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
What is the purpose of the let down flow control valves? How many are there?
to maintain pressurizer level
2
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
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 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