Primary Chemistry Flashcards
State the four reasons for maintaining primary chemistry control
Maintain Material Integrity
Assist Reactor Control
Minimize Corrosion
Reduce radioactivity
State the primary source of oxygen in the RCS at power
Radiolytic decomposition of water
State the oxygen control agent used in the RCS at power.
Hydrogen scavenges O2
State where the oxygen control agent is added to the RCS at power
Gas blanket on the VCT
State two reasons for the upper limit of the oxygen control agent
H2 is wasted
problems with degassing
explosive
State the name of the control agent used in Mode 5
Hydrazine
State how the hydrazine functions to reduce oxygen
Oxygen Scavenger
N2H4 + O2 —-> 2H2O + N2
State why hydrazine has an upper temperature limit of effectiveness
Added between 140 to 180 F because it breaks down >200 F
State the reason that the CVCS ion exchangers must be bypassed with hydrazine present in the RCS coolant
Results in resin exhaustion and release of undesirable chemicals in the RCS
State TRM temperature values where oxygen concentration limits are in effect
> 250 F
O2 < 0.1 ppm
State the pH control agent added to the RCS
Lithium Hydroxide
State the reason for using Li7 as pH additive
Li6 produces tritium
State how to remove excess Lithium from RCS
Cation Bed
State why the concentration of Lithium is allowed to lower over core life
Less Boron later in core life due to dilution.
Boron neutron capture results in Lithium 7.
State two methods of demineralizer purification
Ion Exchange
Mechanical Filtration
Describe DF Decontamination Factors for newly generated, completely exhausted, and nearing exhaustion resin beds
New resin DF about 25
Completely exhausted = 1
Resin approaching exhaustion > 1 but low.
State the type of resin for Normal Use mixed bed (In Service)
LiOH
State the type of resin for STBY Mixed bed
HOH
State the type of resin used in Cation Bed
H+
State the type of resin used in deborating beds
OH-
State 2 reasons for using cation beds
Remove Lithium
Removes CS-137 in event of fuel failure
State when deborating demins used and why
EOC due to lower levels of Boron concentration would require to much dilution
State the effect of differential pressure on Demins
If solids form a layer on the resin bed the differential pressure may become great and could cause flow obstruction/blockage
State how demin DP can determine condition of the resin bed
Changes(+) in differential pressure can give indications of resin fouling and may indicate resin depletion (Chemistry sampling can give you a DF)
Define Channeling in a demin
Excessive flow rate can create flow channels in the bed
State the effects of channeling in a demineralizer
Reduced efficiency, localized exhaustion and low DP
List gasses present in the RCS coolant
Nitrogen, Oxygen, Argon, Helium, Xenon, Krypton
State 3 locations in RCS or subsystems where gasses can be removed
VCT (Degas)
Boric Acid Evaporator ( Gas Stripper)
CVCS Holdup Tank (Low pressure so gasses come out)
Pressurizer (Spray)
