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Flashcards in Chemical Volume and Control Deck (37)

What is the purpose of CVCS?

  • Maintain the required volume of water in the PCS over the range of full to zero power without requiring makeup.
  • Maintain chemistry and purity of the PCS.
  • Maintain the desired boric acid concentration in the PCS.
  • Pressure test the PCS.





CV-2001 (Letdown Isolation Valve)

Handswitch on C-02 has 3 positions:  Close/Auto/Open.

Auto (opens valve) will isolate Letdown on high temp down stream of Regen Hx as indicated on TICA-0201, Regen Heat Exchanger Temperature Indication.

Setpoint 470°F.

Has a latching circuit. Must take HS back to close to reset.

Open position will override temperature closure setpoint. 

Amber = valve in automatic (open)


a.      E-56 (Regenerative Heat Exchanger)

Initial cooling of letdown and preheating of charging

Two pass shell and tube.  Charging in shell side.

Letdown temperature depends on amount of Letdown and Charging flow.

Designed to maintain Letdown outlet temperature <450°F with maximum Letdown and minimum Charging


TICA-0201 (Letdown Temperature Indicator)

Temperature depends on amount of Letdown and Charging flow.

Alarm @ 460°F, EK-0701 (Regen Hx Tube Outlet Hi Temp)

Auto isolation of Letdown @ 470°F (CV‑2001 closes if Handswitch is in Auto).


CVs-2003, 2004, 2005 (Letdown Orifice Stop valves)

Handswitch on C-02 has 3 positions:  Close/Auto/Open

CV-2003 will close if LIC-0101A (Pressurizer Level Control Channel 1) or B (Pressurizer Level Control Channel 2) is <36%, open when level is >36%.

CV-2004 and CV-2005 open and close by either the normal Pressurizer level control system or the backup Pressurizer level control system.

The CVs send an anticipatory signal to PIC-0202 (Intermediate Pressure Letdown Controller)


RO-2003, RO-2004, RO-2005 (Letdown Orifices)

Calibrated to flow 40 gpm at rated temperature and pressure.

Reduces Letdown pressure.


CV-2002, Letdown Orifice Bypass valves

Used during PCS low pressure operation to raise letdown flow when there is not enough PCS pressure to force Letdown through the orifices.

CV-2002 - Has Two HS: Each Handswitch controls one Solenoid Valve.  The Solenoid valves are in series so both have to be open to open CV-2002.

  • SV-2002A: HS Open / Auto / Close
    • Closes on 500 psig on PS-0220 (Intermediate Letdown Pressure Switch) prevents opening RV‑2006 (and allows for a smaller RV‑2006.
    • Closes on 190 psig on PS-0222 (Letdown Pressure Switch) (protect demins)
  • SV-2002B: HS Open / Auto / Close
    • Closes on 500 psig on PS-0221 (Intermediate Letdown Pressure Switch) prevents opening RV‑2006 (and allows for a smaller RV-2006)
    • Closes on 160 gpm on FIC‑0202 (Letdown Flow Indicator Controller) excess flow can cause channeling (protects demins).



What is the setpoint, purpose and where does RV-2006 relieve to?


Protects Letdown Line and Components

Lifts at 600 psi

200 gpm

Relieves to Quench Tank


When and why does TIA-0202, RV-2006 Outlet Temp come in?

TIA-0202, RV-2006 Outlet Temp

Alarms at 200F

Indicates RV-2006 has lifted

Located on C-02


Where does, Low Pressure Letdown Pressure Transmitter, PT-0202 send its signal?

PT-0202 (Low Pressure Letdown Pressure Transmitter)

Signal Sent To:

  • PIC-0202 Intermediate Letdown Regulating valve (Backpressure Controller)
  • PA-0202
    • Alarms EK-0704 (Letdown Ht Ex Tube Inlet Hi-Lo Press) on either
    • High pressure @ 500 psig
    • Low @ 400 ps


What is E-58 (Letdown Heat Exchanger)?

