Primary Chemistry Flashcards
State the four reasons for maintaining primary chemistry control.
Maintain Material Integrity
Minimize Corrosion
Reduce Radioactivity
Assist in Reactor Control
State the primary source of oxygen in the RCS at power.
Radiolytic decomposition of water
State the oxygen control agent is added to the RCS at power.
H2 blanket is established in the VCT
State where the oxygen control agent is added to the RCS at power.
H2 blanket is added to the VCT
State two reasons for the upper limit of the Oxygen control agent (when added at power)
Excess H2 is a waste
Greater H2 concentrations cause a problem degassing
Excess H2 an be an explosive concern
Name the oxygen control agent used in mode 5 and below
Hydrazine (N2H4) is added to the CVCS
state how the (mode 5 and below) control agent (Hydrazine (N2H4)) functions to reduce Oxygen
N2H4 + O2 => 2H20 + N2
State why the oxygen control agent used in mode 5 and below (Hydrazine N2H4) has an upper temperature limit of effectiveness
At greater than 200 degF Hydrazine breaks down
Hydrazine breaks down above 200 ° F so we do the additions in the 140 ° F to 180 ° F range
State the reason that the CVCS ion exchangers must be bypassed with the oxygen control agent present in the RCS coolant. (Mode 5 and below)
Decomposition products in Hydrazine will exhaust resin and cause release of chlorides into the RCS.
State the TRM temperature values where Oxygen limits are in effect
O2 limits are applicable when RCS is >250 degF
State the pH control agent added to the RCS
Li7OH (Lithium-7) is used to raise pH and offset the Boric acid
State the reason for using enriched Lithium-7 as pH control additive
Lithium-6 will generate tritium
State how excess Lithium is removed from the RCS
Cation demineralizer removes the excess lithium
State why the concentration of Lithium is allowed to lower over core life
as less Boron is needed to control reactivity, Less Lithium is required to maintain the pH
State two methods by which the demineralizer purifies water
Filtration
Ion Exchange
Given a list of Decontamination Factor values, choose the values that match the following conditions.
a. Newly regenerated resin. b. Completely exhausted resin. c. Resin approaching exhaustion.
25 - - a. Newly regenerated resin.
1 – b. Completely exhausted resin.
3-4 – c. Resin approaching exhaustion
What type of Resin is used in the NORMAL IN SERVICE Mixed Bed Demin?
Li7OH Mixed bed Resin
What type of Resin is used in the STANDBY Mixed Bed Demin?
HOH resin
What type of Resin is used in the CATION Demin?
H+ resin
What type of Resin is used in the DEBORATING Demin?
OH- resin intended to remove up to 50 ppm boron per bed
State two reasons for using the cation demineralizers
Remove radioactive impurities (Cs137)
control RCS Lithium
State when in core life a deborating demineralizer would be used and why
Deborating beds are designed to remove 50 ppm per bed
End of Core life is when they are used to avoid the massive dilution volumes that would be required.
State the effect of Differential Pressure on Demineralizer performance
As solids form a layer on the resin bed the DP may become great and could cause flow obstructions or blockages
How can you use Differential Pressure to determine the condition of a Demin Resin bed
increase in DP can give indication of resin fouling and may indicate resin depletion.
Define Channeling in a Demineralizer
Excessive flow can create flow channels in the bed
State the effects of channeling in a demineralizer
it will eliminate or reduce contact time with the resin to make Ion exchange ineffective
may be indicated by Low DP across bed
List 5 gases that would normally be present in the RCS coolant
Oxygen (O2) Nitrogen (N2) Argon (Ar) Helium (He) Xenon (Xe) Krypton (Kr)
State the 3 locations in the RCS systems or subsystems where RCS gases could be removed
Gas comes out of a solution in low pressure areas:
CVCS Hold Up Tanks
BA Evaporator gas stripper
VCT during RCS degas
Pressurizer due to High Temps
