CD Demins

Question 1

What is the purpose of the CD Demins?

Answer 1

to maintain required condensate chemistry

Question 2

What size leak can the demins handle?

Answer 2

1 GPM on a continuous basis

Question 3

What do cations and anions remove?

Answer 3

Cation - +M

Anion - -M

Question 4

What type of resin do we use in the demins?

Answer 4

Mixed bed H-OH resin

Question 5

What happens to the H & OH that is released from the resin in the ion exchange?

Answer 5

They combine to make H2O

Question 6

What is it called when all exchange sites have the same form?

Answer 6

The resin is saturated, spent, or exhausted

Question 7

What is the release of unwanted contaminants into the system from resin called?

Answer 7

Throwing ions

Question 8

What is the relative attractiveness for one ionic species over another called?

Answer 8

Affinity

Question 9

What does high D/P across a vessel indicate?

Answer 9

a clogged resin trap

Question 10

What does low D/P indicate?

Answer 10

Channeling in a resin bed

Question 11

What provides clean water for the CD demins for transferring, cleaning, and rinsing resin?

Answer 11

CT (the CST)

Question 12

What does the CI (chlorine injection system) do for the CD demins?

Answer 12

it provides the sulfuric acid for demin regeneration. Only for the Cation bed

Question 13

What is used to regenerate the anion bed?

Answer 13

caustic (sodium hydroxide) from the CC system

Question 14

Where can the low TDS sump be pumped to?

Answer 14

the LR system if there is evidence of radioactive contamination, but normally it’s pumped to the circ water canal

Question 15

Where is the high TDS sump pumped to?

Answer 15

to the CM system’s chem waste neutralizing tank

Question 16

Where can the demin vessels be isolated from?

Answer 16

the control room or the Demin panel

Question 17

What happens when the switch for the inlet valve to a demin vessel is taken to open?

Answer 17

a bypass valve opens. the D/P across the valve is sensed by a D/P switch and when it reaches a set value, the inlet valve opens and the bypass closes.

Question 18

What happens if you release the switch from the open position before the D/P switch gets its signal?

Answer 18

The bypass will close and the valve will not open.

Question 19

Which of the 6 lights that indicate the status of a demin vessel are used?

Answer 19

Rinse, Resin transfer (red)
Standby (white)
In service (Green)

Question 20

Which regen vessels can take a full resin load?

Answer 20

Cation and the mixing & holding vessel

Question 21

Where is all resin added?

Answer 21

Into the hopper that goes to the Cation Regen vessel

Question 22

How many positions are there for the bottom water flow valve on the cation regen vessel?

Answer 22

4 positions that control air to the valve and thus control water flow.

Question 23

What interlock is there for the vent valve on the cation regen vessel?

Answer 23

if pressure gets too low on the inlet to the cation vessel, a pressure switch will close the valve. This happens because the low pressure is an indication of failure of the resin trap

Question 24

What does the Acid Day Tank do?

Answer 24

it holds 96% sulfuric acid that is used to regenerate the cation resin.

Question 25

What will cause the acid day tank fill valve to close?

Answer 25

Hi-Hi level in the tank

Question 26

Where do the acid pumps take a suction?

Answer 26

from the acid day tank. they discharge acid to the mixing tee to go to the cation regen vessel

Question 27

What does the caustic day tank do?

Answer 27

it holds the supply of 8% sodium hydroxide used for regen of the anion resin

Question 28

What will auto stop the caustic pumps?

Answer 28

low level in the caustic day tank

Question 29

What do the transfer pumps do?

Answer 29

take a suction on the CST and supply water for the various resin transfer operations. they are located outside north of the CST

Question 30

Where does the waste collection discharge to?

Answer 30

Either to the low TDS sump to go to the Circ water canal or the High TDS sump to go to the CWNT

Question 31

How is acid transferred to the acid day tank?

Answer 31

using the Acid Transfer pumps.

Question 32

Where are the acid transfer pumps operated from?

Answer 32

1) local at the pump
2) at the acid day tank
3) at the CWNT

Question 33

What is the bleed hole for in the check valves on the discharge of the Acid transfer pumps?

Answer 33

it protects the piping from overpressurization

Question 34

What is the capacity of the Turbine Building Acid Storage tanks?

Answer 34

11,000 gallons each (one is used at a time)

Question 35

What is used to preclude the formation of water vapor in the Turbine building acid storage tanks?

Answer 35

IA pressure of 1.2 psig

Question 36

How many demin vessels are in service at one time (max)?

Answer 36

5 with one being in standby to replace one if it becomes exhausted

Question 37

What must be done before the standby vessel can be put in service?

Answer 37

it must be purged with rinse water to ensure effluent quality

Question 38

What happens when resin is exhausted?

Answer 38

1) resin is moved from the demin vessel to the cation regen vessel.
2) resin is moved from the M&H tank to the demin vessel and it is put in standby
3) Resin in the cation regen vessel is air scrubbed
4) The resin is backwashed for 30-60 minutes
5) Anion resin is transferred to the anion vessel
6) The anion resin is regenerated and then the cation resin is regenerated.
7) it’s then transferred to the M&H tank