1 / 15

MFW Pump Discharge Check Valve OE Follow Up

Learn about the corrective action and current status of the MFW pump discharge check valve at North Anna Power Station. Details on valve application, Enertech supply, failure analysis, corrective actions, and valve performance are covered in this outline.

margaret-emerson
Download Presentation

MFW Pump Discharge Check Valve OE Follow Up

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. MFW Pump Discharge Check ValveOE Follow Up Dominion North Anna Power Station Gary W. Liffick FW System Engineer FSRUG, Feb 21-24, 2011

  2. Outline North Anna Power Station: MFW Pump Discharge Check Valve • Application Overview • Background of OE31369 (update of OE29594) • Corrective Action • Current Status

  3. Application Overview North Anna Power Station: MFW Pump Discharge Check Valve • PWR, 963 MWe, Westinghouse NSSS Operational Since: • June 1978 Unit 1 • Dec 1980 Unit 2 • Application is Main Feedwater Pump Discharge • 3 Pump Circuit, 2 Active, 1 Standby • NozzleCheck Replaced the Tilting Disk Check • October 2007 at 1-FW-19 • Feedwater Normal Conditions: • 390 F, 1,180 psi, 15,000 GPM per Feedwater Pump • Enertech Supplied: • type DRV-B,18”-900#, RF Flanges, Commercial Grade

  4. Application Overview North Anna Power Station: MFW Pump Discharge Check Valve Enertech Supplied Type DRV-B: • 18”-900# • RF Flanges • Commercial Grade • WC6 body • ASTM A351 CF8M Diffuser and Disk • Inconel X-750 Spring

  5. OE31369, MFW Pump Discharge check valve failed to fully close. Original OE29594. North Anna Power Station: MFW Pump Discharge Check Valve • During March 2009 Outage, backflow detected through check valve. • Disassembly showed 1 broken spring and 2 with visible wear of spring coils due to friction. • Remaining Components indicate normal wear. • Factory installed new springs, radial guide assembly, performed seat leak test. • Returned to site as spare

  6. Corrective Action North Anna Power Station: MFW Pump Discharge Check Valve • Increased clearance of spring holder and spring cavity. • Eliminate possible solid height of spring • No change to spring design • Improve check valve reliability without changing Vmin or disk closure force with zero flow

  7. NozzleCheck Valve, Type DRV-B 18”-900# RF North Anna Power Station: MFW Pump Discharge Check Valve

  8. DRV-B Cutaway North Anna Power Station: MFW Pump Discharge Check Valve

  9. NozzleCheck Valve, Animation, Type DRV-B 18”-900# RF North Anna Power Station: MFW Pump Discharge Check Valve

  10. Spring Holder and Spring North Anna Power Station: MFW Pump Discharge Check Valve

  11. Spring Holder and Spring North Anna Power Station: MFW Pump Discharge Check Valve Spring coil wear Spring holder wear

  12. Spring Holder and Spring North Anna Power Station: MFW Pump Discharge Check Valve Spring coil wear

  13. Current Status North Anna Power Station: MFW Pump Discharge Check Valve • Valves incorporating design changes were installed in all six check valve locations (3 per unit) during 2010 • Two valves removed for modification & refurbishment Sept. 2010 • Factory evaluation shows spring wear after 12 months and 18 months of service • Valves with the modification are operating per design

  14. Status as of Jan 2011 North Anna Power Station: MFW Pump Discharge Check Valve Conclusion • Final conclusion is pending the removal of the check valves from service to confirm spring wear has been eliminated • Current PM frequency is 4.5 years • Next valve scheduled for removal/PM is during Spring 2012

  15. Questions? North Anna Power Station: MFW Pump Discharge Check Valve Gary W. Liffick, FW System Engineer Dominion – North Anna Power Station PH 540 894-2429 Gary.Liffick@dom.com

More Related