United States Nuclear Regulatory Commission - Protecting People and the Environment

Bulletin 74-015: Misapplication of Cutler-Hammer Three Position Maintained Switch Model No. 10250T



BL74015 

                                     12/6/74 
                                     Directorate of Regulatory Operations 
                                     Bulletin  74-15 

MISAPPLICATION OF CUTLER-HAMMER THREE POSITION MAINTAINED SWITCH MODEL NO. 
10250T 

An abnormal occurrence report submitted by the Wisconsin Public Service 
Corporation indicates a potential problem with Cutler-Hammer switches of 
Model No. 10250T which could effect the performance of control systems in 
which they are used. 

Description of Circumstances: 

The emergency diesel generators at Kewaunee Nuclear Power Plant received an 
automatic start signal. One of the diesels failed to start even though the 
local mode switch appeared to be in the "AUTO" position. Investigation by 
the licensee revealed a "dead" area between the "OFF" and "AUTO" positions 
of the Cutler-Hammer three position maintained switch, Model No. 1025OT4023. 
It was determined that the switch could be positioned so that it appeared to 
be in "AUTO" but was actually in a position between "AUTO" and "OFF" such as 
to prevent either automatic starting of the diesel or actuation of the "NOT 
IN AUTO" annunciator. The same switch was installed on each of the two 
General Motors diesel generators supplied to the Kewaunee plant by the 
Western Engine Corporation. 

Investigation by the AEC has revealed the use of Cutler-Hammer Model No. 
1025OT4023 switches in control panels for Fairbanks Morse diesel generators 
at one power reactor facility and in the emergency switching logic for the 
hydro emergency power source at another. 

While this potential problem has been identified with the use of the 
Cutler-Hammer Model No. 1025OT4023 switch, all switches of the basic 
Cutler-Hammer three position maintained Model No. 10250T are subject to 
potential malfunction similar to that described above. 

Action Requested of Licensees: 

Review the use, or planned use in the case of facilities under construction,
of Cutler-Hammer three position maintained switches of basic Model No. 
10250T in safety-related systems of your, power reactor facility(ies), and: 

1.   If such switches are in use, or planned for use, in safety-related 
     systems, notify this office in writing within 30 days of the extent 
.

                                       12/6/74 
                                       Directorate of Regulatory Operations 
                                       Bulletin 74-15 

     of their use and what action you have taken or plan to take to pre- 
     vent malfunction of the type described above. Your written notification
     should include the date(s) when your actions in response to this 
     Bulletin were or will be completed. 

2.   If you find from your review that switches of the type described above 
     are not in use, or planned for use, in safety-related systems of your 
     power reactor facility(ies) notify this office of this finding within 
     30 days. 
Page Last Reviewed/Updated Tuesday, July 23, 2013