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2013 Feedwater OPEX Round-Up

2013 Feedwater OPEX Round-Up. Eric Backus FW System Engineer Exelon - LaSalle Station FSRUG Executive Board Member. Summary of 2013 OPEX Issues. 137 OPEX entries Feedwater , Heater Drains, Condensate, MSR. Feedwater Scrams. 12 Feedwater Scrams occurred during 2013

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2013 Feedwater OPEX Round-Up

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  1. 2013 Feedwater OPEX Round-Up Eric Backus FW System Engineer Exelon - LaSalle Station FSRUG Executive Board Member

  2. Summary of 2013 OPEX Issues • 137 OPEX entries • Feedwater, Heater Drains, Condensate, MSR

  3. Feedwater Scrams • 12 Feedwater Scrams occurred during 2013 • Failed fuse on an inverter on a non-safety vital bus. This caused a loss of 120VAC instrumentation power and caused all Feed Pumps driving to minimum output. This was a known SPV in DFW. • Failure of air line on FRV actuator caused FRV to go closed. Caused by unanticipated harmonic vibrations after steam generator replacement. • Loss of condenser vacuum due to FW Long Cycle Return Valve due to vibration from seat leakage. The valve was not of a sufficient design.

  4. Feedwater Scrams (cont.) • Loss of condenser vacuum from a leak on a heater level control line. The leak occurred from vibrations due to failed tubes and leaking drain valves. • Loss of one Feedwater pump due to coupling failure. The coupling failed along a pump end weld seam, with damage found on a turbine end weld seam. • An instrument air line failed at a soldered coupling causing loss of air to FRV. Air line failed after excavation, was due to poor original quality.

  5. Feedwater Scrams (cont.) • A secondary system transient occurred causing both HD pumps to trip, causing a FW pump trip on low NPSH, causing a scram on low level. There was inadequate procedure guidance on the automatic control of heater bypass control valve. • Short in flex conduit caused false indication of low FW pump seal cooling on both FW pumps. Both FW pumps tripped due to the lost indication. • Loss of bus caused instrument loop on all 3 FW pump recirculation valves to fail all recirc valves open. This known SPV was introduced in a mod.

  6. Feedwater Scrams (cont.) • A coding error in FWLC logic caused high water level and trip when transitioning FWLC modes during a planned shutdown. • Online maintenance of FW turbine caused loss of condenser vacuum when turbine casing was lifted because of excessive leakage past exhaust valve. • Feedwater level oscillations occurred due to air leakage past degraded o-rings in the FRV actuator. Operators manually scrammed due to being unable to stop oscillations in manual control.

  7. Questions?

  8. Full OPEX Summary Table

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