CD Demins Flashcards
What is the purpose of the CD Demins?
to maintain required condensate chemistry
What size leak can the demins handle?
1 GPM on a continuous basis
What do cations and anions remove?
Cation - +M
Anion - -M
What type of resin do we use in the demins?
Mixed bed H-OH resin
What happens to the H & OH that is released from the resin in the ion exchange?
They combine to make H2O
What is it called when all exchange sites have the same form?
The resin is saturated, spent, or exhausted
What is the release of unwanted contaminants into the system from resin called?
Throwing ions
What is the relative attractiveness for one ionic species over another called?
Affinity
What does high D/P across a vessel indicate?
a clogged resin trap
What does low D/P indicate?
Channeling in a resin bed
What provides clean water for the CD demins for transferring, cleaning, and rinsing resin?
CT (the CST)
What does the CI (chlorine injection system) do for the CD demins?
it provides the sulfuric acid for demin regeneration. Only for the Cation bed
What is used to regenerate the anion bed?
caustic (sodium hydroxide) from the CC system
Where can the low TDS sump be pumped to?
the LR system if there is evidence of radioactive contamination, but normally it’s pumped to the circ water canal
Where is the high TDS sump pumped to?
to the CM system’s chem waste neutralizing tank
Where can the demin vessels be isolated from?
the control room or the Demin panel
What happens when the switch for the inlet valve to a demin vessel is taken to open?
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.
What happens if you release the switch from the open position before the D/P switch gets its signal?
The bypass will close and the valve will not open.
Which of the 6 lights that indicate the status of a demin vessel are used?
Rinse, Resin transfer (red)
Standby (white)
In service (Green)
Which regen vessels can take a full resin load?
Cation and the mixing & holding vessel
Where is all resin added?
Into the hopper that goes to the Cation Regen vessel
How many positions are there for the bottom water flow valve on the cation regen vessel?
4 positions that control air to the valve and thus control water flow.
What interlock is there for the vent valve on the cation regen vessel?
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
What does the Acid Day Tank do?
it holds 96% sulfuric acid that is used to regenerate the cation resin.
What will cause the acid day tank fill valve to close?
Hi-Hi level in the tank
Where do the acid pumps take a suction?
from the acid day tank. they discharge acid to the mixing tee to go to the cation regen vessel
What does the caustic day tank do?
it holds the supply of 8% sodium hydroxide used for regen of the anion resin
What will auto stop the caustic pumps?
low level in the caustic day tank
What do the transfer pumps do?
take a suction on the CST and supply water for the various resin transfer operations. they are located outside north of the CST
Where does the waste collection discharge to?
Either to the low TDS sump to go to the Circ water canal or the High TDS sump to go to the CWNT
How is acid transferred to the acid day tank?
using the Acid Transfer pumps.
Where are the acid transfer pumps operated from?
1) local at the pump
2) at the acid day tank
3) at the CWNT
What is the bleed hole for in the check valves on the discharge of the Acid transfer pumps?
it protects the piping from overpressurization
What is the capacity of the Turbine Building Acid Storage tanks?
11,000 gallons each (one is used at a time)
What is used to preclude the formation of water vapor in the Turbine building acid storage tanks?
IA pressure of 1.2 psig
How many demin vessels are in service at one time (max)?
5 with one being in standby to replace one if it becomes exhausted
What must be done before the standby vessel can be put in service?
it must be purged with rinse water to ensure effluent quality
What happens when resin is exhausted?
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
