ML19329E827
| ML19329E827 | |
| Person / Time | |
|---|---|
| Site: | Midland |
| Issue date: | 08/02/1974 |
| From: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Howell S CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| References | |
| NUDOCS 8006180613 | |
| Download: ML19329E827 (1) | |
Text
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UNITED STATES 3
ATOMIC ENERGY COMMISSION
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DIRECTORATE OF REGULATORY OPERATIONS
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REGION Ill
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799 ROOSEVELT ROAD GLEN ELLYN. ILLINOIS 60137 012) 854-2s60 AUG 2 1974 s%
Consumers Power Company Docket No. 50-329/
ATTN:
Mr. Stephen H. Howell Docket No. $5~.T50 V!ce President 1945 West Parnall Road Jaeh
, Michigan 49201 Gentlemen:
The enclosed DRO Bulletin No. 74-8, " Deficiency in ITE Molded Case Circuit Braakars, Type HE-3 " is sent to provida you with information reported by Portland General Electric Company as a deficiency identified at tha Trojan reactor facility.
This infornation may have applicability at your facilities. Action requested on your part is identified in Section B of the enclosed Bu11stin.
Sincerely, James G. Keppler Regional Director
Enclosure:
DRO Bulletin No. 74-8 bec: DR Central Files R0 Files PDR Local PDR OGC, Beth, P-506A Ronald Callen n
5.waynez. North THis DOCUMENT CONTAINS Myron M. Cherry POORQUAUTYPAGES j
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August 2, 1974
.,b ' A DRO Bulletin No. 74-8 DEFICIENCY IN THE ITE MOLDED CASE CIRCUIT BREAKERS, TYPE E-3 We recently received information from the Portland General Electric Company describing a deficiency of the magnetic trip elements in ITE Type E -3 molded case circuit breakers, current rating of 20-90 amperes, that was discovered during preoperational testing at the Trojan nuclear power plant. This model circuit breaker could be used in any nuclear power plant.
A.
Description of Circumstances The pickup points for the magnetic (instantaneous) trip elements are substantially higher than the published ITE time-current 3
> curves'for these breakers.
Portland General Electric Company stated that (1) the excessively high pickup points of the instanteneous trip elements could lead to undetected cable damage due to overheating under certain fault conditions and (2) trip coordination of these breakers with the upstream load center breakers may also be adversely affected.
Therefore, ITE is replacing all of the Type E-3 breakers delivered to Trojan with new, modified E-3 breakers. The modified breakers utilize a different magnetic structure which ITE released for production on similar breakers (150A Frame) two years ago.
ITE stated that all E-3 breakers dated May 1974 and later will have the new magnetic structure.
l Further, ITE will perform 100% inspection on all replacement
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breakers to ensure that required time-current trip range limits are met when tested one pole at a time. The 20A through 40A and the SOA through 90A breakers will be tested to meet the fixed instantaneous trip se,tting shown on the manufacturers appropriate time-current characteristic curve. Breakers which successfully pass these trip range limits will satisfy the cable protection and breaker coordination i
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requirements.
It should be noted that normal production testing would not be expected to reveal this problem. Portland General Electric has be.en advised that this particular breaker model bas been manufactured
-by ITE since 1968/1969.
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Action Requested
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-J It is requested that you notify the RO Regional Office in writing, within 20 days:
(1) whether or not similar circumstances or the potential for similar circumstances described above exist at your facilty for Class IE equipment, or_ (2) the date(s) when action to determine whether a similar circumstance exists will be completed.
' ' ' t, If the findings as a result of the action above indicate that similar circumstances exist, the specific findings together with the description of the corrective action taken or planned, including
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the scheduled completion date of the planned corrective action should be submitted to this office within 20 days of the findings.
If there are no such units at your facility, a negative report is requested.
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