Introduction: "The uranium-5 w/o chromium alloy has been intensively investigated for use in a power reactor in the as-cast condition. However, when cast sample fuel elements were subjected to irradiation, their stability was found to be unsatisfactory. In order to improve the behavior of the alloy, a program of grain refinement by heat treatment was begun. The effect of chill casting on the heat-treated grain size was also investigated."

The following report describes procedures taken to utilize the photelometer to procure the most rapid and reliable determinations, but the goal of the tests presented was to create satisfactory dispersions of particles to analyze.

This report discusses a proposed method for treating the effect of increasing critical mass of plutonium solutions, which occurs when hydrogen density is reduced by dilution with heavier nuclei.

Report discussing the progress made on a research project for the preparation of ductile zirconium during April 1949.

This report describes the use of pile control over atomic power, including the different methods of control.

Bench scale studies have been made of the recovery of uranium from acid leach liquors (and slurries) by solvent extracting with di (2-ethylhexyl) phosphoric acid in an organic diluent. Uranium may be stripped from the organic solvent by either alkaline or acidic reagents, the former having been studied in greater detail. On the basis of these tests, a recovery process may be considered which shows promise both from the standpoint of operation and chemical costs. Under proper conditions, vanadium can also be extracted by the di (2-ethylhexyl) phosphoric acid and stripping again may be accomplished with either acidic or alkaline reagents. Preliminary studies have been made of these possibilities. In addition to di (2-ethylhexyl) phosphoric acid, some other organophosphorus acids, have been cursorily examined in respect to their extraction and/or stripping performance.

Technical report includes three reports of research progress: 1)Meson Mass Determination by Grain Counting, W. H. Barkas; 2) The Magnetic Beta Ray Lens Spectrograph, A. C. Helmholz; 3) Anthracene Counters, E. Martinelli.

Activities in a program to develop techniques in the use of pulsed neutron sources to measure shutdown parameters related to large thermal power reactors are reported. The experimental work centers around aspects of detecting neutrons in the presence of 10/sup 7/ r/hr gamma fields. Boric acid experiments and Humboldt Bay experiments are reported.