CH- Chemical and Volume Control System Flashcards
When does the Charging system provide auxiliary spray to the pressurizer?
final stages of plant shutdown when RCS pressure is too low to operate RCPs
during natural circulation
What does auxiliary pressurizer spray allow the operator to control manually?
pressure and pressurizer cooldown
When will the letdown line penetrating containment automatically isolate?
SIAS
CIAS (containment isolation actuation signal)
What CVCS containment penetrations will automatically isolate and what actuation signals will isolate them?
letdown line- SIAS or CIAS
RCP seal controlled bleed off flow- CSAS
RDT outlet-CIAS
What chemistry and purity control does CVCS accomplish in the RCS?
corrosion
pH
remove corrosion and fission products
remove dissolved/entrained gases
CVCS maintains RCS inventory control. What does is it make up for?
small leaks
make up necessary for safe shutdown during natural circulation
CVCS provides RCS reactivity control. How does it accomplish this?
maintain boron concentration during normal operation and dilution
borate RCS for safe shutdown during nat. circ.
detecting and terminating an inadvertent deboration that would cause a loss of shutdown margin
RWT sized to fill the refueling pool and transfer canal
CVCS process indication provides a means to identify and quantify what?
normal RC leakage
What is provided to identify the occurrence of a letdown line break outside containment?
instrumentation
What support functions does CVCS provide?
alternate make up to S/G
Spent fuel pool make up
forward flow testing SI check valves
alternate control for RCS inventory when leakage through RCP seals is less than or equal to 83gpm
What is the maximum administrative rate to heat up the RCS for CVCS to accept letdown?
75*F/hr
What is the maximum administrative rate of cooling the RCS for CVCS to make up using 2 of 3 CH pumps?
75*F/hr
Where does the Letdown line take suction from in the RCS?
up stream of the RCP on the 2B leg
What is the purpose of the delay coils?
to allow N-16 to decay for 95 seconds before continuing in the system
half life of N-16 is 7 seconds
What is the purpose of the CHB-UV-515 and CHA-UV-516 valves?
containment isolation
What is the purpose of the regenerative heat exchanger?
to increase system efficiency by reclaiming some of the heat from letdown and heating up the charging flow back into the RCS
This helps letdown to temp (<100F) suitable for purification ix, minimize thermal transients on charging nozzles & conserve RCS heat
What is the purpose of the let down flow control valves? How many are there?
to maintain pressurizer level- by adjusting letdown flow via PLCS and reducing letdown pressure
2 (CHE-LV-110P & CHE-LV-110Q)
Where does SDC tap into the CVCS system and why?
upstream of the letdown heat exchanger
enables purification during shutdown conditions
What cools the letdown heat exchanger?
nuclear cooling water maintains outlet temp of 115F
What is the purpose of the valves down stream of the let down heat exchanger?
the back pressure control valves maintain system pressure upstream of the heat exchanger to prevent flashing the coolant to steam when exiting the heat exchanger
What condition causes letdown to bypass the boronometer and radiation monitor?
high letdown temperature
How many ion exchangers are required for full letdown flow?
1 of 3
What are the three ion exchangers used for?
one is for deborating, another for delithiating, the third is for purification
How often is the delithiating ion exchanger in service?
for a short period every night
Why is lithium removed from the RCS?
pH control
How long does it take for the delithiating ion exchanger to exhaust? (EXPLANATION QUESTION)
the core cycle
When is the deborating ion exchanger used?
near the end of core life
In regards to the ion exchangers, what is done when there is a high temperature alarm?
Ix are bypassed to protect the resins
What is the downstream component of the ion exchangers? What is its purpose?
strainer
collect resin particles (fines)
What is the purpose of the VCT?
scavenge oxygen in the gas space (from adding Hydrogen)
RCS surge tank (for letdown/charging mismatch)
collect RCP seal bleed off for reuse
NPSH to charging pumps
Provide make up point for RCS
What happens when the VCT reaches a high water level (60% full)?
excess water is diverted to PHIX (Pre-holdup Ion Exchanger), the radioactive collection, processing and storage part of CVCS
What is the purpose of the gas space in the VCT?
filled with hydrogen, the letdown flow enters the VCT through the gas space and scavenges oxygen, thus aiding RCS chemistry
What is the normal status of the charging pumps?
