspector Mr. Robert Guild, Esq.
Catawba Nuclear Station Attorney-at-Law P. O. Box 12097 Palmetto Alliance Charleston, South Carolina 29412 21351 Devine Street i
Columbia, South Carolina 29205 i
8312000119 831031 PDR ADOCK 05000413 S
PDR 1
GFFICIAL COPY [
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JP0/HBT/LTP October 31, 1983 Catawba Nuclear Station Report #: SD 413-414/83-15 r
Report Date: October 31, 1983 i
Facility:
Catawba Nuclear Station - Units 1 & 2 Identification of Deficiency:
Westinghouse has reported to us that their SA1 differential relays contain tantalum capacitors that are subject to electrolyte leakage. Also reported to us is a possibility that some sal's may contain defective SCR's. These problems were brought tc our attention through letters dated September 12 and October 5 describing the potential problems with an SA1 bought for McGuire.
Subsequent conversations with Westinghouse have confirmed that the potential problems are generic in nature and therefore could exist on Catawba relays also.
Initial Report:
On October 24, 1983, Mr. Greg Nejfelt of the NRC Region II office was contacted and notified of tnis item by L. M. Coggins, M. L. Childers, T. L. Utterback, and E. M. Brinson (all of Duke Power Co., 422 S. Church Street, Charlotte, NC 28242).
Component and/or Supplier:
This deficiency pertains to Westinghouse type SA1 differential relays.
Description of Deficiency:
Westinghouse has discovered that given tantalum capacitors used internal to their SA1 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 SA1 relays which contain SCR's manuiactured by ST Semicon are subject to false tripping. Note that due to manufacturing dates, it is not believed that the relays at Catawba contain this SCR.
At Catawba, the SA1 relay is used to protect the Class 1E 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 SA1 produces a trip output, the affected diesel generator's main circuit breaker will trip. A shutdown of the engine and generator will also occur.
Analysis of Safety Implications:
If a situation were to occur at Catawba in which all offsite power was lost,-
the two Class IE diesel generators per unit (Train A and Train B) would provide the required on-site AC power.
In the event that a false trip of an SA1 were
Pega Two JP0/HBT/LTP October 31,1983 r
to take place during the above event, one of the on-site AC sources would be lost until it could be determined that a false trip had occurred.
In order to restore power to the affected train, the lockout relay tripped by the SA1 would have to first be reset. The affected diesel generator would then have to be restarted and loaded.
In the situation described above, there would be no effect on the health and safety of the public. The AC power needed to shut down the plant would be provided by the unaffected diesel generator.
Duke Power has employed the Westinghouse SA1 relays in various applications for years (since 1960's) both for IE and non Class IE service. No false trips of these relays have ever been reported attributable to either capacitor leakage or SCR failures. Furthermore, all these relays on the Duke system are inspected and tested on a regular basis (12-24 month cycle depending 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.
Corrective Action Westinghouse intends to make available to us new replacement capacitors that are hermetically sealed as well as new SCR's, if required.
It is our intention to remove the SA1 relays from service, replace the capacitors, inspect the SCR and replace if necessary, before August 1,1984. Design Engir.aering will arrange shipment of parts and Transmission Department will be responsible for installation and checkout.
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