Containment Air Coolers Flashcards Preview

Systems > Containment Air Coolers > Flashcards

Flashcards in Containment Air Coolers Deck (40)

What is the function of the Containment Air Coolers?


  • Normal - cool the air in containment (140F) and remove vapor
  • DBA - pressure reduction (<50% by 24 hours) by cooling and removing vapor
  • Act as a barrier, limiting radioactive releases from containment. (piping)
  • If CHP not reached or CS not available it is only means.



Explain the purpose/function of the service water high capacity valves.


  • CV-0861, CV-0864, CV-0873 and CV-0867 - High Caps
  • 8-inch butterfly valves
  • Air to Close
  • Run with all open.
  • Can be closed to help control Containment temperature.



Explain the interface between Containment Air Coolers and the hydrogen monitoring system.


For a representative sample, the fans need to be operating to mix the contents of the containment building.



What is the containment temperature limit?


Design Limit: 283F

T.S. 3.6.5 <= 140F in Modes 1-4 

Administrative limit

  • ≤ 135.96°F on PPC pt. TE-1815
  • 130°F if TI-1815 (Containment Dome Temperature indication on panel C-13)
  • 50F if PPC pt TE-1815
  • 55F if TI-1815



Explain the interface between Containment Air Coolers and the Process Radiation Monitoring System.


  • The sample line from the discharge header of the fans is sent to radiation monitor RIA-1817 for trends of containment activity.
  • Each sample line’s SV is interlocked with either the “A” or “B” fan.
  • Either fan, operating, causes the SV to open and provides sample.

Securing all Containment Air Cooler Fans will secure air flow to RIA-1817, Containment Ventilation System Radiation and result in annunciation of EK-1370,
Radiation Monitors Samplers Flow Failure (alarm may be delayed). Secure the RIA-1817 Sample Pump when air flow is secured.



Explain the interface between Containment Air Coolers and the Critical Service Water System.

Cooling medium is critical service water from B Header


What is a design concern with the high capacity outlet valve CV-0873 for VHX-3?


The valve might fail to open due to silt/sand accumulation on the closed disc, the valve is maintained normallyopen per SOP-5.

If closed longer than 72 hours, valve is inoperable.

Becomes operable upon openning.



What are the power supplies for VHX 1-4 75hp A fans?

  • VHX 1-3A are on LCC-12
  • VHX-4A is on LCC-11.


What are the power supplies for VHX 1-4 30hp B fans?

VHX 1-3B are on MCC-3

VHX-4B is on MCC-4.


What is the air flow path for each cooler?

  • Air drawn from Steam Generator compartment through inlet ductwork to cooler housing.
  • Separate inlet duct routed from containment dome area to inlet plenums for VHX-3 and VHX 4.
  • Inlet filter assembly located just inside cooler housing. Cooling coils cool air/vapor mixture before passing through to fans.
  • Outlet ductwork routed vertically through space between S/G compartment walls and containment liner.


Discuss the cooler sump and drains.

Sump drains sized for 20 gpm,

Flapper blade drain, sized to pass 150 gpm, held closed due to fan suction until water level rises to alarm setpoint. Drains to containment sump.


What protects cooler internals from rapid pressure rise event?

  • Blowout panel on suction elbow.
  • Rivets break at 1 psig.


What is the status of CV-0867 (VHX-4) high cap outlet bypass?

It is failed closed, air supply removed.


Do the high cap bypass valves perform an automatic temperature control function?


The bypass valves, CV 0838, CV- 0863 and CV-0872 for VHX 1-3, are kept full open (they are air to open valves).

VHX 4 Outlet Bypass Control Valve (CV 0843) is failed closed to support accident analysis requirements for service water flow.


What is Containment Cooling Train 1?

  • EDG 1-1
  • P-54B/C
  • CV-3001


What is Containment Cooling Train 2?

  • EDG 1-2
  • P-54A
  • CV-3002
  • V-1A, 2A, 3A
  • 2 SW Pumps (P-7A/C)



What happens to CAC during SIAS?



  • All “B” fans trip,
  • All High Capacity Valves OPEN
    • CV-0861, CV-0864, CV-0873, CV-0867
  • CV-0869, VHX-4 inlet valve closes.
    • Fails closed on loss of air



What is unique about CV-0869, VHX-4 inlet valve.

It has an air supply needle valve throttled to open the valve slowly (about 12 seconds).



What is the design/function of the Pressurizer Shed Cooling Fans (V-61 A/B/C)?



  • 5000 scfm blower with a 2 HP motor.
  • Normally started during performance of the PCS 250# Heatup Checklist
  • Pushbutton Control Stations located on north side of pillar adjacent to MCC-10, 625’ Turbine Deck.
  • Failure could result in PORV tailpipe temp alarm



What is the design/function of the Iodine Removal Fans (V-940 A/B)?


6,000 scfm, Vaneaxial fans with 20 HP motor.

Lined up for remote control during all modes of operation. Normally started, as necessary, during performance of GOP-8, GCL 8.1.

Control Switches (circuit breakers) located on Panels C-266/267 (local panels in containment at fans).

Start/Stop pushbuttons located on stairway from D Bus to C.R. Viewing Gallery



What is the purpose/function of SW Containment Isolation Valves (CV-0824, CV 0847)?

  • CV-0847, CV-0824, electrically locked open
  • 16” butterfly valves.
  • Air to Close
  • N2 backup from N2 Station 1A for CV-0847
  • N2 Station 3B for CV-0824.


What is T.S. 3.6.6, Containment Cooling, and its action statements?


T.S. 3.6.6

  • Two containment cooling trains shall be OPERABLE in Modes 1, 2 and 3
    • One or more containment cooling trains inoperable
    • Restore to OPERABLE within 72 hours
  • Less than 100% of the required post accident containment cooling capacity available.
    • Enter LCO 3.0.3 Immediately




What is the accident basis for T.S. 3.6.6, Containment Cooling?



