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
On a loss of power or high temperature signal to the Ion Exchanger Bypass Valve (CHE-UV-520), what must be done in the CR?
reset the handswitch so the valve will come out of bypass
three position switch (ION X/Normal/Bypass)
What is the purpose of the Low Pressure Letdown Relief Valve (CHN-PSV-354)?
at what pressure does it lift?
where does it relieve to?
protect the boronometer from over pressure
200 psig
relieves to the EDT
How does Letdown temperature affect ION exchanger affinity for boron?
What happens to the resin if temperature gets too high?
lower temp, more boron absorbed (RCS concentration lowers)
higher temp, less boron absorbed (RCS concentration raises)
resin melts
What is the purpose of the Purification and Deborating Ion Exchangers (CHN-D01A, D01B, D02)?
How are they used in the plant?
remove ionic impurities, particulates, and radionuclides from RCS
1 is always in service for mechanical filtering and boron control (lithium saturated)
1 is a delithiating bed to control lithium concentration (pH) (boron saturated)
1 is a deborating bed to remove boron at end of core life
When placing a standby or previously isolated IOX in-service, what must be done prior?
IOX must be pre-borated
If not could inadvertently add positive or negative reactivity
what is the purpose of the Volume Control Tank Inlet Valve (CHN-UV-500)?
how is it operated?
how does it fail?
when does it auto divert?
Control letdown flow to the VCT
air operated
fails to VCT on loss of air or NK
60% VCT level, resets at 58%
What must be done to reset the Volume Control Tank Inlet Valve (CHN-UV-500) on a loss of power?
take handswitch to VCT reset
Where does the Volume Control Tank Inlet Valve (CHN-UV-500) divert to?
how does the plant respond to a divert signal?
from VCT to the Pre-Holdup IOX (PHIX) then towards gas stripper (bypassed) and on to the CVCS HUT
diverts UV-500 to PHIX
stops reactor drain pumps
stop CVCS HUT pumps if V686 is open
How does Letdown support Shutdown Cooling?
provides purification
receives water flow from SDC just downstream of the LDCV’s and sends the water back to SDC downstream of the IOX but upstream of UV-500
What could bring in this alarm?
Any of a number of LD parameters out of range
including
LD temperatures, pressures and flows HI
LD filter and IX DPs HI
NC Temperature HI
LD Hdr Backpressure HI or LO.
What could bring in this alarm?
LD Radiation Monitor Flow HI-LO
High: 9.5 gpm
Low: 6 gpm
What components in the Letdown subsystem have SESS alarms?
CHB-UV-515
CHA-UV-516
CHB-UV-523
Where do the Charging Pumps receive power from?
PGA-L31 - ‘A’ CHP
PGB-L32 - ‘B’ CHP
PGA-L35/PGB-L36 - ‘E’ CHP
breaker has to be moved between L35 and L36
power also goes through the disconnect switch on 100’ Aux Building
What is the normal flow rate of each charging pump?
Normal discharge pressure?
44 gpm
2375 psig
What purposes do the charging pumps provide?
RCS makeup
RCP seal injection
Aux spray flow
What are some indications of gas binding in all the charging pumps?
Charging header flow fluctuations
Charging header pressure fluctuations
Charger header flow less than expected for running Charging pumps
Charging suction source (VCT, RWT) level lost
isolation of letdown due to a Regenerative Heat Exchanger outlet temperature.
What suction flow paths are available for the charging pumps?
VCT through V501
VCT makeup through 210X/Y
BAMP through V514
RWT through V536
RWT through alternate RWT suction V327
Where can the charging pumps discharge to?
Charging header - into RCS between RCP 2A and Rx vessel
HPSI ‘A’ cold leg
HPSI ‘B’ hot leg
What is the low suction pressure trip for the charging pumps?
Purpose of this trip?
13 psia
Anti pumps CHP
prevent cavitation damage
Where is the Rem/Local switch located for the ‘B’ charging pump?
what automatic features are still avail
PGB-L32
trips on low suction pressure and electrical protection
What are the charging pump handswitch positions?
Auto-After-Start (Red Flagged)
- pump doesnt respond to PLCS but will still trip/load shed as needed
Auto-After-Stop (Green Flagged)
Pull-To-Lock (PTL)
Stop
How are charging pump lockout relays reset in the control room?
take handswitch to STOP position
What do the positions mean on the 4 position charging pump mode selector switch?
