Bulletin 74-008: Deficiency in ITE Molded Case Circuit Breaker, Type HE-3
BL74008
UNITED STATES
ATOMIC ENERGY COMMISSION
WASHINGTON. D.C. 20545
JUL 23 1974
J. P. O'Reilly, Director of Region I
N. C. Moseley, Director of Region II
J. G. Keppler, Director of Region III
E. M. Howard, Director of Region IV
R. H. Engelken, Director of Region V
RO BULLETIN #74-8 DEFICIENCY IN ITE
MOLDED CASE CIRCUIT BREAKER, TYPE HE-3
The enclosed RO Bulletin #74-8 is forwarded for dispatch to all holders of
Construction Permits or Operating Licenses.
Harold D. Thornburg, Chief
Field Support and Enforcement Branch
Directorate of Regulatory Operations
Enclosure:
DRO Bulletin #74-8
cc: D. F. Knuth, RO
P. A. Morris, RO
B. H. Grier, RO
C. W. Kuhlman, RO
G. W. Roy, RO
A. Giambusso, L
F. Schroeder Jr., L
R. C. DeYoung, L
R. S. Brodsky, NR
.
Gentlemen:
The enclosed DRO Bulletin No. 74-8, "Deficiency in ITE Molded Case Circuit
Breakers, Type HE-3, It is sent to provide you with information reported by
Portland General Electric Company as a deficiency 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,
Director
Enclosure:
DRO Bulletin No. 74-8
.
RO Bulletin No. 74-8
DEFICIENCY IN 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 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 HE-3 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 50A 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.
.
B. Action Requested
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
facility for Class IE equipment, or (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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