United States Nuclear Regulatory Commission - Protecting People and the Environment

Morning Report for March 3, 2004

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Part 21 - 2004-0002-00 - Undersized Emergency Feedwater Pump Shaft (EN 40453)




License No:

MR Number: H-2004-0007
Date: 01/16/2004

Source Document: Call / Fax from Licensee



Part 21 - 2004-0002-00 - Undersized Emergency Feedwater Pump Shaft (EN 40453)

On January 16, 2004, the Seabrook licensee reported a condition involving an undersized shaft in a rotating assembly for a refurbished motor-driven emergency feedwater pump. The emergency feedwater system includes both a motor-driven pump and a turbine-driven pump. The undersized shaft, discovered during post-maintenance testing following shaft replacement, was 0.001 inch smaller than the minimum diameter specified by the vendor, Ingersol-Rand (now Flowserve). The licensee does not consider the condition as a defect in the turbine-driven pump because of the different driver. Because the steam-driven pump must be assumed to not be available (considering an additional single failure), this deviation could result in the system not fulfilling its safety function.

Additionally, while troubleshooting and communicating with Flowserve, the licensee identified that the design tolerances for the shaft and coupling hub could have resulted in a size-to-size (0.000 inch interference) fit had the shaft not been undersized. Before returning the pump to operable status, the licensee implemented a design change to secure this connection, eliminating axial movement between the coupling hub and the shaft.

Information for this issue as well as other Part 21s is available at the NRC's Operating Experience web page at: http://www.nrc.gov/reading-rm/doc-collections/event-status/.

Accession Numbers:

Accession No Accession Date
ML040420567 02/03/2004


Name Office Abbrev Phone No E-Mail
HODGE, VERNON NRR (301) 415-1861 CVH@nrc.gov
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