United States Nuclear Regulatory Commission - Protecting People and the Environment

IE Circular No. 79-20 - Failure of GTE Sylvania Relay, Type PM Bulletin 7305, Catalog 5U12-11-AC with a 120V AC Coil



CR79020 
                                                            SSINS No.  6830 
                                                            ACC 7908220118 

                            September 21, 1979 

MEMORANDUM FOR:     B. H. Grier, Director, Region I 
                    J. P. O'Reilly, Director, Region II 
                    J. G. Keppler, Director, Region III 
                    K. V. Seyfrit, Director, Region IV 
                    R. H. Engelken, Director, Region V 

FROM:               Norman C. Moseley, Director, Division of Reactor 
                      Operations Inspection, IE 

SUBJECT:            IE CIRCULAR NO. 79-20 - FAILURE OF GTE SYLVANIA RELAY, 
                    TYPE PM BULLETIN 7305, CATALOG 5U12-11-AC WITH A 120V AC
                    COIL 

The subject Circular is transmitted for issuance on September 24, 1979. The 
Circular should be issued to all power reactor operating facilities and all 
utilities having a construction permit. 

The text of the Circular and draft letter to the licensees and permit 
holders are enclosed for this purpose. 


                                   Norman C. Moseley, Director 
                                   Division of Reactor Operations 
                                     Inspection 
                                   Office of Inspection and Enforcement 

Enclosure:
1.   Draft Transmittal Letter 
2.   IE Circular No. 79-20 

CONTACT:  V. D. Thomas, IE 
          49-28180 
.

(Draft transmittal letter for IE Circular No. 79-20, to each holder of an 
Operating License or a Construction Permit.)  

                                                     IE Circular No. 79-20 

Addressee: 

The enclosed IE Circular No. 79-20 , is forwarded to you for information. No
written response is required. Should you have any questions related to your 
understanding of this matter, please contact this office. 

                                        Sincerely, 


                                        Signature 
                                        (Regional Director) 

Enclosures:
1.   IE Circular No. 79-20 
2.   List of IE Circulars Issued
       in the Last 6 Months
.

                             UNITED STATES 
                      NUCLEAR REGULATORY COMMISSION 
                   OFFICE OF INSPECTION AND ENFORCEMENT 
                          WASHINGTON, D. C. 20555 
                                     
                            September 24, 1979 

                                                     IE Circular No. 79-20 

FAILURE OF GTE SYLVANIA RELAY, TYPE PM BULLETIN 7305, CATALOG 5U12-11-AC 
WITH A 120V AC COIL 

Description of Circumstances: 

During inspection of relays in the Engineered Safeguards Actuation System at
Metropolitan Edison Three Mile Island Nuclear Station Unit #1, relay 
62X2B/RC1A failed to drop out when the coil was deenergized. The failed 
relay would not prevent component starting but would have reduced the 2 of 3
coincidence logic to 2 of 2, affecting Decay Heat Closed Cooling Pump A and 
Nuclear Services Closed Cooling Pump A or B. The cause for failure was 
attributed to a notch in the armature operating rod. The notch occurs where 
the rod vibrates against the magnet assembly due to coil hum. A review of 
the history of this component indicates that similar relays failed during 
1977 through 1979 at least one of which was attributed to notching. An 
inspection of forty-eight (48) relays by this licensee indicated that 
twenty-five (25) of the relays had detectable notches ranging from 0.001 to 
0.003 inches deep. 

Recommended Actions for Licensees' Consideration: 

1.   Ensure that all GTE Sylvania Relays Type PM Bulletin 7305, with a 120V 
     AC Coil used in or affecting the operation of safety-related equipment 
     are examined to ensure that the armature operating rod is not notched 
     and is operating freely. 

2.   Relays found with detectable notches on the operating rod should be 
     corrected. If correction cannot be accomplished then administrative 
     controls should be initiated to assure demonstrated operation until the
     relay condition is corrected. 

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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