Fly ash specimens from four power plants in the Tennessee Valley Authority system have been separated into three matrices: glass, mullite-quartz, and magnetic spinel. Chemical species of trace elements are defined to a large extent by the matrices that contain them. The magnetic component of fly ash is ferrite. The mullite-quartz phase is relatively pure and can be recovered as a resource.

Uranium and thorium were measured by absolute neutron activation analysis in high-pcrity materials used to manufacture semiconductor memories. The main thrust of the study concerned aluminum and aluminum alloys used as sources for thin film preparation, evaported metal films, and samples from the Czochralski silicon crystal process. Average levels of U and Th were found for the source alloys to be ^65 and ^45 ppb, respectively. Levels of U and Th in silicon samples fell in the range of a few parts per trillion. Evaporated metal films contained about 1 ppb U and Th, but there is some question about these results due to the possibility of contamination. *0perated by Union Carbide Corporation for the U.S. Department of Energy, under Contract No. W-7405-eng-26.

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