This quarterly progress report details the ongoing research happening at the Oak Ridge National Laboratory. In particular, this report discusses the current status of the Homogenous Reactor Experiment, boiling reactor and slurry studies, and general homogenous reactor studies.

Laboratory fabrication and testing of an inline densimeter.

Report that "compares gas turbines with steam turbines as means of producing electric power from gas-cooled reactors with all-ceramic fuel elements." (p. 1)

Report documenting the a study with the goal of identifying the factors that might influence the growth patterns of the fuel processing industry, especially regarding the siting of reprocessing and disposal facilities for high-level waste.

Report documenting the design and testing progress of the Oak Ridge National Laboratory's Gas-Cooled Reactor Program.

From introduction: "This is the third of a series of quarterly reports which will cover the progress and results from the conceptual design, economic evaluations and research and development work performed by the General Electric Company as part of the Nuclear Superheat Project."

From introduction: "This is the tenth of a series of quarterly reports which will cover the progress and results from the conceptual design, economic evaluations and research and development work performed by the General Electric Company as part of the Nuclear Superheat Project."

Quarterly progress report discussing activities related to the Vallecitos Boiling Water Reactor (VBWR) and related facilities.

From abstract: "This report summarizes the work performed on the Research and Development Program for the Southwest Experimental Fast Oxide Reactor."

Report documenting ongoing research and developments at the Oak Ridge National Laboratory's Gas-Cooled Reactor Project. From summary: "A study was made of the effect of the energy of extraneous source neutrons on the amplitudes of higher modes in the flux distribution of a subcritical reactor."

Report containing ongoing projects and experiments undertaken by the Oak Ridge National Laboratory's Molten-Salt Reactor Program.

Report issued by the Oak Ridge National Laboratory displaying a single chart showing measurements of the gamma-ray, fast-neutron, and thermal-neutron dose rates.

This paper summarized the work at ORNL in controlled-potential dc polarography since mid 1959 and states conclusion and viewpoints that have been reached in the course of this work. The following topics are discussed: (1) Potentiostatic Compensation for Polarographic Cell Resistance; (2) Time-Derivative DC Polarography; (3) Signal-to-Noise Ratio (S.N); (4) Resolution; and (5) DC Polarography in Non Aqueous Solvents and, Particularly, in Solvent Extracts.

The subject which I will discuss is the distorted - waves theory of direct reactions and its application to the study of nuclei. I shall mainly be concerned with a study of the reaction theory, its range of validity, and its ability to give quantitative information about nuclear structure.

The series of papers that we are about to discuss is primarily concerned, not as the first part of the session title indicates, with photochemistry of nucleic acids, but, as the second part indicates, with the biological implications of the photochemistry. We know that ultraviolet acts on nucleic acids in cells, and we know a good deal about the photochemistry of this interaction in vitro. The question we ask here is, which test tube reactions are of importance to the survival of the cell?

The quasi reference electrode ( Q.R.E. ) is a bright platinum wire or other inert conductor immersed directly in the solution; it may have a very small area. It is used instead of a true reference electrode but must be used with potentiostatic or other circuits that prevent the drawing of cell current through the Q.R. E. When used in appropriate situations, the results obtained by use of a Q.R.E. are like those obtained with a true reference electrode except for the lack of thermodynamic meaning of the Q.R.E. potential ; hence , this simple electrode is called a quasi reference electrode.

Two 500-kw fused-fluoride-to-Nak heat exchangers, two 500-kw NaK-to-air radiators, and a 20-tube high-velocity heat exchanger were fabricated for a heat-exchanger development program. A construction procedure, utilizing both inert-arc-welding and high temperature dry-hydrogen brazing, was used successfully on all of the units. The tube-to-header joints were welded and back-brazed; the manifold joints were inert-arc-welded with full penetration; and the tube-to-fin joints were brazed. A detailed description of the fabrication of each type of component is discussed and a cost analysis of the 500-kw units is presented.

This semiannual progress report and future reports will be published as two documents to permit a wider distribution of the unclassified material. The report numbers are assigned in sequence so that the two reports will fall together when filed by report number.

