(Invited) Oxidation of Alloy-X in Near Supercritical and Supercritical Water

Abstract

Supercritical water is a growing medium for power production, hazardous waste remediation, and chemical synthesis. These broad applications require robust materials that can withstand exposure to the high operating temperatures and pressures of supercritical water, while achieving these conditions necessitates that water transitions from the subcritical state to the higher enthalpy supercritical state. This region of transition has been observed to be the region with the greatest variation in thermophysical properties, with reports of a local maximum in corrosion rate. Experimental procedures have been employed to study the effects of exposure of Alloy X to the near supercritical and supercritical region in the supercritical water loop at The University of Nevada, Reno, which is of a design that allows for controlled exposure to the transition region between subcritical and supercritical water. An investigation into the oxidation of Alloy X included characterization by Raman spectroscopy, X-ray diffraction pattern analysis, scanning electron microscopy coupled with energy dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy. Observation and characterization of the oxidation as a result of exposure will allow for the evaluation of Alloy X as a candidate for application in processes utilizing supercritical water, as well as increased understanding of the specific demands of exposure to the transition region between subcritical and supercritical water.Acknowledgements: The SCWL was funded by the Department of Energy through a Nuclear Energy grant: DE-NE0000454. Kenny Osborne serves as the program manager for the DOE award. This work was performed under the auspices of the US Nuclear Regulatory Commission Faculty Development Program under contract NRC-HQ-11-G-0039. Nancy Hebron-Isreal serves as the grants program officer for the NRC award.