ML043170256
| ML043170256 | |
| Person / Time | |
|---|---|
| Site: | Harris  |
| Issue date: | 11/10/2004 |
| From: | Fredrickson P NRC/RGN-II |
| To: | |
| References | |
| Event #41179 MR-II-04-0016 | |
| Download: ML043170256 (1) | |
Text
PRIORITY ATTENTION REQUIRED MORNING REPORT - REGION II Morning Report Date: NOV 10, 2004 Licensee/Facility: Notification:
CAROLINA POWER & LIGHT CO. MR Number: 2-2004-0016 Harris Date: 11/07/2004 Raleigh, North Carolina Dockets: 050-00400
[1] W-3-LP
Subject:
FAILURE OF HARRIS FEEDWATER ISOLATION VALVE DURING REFUELING OUTAGE STARTUP Discussion:
On November 7, 2004, at 4:35 p.m, with the plant at approximately 7% power, preparing for startup from a refueling outage, Shearon Harris manually started the A motor driven auxiliary feedwater (MDAFW) pump in response to unplanned lowering of steam generator (S/G) level in the C S/G. The licensee made event notification #41179 for this valid actuation of a safety system.
The licensee's initial investigation focused on the C main feedwater (MFW) regulating bypass valve and identified a leaking air connection. The bypass valve is designed to fail closed on loss of air. Following repair, power was again increased. The C S/G level failed to control and the power ascension was aborted. Additional trouble shooting was unsuccessful and the reactor was brought to hot shutdown on November 8.
Subsequent investigation determined that the lowering of S/G level resulted from the C MFW isolation valve, a double wedge gate valve, being closed instead of open. Although the valve's position indicated closed in the control room, the valve actually failed to open indicating a possible valve stem separation. The AFW flow path, however, is separate from MFW and was not impacted by the failed valve.
On November 10, the licensee verified that the MFW isolation valve stem had separated from the disc, and brought the plant to cold shutdown. Disassembly and examination of the valve identified internal damage to the valve disc and seat.
The licensee plans to investigate the cause of the valve failure, assess past operability, and inspect the two remaining feedwater isolation valves.
Accession No. Accession Dt.
ML043170256 11/10/2004
Contact:
Org: Phone No: Email:
FREDRICKSON, PAUL E R2 (404) 562-4530 PEF@nrc.gov