ML20210B015
| ML20210B015 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley |
| Issue date: | 04/20/1987 |
| From: | Carey J DUQUESNE LIGHT CO. |
| To: | Murley T NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| References | |
| 2NRC-7-087, 2NRC-7-87, 87-06, 87-6, NUDOCS 8705050213 | |
| Download: ML20210B015 (3) | |
Text
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T/95 M
2NRC-7-087 Bene Vall
- o. 2 Unit Project Organization Telecopy 64 Ext.160 P.O. Box 328 April 20, 1987 Shippingport, P A 15077 United States Nuclear Regulatory Commission Region 1 631 Park Avenue King of Prussia, PA 19406 ATTENTION:
Dr. Thomas E. Murley Administr ator
SUBJECT:
Beaver Valley Power Station - Unit No. 2 Docket No. 50-412 Automatic Closing of Brown Boveri/ITE 4KV Category IE Circuit Breakers Potential Significant Deficiency Report 87-06 Gentlemen:
This Potential ly Reportable Significant Deficiency Report is being submitted pursuant to the requirements of 10CFR50.55(e).
It is anticipated that no additional reports will be required.
DUQUESNE LIGHT COMPANY I
By J. J."Larey Sr. Vice President LMR/tjr NRC/l MR/SDR/8706 Attachment AR/NAR cc:
Mr. P. Tam, Pr oject Manager (w/a)
Mr. J. M. Taylor, Director (3) (w/a)
Mr. J. Beall, Sr. Resident inspector (w/a Mr. L. Prividy, NRC Resident inspector (w/a)
INPO Records Center (w/a)
NRC Document Control Desk (w/a) l EPA 888g8e8%
SEs1 Ip vn
ATTACHMENT t
l 1.
Summary With 4KV breaker 4KV*E10 racked onto the bus,125 VDC control power was applied, the springs charged and the breaker immediately closed and opened several times before the control power could be turned off.
Thirty-two (32) Brown Boveri/ITE Category IE 4KV Breakers Type 5HK-350 ITE have the potential _ to experience this same condition.
2.
-Immediate Action Taken Non-conformance and Disposition Report (N&D) 12461 was written to have the l
breaker sent to the vendor, Brown Boveri Company (BBC), to determine the I
cause of the closure.
Mr. L. M. Rabenau, Lead Compliance Engineer, Beaver Valley Power Station Unit No. 2, contacted Mr. Dave Limroth, NRC Region I, of this concern on March 20, 1987.
3.
Description of Deficiency When 125VDC control power was applied to the breaker's control circuit, the closing spring charged and the breaker closed immediately.
It was determined by field testing that the closing coil was not being energized.
Subsequently, the breaker was sent to the vendor for further investiga-tion.
The cause of the breaker closing and opening was attributed to the shock resulting from the end of the closing cycle.
When the closing spring completes its charging cycle, the close latch roller hits against the close latch.
The resulting shock from the latch and associated linkages is such that the latch roller does not latch.
This starts the charging cycle over again.
While breaker 4KV*E10 was at the BBC service division in Monroeville, PA, the vendor identified an April 28, 1983 letter from their Switchgear Sys-tems Division to the NRC concerning the same problem.
This letter was a follow-up to the Philadelphia Electric Company, Limroth plant filing of a 10CFR50.55(e) report. BBC identified this same problem and the subsequent fix.
4.
Analysis of Safety Implication Inadvertant operation of the 4KV Category IE breakers could adversely impact the safe operation of the plant.
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Corrective Action to Resolve the Deficiency l
All of the Brown Boveri/ITE Category IE 4KV breakers Type SHK have been sent to the vendor for the addition of " anti-shock springs".
The " anti-shock springs" are added to the close latch in the circuit breaker opera-ting mechanism.
The addition of this spring forces the clearances in the close latch and associated linkages to be taken up in one direction.
This reduces the shock from the latch and linkages so that when the close latch roller, which is part of the cam assenbly, is driven by the closing springs at the end of the charging cycle hits against the close latch, the latch is held and does not slip.
6.
Additional Report No Additional Reports are expected.
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