Main turbine Vacuum Killing

Main turbine Vacuum Killing

  • Ensure Boiler Stop Valves (MS01 & MS02 ) and its IBV ( MS03 , MS04 , MS05 & MS06 ) are in closed condition.
  • Ensure all drains to UFT are opened & all drains to SDFT are closed
  • Ensure complete de-pressurization of Main Steam line
  • Ensure TDBFP common aux steam supply MOV or manual valve (At Aux PRDS Floor ) is in closed condition).
  • Ensure MAW15AA001 (Seal steam supply bypass MOV) is in closed condition
  • Close MAW10AA011 (Seal steam header Drain going to HPFT) & open its atmospheric drain
  • Stop both vacuum pump & its recirculation pump.
  • Open Vacuum Breaker. 
  • At Vacuum –0.2 ksc , isolate seal steam to turbine by closing the Supply header Control valve & its isolation MOV ( MAW10AA010 ) .
  • Stop GSC fan .Open the chimney valve if required.
  • Close seal steam manual isolation valve (at 8.5 m).Close also main turbine seal steam motorized valve at  TG 17m
  • After Vacuum killing , Main turbine speed is to be monitored . It should be around 65-80 RPM. If speed drops below 65 rpm inform TMD immediately.
  • Deaerator & Hot well level is to be maintained at its normal value.

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