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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