The peak containment pressure case is the large break LOCA with initial (pre-accident) conditions of 145°F and 15.7 psia.

The peak temperature case is the hot zero power MSLB with initial (pre-accident) conditions of 145°F and 16.2 psia. Review Basis Document.



What are the C-03/C-08 Panel Controls/Indications:


  • VHX 1-4 SW Inlet/Outlet Control Valve Handswitches
  • A & B Critical SW Header Pressure
  • Containment SW Supply/Return Cont Isolation CV Handswitches
  • A & B Fan Control HS
  • PI-1805 and PI-1812 WR Containment Building Pressure



What are the C-13 Panel Controls/Indications?


  • PI-1814/1815 NR Containment Pressure
  • Rx Cavity Temperature and Humidy
  • A & B SG Compartment Temperature and Humidity
  • Containment Temperature and Humidity
  • Left/Right Channel Containment Pressure/Sump Level/Water Level recorder
  • Left and Right SIS Sequencer Actuation Component Indicator Lights




Sensor: LS-0817

Trip Setting: +6” from bottom

Response: If SW leak suspected, close CV 0862 - VHX-1.

If alarm clears, declare CAC inoperable and refer to TS 3.6.6

Follow-up: Inspect CAC ASAP. If no major leak present and standing water, initiate WR to rod out drain line. Refer to TS 3.4.15. If major leak, isolate CAC





Sensor: FS-0885

Trip Setting: 300 gpm difference between service water into Containment (FT-0883) and service water out of Containment (FT 0884)

Response: Close then open SW inlet to each cooler one at a time to attempt to clear alarm. Refer to TS 3.6.6

Follow-up: Inspect SW header and any identified leaking CAC ASAP. Isolate affected CAC. Notify System Engineer and initiate CR





Sensor: PSX-1801, PSX-1802, PSX-1803, or PSX-1805

Trip Setting: 4 psig

  • Containment Pressure administrative limits
    • MODEs 1 and 2 < .85 psig
    • MODEs 3 and 4 <1.35 psig. 
  • TS 3.6.4 limit for MODEs 1 and 2 ≤ 1.0 psig
    • MODEs 3 and 4 ≤ 1.5 psig.

Response: Refer to EOP






Sensor: PIA-1814 or PIA-1815

Trip Setting: 0.8 +-  0.2 psig

Response: Check Containment humidity, pressure, and temp indicators for evidence of PCS or Main Steam leak.




What are the C-33 Panel Controls?


CAC SW Supply/Return Containment Isolation CV Handswitches

VHX 1-4 SW Inlet and Outlet CV Handswitches


What are the SOP precautions for Starting and Stopping SW flow to CAC?

  • CAC Outlet valves should be opened before opening or closing cooler inlet valves.
  • SW Containment Isolation valves should be opened before opening CAC Inlet Valves
  • Smoothly starting and stopping SW flow to  CAC will minimize hydraulic transients.


Under what conditions does a SW leak in containment not impact operability of CAC, Containment or SW?

  • Leak is observable and accessible
  • Leak is quantifiable
  • Containment, SW System and CAC remain capable of fulfilling their safety functions considering water lost, make up capability, cooling requirements and potential Containment leakage (previous operability evaluations have determined leaks less than 1.0 gpm were acceptable)
  • Leak is "pinhole" (small hole and not crack)
  • Adverse effect of leakage on other systems (such as local flooding, spraying and impingement) is tolerable
  • If it is a leak in a mechanical joint (such as gasket or packing)
    • No structural degradation or deformation of the joint components is observed


Under what Critical SW Header pressures are SW Pumps started?

IF, all four high caps open and Any of the following occur:

  • Either Critical Header < 50 psig


  • SW Pump discharge pressure < 53 psig


  • Loss of temperature control on any SW cooled component due to low SW flow


Start third SW pump

  • Prevents SW pump runout and ensures adequate cooling of supplied components.


Under what Critical SW Header pressures are SW Pumps stopped?

If three SW pumps running AND any of the following conditions exist:

  • Both Critical SW Header Pressures >70 psig


  • Operating SW pump discharge pressure >73 psig


  • Shutdown one of the running SW pumps.
    • Prevents low flow conditions on SW pumps.


What is the implication of the PPC flow limit on SW to containment?

Limit is 7500 gpm on PPC readout

With all four High Caps open and all three SW pumps operating, SW flow to containment can exceed 7500 gpm.

May look like a SW leak in containment.


When is SW flow to containment required to be in service?

Prior to Mode 3.


What combinations of equipment meet the 100% containment cooling capability with the MSIV Bypass valves closed?

  • 2 Containment Spray Pumps
  • 2 Spray Headers


  • 1 Spray Pump
  • 2 Spray Headers
  • 3 CAC
  • 2 SW Pumps


What combinations of equipment meet the 100% containment cooling capability with the MSIV Bypass valves open?

  • 2 Spray Pumps
  • 2 Spray Headers
  • 2 CACs
  • 2 SW Pumps


  • 1 Spray Pump
  • 1 Spray Header
  • 3 CAC
  • 3 SW Pumps


When is FS-0885 required to be available?

When in Modes 1 and 2, FS-0885, Service Water Loss in Containment Flow shall be available.


How does N2 backup interact with CV-0847 and CV-0824?

N2 Station 1A backs up IA for CV-0847, SW Supply to Cont

Functional 54 to 150 psig.

N2 Station 3B 

Functional 73 to 130 psig

  • If 1A AND 3B non-functional - T.S. 3.7.8
    • Would need 2 SW pumps to maintain 100% Cooling