First pump listed is ‘always running’ (NKN-D42 is sending this signal)
Second pump listed is ‘normally running’ (NNN-D11 signal from PLCS)
Third pump listed is ‘standby’
What is ‘Mode 1’ in the Load sequencer regarding the charging pumps and how are they operated?
SIAS or CSAS
Pumps not tripped (What was running before stays running)
Load Sequencer prohibits auto-starts for 40 seconds
After 40 seconds pumps can auto-start
What is ‘Mode 2’ in the Load sequencer regarding the charging pumps and how are they operated?
LOP and SIAS (Mode 2)
Pumps load shed For 40 seconds after DG output breaker closes
load sequencer blocks auto-start signals
When 40 seconds is up, PLCS can start as needed.
Pumps will start by PLCS if green flagged.
What is ‘Mode 3’ in the Load sequencer regarding the charging pumps and how are they operated?
LOP/ No SIAS
All Charging Pumps that were running are stopped and anti-pumped from locked in NKN-D42 signal.
Pumps can be manually re-started by green flagging the associated pump HS. (Green flagging means go to Stop)
What is ‘LOOP’ in the Load sequencer regarding the charging pumps and how are they operated?
Always running charging pump anti-pumped (locked in NKN-D42 signal)
Normal and standby controlled by PLCS
How does the PLCS control the Normally running and Stanby Charging pumps?
Normally Running
○ Stops at +15% level deviation going up
○ Starts at +14% level deviation going down
Standby
○ Starts at -23% level deviation going down
○ Stops at -14% level deviation going up
How long before PLANNED charging pump runs does the seal lube pump need to run?
10 minutes
How long can you run a charging pump without seal lube?
</= 50 hours (emergency use only)
What is the purpose of the suction stabilizers?
What pressure are they maintained at?
Absorbs pressure surges in the charging pump suction piping
19 psig Nitrogen bladder
What is the purpose of the discharge dampeners?
What pressure are they maintained at?
absorb pressure fluctuations dude to the pumps being PDPs
1500 psig N2
Adjust N2 pressure to RCS pressure/ Charging header discharge header as cooled down
When the charging pumps are gas bound, where do you vent them to?
If VCT level is > 0%, vent to recycle drain header
If VCT level is < 0%, vent to Vent Receiver tank
What is the Gas binding OE for the Charging Pumps?
Gas went backward through the pump plate valves (check valves?) to lower pressure side of piping.
It expanded on suction pressure side and gas bound all three charging pumps
The thought is that the standby charging pump would have to be the one to fail to get the three Charging Pump loss
Why is CHA-HV-524, Charging Header Isolation Valve, so important?
Where does it receive power from?
It is the outside Containment isolation valve.
NRC requires it the power supply breaker be locked open to prevent isolating Aux. Spray.
PHA-M35 powered, indication from M33
What is the purpose of CHE-HV-239, Charging Line Isolation Valve?
What operates it?
How does it fail?
The Charging Line Isolation Valve prevents the loss of Pressurizer Auxiliary Spray if PDV-240, Charging Line Back Pressure Control Valve, fails open.
Air operated
fails closed on a loss of air or NK
What is the purpose of CHN-PDV-240, Charging Line Back Pressure Control Valve?
What operates it?
How does it fail?
What back pressure does it maintain?
maintains sufficient charging header backpressure to provide Reactor Coolant Pump seal injection and Pressurizer Auxiliary Spray flow
Air operated
fails closed on a loss of air or power (NNN-D12)
105 psid
What is the purpose of the CHE-V435, Spring-Loaded Bypass Check Valve?
At what pressure does it open?
Ensures continued charging flow and sufficient backpressure to supply Reactor Coolant Pump seal injection and Pressurizer Auxiliary Spray if PDV-240 and/or HV-239 fail closed
200 psid
What is the purpose of CHA-HV-205 and CHB-HV-203, Auxiliary Spray Valves?
How are they operated?
How do they fail?
Where is the Local-Remote disconnect for the ‘B’ train valve?
provide Pressurizer Pressure Control when normal pressure control is unavailable (loss of main spray from RCPs secured or loss of IA to containment)
solenoid valve
fail closed on a loss of PK
‘B’ Train valve local/ Local-Remote disconnect at RSP
What is the purpose of CHE-UV-231P, RCP Seal Injection Isolation Valve?
How is it operated?
How does it fail?
Original design was to control flow through the Seal Injection Heat Exchanger.
It is now fully open or fully closed.
air operated
fails open on a loss of air or NK
When does CHE-UV-231P, RCP Seal Injection Isolation Valve auto close?
