CW- Circulating Water Flashcards
The CW system serves as a discharge point for what sources?
CD system overboarding, CD and blowdown demineralizers low TDS Sumps, yard area sump pumps and Essential Spray pond Backwash Sump Pumps, Turbine building run off
Can be used as an emergency fire water source
What does TB do for the CW system?
Supplies makeup water from the storage reservoirs to the CW system to replace water losses due to evaporation, blowdown, and drift from the cooling towers
Provides blowdown paths to the evaporation ponds to allow constant blowdown for chemistry control and for level control in the canal
Why are we worried about silica in the CW system?
Plates out on the surfaces of the titanium tubes in the condenser
What chemicals are added to the CW canals with the CI system?
Hypochlorite, foam control agent, sulfuric acid, and scale dispersant
Who normally maintains the CW canal chemistry?
Water Resources
How does PW interact with CW?
The PW pumps share the intake canal with the CW pumps, utilize the Cooling Towers for cooling, and return their discharge to the CW return piping
What system provides air to the Cooling Tower Makeup Anti Cavitation Air Injection to prevent valve chattering in the Canal Level Control valve? What else does this system do?
Instrument Air
operates control valves and controllers
What is the approximate evaporation rate of the CW system at each unit?
18,000 gpm
Approximately how much water is lost to blowdown at each CW canal?
~700 gpm
but up to 2000 gpm
What is provided at each CW pump bay to prevent large debris from entering CW system?
Trash screens
Why are each of the pump slots provided with a Stop Gate?
In the event that maintenance is required on individual pumps while the system continues to operate
What provides water for screen spraying?
PW pumps
Due to recent modifications, where are the Turbine Building Roof drains directed to?
Their respective CW intake canals
What is the normal level setpoint of the CW canal?
23 ft
How often are local grab samples performed on the canal and what are they used for?
Daily
Used to determine the required blowdown flowrate for control of the chemistry parameters
What is the capacity of each CW pump? What is the normal discharge pressure of each pump?
25% (140,000 gpm)
~45 psi
What provides cooling to the CW pump lube oil cooler?
Turbine Cooling Water
What needs to be met in order for the CW pump to start when the switch in the Control Room is taken to START-OPEN?
Pump discharge valve is fully closed
Either the same flow train condenser outlet valve is open or the CONDENSER OUTLET VALVE INTERLOCK OVERRIDE pushbutton is depressed
The pump-start signal is sent to what other components?
Open signal for the pump’s discharge valve
Permissive signals to the CI system acid injection pump, CI system chlorine injection valves, and the same flow train CW pump discharge valve
What happens when I take the CW pump which to STOP-CLOSE position?
A closing signal is sent to the pump’s discharge valve
When the valve closes to less than 8% open, the pump’s breaker will open, stopping the pump
A signal is also sent to the CW supply header cross-tie valve and to the other CW pump discharge valve control logics