United States Nuclear Regulatory Commission - Protecting People and the Environment

Morning Report for January 19, 2006

Headquarters Daily Report

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Part 21 Update: A Potential Safety Hazard with the Woodward Digital Reference Unit (DRU)




License No:

MR Number: H-2006-0003
Date: 01/12/2006

Source Document: Call / Fax from Licensee



Fairbanks Morse Engine evaluation has determined a potential safety hazard exists for Woodward Digital Reference Units (DRUs). The FM P/N is 12998236, and the Woodward P/N is 9903-439. The defect exhibits erratic ramp up of speed and hence the inability to reach rated RPM and inability to apply load to the engine. The cause has been traced to a random interaction between solder flux and integrated circuit (IC) material causing chip delamination. This condition is further described in Woodward Service Bulletin 01363, dated December 2005.

This same problem had been previously reported on 4/23/04 (EN 40699), and at that time was thought to only affect DRU's manufactured between November 2000 thru January 2002. The manufacturer thought they had purged their stock of the specific IC chips that manifested the problem, but additional chips have been found in their system that now extends the affected time period to December 2005.

DRU's that have had IC chips replaced per the earlier Part 21 notification are not affected due to the use of a different solder flux that does not introduce the problem. The utility that FM has supplied DRU's to in the timeframe identified that are affected Include; Fermi, Beaver Valley-2, and VC Summer.

Engine System Inc. (ESI) in a letter to NRC on 4/30/2004 stated that it had supplied similar DRUs to River Bend, Millstone, Cooper, Byron, and McGuire. A detailed list of DRU part numbers supplied by ESI is available in ADAMS with accession number ML041320381.

This information will be updated as new information becomes available. More information concerning Part 21 notifications is available on NRC Homepage at http://www.nrc.gov/reading-rm/doc-collections/event-status/part21/


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