Seal Injection Temperature:
HI-Hi (150F)
Lo-Lo (70F)
What type of valve operator does CHB-HV-255, RCP Seal injection header isolation valve (containment isolation valve) have?
Where does it receive power from?
How does it fail?
Motor operated
PHB
As is
How are CHE-FV-241/242/243/244, RCP Seal Injection Flow Control Valves operated?
How do they fail?
Reverse acting or direct acting?
Air operated
fails open on a loss of:
air (loss of NKN-D42)
power (D11 - 241/242: D12 - 243/244)
reverse acting:
Output- 0%- Valve Open
Output- 100%- Valve Closed
When shall RCP seal injection be inservice?
when can it NOT be inservice?
prior to 195*F or 215 psia
stop seal engaged - damage seals
Where does RCP controlled bleed off normally go?
Where else can it go?
VCT
RDT
What type of valve operators do CHA-UV-506 and CHB-UV-505), Seal Bleedoff Containment Isolation Valves, have?
How do they fail?
When will they auto close?
air operated
fail closed on loss of air or PK
CSAS (override available)
What is the purpose of CHN-PSV-199, Seal Bleedoff Header Relief Valve?
When does it lift?
maintains controlled bleed off flow on a loss of PK to CHA-UV-506 and CHB-UV-505
225 psig
How is CHA-HV-507, Seal bleedoff Header Relief Valve Isolation Valve operated?
how does it fail?
air operated
fails open on a loss of air or PK
How do you calculate charging flow?
Charging = Letdown + Bleedoff (with NO RCS leakage)
What could bring in this alarm?
Charging parameters out of range:
* Charging Pumps to Regen Heat Exchanger Flow Lo
* Charging Pumps to Regen Heat Exchanger Press Lo
* Regen Hx to Loop 2A Diff Press Hi-Lo
* Charging Pump Electrical Protection Pre-trips
* Charging Pumps Not-In-Auto
* Charging Pump Oil pressure Lo
* Charging Pump Seal Lube Pressure Hi/Lo
* ‘E’ Charging Pump breaker misaligned
What could bring in this alarm?
Seal Injection parameters out of range:
* Seal Injection to RCP Flow Hi
* Control Bleed-off line pressure Hi
* RCP Seal Injection Filter DP Hi
* RCP Seal Injection HX Outlet Temp Hi-Lo
What could bring in this alarm?
Reactor Coolant Pump Seal Injection Temp Hi-Hi
Reactor Coolant Pump Seal Injection Temp Lo-Lo
What could bring in this alarm?
Seal Injection to Reactor Coolant Pump Flow Hi-Hi
Seal Injection to Reactor Coolant Pump Flow Lo
What could bring in this alarm?
Control Bleed-off flow line pressure is Hi-Hi
What components in the Charging system have SESS alarms?
CHA-UV-506
CHB-UV-505
How many gallons per % level in the VCT?
41 gal/%
What is normal VCT pressure?
What is the administrative lower pressure limit?
Why?
20-25 psig
No lower than 3 psig
could challenge charging pump suction pressure trip
What is normal VCT pressure?
What is the administrative lower pressure limit?
Why?
20-25 psig
No lower than 3 psig
could challenge charging pump suction pressure trip
What is the purpose of each VCT level transmitter, LT-226 and LT-227?
LT-226 (dry ref. leg) - Auto Make up
- maintains VCT level 34-44%
LT-227 (wet ref. leg) - Controls Divert and Lo-Lo levels
- @ 60% level, diverts through PHIX to HUT, resets @ 58%
- @ 5% level, VCT shifts CHP suction to 514 (Closes 501) or 536 if 514 doesn’t have power, resets @ 15% level
Why is VCT O2 concentration kept <2%?
reduce probability of explosive H2/O2 mixture
DO NOT add H2 with O2 >2%
Can CHN-UV-512 and CHN-UV-527 be open at the same time?
No
if 512 goes open when 527 is open, 527 will close
What is the purpose of CHN-UV-512, Normal VCT Makeup Supply Valve?
How is it operated?
How does it fail?
auto opens and closes during auto makeup
air operated
fail closed on loss of air or NK
What is the purpose of CHN-UV-527, Boric Acid Makeup to the Charging Pump Suction Valve?
how is it operated?
how does it fail?
provide flow to the suction of the CHPs when Make-up mode is not in Auto (Manual, dilute, or borate)
air operated
fails closed on loss of air or NK
What is the purpose of CHN-UV-514, Boric Acid Makeup to the Charging Pump Suction Valve?
how is it operated?
how does it fail?
provide flow to the suction of the CHPs
-Auto Opens
–5% VCT Lo-Lo level (LT-227)
-Auto Closes
–15% VCT Lo-Lo level clears (LT-227)
Motor operated (NH)
fails as is
What is the purpose of CHN-UV-536, RWT Gravity Feed to Charging Pump Suction Valve?
how is it operated?
how does it fail?
