The Viability of pH Measurements in Supercritical Aqueous Systems

The measurement of pH of aqueous systems at high temperature is becoming increasingly important because of the need to monitor the chemistry of nuclear power plant cooling water systems and the cycle chemistry of fossil‐fueled power reactors. We have previously shown that the yttria‐stabilized zirconia pH sensor can be used for accurate pH measurements of aqueous systems up to 320°C. This paper describes the viability of pH measurement of aqueous systems up to and above the critical temperature of water.