Methods for the determination of plutonium and uranium in highly radioactive scrup dissolver solutions have been developed. Plutonium was separated from the dissolver solutions by solvent-extraction and ion-exchange techniques and determined by potentiometric titration. Uranium was separated by ion exchange and determined by potentiometric titration. Solutions that were similar to the actual dissolver solutions and that contained known amounts of plutonium and uranium were analyzed by these methods. Evaluation of the data secured for the determination of plutonium and uranium by the methods given herein indicated that, within the limits of the precision of the methods, there was no bias. The precision of the data obtained for the determination of plutonium, expressed as the relative standard deviation, was better than 2% for plutonium in the concentration range of 0.27 to 0.64 mg/ml. The precision for uranium was estimated to be about 0.2% for uranium concentrations of 425 mg/ml. These methods and the data obtained by then are discussed in this report; the procedures are appended.

A theoretical and experimental investigation of the coefficient for diffusion of ions across a magnetic field Is described. The resultant diffusion coefficient is found to vary inversely as the square of the magnetic field strength, in accord with the usual collison-diffusion theory. The magnitude of the coefficient is much larger (x700) than the coefficient predicted by the usual ambipolar diffusion theory. This discrepancy is resolved by showing that diffusion across a magnetic field is not ambipolar in character in most arc experiments. The final experimental and theoretical values are in good agreement, and it is unecessary to postulate any additional diffusion mechanisms, such as plasma oscillations.

The development of the reactor layout is continuing. New features that have been incorporated because of stress, fluid flow, or fabricability considerations include an elliptical fuel expansion tank, a rounded dome to enclose the top of the reactor, a newly designed sodium pump impeller, and other related items. Recently completed heat exchanger tests yielded consistent data from which a series of heat exchangers is being designed. The most promising of these will be chosen for the ART.

Experiments in the controlled melting of irradiated fuel specimens, particularly of the APPR, STR, and MTR types have confirmed that prolonged heating in air at temperatures in excess of the melting point results in the release of a large portion of the radioactivity. On the other hand, a moderate amount of heating in air or steam sufficient only to melt a specimen results mainly in the partial volatilization of the rare gases; the halogens, iodine and bromine; and the alkali metals, cesium and rubidium. In the presence of air or water vapor, strontium and other fission products are not released. At trace concentration of fission products, slow melting of the APPR plate at 1525 C in air or steam effected the release of 50 percent of the rare gases, 33 percent of the iodine, 9 percent of the cesium and traces of strontium. After 25% burn-up, the cesium value increased to about 60 percent. Aluminum alloy of the MTR type, also at trace concentration, upon melting at 700 C released up to 2 percent of the iodine, 10 percent of the rare gases, and negligible portions of other fission products. Zirconium alloy of the STR type after 15 percent burn …

An estimate has been made of the critical fuel concentration in the HRT, taking into account the effect of the core corrosion sample assembly. The estimate is based on a number of previous calculations of critical concentration in an un-poisoned reactor and one calculation of critical concentration as a function of poison level. The makeup of the first core corrosion sample assembly was used in calculating equivalent neutron poisoning effects. Figure 1 shows the estimated critical concentration as a function of temperature with the corrosion sample assembly in place. At 280°C, the assembly raises the critical concentration by 0.6 g U-235/kg D2O. This effect is equivalent to a uniformly distributed poison equal to 4.1% of the fission cross section. The equivalent poison is greater at lower temperatures, where the uranium concentration is lower.

Various nuclear characteristics of two-region spherical homogeneous reactors have been computed in order to provide information for the design of HRE-3. Equilibrium isotope concentrations were established using an ORACLE code, and a two-group model was used to obtain critical concentrations and flux distributions. Breeding ratio is plotted as a function of reactor size, blanket thorium concentration, and other design and operating parameters, and the time required for a demonstration breeding is discussed. Tables of results, including neutron balances, are given for selected reactors. a number or relations are presented for estimating the effects of fission products, copper, corrosion products, H2O, and the core tank on breeding ratio.