United States Nuclear Regulatory Commission - Protecting People and the Environment

Information Notice No. 82-50: Modification of Solid State AC Undervoltage Relays Type ITE-27

                                                            SSINS No.: 6835 
                                                            IN 82-50 

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

                             December 20, 1982 

Information Notice No. 82-50:   MODIFICATION OF SOLID STATE AC 
                                   UNDERVOLTAGE RELAYS TYPE ITE-27 

Addressees: 

All holders of a nuclear power reactor operating license (OL) or 
construction permit (CP). 

Purpose: 

This information notice is provided as a notification of a potentially 
significant problem pertaining to Solid State AC Undervoltage Relays Type 
ITE-27. It is expected that recipients will review the information for 
applicability to their facilities. No specific action or response is 
required at this time. 

Description of Circumstances: 

Solid State AC Undervoltage Relays Type ITE-27 Series 211B and Series 211L 
manufactured by Brown Bovery Electric, Inc. are used on Class 1E switchgear 
and require a source of DC control power for proper operation. When the DC 
control power in these relays is lost, or temporarily interrupted because of
a DC bus transfer, an alarm and feeder breaker trip sequence is initiated 
without actual bus undervoltage. 

This condition could lead to the inadvertent isolation of a Class 1E 
switchgear. If this were to occur at a time when offsite power was not 
available, the supply breaker would be locked out and the switchgear would 
have to be reconnected manually. This condition could lead to a situation 
whereby no power was available for a period of time until the 
switchgear.could be manually reconnected; this condition could adversely 
affect plant safety. 

It should be noted that the ITE-27 Series 211B and 211L relays are operating
as designed. The problem is one of misapplication. In the plants noted 
below, the function of the ITE-27 Series 211B and Series 211L relays are to 
monitor AC bus undervoltage conditions. The Series 211R relay rather than 
the Series 211B and Series 211L should have been used for this application, 
since the Series 211R does not drop out upon on loss of DC power. 

On August 5, 1982, TVA reported this condition under 10 CFR Part 21 for the 
Bellefonte Nuclear Plants, Units 1 and 2. Bellefonte returned the relays to 
the vendor for internal circuit modification to the Type ITE-27 Series 211R 
to prevent dropout on loss of DC power. Other TVA plants are presently under
review to determine if similar conditions exist. 

8208190268  
.

                                                           IN 82-50 
                                                           December 20, 1982 
                                                           Page 2 of 2 

Similar conditions were found at: 

     Duke Power Company - McGuire, Oconee, and Catawba Nuclear Plants 
     Rochester Gas and Electric - Ginna Nuclear Plant Houston Light and 
     Power Company - South Texas Project 

A relay modification to the Series 211R has been completed to prevent 
dropout on loss of DC power at the Duke Power Company and Rochester Gas and 
Electric sites. Houston Light and Power is presently in the process of relay
modification for the South Texas Project. 

Brown Bovery Electric, Inc. provided a list of nuclear plants which received
and used Type ITE-27 undervoltage relays (see Attachment 1). It should be 
noted that not all these nuclear plant relay applications may be the same or
pertain to Class 1E switchgear or other safety-related circuits and, 
therefore, it is suggested that licensee's evaluate the relay application to
determine if the appropriate series is used. 

If you have any questions regarding this matter, please contact the 
administrator of the appropriate NRC Regional Office or this office. 


                                   Edward L. Jordan, Director  
                                   Division of Engineering and  
                                     Quality Assurance 
                                   Office of Inspection and Enforcement 

Technical Contact:  W. Laudan, IE 
                    301-492-9759 

Attachments: 
1. List of Plants with ITE-27 
2. List of Recently Issued IE Information Notices

Page Last Reviewed/Updated Tuesday, November 12, 2013