ML19209A831
| ML19209A831 | |
| Person / Time | |
|---|---|
| Site: | Dresden, Byron, Braidwood, Quad Cities, Zion, LaSalle  |
| Issue date: | 08/14/1979 |
| From: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Brian Lee COMMONWEALTH EDISON CO. |
| References | |
| NUDOCS 7910050455 | |
| Download: ML19209A831 (1) | |
Text
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[panrop jo UNITED STATES g
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NUCLEAR REGULATORY COMMISSION
- g., g '(j gr REGION ill S
799 ROOSEVELT ROAD
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Docket Nos. 50-10, 50-237, 50-249, AUG 141979 50-254, 50-265, 50-295, 50-304, 50-373, 50-374, 50-454, 50-455, 50-456 and 50-457 Commonwealth Edison Company ATTN:
Mr. Byron Lee, Jr.
Vice President Post Office Box 767 Chicago, IL 60690 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 inforination 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 Regional Office.
Sincerely, 0$
/
f ames G. Kepplef Director
Enclosures:
1.
IE Circular No. 79-17 2.
List of IE Circulars Issued in the Last 6 Months cc w/ encl:
Mr. B. B. Stephenson, Mr. R. Cosaro, Project Station Superintendent Superintendent Mr. N. Kalivianakis, Central Files Station Superintendent Director, NRR/DPM Mr. N. Wandke, Station Director, NRR/ DOR Superintendent PDR Mr. L. J. Burke, Site Local PDR Project Superintendent NSIC Mr. T. E. Quaka, Quality TIC Assurance Supervisor Anthony Roisman, Esq.,
Mr. R. H. Holyoak, Station Attorney Superintendent Mr. Dean Hansell, Office Mr. Gunner Sorensen, Site of Assistant Attorney Project Superintendent General 1127 102 W,
79.10050
a Accession No:
7908090272 SSINS:
6830 UNITED STATES HUCLEAR 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.
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