mfw pump discharge check valve oe follow up
DESCRIPTION
MFW Pump Discharge Check Valve OE Follow Up. Dominion North Anna Power Station. Gary W. Liffick FW System Engineer FSRUG, Feb 21-24, 2011. Outline. North Anna Power Station: MFW Pump Discharge Check Valve. Application Overview Background of OE31369 (update of OE29594) - PowerPoint PPT PresentationTRANSCRIPT
MFW Pump Discharge Check ValveOE Follow Up
DominionNorth Anna Power Station
Gary W. LiffickFW System Engineer
FSRUG, Feb 21-24, 2011
Application Overview
Background of OE31369 (update of OE29594)
Corrective Action
Current Status
OutlineNorth Anna Power Station: MFW Pump Discharge Check Valve
Application Overview
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
North Anna Power Station: MFW Pump Discharge Check Valve
Application Overview
Enertech Supplied Type DRV-B:
18”-900#
RF Flanges
Commercial Grade
WC6 body
ASTM A351 CF8M Diffuser and Disk
Inconel X-750 Spring
North Anna Power Station: MFW Pump Discharge Check Valve
OE31369, MFW Pump Discharge check valve failed to fully close. Original OE29594.
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
North Anna Power Station: MFW Pump Discharge Check Valve
Corrective Action
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
North Anna Power Station: MFW Pump Discharge Check Valve
NozzleCheck Valve, Type DRV-B 18”-900# RFNorth Anna Power Station: MFW Pump Discharge Check Valve
DRV-B CutawayNorth Anna Power Station: MFW Pump Discharge Check Valve
NozzleCheck Valve, Animation, Type DRV-B 18”-900# RFNorth Anna Power Station: MFW Pump Discharge Check Valve
North Anna Power Station: MFW Pump Discharge Check Valve
Spring Holder and Spring
Spring holder wear Spring holder wear
Spring coil wearSpring coil wear
Spring Holder and SpringNorth Anna Power Station: MFW Pump Discharge Check Valve
Spring coil wearSpring coil wear
Spring Holder and SpringNorth 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
Current StatusNorth Anna Power Station: MFW Pump Discharge Check Valve
ConclusionFinal 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
Status as of Jan 2011North Anna Power Station: MFW Pump Discharge Check Valve
Gary W. Liffick, FW System Engineer
Dominion – North Anna Power Station
PH 540 894-2429
Questions?North Anna Power Station: MFW Pump Discharge Check Valve