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Oxide and carbide coatings and methods of applying them to graphite crucibles were evaluated at the National Lead Company of Ohio on a laboratory scale. The objectives were to find a better crucible and mold coating than magnesia (MgO), which is currently used in the Metal Production Plant remelt operation, and a better method of application than brushing. The evaluation consisted of the vacuum-melting of slug uranium charges and derby uranium "as reduced" charges in graphite crucibles having different coatings, followed by studies of (1) the appearance of the coatings and (2) the metal quality (impurity levels) of the products.
This compilation contains 958 references to report and published literature. The references pertain primarily to reactor grade graphite, although information on the manufacture and uses of graphite in other fields is included. The references were selected from Nuclear Science Abstracts (NSA), covering the period 1948 through mid-1961. Subject, author, and availability indexes are provided.
Reduction of small charges of uranium tetrafluoride with magnesium proved to be successful. By hand-tamping of UF4- Mg blend, tap densities ranging between3.1 and 3.4 g/cc were obtained. The reduction yields for these densities ranged from 72.79 to 93.71%. In the case of machine-compacted UF4-Mg blend having tap densities from 3.58 to 3.68 g/cc, reduction yields were higher, ranging between 91.45 and 97.2%. Machine-compacted blends gave much more uniform temperature distribution curves during the preheating period, as a result of higher tap densities. The best yields were obtained by firing a machine- compacted blend containing 5% Mg excess at a furnace temperature of 650 deg C, giving an average crude metal yield of 96.3%. However, the high carbon content of 174 ppm in the crude uranium biscuits obtained by compacts reduction, as a result of hydrocarbon binder presence, appeared to be a disadvantage. Attempts were also made to demonstrate the initiation of the reduction reaction at temperatures lower than 500 deg C by taking x-ray-diffraction patterns of the samples of the UF4-Mg charges heated up to various temperatures.