Although supercritical water oxidation (SCWO) is a technology which can effectively destroy various civilian and military wastes, the process must be carried out in a reactor which will withstand not only the high temperature and pressure conditions but also a very corrosive environment.
Results from laboratory and pilot-scale SCWO systems presently in operation indicate that wastage (accelerated general corrosion), pitting and stress corrosion cracking are corrosion phenomena encountered in the various sections of SCWO systems. As process conditions are severe, corrosion could, ultimately, be the limiting factor in the useful application of this technique; nevertheless, little information relevant to degradation within such systems is available in the current literature.
Systematic exposure testing to assess the effect of time, temperature, environment and material type at operating conditions that simulate those of the various regions within a full-size SCWO reactor has been initiated. Samples are monitored for weight loss and subsequently examined to provide comprehensive information on both the rate and form of degradation. Additionally, preliminary elevated temperature electrochemical experiments will be carried out in a pressure vessel designed to permit the standard three electrode electrochemical cell configuration. In addition to the standard de techniques, electrochemical impedance spectroscopy (EIS) will be used to provide a fundamental understanding of degradation phenomena over the temperature range studied.