IE Circular 76-02 - Relay Failures - Westinghouse BF (ac) and BFD (dc) Relays

 

CR76002 

                      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) 
RELAYS 

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 
                                          Enforcement 

Enclosures: 
1.   Circular 76-02 
2.   Transmittal letter
.

                                 - 2 - 

(Transmittal letter for circular 76-02 to each holder of Construction Permit
or Operating License.) 

Addressee: 

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. 







Enclosure: 
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 
     position. 
.

                                 - 2 - 

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) 

ATTACHMENT: 
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. 

RECOMMENDED ACTION 

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.