United States Nuclear Regulatory Commission - Protecting People and the Environment

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. 
     
Page Last Reviewed/Updated Tuesday, July 23, 2013