Another technique:

Another technique sometimes used to erase dissolved gases from water is deaeration.  In this procedure, the water is stored in vented tanks holding electric heaters or steam coils.  Water is heated to a temperature enough for slow boiling to occur.  Those boiling strips dissolved gases from the stored water, or these gases are then vented to the atmosphere.  Commonly, the vented gases are directed by a small condenser to limit the loss of water vapor which would escape as steam along with the gases. This technique is particularly effectual in removing dissolved oxygen as well as other entrained gases (CO₂, N₂, and Ar).

Removal of dissolved gases from the reactor coolant system is commonly accomplished through venting a steam space or high point in the system.  Within pressurized water reactors (PWR), this is generally accomplished in the pressurizer. The steam space is the high point of the system, or the boiling and condensing action causes a constant stripping of dissolved gases to happen.  The steam space is vented either constantly or intermittently, and the gases are carried off in the procedure.

Further to the mechanical means mentioned above, a use of scavengers in a PWR avoids the presence of dissolved oxygen.  Two techniques are generally used in this regard. While facility temperature is above approximately 200ºF, gaseous hydrogen is added and managed within the main coolant to scavenge oxygen through the following reaction.

 2H₂ + O₂ →   2 H₂O                                                                           (4-10)

The other scavenger is hydrazine (N₂H₄).  Hydrazine is thermally unstable and decomposes at temperatures  above  200ºF  to  form  ammonia  (NH₃),  nitrogen  (N₂),  or  hydrogen ₂ (H ).

As a result, the use of hydrazine as an oxygen scavenger is limited to temperatures below 200ºF.  Hydrazine scavenges oxygen through the following reaction.

N₂H₄   + O₂    → 2 H₂O + N_{2 ↑}                                                                                 (4-11)

The presence of dissolved gases within the steam facility of a PWR is as detrimental as the presence of these gases is in the reactor coolant systems.  Since steam facility systems hold metals other than stainless steel that are even more susceptible to certain categories of corrosion in the presence of oxygen and carbon dioxide.  Removal of dissolved gases from the steam system is completed in two ways: through mechanical means like as air ejectors or mechanical pumps; and through using chemicals which scavenge oxygen.

Since boiling occurs within the steam generators, any dissolved gases entrained in the feedwater will be stripped out in during the boiling procedure.  These gases are carried along with the steam through the turbines and auxiliary systems and ultimately end up in the condensers.  A design of the condensers is like that noncondensible gases (for instance, O₂, CO₂) are collected and routed to the air removal system (that consists of air ejectors or mechanical pumps), where they are then discharged to the atmosphere.

Scavenging includes the use of solid additives and volatile chemicals.  One generally-used solid chemical additive is sodium sulfite (Na₂SO₃).  The Scavenging of oxygen occurs through the subsequent reaction.

2 Na₂SO₃ + O₂ → 2 Na₂SO₄                                                             (4-12)

As could be seen through Reaction (4-12), oxygen is consumed within the reaction resulting in the configuration of sodium sulfate, Na₂SO₄ (a soft sludge).  Addition of this scavenging agent is limited to drum- type steam generators. At one Thru Steam Generators (OTSG) do not use these techniques, but alter use controls which keep all scale-forming chemicals out of the steam generators.