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 FWHDFWLCUFMCDMSRTotal I&C Control Valve Human Performance Ageing Electrical6 3 9 Design6 2 8 Pump UFM 7 7 Oil System5 5 Other8811 Total

Feedwater Scrams 12 Feedwater Scrams occurred during 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. 2. Failure of air line on FRV actuator caused FRV to go closed. Caused by unanticipated harmonic vibrations after steam generator replacement. 3. 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. 3

Feedwater Scrams (cont.) 4. 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. 5. 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. 6. 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. 4

Feedwater Scrams (cont.) 7. 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. 8. 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. 9. 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. 5

Feedwater Scrams (cont.) 10. A coding error in FWLC logic caused high water level and trip when transitioning FWLC modes during a planned shutdown. 11. Online maintenance of FW turbine caused loss of condenser vacuum when turbine casing was lifted because of excessive leakage past exhaust valve. 12. 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. 6

Questions? 7

Full OPEX Summary Table 8 CDFWFWLCHDMSRUFMTotal I&C Control Valve Human Performance Ageing Electrical36 9 Design 62 8 Pump UFM 77 Oil System 5 5 Unknown Process/Procedure 3 3 FW SCS 2 2 Heater 2 2 Check Valve 1 1 Engineer (Good) 1 1 HD System 1 1 N/A 1 1 Strainer 1 1 Vendor Issue 1 1 Total