Abstract: "In a study of the preparation and properties of delta-phase zirconium hydride it was found that large, sound bodies of the hydride can be prepared by direct combination of the elements if the rate of the reaction is retarded by limiting the supply of available hydrogen. Specimens up to 1-in. diameter were prepared using this technique. Because delta phase zirconium hydride does not readily form eutectics with iron-and nickel-base alloys below 1800 F these materials may be utilized for clodding the hydride. Delta-phase zirconium hydride is unaffected by exposure to liquid NaK or to nitrogen gas at temperatures below 1000 F. The hot hardness of delta-phase zirconium hydrid is about 130 kg per mm-2 at room temperature and 40 kg per mm-2 at 1500 F. The mean coefficient of thermal expansion (68 to 1337 F) is 6.5 x 10^-6 per deg F. The thermal conductivity varies from 5.7 Btu/(ft)(hr)(F) at 300 F to 5.1 Btu/(ft)(hr)(F) at 1300 F."

Abstract: A study has been made of the cladding of solid and powdered delta-phase zirconium hydride is both red and flat shapes with stainless steel. The program included investigations of metallurgical bonding, both with and without the sore of metallic barrier materials. Types 304 and 347 stainless steel were used for cladding material. The intermediate barrier-layer materials used were niobium, molybdenum, a combination of copper and molybdenum, and a combination of copper and niobium. The pressure-bonding techniques, involving the use of gas pressure at elevated temperatures, was employed in this study. Variable times and temperatures with a constant pressure of 10,000 poi were utilized by produce bonding. In this study, the best results were archived is cladding delta-phase zirconium hydride directly with Types 304 or 347 stainless steel. Good bonds were obtained by pressure bonding at 1600 F for 3 or 4 hr subsequent to pressure bonding at 1900 F for 1 to 2 hr at a pressure of 10,000 poi. Partial bonding was achieved between niobium and zirconium hydride and molybdeum and girconium hydride.

From introduction: "One of the most important factors which must be considered in the chemical processing of spent fuel elements is the safe and economic disposal of gaseous radioactive fission product wastes given off in the fuel element dissolution operation. For this reason work is underway at ORNL to study the various gas disposal methods that might be used to handle the radioactive fission product gases, krypton, xenon, and iodine."

From abstract: "An instrument for detecting aluminum-silicon alloy penetrations in the aluminum jacket of fuel slugs is described. The instrument is of the eddy current type and the sensing element is a small probe that does not touch the specimen under inspection. Al-Si inclusions 0.020 inch in diameter that penetrate to within 0.005 inch of the can surface can be detected. The response of the circuits is such that a slug 8 inches long can be scanned in 45 seconds."

Development work continued on a fused salt process for the recovery of uranium from zirconium-matrix fuel alloys. The fuel is dissolved in a sodium fluoride-zirconium fluoride melt at 600°C by hydrogen fluoride sparging. The melt is then sparged with fluorine gas which volatilizes the dissolved uranium as the hexafluoride. The final decontamination and purification of the uranium hexafluoride are accomplished by fractional distillation. The testing of graphite as a container material for the hydrofluorination step was continued. Additional thermal cycling experiments were performed, using a helium sparge in equimolar sodium fluoride-zirconium fluoride melt at 600°C. The extent of penetration of the fused salt into the graphite was determined. No mechanical degradation was present. Dimensional change data were also obtained for graphite vessels in which the fused salt was sparged with hydrogen fluoride.

Ore concentrates have been converted directly to crude uranium tetrafluoride by hydrogen reduction and hydrofluorination in fluidized-bed reactors. Small-scale laboratory experiments demonstrated that this process can be extended to the production of crude uranium hexafluoride through fluorination of the uranium tetrafluoride in a fluidized bed. The satisfactory temperature range for the reaction lies between 300°C and 600°C. At 450°C the fluorine utilization is between 50 and 80 per cent. With excess fluorine, over 99 per cent of the uranium is volatilized from the solid material. The fluidization characteristics of certain materials are improved by the addition of an inert solid diluent to the bed.

In homogeneous nuclear reactors significant quantities of radioactive inert gaseous fission products must be separated from the fuel solution for disposal. The present disposal scheme, which is employed on the HRT, is to pass the mixture of fission product gases and oxygen through a charcoal adsorption bed. the oxygen passes through the bed relatively un-adsorbed, but the radioactive inert gases are adsorbed and are displaced from the bed bed very slowly giving the gases a much greater residence time than would exist if no bed were used. This long residence or "holdup" time permits the short-lived inert gases to decay away before emission to the atmosphere and thus greatly reduces the safety hazard produced by disposal of the gases to the atmosphere. The same effect could be obtained by using a large holdup tank, but the charcoal bed is much more compact and thus required less shielding.