United States Nuclear Regulatory Commission - Protecting People and the Environment

Information Notice No. 82-02: Westinghouse NBFD Relay Failures in Reactor Protection Systems at Certain Nuclear Power Plants

                                                            SSINS:  6835 
                                                            Accession No.: 
                                                            8107230046 
                                                            IN 82-02 

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

                              January 27, 1982

Information Notice No. 82-02:  WESTINGHOUSE NBFD RELAY FAILURES IN 
                                  REACTOR PROTECTION SYSTEMS AT CERTAIN 
                                  NUCLEAR POWER PLANTS 

Discussion: 

Westinghouse has notified the NRC of a higher-than-expected failure rate of 
Westinghouse type NBFD relay coils in reactor protection systems at certain 
power reactor plants.  Investigation into the cause for failure revealed 
that, at high ambient temperature conditions, relay coils could fail due to 
the inductive voltage spike generated by the deenergization of the relay 
coil.  It was also determined that the relay coil failures have been 
confined to normally energized relays used in the reactor protection systems 
where high ambient temperature conditions exist due to heat generated by the 
normally energized relays. 

To date, no failures of NBFD relay coils have been reported in safeguard 
cabinets where these relays are normally in a deenergized state and 
temperature conditions are normal. 

After reviewing the NBFD relay problem, Westinghouse issued technical 
bulletin NSD-TB-81-14 on December 7, 1981 to Westinghouse-designed power 
plants using BFD or NBFD relays in the reactor protection and safeguard 
systems.  An extract of this bulletin is attached for your information and 
appropriate use. The bulletin provides interim test methods for verifying 
the operability of normally deenergized and energized NBFD relay 
applications and recommends replacement of NBFD relays manufactured prior to 
January 1, 1981.  The bulletin also provides relay coil numbers as well as 
data codes to facilitate affected licensees' replacement efforts if 
required. 

This information notice is provided as an early notification of a 
potentially significant matter.  It is expected that recipients will review 
the information for applicability to their facilities.  No specific action 
or response is required at this time.  If you have any questions regarding 
this matter, please contact the Regional Administrator of the appropriate 
NRC Regional Office. 

Attachments:
1.  Extract of Westinghouse technical bulletin NSD-TB-81-14, dated 12/7/81
2.  Recently issued IE Information Notices

Page Last Reviewed/Updated Tuesday, November 12, 2013