Primary Chemistry

Question 1

State the four reasons for maintaining primary chemistry control.

Answer 1

Maintain Material Integrity
Minimize Corrosion
Reduce Radioactivity
Assist in Reactor Control

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 is added to the RCS at power.

Answer 3

H2 blanket is established in the VCT

Question 4

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

Answer 4

H2 blanket is added to the VCT

Question 5

State two reasons for the upper limit of the Oxygen control agent (when added at power)

Answer 5

Excess H2 is a waste

Greater H2 concentrations cause a problem degassing

Excess H2 an be an explosive concern

Question 6

Name the oxygen control agent used in mode 5 and below

Answer 6

Hydrazine (N2H4) is added to the CVCS

Question 7

state how the (mode 5 and below) control agent (Hydrazine (N2H4)) functions to reduce Oxygen

Answer 7

N2H4 + O2 => 2H20 + N2

Question 8

State why the oxygen control agent used in mode 5 and below (Hydrazine N2H4) has an upper temperature limit of effectiveness

Answer 8

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

Question 9

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)

Answer 9

Decomposition products in Hydrazine will exhaust resin and cause release of chlorides into the RCS.

Question 10

State the TRM temperature values where Oxygen limits are in effect

Answer 10

O2 limits are applicable when RCS is >250 degF

Question 11

State the pH control agent added to the RCS

Answer 11

Li7OH (Lithium-7) is used to raise pH and offset the Boric acid

Question 12

State the reason for using enriched Lithium-7 as pH control additive

Answer 12

Lithium-6 will generate tritium

Question 13

State how excess Lithium is removed from the RCS

Answer 13

Cation demineralizer removes the excess lithium

Question 14

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

Answer 14

as less Boron is needed to control reactivity, Less Lithium is required to maintain the pH

Question 15

State two methods by which the demineralizer purifies water

Answer 15

Filtration

Ion Exchange

Question 16

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.

Answer 16

25 - - a. Newly regenerated resin.
1 – b. Completely exhausted resin.
3-4 – c. Resin approaching exhaustion

Question 17

What type of Resin is used in the NORMAL IN SERVICE Mixed Bed Demin?

Answer 17

Li7OH Mixed bed Resin

Question 18

What type of Resin is used in the STANDBY Mixed Bed Demin?

Answer 18

HOH resin

Question 19

What type of Resin is used in the CATION Demin?

Answer 19

H+ resin

Question 20

What type of Resin is used in the DEBORATING Demin?

Answer 20

OH- resin intended to remove up to 50 ppm boron per bed

Question 21

State two reasons for using the cation demineralizers

Answer 21

Remove radioactive impurities (Cs137)

control RCS Lithium

Question 22

State when in core life a deborating demineralizer would be used and why

Answer 22

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.

Question 23

State the effect of Differential Pressure on Demineralizer performance

Answer 23

As solids form a layer on the resin bed the DP may become great and could cause flow obstructions or blockages

Question 24

How can you use Differential Pressure to determine the condition of a Demin Resin bed

Answer 24

increase in DP can give indication of resin fouling and may indicate resin depletion.

Question 25

Define Channeling in a Demineralizer

Answer 25

Excessive flow can create flow channels in the bed

Question 26

State the effects of channeling in a demineralizer

Answer 26

it will eliminate or reduce contact time with the resin to make Ion exchange ineffective

may be indicated by Low DP across bed

Question 27

List 5 gases that would normally be present in the RCS coolant

Answer 27

Oxygen (O2)
Nitrogen (N2)
Argon (Ar)
Helium (He)
Xenon (Xe)
Krypton (Kr)

Question 28

State the 3 locations in the RCS systems or subsystems where RCS gases could be removed

Answer 28

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