1 always running- no auto control action from PLCS can stop this pump
1 normally running-pressurizer high level signal auto stops this pump
1 in standby-pressurizer low level signal will auto start standby pump and stops it when it clears
Where does charging flow re-enter the RCS after passing through the regenerative heat exchanger?
2A leg In the RCP discharge
Where does the aux spray line tap off the main charging line?
after the regenerative heat exchanger
Where are the delay coils located?
inside bio-shield wall, 110’ near RCP 2B
When does CHB-UV-515, Letdown to Regenerative HX isolation valve, close automatically?
SIAS
413*F regenerative heat exchanger outlet temp
When does CHA-UV-516, Letdown to Regenerative HX isolation valve, close automatically?
SIAS
CIAS
When does the CHB-UV-523 close?
CIAS
let down heat exchanger high outlet temperature of 135*F
What temperature closes the let down heat exchanger outlet valve?
135*F
How are the regenerative heat exchanger isolation valves operated and how do they fail?
air operated
fail closed
Where can the regenerative heat exchanger isolation valves be operated from?
515 and 516:
control room
remote shutdown panel
523:
from control room only
If the CHB-UV-515 hand switch is in the local position, are the auto close features still available?
SIAS is not
Hi RHX out let temp is
Where are the UV-516, -516 valves located?
100’ containment, RCP 2B pump bay entrance
Where is UV-523 located?
aux building west wrap 90’ mezzanine
What type of HX is the RHX?
shell and U-tube
Where is the RHX?
110’ containment behind the elevator, above UV-515, -516
What are the letdown control valves?
CHE-LV-110P
CHE-LV-110Q
What is the purpose of the letdown control valves?
maintain pressurizer level by adjusting letdown flow
reduce let down pressure
How are the let down control valves operated and how do they fail?
air operated
fail closed
What maintains letdown flow between 30 and 135 gpm?
pressurizer level control system?
What determines the number of letdown control valves in service? Why?
While heating up, above 1000 psi only one valve is open to prevent lifting the relief valve
While cooling down, below 1050 psi, two valves are open to provide adequate letdown flow
What is the purpose of the letdown control valve bypass valve?
CHN-HV-526 is solenoid operated along with a flow orifice to allow .5 gpm to flow constantly to keep downstream components warm
When letdown is isolated for greater than 22 minutes, how long must CHN-HV-526 be open prior to initiating letdown flow?
4 minutes
Where are CHE-LV-110P and -110Q located?
Aux building 110’ and 100’ above and below each other, 110P on top
Where is CHE-HV-526 located?
aux building 100’
At what temperature is nuclear cooling water regulated to maintain the let down heat exchanger outlet?
~110*F
Where is the LDHX located?
aux building 100’ by CHE-LV-110Q
At what pressure do the letdown back pressure control valves maintain upstream? Downstream?
~375 psi
40-90 psi
What are the valve names for the letdown back pressure control valves?
CHE-PV-201P
CHE-PV-201Q
What auto closes the letdown back pressure control valves?
LDHX outlet temp of 148*F
loss of air
Where are the back pressure control valves located?
aux building 100’ and 110’, LDHX valve gallery
What is the lift pressure of the LDHX relief valves and where to they relieve to?
upstream is 600
downstream is 200
EDT
What are the two conditions in which the Letdown purification filters will be replaced?
D/P higher than 25 psi
filter rad levels exceed 5 R/hr
Where are the purification filters located?
aux building 120’
What does the RCS letdown radiation monitor detect?
SQN-RU-155 detects possible fuel cladding failure
Where is SQN-RU-155 located?
aux building 120’ next to boronometer room
What is the normal reading on SQN-RU-155? alert set point? high alarm set point?