E-58 (Letdown Heat Exchanger)

Cools Letdown from Regen Hx outlet to within design limits of the demineralizers

CCW on Shell Side, Controlled via DPIC-0909

  • Limit CV-0909 opening to <12 psid
  • Alarms @ 14  psid, EK-0706 (Letdown Hx Cooling Excess Flow)


What is the function of TIC-0203, Letdown Temperature Controller

TIC-0203 (Letdown Temperature Controller)

Behind Panel Cover on C-02

Normally set at 110°F

Automatic - PB raise/lower setpoint

  • Red = Variable, Blue = Setpoint
  • Lever has no function

Manual - Lever control output signal to CV-0909

  • PB has no impact on temperature

Cascade - no function


What is the function of TICA-0204, Letdown Flow Local Temp Controller Indication?

TICA-0204 (Letdown Flow Local Temp Controller Ind)

Alarms and actuates at 130°F

  • EK-0703 (Letdown Ht Ex Tube Outlet Hi Temp)
  • Sends bypass signal to CV-2023 (Ion Exchange Bypass Valve) to prevents damage/melting of resins

No indication in control room


What is the function of CV-2009, CVCS Containment Isolation valve?

CV-2009 (CVCS Containment Isolation valve)

Two position HS - Open or Closed

Closes Automatically on CHP and CHR

Has latching circuit



What is the function of CVs-2012, 2122, Intermediate Letdown Regulating Valves?

CVs-2012, 2122 (Intermediate Letdown Regulating valves)

2 Valves in Parallel

Function to

  • Maintains above saturation (ressure between the letdown heat exchanger and pressure reduction orifices.  Prevents flashing of letdown fluid prior to being cooled by the letdown heat exchanger.
    • Setpoint 460 psigs = 461F saturation temp
  • Reduces pressure to Demin design pressure
  • Controls Pressure during Solid Plant Operations


What i the function of PIC-0202, Intermediate Pressure Letdown Controller?

PIC-0202 (Intermediate Pressure Letdown Controller)

Red is process variable, Blue is setpoint


  • Signal from PT‑0202 (Low Pressure Letdown Pressure Transmitter)
  • Anticipatory signal from the Letdown Stop Valves to prevent/-reduce pressure transients and reduce cycling of RV-2006.
  • PIC-0202 "remembers" what its output should be for 1, 2 and 3 orifices open. 


  • Lever will open and close CV



What is the function of HIC-2122, Intermediate Pressure Letdown Controller?


HIC-2122 (Intermediate Pressure Letdown Controller) on C-12

Manual control only

  • Red is letdown pressure, Blue is output to CV
  • Knob opens and closes CV


What is the function of HS-0202 on C-12?


2 positions

  • CV-2122 Manual / CV-2012 Auto (preferred)
    • CV-2122 is controlled by HIC-2122 and CV-2012 is controlled by PIC‑0202
  • CV-2122 Auto / CV-2012 Manual​

    • CV-2122 is controlled by PIC-0202 and CV-2012 is controlled by HIC‑2122

    • I&C must reprogram. Pressure fluctuations & RV lifting



What is the function of PS-0222, Letdown Pressure Pressure Switch?

PI-0222, Letdown Pressure Indication?

PS-0222 (Letdown Pressure Pressure Switch)

No Control Room indication

  • 190 psig  sends close signal to CV-2002 (Letdown Orifice Bypass valve)
  • Demin Protection

PI-0222 (Letdown Pressure Indication)

  • Local indication of Letdown pressure located in 590' hallway, Aux Building


CV-2014, Failed Fuel Monitor Isolation valve

CV-2014 (Failed Fuel Monitor Isolation valve)

Failed closed due to retirement of failed fuel monitor


What is the function of FIC-0202, Letdown Flow Indicator?

FIC-0202 (Letdown Flow Indicator)

Indication on C-02

  • High flow alarm at 160 gpm, - protects demins
  • EK-0705 (Pri Letdown Flo Indicator Controller Hi Flow)
  • Will send a close signal to CV-2002 (Letdown Orifice Bypass valve)


What is the function of RV-2013, Low Pressure Letdown Line Safety Relief Valve?

RV-2013 (Low Pressure Letdown Line Safety Relief Valve)

  • Setpoint at 200 psig
  • Discharges to the Volume Control Tank


What is the function of F-54 (Pre-Filter)?

