Oxygen chemistry in liquid sodium–potassium systems

Oxygen is one of the main contaminates when using an alkali metal as a coolant in a nuclear reactor system. Some oxygen will be present in the coolant at the start of operation, and during normal operation some oxygen may diffuse through the clad into the coolant. Assuming UO2 fuel, a breach of the cladding of one or more fuel pins, and with the coolant contacting the fuel pellets, the oxygen level in the coolant can increase. The present study examines oxygen chemistry in liquid NaK by extending the existing knowledge of oxygen chemistry in liquid sodium. New explanations and correlations for the formation of oxygen compounds in the liquid metal have been developed. This study includes the effect of oxygen level, measurement and control methods, and the effects of oxygen and oxygen compounds on the compatibility between the liquid and the structural materials.