Carbothermic Synthesis of ~820- m UN Kernels. Investigation of Process Variables

Technical Report · Mon Jun 01 00:00:00 EDT 2015

DOI:https://doi.org/10.2172/1254083· OSTI ID:1254083

Lindemer, Terrence ^[1]; Silva, Chinthaka M ^[1]; Henry, Jr, John James ^[1]; McMurray, Jake W ^[1]; Jolly, Brian C ^[1]; Hunt, Rodney Dale ^[1]; Terrani, Kurt A ^[1]

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1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

This report details the continued investigation of process variables involved in converting sol-gel-derived, urainia-carbon microspheres to ~820-μm-dia. UN fuel kernels in flow-through, vertical refractory-metal crucibles at temperatures up to 2123 K. Experiments included calcining of air-dried UO₃-H₂O-C microspheres in Ar and H₂-containing gases, conversion of the resulting UO₂-C kernels to dense UO₂:2UC in the same gases and vacuum, and its conversion in N₂ to in UC_1-xN_x. The thermodynamics of the relevant reactions were applied extensively to interpret and control the process variables. Producing the precursor UO₂:2UC kernel of ~96% theoretical density was required, but its subsequent conversion to UC_1-xN_x at 2123 K was not accompanied by sintering and resulted in ~83-86% of theoretical density. Decreasing the UC_1-xN_x kernel carbide component via HCN evolution was shown to be quantitatively consistent with present and past experiments and the only useful application of H2 in the entire process.

• Research Organization: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: USDOE Office of Nuclear Energy (NE)
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 1254083
• Report Number(s): ORNL/TM-2015/301; AF5810000; NEAF278
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
36 MATERIALS SCIENCE