Information Notice No. 82-50: Modification of Solid State AC Undervoltage Relays Type ITE-27
SSINS No.: 6835
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
All holders of a nuclear power reactor operating license (OL) or
construction permit (CP).
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.
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
Office of Inspection and Enforcement
Technical Contact: W. Laudan, IE
1. List of Plants with ITE-27
2. List of Recently Issued IE Information Notices
Page Last Reviewed/Updated Friday, May 22, 2015