CHEMICAL ENGINEERING DIVISION SUMMARY REPORT FOR JANUARY, FEBRUARY, MARCH 1958

Fluoride Volatilization Separation Process. Corrosion tests were made on a variety of metals to find a material of construction suitable for the fluorination step. All metals tested, with the exception of Hastelloy B, were attacked on the permeation of a six-inch graphite crucible by molten NaF- ZrF/sub 4/. Carrier-free tracer experiments were performed on the behavior of Nb and Ru in the fused fluoride process. Pilot plant operations were directed toward development of two operations basic to fluoride volatility processes, namely, the fused fluoride dissolution of U-Zr alloy fuels and purification of UF/sub 6/ by fractional distillation are discussed. Liquid Metal Fuel Reprocessing. The development of a fluoride volatility process to recover and purify the core fluid from the Liquid Metal Fuel Reactor (LMFR) is presented. Corrosion tests of materials of construction having pctential use in the fluoride volatility process for reprocessing LMFR core fluid showed Ag, Au, Mo, and Pt to have promise when in contact with hydrofluorinated NaF- ZrF/sub 4/ melts. Fluidization Studies. Work was continued on the fluid-bed drying of zirconiumuranium -fluoride solutions. Laboratory studies were made to evaluate reducing agents which will completely and quickly precipitate the UF/sub 4/ in the feed solutions to the fluid-bed driers. Work was continued on fluid-bed calcination of waste solutions. Application of a fluid-bed technique to apply a ceramic-glaze coating on calcined oxide continued. Qualitative mixing studies were started in stralght and tapered fluidized bed columns. Pilot-plant study of the fluidized-bed fluorination of UF/ sub 4/ to UF/sub 6/ was begun. Reactor Chemistry. The efforts to clarify the factors involved in the pyrophoricity of reactor materials were continued. Isothermal oxidation studies of U were directed toward understanding the mechanism oxidation which proceeds in two stages attempting correlation with ignition test results. A new procedure to test the ignition characteristics of Zr did not yield satisfactorily reproducible results. Isothermal oxidation studies of Zr alloys were continued. ChemicalMetallurgical Processing. Studies to determine the behavior of tracer-level fission elements in the meltrefim-ng process continued for fuels similar to discharged EBR-ll reactor fuel. The distribution of Pu and U for two meltrefining experiments employing "fissium" alloy contalning 69 wt.% U-20 wt.% Pu-11 wt.% fissium was followed. A study of the coprecipitation of La by U/sub 2/Zni/sub 7/ from liquid Zn was compared. Auxiliary studies were made to determine the optimum container materials, methods of oxidation prevention, phase-separation methods for the utilization of the Pyrozinc processes in large-scale operations. Experiments are in progress to determine the decontamination of irradiated U possible by the use of the Pyrozinc Process. The electrochemical cell study of the U-Zn system yielded data on the free energy of formation of U/sub 2/Zn/sub 17/. Analytical Research and Services. A method was devised for the determination of 0.001% sulfate in UC/sub 3/. The selective dissolution of U from LMFR samples was accomplished by first amalgamating the Bi and then leaching the U with 4M hydrochloric acid-lM hydrofluoric acid. An x-ray spectrochemical analysis for Mo and U in U-fission alloys was developed. (For preceding period see ANL-5820.) (W.L.H.