F-54 (Pre-Filter)

No filter installed, preferred to have high activity confined to demins


What is the function of CV-2023, Demin bypass valve?

CV-2023 (Demin bypass valve)

Handswitch on C-02 has 3 positions:  Bypass/Auto/To Ion Exchanger

  • left red = bypass demineralizers
  • amber = valve in automatic (to demineralizers)
  • right red = to demineralizers


  • Bypass demins with TICA-0204 (Letdown Flow Temperature Controller) at 130°F


T-51A (Delithiating Demineralizer)

T-51A (Delithiating Demineralizer)

Removes lithium from the PCS for pH control

  • Lithium is caustic (will raise pH).
  • Lithium is created constantly during power operation (B10 to B11 to Li7)

Has cation resin only

  • Cation resin does not have an affinity for Boron, therefore, will not affect reactivity

When this demin is placed in service, it is in parallel with the purification demin to minimize wear on the manual valves


What is T-51B?


Used as a Purification Demineralizer

Has mixed bed resin

  • May affect reactivity based on the anion resin having an affinity for boron atoms.



What is the function of T-52 (Deborating Demineralizer)?

T-52 (Deborating Demineralizer)

Has low or no boron in it, boron will be removed from the PCS when in service

The rate of boron removal is related to the letdown flow rate


What is function of F-54A, B (Post Filter)?

F-54A, B (Post Filter)

Removes resin fines and non-solubles

One I/S, other is spare

Alarms at 35 psid on C-40


What is function of CV-2056 (Diverting Valve)?

CV-2056 (Diverting Valve) - VCT

Handswitch on C-02 has 3 positions:  To VCT/Auto/To CWRT


LS-0204 (VCT level) at 94.4% diverts to CWRT

LS-0204 at 91.4%, diverts to VCT

  • left red = valve open to Volume Control Tank
  • amber = valve in automatic (valve open to Volume Control Tank)
  • right red = valve open to Clean Waste Receiver Tank


What is the function of CV-2083 and CV-2099, PCP Controlled Bleedoff Containment Isolation?

CV-2083 and CV-2099 (PCP Controlled Bleedoff Containment Isolation)

  • Closes on CHP/CHR
  • Has Latching Circuit

Open/Close Switch on C-02

RV-2082 (PCP Controlled Bleedoff Relief Valve) will lift (to the PSDT) to maintain 145 psig backpressure


What is the function of CV-2191, PCP Controlled Bleedoff Stop?

CV-2191 (PCP Controlled Bleedoff Stop)

Isolates PCP Bleedoff

Fails Closed on Loss of Air

  • Has an accumulator and a check valve to keep valve open

RV-2082 (PCP Controlled Bleedoff Relief Valve) will lift (to the PSDT) to maintain 145 psig backpressure


What is the function of T-54, Volume Control Tank?

T-54 (Volume Control Tank)

Sized to accommodate a zero to full power rise without diversion and can compensate for a full to zero power lowering without makeup

  • Level band: 68% to 78% and pressure between 21 - 35 psig


  • Used to scavenge oxygen. 27-35 cc/kg is normal range


  • Used purge Hydrogen for shutdown

Higher VCT pressures causes higher dissolved gas concentrations.  Lower VCT temperatures causes higher dissolved gas concentrations


What is the function of TIA-0205, VCT Temp Alarm Indicator?

TIA-0205 (VCT Temp Alarm Indicator)

  • Alarms @130°F
  • EK-0707 (Volume Control Tank Hi Temp)


What is function of LT-0205, VCT Level Transmitter?

LT-0205 (VCT Level Transmitter)

Has 2 outputs

LA-0205 (VCT Level Alarm)

  • Alarms @ 96.6% (high) and 62.5% (low),
  • EK-0709 (Volume Control Tank Hi-Lo Level)

LIC-0205 (VCT Level Indicator Controller)

  • Indication only, not used for level control any longer.


What is the function of PIA-0205, VCT Pressure Indicator Alarm?

PIA-0205 (VCT Pressure Indicator Alarm)

Alarms at 50 psig (high) and 4 psig (low),

EK‑0708 (Volume Control Tank Hi-Lo Pressure