10 mR/hr
85mR/hr
120 mR/hr
What is the purpose of the valves controlling flow or bypassing flow to SQN-RU-155?
allows 8 GPM to flow to it
bypasses on high letdown temp
What directs letdown flow through or around the CVCS ion exchangers?
a three way valve, CHE-UV-520
What causes the ion exchangers to be automatically bypassed?
high letdown temperature is 135*F
If CHE-UV-520 loses air or power, will the ion exchangers be in service or bypassed?
bypassed
What type of resin is used in the CVCS ion exchangers?
H-OH mixed bed
When is lithium added and removed from the RCS?
added at the beginning for pH control due to high boron concentration
removed nightly for pH control as boron concentration lowers through core life
To remove boron, is anion or cation resin used?
anion
When valving in a CVCS ion exchanger, what is the rate at which it is valved in? How long does it take to see a change in the RCS?
slowly
7 minutes
How does letdown temperature affect RCS temp?
higher letdown temp. makes resin release boron, raising RCS concentration and lowering RCS temp.
lower letdown temp, makes resin absorb more boron, lowering RCS concentration and raising RCS temp.
The AO can affect letdown temp. with changes in:
nuclear cooling water and plant cooling water through the nuclear cooling heat exchanger
What is the capacity of the VCT?
4900 gallons
Why is it important to remove oxygen from the RCS?
to prevent corrosion
What is the normal VCT pressure?
20-25 psig
How does the VCT pressure affect RCP bleed off flow rate?
increases the back pressure for the bleed-off flow, decreasing the flowrate
When and why is nitrogen added to the VCT?
during shutdown to ensure that oxygen does not collect in the VCT
Are the RWT and RMWT borated or unborated?
RWT is borated
RMWT is unborated
What do the RWT and RMWT have to do with RCS dilutions?
both tanks supply borated and unborated water to be blended to a specific boron concentration and is added to the VCT
What are the purposes of the dry and wet reference legs on the VCT?
dry leg provides auto make up
wet leg provides high and low level actuations
Where is the VCT located?
aux building 120’
What are the main purposes of the charging pumps?
provide charging flow from the VCT, RWT or SFP to the RCS, seal injection and aux spray
RCS boration
What is the discharge flow, discharge pressure and power origin for the charging pumps?
44 gpm each
2375 psig
class 480v LC (PG power)
In regards to the always running charging pump, What can automatically stop the pump? The normally running pump?
nothing
pressurizer high level signal
What auto starts the standby charging pump?
pressurizer low level alarm
What prevents the E charging pump from being powered from both PGA and PGB at the same time?
Two breaker cubicles, only one breaker
disconnect switch operation for pump
Describe the charging pump seal water system.
controls reactor coolant leakage from the pump seal
seal water pump starts when its respective charging pump starts
for testing, the seal lube water pump is ran for 10 minutes prior to running charging pump
How long, in an emergency situation, can the charging pumps run without seal lube water?
50 hours
seal water expansion tank automatically makes up from where?
RMW header
What is used in the suction of the charging pumps to reduce pressure surges and vibration?
suction stabilizers
Describe the suction stabilizers.
10 gallon capacity with nitrogen charged bladder and flow detector. charged to 19 psi
Describe the charging pump pulsation dampeners.
located in the discharge piping, 1500 psi nitrogen charged bladder, spring loaded poppet and a fixed flow diversion baffle
In regards to the charging pumps pulsation dampeners, bladder pressure is adjusted during startups and shutdowns, what is the pressure range and target?
30-70% of CH header pressure with a target of 60%
Where are the charging pumps located?
aux building 100’
What charging system valve is required by the NRC to have its respective breaker locked open?
CHA-HV-524, charging pumps discharge header to RHX isolation valve
What does CHE-PDV-240 do?
the charging line backpressure control valve ensures proper distribution to aux spray and RCP seal injection
Check valve CHE-V435 ensures how much PSI backpressure for aux spray and seal injection?
200psi
What is the purpose of CHB-HV-203 and CHA-HV-205, pressurizer aux. spray valves?
provide pressure control to the pressurizer when main flow is unavailable
isolate CH from the RCS
What are the tech specs related to the charging pumps?
While shutdown:
at least one charging pump, HPSI or LPSI must be functional in the boron injection flow path (mode 5, 6)
While operating:
two charging pumps shall be functional (mode 1-4)
What is the tech spec related to the Aux. spray valves?
