United States Nuclear Regulatory Commission - Protecting People and the Environment

Morning Report for June 17, 2004

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Part 21 - 2004-0012-00 - Instantaneous Trip Unit on Type CO and COM Relays




License No:

MR Number: H-2004-0014
Date: 05/13/2004

Source Document: Letter


Part 21 - 2004-0012-00 - Instantaneous Trip Unit on Type CO and COM Relays

On May 13, 2004, ABB, a vendor of relays, reported a potential defect concerning the indicating instantaneous trip (IIT) unit on Class 1E type CO and COM relays. In October 2003, four Class 1E type CO relays were returned for cause determination of heat deformed sleeving on the IIT unit tap screws. The probable cause for the deformation of the sleeving was excessive heat from the tap screw being loose. Several combined manufacturing process outputs with one or more external factors (i.e., ambient temperature, ac current) provides for the potential movement of the molded insert to which the tap screw mates. The potentially affected relays were manufactured between July 1, 1998 and December 20, 2003. The vendor indicated that all purchasers of potentially affected relays will be promptly notified.

Accession Numbers:

Accession No Accession Date
ML041450498 05/13/2004


Name Office Abbrev Phone No E-Mail
BARKER, ALLAN NRR (301) 415-4006 ARB3@nrc.gov
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