Use of Ammonia to Supress Oxygen Production and Corrosion in Boiling-Water Reactors^✫

Radiolysis of the coolant in nuclear reactors cooled by boiling water results in oxygen in the steam and recirculated water phases. This has dictated the use of stainless steels as the major circuit materials for these reactors. It is shown that ammonia additions to the coolant eliminate oxygen production, permitting the use of mild steel for circuit construction with consequent savings in capital cost Corrosion data are presented for various out-reactor materials (carbon steel, low alloy steels, stainless steels, Monel alloy 400, Inconel alloy 600) exposed out-of-flux to the coolant of two phase in-reactor loops when operated neutral and with ammonia addition. Activation of corrosion products from different origins is discussed. Intergranular attack is related to the presence of oxygen or oxidizing radiolytic species in the water.