Pressurizer Level Control Flashcards
LCO 3.4.9 “Pressurizer” requirements
The pressurizer shall be operable with:
- Pressurizer water level <62.8% (not applicable in Mode 3 until after a bubble has been established in the pressurizer and pressurizer water level has been lowered to within its normal operating band)
- > = 375 kW of pressurizer heater capacity available from bus 1D
- > = 375 kW of pressurizer heater capacity available from bus 1E with the capability of being powered from an emergency power supply (‘A’ dilution water pump breaker on bus 1C)
LCO 3.4.9 “Pressurizer” applicability
Modes 1-3
What is the purpose of the PZR level control system?
Maintains PCS pressure and compensates for changes in volume during load changes.
What is the relationship between power level, Tave, and PZR level?
0% power = 532 F Tave = 42% PZR level
100% power = 560 F Tave = 57% PZR level
How does the PZR level control system control PZR level?
- Opening/closing letdown orifice stop valves
- Starting/stopping P-55B/C, Charging Pumps
- Controlling the speed of P-55A, Charging Pump
What are the power supplies for the PZR level controllers?
LIC-0101A from Y-10
LIC-0101B from Y-20
How does the PZR level control system respond to a lowering PZR level?
Sends a signal for more charging (raising P-55A speed or starting P-55B and/or P-55C) and less letdown (closing letdown orifice stop valves)
How does the PZR level control system respond to a rising PZR level?
Sends a signal for less charging (lowering P-55A speed or stopping P-55B and/or P-55C) and more letdown (opening letdown orifice stop valves)
What are the modes of operation of the PZR level controllers?
CASCADE - receives a signal from selected Tave controller and generates a PZR level setpoint
AUTO - operator selects a PZR level setpoint for the controller to maintain
MANUAL - operator controls output signal with slide bar on the controller
How does the PZR backup level control work?
- Still controls level through the same in service level controller as the normal level control program.
- Separate on/off control signals independent of normal level control signals.
- Only controls P-55B/C, and CV-2004/2005, Letdown Orifice Stop Valves.
- Backup level control signals override the normal level control signals in all modes of operation (cascade/auto/manual).
How is the out of service PZR level controller maintained and why?
Maintained in MANUAL with output set to 50%. This is to keep the controller immediately available for use, and to prevent it from becoming “saturated” due to “fighting” the in service controller if setpoints are slightly different.
What is indicated on the PZR level recorders?
- PZR pressure
- Actual PZR level
- PZR level setpoint (either the auto generated setpoint while in CASCADE, or the setpoint that is manually set by the operator when in AUTO)
How many gallons/% in the PZR?
66
How many gallons/% in the VCT?
34
What is the PZR Hi/Lo level alarm setpoint?
5.75% deviation from setpoint