ML19209A847
| ML19209A847 | |
| Person / Time | |
|---|---|
| Site: | Big Rock Point, Palisades File:Consumers Energy icon.png |
| Issue date: | 08/14/1979 |
| From: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Dewitt R CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| References | |
| NUDOCS 7910050476 | |
| Download: ML19209A847 (1) | |
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UNITED STATES l" A
'o't NUCLEAR REGULATORY COMMISSION nE REGION lli o,
[
799 ROOSEVELT ROAD
- g' GLEN ELLYN,ILLINOls 60137 AUG141979 Docket No. 50-155 Docket No. 50-255 Consumers Power Company ATTN:
Mr. R. B. DeWitt Manager of Nuclear Plant Operations 212 West Michigan Avenue Jackson, MI 49201 Gentlemen:
This Circular No. 79-17 is provided as an early notification of a possible significant matter.
It is expected that recipients will review the information for possible applicability to their facilities. No specific action or response is requested at this time.
If further NRC evaluations so indicate, an IE Bulletin will be issued to recommend or request specific licensee actions.
If you have questions regarding this matter, please contact the Director of the appropriate NRC Pegional Office.
Sincerely, Yh 0 hamesG.Keppler u Director
Enclosures:
1.
IE Circular No. 79-17 2.
List of IE Circulars Issued in the Last 6 Months cc w/ encl:
Mr. C. J. Hartman, Local PDR Plant Superintendent NSIC t:r. J. G. Lewis, Plant TIC Superintendent Ronald Callen, Michigan Public Central Files Service Commission Director, NRR/DPM Anthony Roisman, Esq.,
Director, NRR/ DOR Attorney PDR Myron M. Cherry, Chicago 1127 140 7910050 h76 P
s 3
Accession No:
7908090272 SSINS:
6830 UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C.
20555 August 14, 1979 IE Circular No. 79-17 CONTACT PROBLEM IN SB-12 SWITCHES ON GENERAL ELECTRIC METALCLAD CIRCUIT BREAKERS The General Electric Company, Switchgear Department in Philadelphia, reported to the NRC on July 3, 1979, an intermittent contact problem in SB-12 switches.
This intermittent contact problem will cause a lack of continuity through the "a" contact of the switch that is used to energize the trip coil of the circuit breaker.
Investigation disclosed that a die used to form a hole in the contact arms of the switch had worn, resulting in elongated holes. This condition could permit the contact bridge member to move laterally relative to the contact arm, occasionally resulting in improper "a" contact wipe.
The worn die has been corrected, and all switches shipped on or after July 1,1979, include this correction. A review of the history of these components indicates that switches shipped in the time period of August 1,1978 to July 1,1979, could have this problem. The trip coil and auxiliary switch portion of the trip circuit is monitored for continuity by a red light on the front door of the switchgear.
This light is lit when the breaker is closed and the control circuits are energized.
If the red light is lit, this indicates that the "a" contacts of the switch are closed, and that a trip signal will trip the breaker.
Based on the above, the licensees are advised to do the following:
1.
Insure that all General Electric Company Metalclad Circuit Breakers shipped to your facilities during the period from August 1,1978 to July 1,1979 and used in or affecting the operation of safety related equipment are furnished with new SB-12 control switches as promptly as possible.
2.
Pending replacement of SB-12 control switches administrative controls should be initated to assure the red light which demonstrates contact continuity, is lit and remains lit each time these circuit breakers are closed.
No written response to this circular is required.
If you require additional information regarding this subject, contact the Director of the appropriate NRC Regional Office.
DUPLICATE DOCUMENT Entire document previously entered into system unde ANO 1127 14I 1
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