United States Nuclear Regulatory Commission - Protecting People and the Environment

LICENSEE: FOXBORO COMPANY
SITE: FOXBORO COMPANY EN NUMBER: 35906
DOCKET: EVENT DATE: 07-09-99
RX TYPE: EVENT TIME:
VENDORS: NOTIFY DATE: 07-09-99
EMERGENCY CLASS: N/A REGION:1 STATE: MA TIME: 10:35
OPS OFFICER: BOB STRANSKY
10 CFR SECTION: CCCC UNSPECIFIED PARAGRAPH
DEFECTIVE RELAYS PROVIDED TO FOXBORO BY VENDOR

"Foxboro Co. has identified a potential defect with N-2A0-L2C-R or N-2A0-L2C-R with ECEP 10273, Contact Output Isolator cards that may contain specific NO152CK or CO147SS relays. These relays, supplied by Potter & Brumfield, were manufactured utilizing pure tin plated contact support arms. As a result, in low voltage, low current applications, the growth of tin whiskers between adjacent metallic surfaces of the contact support arms can lead to the establishment of a resistive shunt path. This shunt path would prevent the relay from functioning as designed. This potential defect is limited to only those relays supplied by Potter & Brumfield manufactured from 1 December 1981 to 31 December 1993.

"Foxboro is taking immediate corrective action to rectify the situation and will notify all Nuclear Utilities that have purchased this product from Foxboro during the time period affected and provide replacement relays."

The representative reported that two failed relays were identified after being returned by a foreign reactor facility.

Page Last Reviewed/Updated Thursday, March 29, 2012