CVCS Flashcards
What is the design purpose of the CVCS system?
- RCS Volume Control
- Maintain chemistry TS limits assuming 1% failed fuel
- Manages Liquid Radwaste
- A single charging pump has sufficient capacity to replace the flow lost due to leaks in small RCS lines, like sample and instrument lines
- Measure RCS fission product activity
- The Refueling Water Tank (RWT) provides a borated water source for safety injection post Loss of Coolant accident, providing 20 minutes of full ESF pump flow prior to sump recirculation.
- Ensures enough boric acid to make the reactor subcritical (Adequate Shutdown margin)
Provides seal injection to RCP seals and accepts seal bleed off, aux spray to pressurizer
Where in the RCS is Letdown tapped off from?
Letdown taps into the RCS between the #2 SG and the 2B RCP (suction side of pump)
What is the purpose of the delay coils?
Allows sufficient time for N-16 decay
1-2” letdown line splits into 2-12’, 16” delay coil pipes
What is the purpose of the Regenerative Heat Exchanger (CHN-E01)?
Conserve thermal energy by transferring heat from the letdown to charging
Minimize thermal shock on the RCS inlet nozzle
Maintains letdown outlet temp less than 450 degrees F under normal operating conditions
What type of valve operator is CHB-UV-515, Letdown Line to Regen Hx?
How does it fail?
When will it auto close?
Can the close signals be overridden?
Is this valve a containment isolation valve?
Air operated
fails closed on loss of air or PKB
SIAS
High temp of 413*F
SIAS can be overridden
Hi temp cannot
No
What type of valve operator is CHA-UV-516, Letdown Line Containment Isolation valve?
How does it fail?
When will it auto close?
Can the close signals be overridden?
Air operated
Fails closed on loss of air or PKA
SIAS or CIAS
both can be overridden
Tech Spec Containment isolation valve
What type of valve operator is CHB-UV-523, Letdown Line Containment Isolation valve?
How does it fail?
When will it auto close?
Can the close signals be overridden?
Air operated
Fails closed on loss of air or PKB
CIAS
LDHX outlet temperature Hi- 135 degrees F
CIAS can be overridden
LDHX outlet temperature Hi Can be overridden if confirmed the high temp condition is invalid, take HS to OPEN
Tech spec containment isolation valve
What is the purpose of the letdown HX?
Reduces letdown temperature from <450 degrees F to 120 degrees F to prevent damage to resin.
Is the Letdown Hx an NC priority load?
No
To what temperature is the LDHX outlet temperature normally controlled?
What is the tech manual/specification setpoint?
What is the maximum flow rate for the LDHX?
Why is this important?
100*F
120*F
1500 gpm
there has been OE with trying to maintain 100*F in the middle of summer and exceeding the 1500 GPM max flow criteria. the expectation is to raise temp setpoint to 120 before we consider exceeding 1500 GPM flow
How does the plant respond to the LDHX outlet temperature reaching 125*F
135*F?
125* CR alarm
135*
shifts 521/520 to bypass RU-155D/ Boronmeter and IOX’s from high temperatures
CHB-UV-523 closes (Lose letdown)
148 degrees F, LDBPCV’s go closed
What is the purpose of CHE-LV-110P/Q, Letdown control valves?
control Pzr level
Pressurizer Level Control System (PLCS)
What type of valve operator is CHE-LV-110P/Q, Letdown control valves?
How does it fail?
When is indication lost?
How many LDCVs normally inservice?
When would that be different?
air operated
fails closed on loss of air and NNN-D11
loss of NKN-D42
1 normally inservice
have two inservice during startup (<1000) and during cooldown (<1050)
If we had two LDCV’s inservice when above 1200 psia in the RCS, what would happen?
lift the Letdown Intermediate Pressure Relief Valve (PSV-345)
What is the purpose of the Letdown Intermediate Pressure Relief Valve (PSV-345)?
What pressure does it lift?
Where does it relieve to?
protect piping upstream of the LDHX
600 psig
to the EDT
What type of valve operator is Letdown Control Bypass Valve, CHN-HV-526?
How does it fail?
solenoid valve
fails closed on loss of NK
What is the purpose of the Letdown Control Bypass Valve, CHN-HV-526?
when would we open it?
what is different about this valve’s controls on the board?
Provides 1/2 gpm flow around letdown control valves to warm the regenerative heat exchanger in the event letdown was secured.
If letdown was lost for 22 minutes or more and RCS temperature is > 130 degrees F.
Open CHN-HV-526 for at least 4 minutes .
Captive key switch (closed/ Locked open-captive part)
What is the purpose of the Letdown Backpressure Control Valves (CHE-PV-201P/Q)
maintain letdown backpressure to prevent steam voiding in the LDHX
What type of valve operator is CHE-LV-110P/Q, Letdown control valves?
How does it fail?
what signal auto closes these valves?
When do you lose indication?
What pressure are these valves normally set to maintain?
How many normally in service?
when does that change?
air operated
fails closed on loss of air or NNN-D12
LDHX temp hi hi (148*F)
loss of NKN-D42
375 psig
1 normally in service
During Low pressure operations, the second one is placed in service
<750 psia, 2nd placed in service
>1000 psia, 2nd is removed from service
What is the purpose of the Letdown purification filters (F19/ F36)?
how many normally in service?
Remove particles from letdown flow, to prevent clogging the Letdown Ion Exchanger
One filter is normally in-service
What is the purpose of the Boronometer/ Process Rad Monitor Flow Control Valve (CHE-FV-204)?
how is it operated?
how does it fail?
maintains normal 8 gallons per minute through boronometer vessel and RU-155D line
air operated
fails open on a loss of air or NK
What is the purpose of the Process monitor flow control valve (CHE-UV-521)?
how is it operated?
how does it fail?
when does it auto shift to bypass?
Protects RU-155D
used to protect boronometer (abandoned in place, internals removed)
air operated
fails to BYPASS on low of air or NK
LDHX temp hi - 135*F
What type of monitor is the Letdown Process Radiation Monitor (SQN-RE-155D)?
what type of radiation does it detect?
What is its purpose?
area monitor
gamma radiation
alarms based on dose rates calculated for 1% failed fuel isotopic mix (cladding failure/fuel damage)
What is the purpose of the Ion Exchanger Bypass Valve (CHE-UV-520)?
How is it operated?
how does it fail?
when does it auto shift to bypass?
protects resin from damage due to high temperature
air operated
fails to bypass on loss of air or NK
LDHX high temp - 135*F