Primary Water Make Up

PROCEDURE FOR TAKING MAKE-UP IN TO THE SYSTEM

• The tank level is to be normally maintained at approximately 220 mm . ( 255 mm HI alarm , 195 LO alarm ) .When ever the tank level drops to below 200 mm the PW system makeup to be taken up to 240 mm .
• The approved committee must be informed before taking PW make up in to the system for any reason.
• Always the make-up should be taken through Ion exchanger circuit only .
• At a time, make-up quantity should not be more than 100 liters. However depending on the requirement thisquantity will vary.

Steps for taking Makeup :

• Put DM make-up line to PW system under flushing up to the inlet valve by opening the drainvalve .
• Isolate the ion Exchange circuit from the main PW system by closing both inlet and outlet valve.Ensure direct makeup is closed.
• Stop alakaliser system & close the valve .
• Stop Flushing of DM water after 2 hours .
• Open the drain after fine filter in treatment circuit  & open the Makeup water valve  to establish flow through the ion exchanger circuit
• Maintain a flushing flow rate of 1m³/hr through drain valve till conductivity after ion exchanger is 1µmho/cm .
• Then get clearance from chemistry for taking makeup into system . Stop flushing by closing the drain valve .
• Note down the Flow Integrator reading & SW tank level .
• Take make-up by opening the ion exchanger circuit outlet valve slowly. Monitor the level in CCR as well as at local through the level gauge glass float & N2 pressure at 8.5 Mtr
• If it is a normal running unit the quantity should not exceed 100 Litres at one go . If it is a shut down unit(Winding remains bypassed ) it is to be taken as per normal requirement i.e up to 300 mm in OH tank .

Precaution During Taking Makeup :-

• Ensure that water does not get filled in the entire tank & enter in to purging gas line during filling oraddition of make up water.
• After taking make-up, close the make-up valve. Line-up the dosing system i.e., open ion exchanger inlet valve fromPW pump discharge line. Adjust the flow in the ion exchanger circuit to 40 LPM ( 2.4 m3 /Hr )
• Start Alaklyser circuit .
• Nitrogen purging to be started immediately as per the following procedure from H2 filling room till O2 < 20ppb .

PROCEDURE FOR N2 PURGING AFTER SW MAKEUP 

Preparatory work

• After initial filling of the primary water circuit and following the addition of larger quantities of primary water (>100dm3 ( 100 Liter ) per month), the primary water tank should be purged with nitrogen to reduce the oxygen contentof the primary water.
• During purging, O2 is extracted from the primary water and discharged to the atmosphere via the vent gas line.

Prerequisites for N2 purging:

• The external primary water circuit was filled with water.
• The primary water pumps must be available
• A reliable nitrogen supply must be available.
• The N2 pressure reducer was set to a gauge pressure of 0.5 bar