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The tensile properties, hot hardness, and heattreatment characteristics of urarnium alloys containing up to 2.9 at.% aluminum or 4.0 at.% zirconium are described. The data shown that zirconium has a favorable effect upon the grain size, hardness, and tensile strength of uranium without materially affecting ductility. Additions of 3.8 at. % zirconium raised the tensile strength of uranium at room temperature fiom about 100,000 psi to about 200,000 psi, while the elongation in 2 in. increased from 14 to 22% and the grain size decreased from about 0.20 mm to less than O.01 mm. The data show that aluminum raises the yield strength, that it has very little effect on either the grain size, hardness, or tensile strength of uranium, and that it decreases ductility. The addition of 2.6 at.% aluminum decreased ihe roomtemperature ductility of ur-anium from l4 to 4%. (auth)

An investigntion was made of the performance of a gas-cooled reactor, designed to provide a source of high temperature heat to a stream of helium. This reactor, in turn, is used as a source of heat for the air stream in a gas- turbine power plant. The reactor design was predicted primarily on the requirement for transferring a large amount of heat to the helium stream with a pressure drop low enough that it will not represent a major loss of power in the power plant. The mass of uranium e uired far criticality under various circumstances was investigated by multigroup calculations, both on desk calculators and on an IBM-704 machine. The gasturbine power plant perfarmance was studied based on a Studebaker-Packard-designed gas-turbine power plant for the propulsion of destroyer-escort vessels. A small experimental program was carried out to study some effects of helium on graphite and on structural steels. (auth)

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Failure, which resulted in the stoppage of fluoride flow in ORNL No. 1, occurred as a NaK to fuel leak in the vicinity of the NaK inlet heater. The reaction of NaK with fuel at this point caused the deposition of nearly pure UF/ sub 3/ around the tubes and, finally, a sufficient increase in the melting point of the fuel to produce solidification. Fluorides throughout the heat exchangers were found to be depleted in uranium and to contain some potassium. Thus it would appear that stoppage of flow occurred after considerable NaK pick-up had taken place. Fluoride attack observed in these heat exchangers, with the exception of the area of failure, agreed substantially with what would be predicted from other dynamic systems. However, in those tubes near the point of failure, attack on the"tension" side of the tubes occurred to depths approximately twice those observed in "unstressed" tubes at comparable temperatures. Mass transferred particles were present in the NaK circuit of ORNL No. 1 to a maximum thickness of 15 mils. Deposit thicknesses varied markedly from header to header. (auth)

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OTS). The situation of a leak of sctiwe material into a flowing air- stream presents the problem of determining possible upstream diffusion of the activity. In a constant velocity one directional flow involving three dimensional diffusion from a point source, the upstream concentration is severely limited compared to that downstream. For all practical values of the flow velocity and diffusion coefficients, this upstream concentration is negligible. It is to be noted, however, that the velocity profile of a flow in a finite channel involves points of very low velocity, and at these points the diffusion effect might predominate, resulting in some upstream diffusion. Even in this case, unknown convection effects would be more important than diffusion effects. (auth)

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The absorption spectra for Pu(III), (IV), (VI), and the red Pu(IV)- peroxy complex were determined in HNO/sub 3/ solution. Extinction coefficients for the above species of Pu were measured. Temperature has little effect on the spectra, but variation of acidity causes shifting of absorption peaks and some changes in the extinction coefficients. The absorption spectra and extinction coefficients in the region 390 to 1200 m mu were measured for chromic, nickelous, manganous, calcium, lanthanum, aluminum, ferrous. ferric, and permanganate ions in HNO/sub 3/ solutions. In addition, the effects of nitrite, oxalic acid, sulfamic acid, hydrogen peroxide, and various HNO/sub 3/ concentrations on the extinction coefficients of some of these ions were determined. The chromic, nickelous, ferrous, and permanganate ions, and ferric ion with oxalic acid, have sufficiently high extinction coefficients to cause inaccuracies in valence determinations of Pu in solutions containing high concentrations of these ions, unless corrections are made. (auth)

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