N2 purging in Primary Water System

N2 purging in Primary Water System

• Fit N2 cylinder in N2 supply station  in Gas Filling room (0 m )
• Isolate the Relief valve by closing isolating manual valve before it.(8.5 m)
• Slowly vent out the N2 in the system up to 0.2 ksc by opening vent open to atmosphere (these all are present at 8.5 m)
• Close the vent when pressure is 0.2 ksc.
• Now start filling N2 through N2 filling station rack
• As pressure reaches 0.5 ksc, Cut off the N2 supply
• Wait for an hour to mix N2 with the system gases.
• Purge out this gaseous mixture from opening vent open to atmosphere upto 0.2 ksc. Close the vent.
• Repeat this process 5-6 times.
• Inform Chemistry to take sample of PW and check Dissolved Oxygen.
• If DO is greater than 20 ppb. Repeat above steps.
• As DO reaches  less than 20 ppb, tightly close vent open to atmosphere and open the isolating valve of Relief valve.