When does it automatically open?
gravity flowpath to charging pump suction
MOV (PHA-M35 through NHN-M72)
Fails as is
VCT Lo-Lo (5% LT-227) IF UV-514 has no power
What type of valve operator does CHN-V501, VCT outlet valve, have?
When does it auto close?
When does it auto open?
MOV (PHA-M35 powered through NHN-M72)
closes on VCT lo-lo
opens when lo-lo is clear
opens if there is no lo-lo and V536 is closed
Where does the VCT vent to?
Waste Gas Surge Tank (GR)
What is the basis of RMWT water volume?
provides sufficient RCS dilution to allow total recycle of the RCS. It also provides dilution for back to back shutdowns and subsequent startups at 90% core life.
How many RMW pumps normally running?
can you run both pumps at the same time?
1
no
Do the RMW pumps restart automatically on a restoration of power to the pump?
no
When do you get the blue light on the RMWP handswitch?
RMWT low level
Loss of Control Power
RMWP Low discharge pressure trip (85 psig)
What is the purpose of CHN-UV-511, Reactor Makeup water pump recirc valve?
When does it auto actuate?
How is it operated?
How does it fail?
allows the RMWP to run in recirculation through the RMW filter
closes when flow through CHN-UV-210X > 20 GPM
opens when flow through CHN-UV-210X < 10 gpm
air operated
fails closed on loss of air or NK
What happens to CHN-FIC-210X, Reactor makeup water controller, when you lose power to NHN-D28?
What is the status when power is restored?
What happens when there is a flow deviation from the setpoint?
controller fails to manual
valve fails closed
controller in manual and 0% output
operator must reset
CHN-UV-512 goes closed
What is the purpose of CHN-HS-37, Reactor makeup flow alarming switch?
In normal, alarm is non-functional
In refuel S/D position, the alarm is functional and alarms when water passes flow switch FSL-250 around 10 gpm
RMW trouble alarm
What is the boron concentration of the RWT?
4000-4400 ppm
where is the RWT vented to?
fuel building normal exhaust
What are the important RWT levels?
> 84.3% T.S. level @ 100% power
73% - BAMPs trip on RWT Lo-Lo level
9.4% - 2/4 channels are met, inputs to PP-ESFAS for RAS
What is special about CHN-HV-532, Boric Acid Makeup Pump Suction Isolation Valve?
How is it operated?
How does it fail?
hand-jacked open with air isolated to prevent isolating Boration Flow paths. (Modes 1-4)
Air operated
fails open on loss of air or NK
When will the blue light come on for the BAMP handswitches?
RWT Low level
Loss of control power
BAMP low discharge pressure trip
When the Makeup Mode Selector Switch, CHN-HS-210, is in Auto, what happens when level reaches 34%?
BAMP and RMWP start
CHN-UV-512 to the VCT opens
FV-210X and UV-210Y throttle open to present values
when flow reaches >20 gpm, recirc valves UV-510 and UV-511 close
44%, auto makeup stops
components revert to normal positions
When the Makeup Mode Selector Switch, CHN-HS-210, is in Manual, how is make up accomplished?
CHN-UV-527 opens allowing makeup flow to the charging pump suction.
BAMP and RMWP manually started
CHN-FV-210X and CHN-FV-210Y will start to modulate open to the preset values
When flow reaches 20 gpm the recirculation valves (CHN-UV-510 and CHN-UV-511) will close.
BAMP and the RMWP manually stopped, valves will revert to their normal positions
When the Makeup Mode Selector Switch, CHN-HS-210, is in Borate, how is make up accomplished?
The batch amount must be manually set on the boric acid flow integrator.
Boric Acid Makeup Pump will start.
CHN-UV-527 opens allowing boric acid flow to the charging pump suction.
CHN-FV-210Y will modulate open to the preset value of boric acid flow.
When flow reaches 20 gpm the recirculation valve (CHN-UV-510) will close.
When batch amount is completed, CHN-FV-210Y will automatically close
UV-510 opens (flow < 10 gpm).
When Makeup Mode Selector Switch moved out of BORATE position, Boric Acid Makeup Pump will automatically stop and CHN-UV-527 will close.
