United States Nuclear Regulatory Commission - Protecting People and the Environment

Information Notice No. 85-93: Westinghouse Type DS Circuit Breakers, Potential Failure of Electric Closing Feature Because of Broken Spring Release Latch Lever

                                                          SSINS No.  6835 
                                                            IN 85-93 

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

                              December 6, 1985

Information Notice No. 85-93:   WESTINGHOUSE TYPE DS CIRCUIT BREAKERS, 
                                   POTENTIAL FAILURE OF ELECTRIC CLOSING 
                                   FEATURE BECAUSE OF BROKEN SPRING RELEASE 
                                   LATCH LEVER 

Addressees: 

All nuclear Power reactor facilities holding an operating license (OL) or a 
construction permit (CP). 

Purpose: 

This information notice is to alert licensees that the electric circuit 
breaker closing function of Westinghouse Type DS circuit breakers could 
possibly malfunction because of a broken spring release latch lever. It is 
expected that licensees will review the information for applicability to 
their facilities and if the defect exists, consider actions to determine 
safety significance and corrective action. However, suggestions contained in
this information notice do not constitute NRC requirements; therefore, no 
specific action or written response is required. 

Description of Circumstances: 

On April 14, 1985, the Westinghouse Nuclear Services Integration Division 
(NSID) issued Technical Bulletin No. NSID-TB-85-17 advising their customers 
of a potential malfunction in Westinghouse Type DS Class 1E circuit breakers
because of broken spring release latch levers. These electrically operated 
type DS breakers will not close electrically when the spring release latch 
lever has been broken off. Twenty-five broken levers have been reported and 
evaluated. This evaluation shows concentrations of incidents traceable to 
manufacturing in the following periods of time: early 1975, April 1976, and 
early 1978. 

This circuit breaker failure, as discussed, adversely affects the safety 
function (closing on demand) when the circuit breaker is used in the 
Engineered Safety Features Systems. However, this failure mode will not 
affect the safety trip function when it is used in the reactor protection 
system. 

Discussion: 

The April 14, 1985 Technical Bulletin recommends the following corrective 
actions for DS Class 1E circuit breakers: (I) advise the responsible 
personnel that the breaker may be closed manually using the operator on the 
front panel of the breaker cubicle, if electrical closing does not occur on 
demand; (2) for applications other than Westinghouse-designed reactor trip 
(RT) function, the 

8512050072 
.

                                                         IN 85-93 
                                                         December 5, 1985 
                                                         Page 2 of 2 

user should evaluate the situation to determine if this condition could 
affect safety; and (3) inspect the latch lever during normal scheduled 
maintenance/inspection of the DS circuit breaker. 

The DS Class 1E circuit breakers also are used in plants not designed by 
Westinghouse. Some of these facilities may not have received Technical 
Bulletin No. NSID-TB-85-17, therefore, it is suggested that these facilities
contact Westinghouse NSID to obtain additional information on performing the
inspections and corrective action. 

No specific action or written response is required by this notice. If you 
have any questions regarding this notice, please contact the Regional 
Administrator of the appropriate NRC regional office or this office. 


                                   Edward L. Jordan, Director 
                                   Division of Emergency Preparedness 
                                     and Engineering Response 
                                   Office of Inspection and Enforcement 

Technical Contact:  L. B. Parker, IE 
                    (301) 492-7190 

Attachment:    List of Recently Issued IE Information Notices 
Page Last Reviewed/Updated Tuesday, November 12, 2013