Peculiarities of Metrological Calibration of Oxygen Activity Sensors in Liquid Metal Coolants
The liquid metal coolants including lead containing metallic melts are used in a number of nuclear reactors at present. The impurities being contained in the coolant, primarily oxygen impurity, exert an important effect on its quality. Knowledge of the true values of the thermodynamic activity (TDA) of oxygen in different parts of the circuit enables this quantity to be held in a proper range. This is necessary to prevent slag formation and oxide phase crystallization in the “cold” parts of the circuit and preserve the protective oxide coating on the inner surfaces of structural materials in the “hot” sites. To do this, the OASCR calibration rig capable of reproducing the different modes of oxygen activity in liquid lead is constructed and tested. The OASCR calibration rig is entered in the State List. In SSC RF IPPE the OAA-1 analyzer is developed as well, to measure the oxygen activity in liquid lead and lead-bismuth. The analyzer makes it possible to take continuous remote measurements of the thermodynamic activity of oxygen in molten lead. In 2011 the OAA-1 analyzers were successfully tested using the OASCR test rig.