Supercritical water-cooled reactor oxides

L. Qiu, D.A. Guzonas, Prediction of metal oxide stability in supercritical water reactors —Pourbaix versus Elhngham, in The 3rd Canada-China Joint Workshop on Supercritical Water-Cooled Reactors (CCSC-2012), Xian, China, April 25—28, 2012. 

S. Penttila, A. Toivonen, Oxidation and SCC behaviour of austenitic and ODS steels in supercritical water, in ISSCWR-6 The 6th International Symposium on Supercritical Water-Cooled Reactors, Shenzhen, Guangdong, China. China CGNPC, March 03—07, 2013. Piqjer ISSCWR6-13029. 

S. Penttila, I. Betova, M. Bojinov, P. Kinnunen, A. Toivonen, Oxidation model for construction materials in supercritical water — estimation of kinetic and transport parameters, in 7th International Symposium on Supercritical Water-Cooled Reactors (lSSCWR-7), March 15-18, 2015. Helsinki, Finland, Paper 2064. 

Behaviour of a Cooled Wall Reactor for Supercritical Water Oxidation... 

Because oxygen, carbon dioxide, methane, and other alkanes are completely miscible with dense supercritical water, combustion can occur in this fluid phase. Both flameless oxidation and flaming combustion can take place. This leads to an important application in the treatment of organic hazardous wastes. Nonpolar organic wastes such as polychlorinated biphenyls (PCBs) are miscible in all proportions in supercritical water and, in the presence of an oxidizer, react to produce primarily carbon dioxide, water, chloride salts, and other small molecules. The products can be selectively removed from solution by dropping the pressure or by cooling. Oxidation in supercritical water can transform more than 99.9 percent of hazardous organic materials into environmentally acceptable forms in just a few minutes. A supercritical water reactor is a closed system that has no emissions into the atmosphere, which is different from an incinerator. 

Supercritical water oxidation (SCWO) is a hydrothermal process for the oxidative destruction of organic wastes. An oxidant and the wastes to be disposed are fed to a reactor in the presence of high concentrations of water heated above the critical temperature and pressure of pure water (374°C, 3,204 psia). These wastes can be fed continuously into the SCWO reactor (continuous SCWO) or, in an alternative design, a small volume of waste is mixed with water and an oxidizer (H2O2) in a pressure vessel, heated to reaction temperature above the critical point of water, and then cooled (batch SCWO). The committee evaluated continuous SCWO in its previons report (NRC, 2001a), but did not evaluate batch SCWO, which was still at a very early stage of development. 

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