IE Circular 76-02 - Relay Failures - Westinghouse BF (ac) and BFD (dc) Relays
NUCLEAR REGULATORY COMMISSION
OFFICE OF INSPECTION AND ENFORCEMENT
WASHINGTON, D. C. 20555
AUG 16 1976
J. P. O'Reilly, Director, Region I
N. C. Moseley, Director, Region II
J. G. Keppler, Director, Region III
E. M. Howard, Director, Region IV
R. H. Engelken, Director, Region V
IE CIRCULAR 76-02 - RELAY FAILURES - WESTINGHOUSE BF (ac) AND BFD (dc)
The subject document is transmitted for issuance by close of business August
18, 1976. The Circular should be issued to all holders of power reactor
operating licenses and construction permits. Also enclosed is a draft copy
of the transmittal letter.
Dudley Thompson, Acting Director
Division of Field Operations
Office of Inspection and
1. Circular 76-02
2. Transmittal letter
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(Transmittal letter for circular 76-02 to each holder of Construction Permit
or Operating License.)
The enclosed Circular, 76-02 is forwarded to you for information and action.
This is the second issue of an expanded system for communication from the
Office of Inspection and Enforcement to applicants and licensees, to
supplement the issuance of IE Bulletins.
Bulletins have been, and will continue to be, limited to subjects considered
to be of appropriate significance to require prompt response. Circulars will
cover subjects of lesser significance, immediacy or for which a longer
response time appears appropriate. Future IE Circulars may be addressed to
any class of NRC licensees, and may or may not require response.
IE Circular 76-02
August 18, 1976
IE Circular No. 76-02
RELAY FAILURES-WESTINGHOUSE BF (ac) AND BFD (dc) RELAYS
DESCRIPTION OF CIRCUMSTANCES:
During testing of Westinghouse BFD relays, the Point Beach nuclear power
plant experienced malfunctions with two relays in the reactor trip system.
The malfunctions were caused by the pin that connects the plunger to the
operating bead rubbing against the contact block. Although the coils were
fully energized the relay contacts remained in the deenergized position. A
similar malfunction occurred in one of a set of relays undergoing
accelerated aging tests at the Westinghouse Beaver facility.
The malfunction relating to pin misalignment may be common to both BF (ac)
and BFD (dc) relays. Portions of a Westinghouse service letter containing
information about these relays are attached to this circular. Further
instructions regarding this relay problem can be obtained from Westinghouse
Nuclear Service Division, Pittsuburgh, Pennsylvania 15230.
ACTION TO BE TAKEN BY LICENSEES AND PERMIT HOLDERS:
The following actions should be taken with respect to all Westinghouse BF
(ac) and BFD (dc) relays in safety related systems:
1. Describe the action taken or that you plan to take to verify that
normally energized relays in safety related systems are in fact
operable and that the relay contacts are in the energized position.
2. Describe the action taken or that you plan to take to verify that
normally deenergized relays in safety related systems operate properly
when energized and that the relay contacts are in the energized
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Reports for facilities with operating licenses should be submitted within 60
days after receipt of this circular, and reports for facilities with
construction permits should be submitted within 90 days after receipt of
this circular. Your report should include the date when the above actions
were or will be completed.
Reports should be submitted to the Director of the NRC Regional Office and a
copy should be forwarded to the NRC Office of Inspection and Enforcement,
Division of Reactor Inspection Programs, Washington, D. C. 20555.
Approval of NRC requirements for reports concerning possible generic
problems has been obtained under 44 U.S.C 3152 from the U. S. General
Accounting Office. (GAO Approval B-180255 (R0072), expires 7/31/77)
Extract from Westinghouse Service Letter:
BF (ac) AND BFD (dc) RELAYS
EXTRACT FROM WESTINGHOUSE SERVICE LETTER:
BF & BFD RELAYS
During the testing of certain Westinghouse BFD relays at an operating
nuclear power plant, two relays in the reactor trip system were found to
have malfunctions. Although the coils were fully energized, the relay
contacts remained in the deenergized position. It was determined that, in
both cases, the pin that connects the plunger to the operating head was
rubbing against the contact block. This rubbing action resulted in friction
that impeded the plunger movement when the relay coil was energized thereby
preventing contact movement. The malfunctioning relays were immediately
replaced. When dissassembled it was found that the relays would operate
normally when the pin was centered in the plunger.
Coincidently, Westinghouse (Beaver) the relay manufacturer, experienced a
similar malfunction in one of a set of similar relays which are currently
undergoing accelerated aging tests.
Westinghouse (Beaver) and Westinghouse (NES) are currently investigating
this situation in detail as it applies to both BF (ac) and BFD (dc) models.
Consideration is being given to various means by which the pin could be held
captive, thereby precluding further pin misalignment, if such a course of
action becomes necessary.
Visually inspect normally energized relays to verify that such relays are in
fact picked up. Observe the performance of normally deenergized relays
during normal periodic testing.
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