Both shall be functional is modes 1-4
What does the flex strategy consist of?
using both on-site and off-site equipment for longer-term response to emergency situations
What is the purpose of the RDT?
Receives discharge from pressurizer safety valves, SDC and SI relief valves, RCP seal bleed off drains and drains and leakages from containment
What pressure is the nitrogen blanket held at in the RDT
.5 psig
What is the minimum quench volume of the RDT?
52%
What psi is the RDT rupture disk set at?
120 psid
Where is the RDT vented to when tank pressure is under 10 psi?
gaseous radwaste
Where is the RDT vented to if tank pressure is above 10 psi?
containment atm
Where is the RDT located?
containment 80’
What is the purpose of the EDT?
receives drainage from recycle drain header and ion exchanger drain header, gas stripper bypass and misc. relief valves outside containment
What is the nitrogen blanket pressure in the EDT?
3 psig
Where does the EDT relieve to on over pressure?
non-esf sump
Where is the EDT located?
aux. building 40’
What is the purpose of the reactor drain pumps?
transfer contents from the RDT or EDT through the reactor drain filter to the PHIX
What is the capacity of the reactor drain pumps?
50 gpm
What prevents both reactor drain pumps from running?
interlocks
How do the reactor drain pumps stop automatically?
low tank levels in RDT or EDT
Where are the reactor drain pumps located?
aux building 40’
What is the purpose of the pre hold up ion exchanger (PHIX)?
letdown purification with abnormally high levels of radionuclides or contaminants
reduces chemical contaminants prior to BAC
What is the maximum letdown flow rate through the pre hold up ion exchanger?
150 gpm
What process liquids does the PHIX purify?
reactor drain pump discharge
VCT diversion
CVCS hold up tank pump discharge
Is the PHIX in service or bypassed when letdown is to be returned to the VCT?
bypassed
How is resin replacement accomplished in the PHIX? Where is the spent resin sent?
sluicing
to solid radwaste
What is the purpose of the gas stripper?
removes non-condensable gases from letdown
What is the purpose of the RCP seal injection?
cool seal cavity and flushes the seal cavity of CRUD
Where is RCP seal bleed off directed to?
bleed off flow is directed to the VCT
face seal leak off is directed to the RDT
What is the flow path for the RCP seal injection water?
Charging pumps send water through a temperature protection isolation valve, then through a HX, through two seal injection filters, and a flow control valve, then into four branches, each going to one RCP
In the case of a containment isolation, where is the RCP controlled bleed off directed to via relief valve?
RDT
What components are in the chemical addition unit for the CVCS system?
Chm. add tank, outlet strainer, pump
Where does the chemical addition pump discharge in to the CVCS system?
upstream of the RHX
How many of the RCP seal water injection filters are normally in service?
1 of 2
What chemicals are added to the chemical addition tank in the CVCS?
lithium, hydrazine and hydrogen peroxide
What is the capacity of the chemical addition tank in the CVCS?
8 gallons
What is the capacity of the CVCS chemical addition pump?
25 gph at 2735 psig
What lithium isotope is added to the RCS?
Li-7
Why is hydrazine added to the RCS during start up?
scavenges oxygen after RCS is filled and vented
Why is hydrogen peroxide added to the RCS?
initiates a CRUD burst
What are the three general areas the radioactive collection, processing and storage subsystem receive water from?
letdown diverted from the VCT
RDT
EDT
What is the purpose of the Reactor drain pumps?
sends the RDT and EDT flows through the reactor drain filter to the PHIX or PHIX bypass
At what high temp. is the PHIX bypassed?
140*F
What does the PHIX remove from the system?
resin
lithium
other ionic radio nuclides
Where does flow go after the PHIX?
gas stripper or gas stripper bypass
What happens when there are gas stripper trouble conditions?
flow is diverted back to the EDT
What are the two possible flow path destinations after the CVCS gas stripper? What is the normal line up?
VCT or hold up tank
VCT
When the VCT reaches a high level, where is the gas stripper outlet flow directed to?
hold up tank
What processes the contents of the hold up tank when it reaches capacity?
boric acid concentrator
In the gas stripper, to what temp. does the heat recovery heat exchanger bring incoming water?
