'The background for the project is briefly reviewed and the work done during the nine months since funding was received is documented. Work began in January, 1997. A post doctoral fellow joined the team in April. The major activities completed this fiscal year were: staffing the project, design of the experimental system, procurement of components, assembly of the system. preparation of the Safe Operating Procedure and ES and H compliance, pressure testing, establishing data collection and storage methodology, and catalyst preparation. Objective The objective of the project is to develop new chemistry for the removal of organic contaminants from supercritical carbon dioxide. This has application in processes used for continuous cleaning and extraction of parts and waste materials. A secondary objective is to increase the fundamental understanding of photocatalytic chemistry. Cleaning and extraction using supercritical carbon dioxide (scCO{sub 2}) can be applied to the solution of a wide range of environmental and pollution prevention problems in the DOE complex. Work is being done that explores scCO{sub 2} in applications ranging from cleaning contaminated soil to cleaning components constructed from plutonium. The rationale for use of scCO{sub 2} are based on the benign nature, availability and low cost, attractive solvent properties, …

A prototype for an all fiber optic hydrogen sensor system was developed. Capability to measure concentrations of hydrogen in air or nitrogen in the range of 0.5 percent to 4.0 percent with a resolution of 0.1 percent was demonstrated. A DC planar magnetron sputter system was procured and assembled for use in the thin metal film deposition necessary for fabrication of the palladium and palladium-silver alloy sensors used in this development. A method was developed to coat the metal films with an organic coating permeable to hydrogen but not oxygen and other reactive gases. The results of tests on these sensors gave positive results but long-term studies are required to confirm protection under conditions expected to be encountered in a real world application. A new type of sensor base on a layered yttrium/palladium structure was constructed and tested. The greater magnitude and wavelength dependence of the spectral response observed may lead to a more robust sensor. However, the need to have oxygen present for this sensor in order for it to rapidly recover after exposure to hydrogen may complicate its use.