Primary Chemistry

Question 1

State the four reasons for maintaining primary chemistry control

Answer 1

Maintain Material Integrity
Assist Reactor Control
Minimize Corrosion
Reduce radioactivity

Question 2

State the primary source of oxygen in the RCS at power

Answer 2

Radiolytic decomposition of water

Question 3

State the oxygen control agent used in the RCS at power.

Answer 3

Hydrogen scavenges O2

Question 4

State where the oxygen control agent is added to the RCS at power

Answer 4

Gas blanket on the VCT

Question 5

State two reasons for the upper limit of the oxygen control agent

Answer 5

H2 is wasted
problems with degassing
explosive

Question 6

State the name of the control agent used in Mode 5

Answer 6

Hydrazine

Question 7

State how the hydrazine functions to reduce oxygen

Answer 7

Oxygen Scavenger

N2H4 + O2 —-> 2H2O + N2

Question 8

State why hydrazine has an upper temperature limit of effectiveness

Answer 8

Added between 140 to 180 F because it breaks down >200 F

Question 9

State the reason that the CVCS ion exchangers must be bypassed with hydrazine present in the RCS coolant

Answer 9

Results in resin exhaustion and release of undesirable chemicals in the RCS

Question 10

State TRM temperature values where oxygen concentration limits are in effect

Answer 10

> 250 F

O2 < 0.1 ppm

Question 11

State the pH control agent added to the RCS

Answer 11

Lithium Hydroxide

Question 12

State the reason for using Li7 as pH additive

Answer 12

Li6 produces tritium

Question 13

State how to remove excess Lithium from RCS

Answer 13

Cation Bed

Question 14

State why the concentration of Lithium is allowed to lower over core life

Answer 14

Less Boron later in core life due to dilution.

Boron neutron capture results in Lithium 7.

Question 15

State two methods of demineralizer purification

Answer 15

Ion Exchange

Mechanical Filtration

Question 16

Describe DF Decontamination Factors for newly generated, completely exhausted, and nearing exhaustion resin beds

Answer 16

New resin DF about 25
Completely exhausted = 1
Resin approaching exhaustion > 1 but low.

Question 17

State the type of resin for Normal Use mixed bed (In Service)

Answer 17

LiOH

Question 18

State the type of resin for STBY Mixed bed

Answer 18

HOH

Question 19

State the type of resin used in Cation Bed

Answer 19

H+

Question 20

State the type of resin used in deborating beds

Answer 20

OH-

Question 21

State 2 reasons for using cation beds

Answer 21

Remove Lithium

Removes CS-137 in event of fuel failure

Question 22

State when deborating demins used and why

Answer 22

EOC due to lower levels of Boron concentration would require to much dilution

Question 23

State the effect of differential pressure on Demins

Answer 23

If solids form a layer on the resin bed the differential pressure may become great and could cause flow obstruction/blockage

Question 24

State how demin DP can determine condition of the resin bed

Answer 24

Changes(+) in differential pressure can give indications of resin fouling and may indicate resin depletion (Chemistry sampling can give you a DF)

Question 25

Define Channeling in a demin

Answer 25

Excessive flow rate can create flow channels in the bed

Question 26

State the effects of channeling in a demineralizer

Answer 26

Reduced efficiency, localized exhaustion and low DP

Question 27

List gasses present in the RCS coolant

Answer 27

Nitrogen, Oxygen, Argon, Helium, Xenon, Krypton

Question 28

State 3 locations in RCS or subsystems where gasses can be removed

Answer 28

VCT (Degas)
Boric Acid Evaporator ( Gas Stripper)
CVCS Holdup Tank (Low pressure so gasses come out)
Pressurizer (Spray)