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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