CH- Chemical and Volume Control System Flashcards
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 purpose of the boric acid batch tank?
to batch crystalline boric acid with water for adjusting boric acid concentrations in the RWT
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
Is the PHIX in service or bypassed when letdown is to be returned to the VCT?
bypassed
What is the temp. range of the RWT?
60-120
Where is the EDT located?
aux. building 40’
In the case of a containment isolation, where is the RCP controlled bleed off directed to via relief valve?
RDT
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
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 purpose of the gas stripper?
removes non-condensable gases from letdown
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 capacity of the reactor drain pumps?
50 gpm
What is the maximum administrative rate of cooling the RCS for CVCS to make up using 2 of 3 CH pumps?
75*F/hr
To remove boron, is anion or cation resin used?
anion
What is the purpose of the reactor drain pumps?
transfer contents from the RDT or EDT through the reactor drain filter to the PHIX
Where can the regenerative heat exchanger isolation valves be operated from?
515 and 516:
control room
remote shutdown panel
523:
from control room only
seal water expansion tank automatically makes up from where?
RMW header
Where is the RDT located?
containment 80’
In what modes of operation should the RWT be operable? What are the limit requirements?
1-4
temperature, boron concentration and volume
Where is SQN-RU-155 located?
aux building 120’ next to boronometer room
The AO can affect letdown temp. with changes in:
nuclear cooling water and plant cooling water through the nuclear cooling heat exchanger
What type of resin is used in the CVCS ion exchangers?
H-OH mixed bed
How long does it take for the delithiating ion exchanger to exhaust?
the core cycle
Where are the UV-516, -516 valves located?
100’ containment, RCP 2B pump bay entrance
When does the CHB-UV-523 close?
CIAS
let down heat exchanger high outlet temperature of 135*F
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 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 minimum quench volume of the RDT?
52%
When and why is nitrogen added to the VCT?
during shutdown to ensure that oxygen does not collect in the VCT
How many ion exchangers are required for full letdown flow?
1 of 3
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 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
When is the deborating ion exchanger used?
near the end of core life
At what pressure do the letdown back pressure control valves maintain upstream? Downstream?
~375 psi
40-90 psi
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.
Describe the suction stabilizers.
10 gallon capacity with nitrogen charged bladder and flow detector. charged to 19 psi
What is the capacity of the RWT?
750,000
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
How are the let down control valves operated and how do they fail?
air operated
fail closed
Where are the charging pumps located?
aux building 100’
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)
Where is the RHX?
110’ containment behind the elevator, above UV-515, -516
At what point is the boric acid powder added to the boric acid batch tank?
> 155*F
What is the purpose of the CHB-UV-515 and CHA-UV-516 valves?
containment isolation
Where does flow go after the PHIX?
gas stripper or gas stripper bypass
What is the lift pressure of the LDHX relief valves and where to they relieve to?
upstream is 600
downstream is 200
EDT
When letdown is isolated for greater than 22 minutes, how long must CHN-HV-526 be open prior to initiating letdown flow?
4 minutes
CVCS process indication provides a means to identify and quantify what?
normal RC leakage
At what high temp. is the PHIX bypassed?
140*F
In regards to the always running charging pump, What can automatically stop the pump? The normally running pump?
nothing
pressurizer high level signal
Why is it important to remove oxygen from the RCS?
to prevent corrosion
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 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
In regards to the ion exchangers, what is done when there is a high temperature alarm?
they are bypassed to protect the resins
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
Where is the RDT vented to if tank pressure is above 10 psi?
containment
What is the purpose of the letdown control valves?
maintain pressurizer level by adjusting letdown flow
reduce let down pressure
Where are CHE-LV-110P and -110Q located?
Aux building 110’ and 100’ above and below each other, 110P on top
How many of the RCP seal water injection filters are normally in service?
1 of 2
What temperature closes the let down heat exchanger outlet valve?
135*F
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 does the EDT relieve to on over pressure?
non-esf sump
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
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
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
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 BAMP recirc valve?
opens when boration flow is less than 20 GPM
closes on full boration flow
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 discharge flow, discharge pressure and power origin for the charging pumps?
44 gpm each
2375 psig
class 480v LCs
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
What is used in the suction of the charging pumps to reduce pressure surges and vibration?
suction stabilizers
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
What process liquids does the PHIX purify?
reactor drain pump discharge
VCT diversion
CVCS hold up tank pump discharge
What is the motive force to draw boric acid out of the BABT through the eductor to the RWT?
RMWP or BAMPs
Where do the BAMPs send water to?
VCT/CH pump suction
boric acid batch tank
SFP
SFP clean up
Where do the RMW pumps send flow to?
VCT/CH pump suction
RWT
EDT
RDT
gas stripper
Can the CH pumps supply the SFP with borated water?
yes