150*F
What is used to heat the flow through the gas stripper package pre heater? What temp. does it bring the flow to?
aux. steam
240*F
What happens in the stripper column of the gas stripper package?
dissolved non-condensable gases are removed
gases rise into the overhead condenser
liquid goes to the suction of the pump
How does the reboiler aid in the stripping process of the stripper column of the gas stripper package?
reboiler heats and steams a small portion of the liquid flow out of the stripper column and heats the stripper column flow
In the gas stripper package, what does the overhead condenser do? What is it cooled by?
reduces gas volume and condensation leaving the stripper column
nuclear cooling water
In the gas stripper package, what purpose does the condensate pot?
collects residual moisture in the gas going to the over head condenser
What temperature is the stripped liquid coming out of the gas stripper after cooler? What cools the after cooler?
130*F
nuclear cooling water
Is the Reactor make up water tank borated?
no
Where do the RMW pumps send flow to?
VCT/CH pump suction
RWT
EDT
RDT
gas stripper
What is the boron concentration of the RWT?
4000-4400
Where do the BAMPs send water to?
VCT/CH pump suction
boric acid batch tank
SFP
SFP clean up
Where can the RWT gravity feed to?
CH pump suction
SI pumps
Can the CH pumps supply the SFP with borated water?
yes
Where does the borated water and non borated water mix to supply make up to the VCT?
blending Tee
What are the outlet flows of the RMWT?
alternate source for Aux. feed pumps
dilution water for RCS
water for in-plant use
What is the capacity and minimum temperature of the RMWT?
480k
40*F
Where does the RMWT over flow to?
CVCS hold up sump
What are the normal and alternate make up water sources of the RMWT?
DW normal
Recycle monitor tank is alt
What are the RMWPs powered from?
NH
What is the status of the RMW recirc valve when dilution flow is below 20 GPM? When is it closed?
open
full dilution flow
What is the purpose of the RMW flow control valve?
measures the flow rate to the RCS and boric acid batch tank and adjusts position
What is the purpose of the RWT?
Provide suction flow to ESF pumps and RCS make up through CH
What is the capacity of the RWT?
750,000
What is the temp. range of the RWT?
60-120
Where is the normal make up supplied from to the Refueling Water Tank?
CVCS hold up tank
What is done shortly before the outage to ensure maximum capacity of the RWT?
boric acid batching
What is used to transfer water from the SITs to the RWT?
LPSI or CS pump
What are the level detections associated with the RWT?
level for isolation on RAS and LPSI trip
to stop BAMPs on low level
level indication and CR alarms
What is the purpose of the BAMPs?
provide borated water to VCT
CH suction
SFP
What are BAMPs powered from?
NH
What is the capacity of the BAMPs based on?
to individually exceed all three charging pumps
What is the purpose of the BAMP recirc valve?
opens when boration flow is less than 20 GPM
closes on full boration flow
What does the boric acid flow control valve measure to position the valve properly?
flow rate from the refueling water tanks to the blending tee
What is the purpose of the boric acid batch tank?
to batch crystalline boric acid with water for adjusting boric acid concentrations in the RWT
To what temperature do you raise the water in the boric acid batch tank to keep boric acid in solution?
155-160*F
At what point is the boric acid powder added to the boric acid batch tank?
> 155*F
What is the motive force to draw boric acid out of the BABT through the eductor to the RWT?
RMWP or BAMPs
What is the motive force flow of the BABT eductor?
33 gpm
In what modes of operation should the RWT be operable? What are the limit requirements?
1-4
temperature, boron concentration and volume
In modes of operation 5 and 6, what borated sources of water must be functional for reactivity control?
spent fuel pool
RWT
How many gravity feed flow paths must be functional from borated sources to RCS during operation? During shutdown?
two
one
What modifications were made to the CVCS to support loss of all AC guidelines?
Using FLEX pumps that take suction from various points on the RWT and injecting that supply into the HPSI discharge headers, or FLEX SFP make up pump suctions when CST is making up SGs
