ML20127P562
| ML20127P562 | |
| Person / Time | |
|---|---|
| Site: | Monticello, Prairie Island  |
| Issue date: | 08/02/1974 |
| From: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Wachter L NORTHERN STATES POWER CO. |
| References | |
| IEB-74-04, IEB-74-4, NUDOCS 9212020253 | |
| Download: ML20127P562 (3) | |
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UNITED CTATED ATOMIC ENER3Y COMMl;':lON i
i.i DIRECTORATE OF CEOULATORY OPERf;TIONO o
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/I' Northern Statse Power Company Docket No. 50-263 ATTN Mr. Leo Wachter, Vica President Docket No.
Power Production and System Docket No. 50-306 Operation 414 Nicollet Hall Minnaapolis, Minnesota 55401 Centlement The enclosed DRO Bulletin No. 74-8, " Deficiency in ITE Holded Case Circuit Breakers, Type HE-3," is sent to provide you with information reported by Portland Canaral Electric Coetpany as a deficiancy identified at the Trojan reactor facility.
This information may have applicability at your facilities. Action requested on your part is identified in Section B of the enclosed Bulletin.
Sincerely, James 0. Esppler Regional Director Enclosures DRO Bulletin No. 74-8 bec DR Central Files RO Files PDR Local PDR OGC, Beth, P-506A Anthony Roisman 4
9212O20253 740802 PDR ADOCK 05000263 G
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- 's it fm August 2, 1974 DRO Bulletin No. 74-8 DEFICIENCY IN THE ITE MOLDED CASE CIRCUIT BREAKERS, TYPE HE-3 We recently received information_from the Portland General Electric Company describing a deficiency of the magnetic trip elements in ITE Type HE-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 curves for these breakers.
Portland General Electric Company stated that (1) the excessively high pickup points of the instantaneous trip elements could lead to undetected cable damage due to overheating under certain f ault 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 HE-D breakers delivered to Trojan with new, modified HE-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 HE-3 breakers dated May 1974 and later will have the new magnetic structure.
Further, ITE will perform 100% inspection on all replacement 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 setting 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 requirements.
'It should be noted that normal production testing would not be expected to reveal this problem. Portland General Electric has been advised that this particular breaker model has been manufactured by ITE since 1968/1969.
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Action Requested
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It is requested that you notify the R0 Regional Office in writing, within 20 dayst (1) whether or not similar circumstances or the potential for similar circumstances described above exist at your facilty for Class IE equipment', cg; (2) the date(s) when action to determine whether a similar circumstance exists will be completed.
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 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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