When the Makeup Mode Selector Switch, CHN-HS-210, is in Dilute, how is make up accomplished?
The batch amount manually set on the Reactor Makeup Water flow integrator.
Reactor Makeup Water Pump will auto start.
CHN-UV-527 opens
CHN-FV-210X will open to the pre-set value of Reactor Makeup Water flow.
When flow reaches 20 gpm, the recirculation valve (CHN-UV-511) will close.
When batch amount is completed, CHN-FV-210X will automatically close
CHN-UV-511 opens (flow < 10 gpm).
When Makeup Mode Selector Switch is moved out of DILUTE position, Reactor Makeup Pump will automatically stop and CHN-UV-527 will close.
If there is a change in boron concentration by more than 50 ppm, what has to be done?
start Pzr heaters to initiate spray flow to equalize the Pzr and RCS
Where does the Reactor Drain Tank receive inputs from?
Receives and condenses discharges from pressurizer safety valves to prevent release into containment
Receives SDC reliefs in containment
Drains from RCP vapor seal leakoff
Other various Rx quality water drains in containment
What is the over pressure on the RDT?
~.5 psig N2
What is the minimum quench volume of the RDT?
Purpose of the quench volume?
52%
condense Pzr safety relief steam flow
When does the RDT rupture disk rupture?
what purpose does this rupture disk serve?
120 psi
protects the tank if a Pzr safety gets stuck open
Where is the RDT normally vented to?
where else can it vent to?
GR header <10 psig
HV-923 to Containment when >10 psig
When does the RDT auto isolate?
What happens?
Hi-Hi RDT pressure @ 10 psig
Closes:
CHA-UV-560, RDT Outlet Isolation Valve
CHN-UV-540, RDT Vent Valve
How do CHA-UV-560/CHB-UV-561, RDT outlet isolation valves (containment isolation valves) fail?
What signals will these valves auto close on?
fail closed on a loss of air or PK
auto close on:
Hi-Hi RDT pressure @ 10 psig (cannot over ride)
CIAS (can be overridden)
How does CHN-UV-540, RDT Vent Valve fail?
What signal will this valve auto close on?
fail closed on a loss of air or NK
Hi-Hi RDT pressure @ 10 psig
How does CHN-UV-580, RDT makeup supply isolation valve (containment isolation valve) fail?
What signal will this valve auto close on?
fail closed on a loss of air or NK
CIAS
How does CHN-HV-923, RDT remote manual vent valve fail?
Solenoid valve
fails closed on loss of NK
What is the over pressure on the EDT?
~ 3psig N2
where is the EDT vented to?
how does pressure get reduced as it is being vented?
Auxiliary Building HVAC exhaust
CHN-PCV-568 reduces pressure going to the exhaust system
At what pressure does the EDT auto isolate?
7 psig
What is the minimum quench volume of the EDT?
35%
How does CHN-UV-563, Suction to RDT pumps from EDT fail?
fails closed on loss of air or NK
How does CHN-UV-562, Misc drains to EDT FCV fail?
When does it auto close?
fails closed on loss of air or NK
closes on EDT Hi-Hi pressure @ 7psig
How does CHN-UV-564, EDT to gas analyzer Isolation valve fail?
When does it auto close?
fails closed on loss of air or NK
closes on EDT Hi-Hi pressure @ 7psig
What is the purpose of the Reactor Drain Pumps?
Pump contents of EDT or RDT to the CVCS HUT
through the Rx drain filter, PHIX, Gas Stripper
When do the Reactor Drain pumps auto trip?
UV-560/561 open and Lo level in RDT
UV-563 open and lo level in EDT
if no flow path available (UV560/561/563 all closed)
letdown diverted to PHIX (prevent deadheading Rx drain pumps)
electrical protection
loss of control power
How does the Pre-holdup Ion Exchanger Temperature bypass valve (CHE-UV-565) fail?
When does it automatically shift?
Fails to bypass on loss of air or NK
Shifts to bypass on IONX high inlet temp @ 140*F
How does the Pre-holdup Ion Exchanger Outlet Valve (CHE-UV-566) fail?
when does it automatically shift?
fails to EDT on a loss of air or NK
shifts to EDT on gas stripper hi-hi
How does Gas Stripper outlet valve (CHN-UV-567) fail?
When does it automatically shift?
Fails to HUT o a loss of air or NK
shifts to HUT on VCT hi-hi level @60%
shifts back to VCT @ 58%
