This is the final report on the progress, "A Wide-Range Neutron Detector and Monitoring Instrument," ARF 1118-6. This report covers activities from May 8, 1958 to May 8, 1959. This report describes the basic design principles of a proportional counter that has been constructed whose cathode diameter increases towards one end.

Abstract: "A method is described for determining moisture on uranium and uranium oxides. This method should also be applicable to solid samples which, when heated, do not decompose to form water or liberate a substance which will react with Fischer's reagent. The method should be especially applicable to samples which are insoluble in alcohol or Karl Fischer reagent under normal titration conditions, or which will themselves react with the reagent. The amount of moisture on uranium and uranium oxide was found to be 0.02% except when the oxide was found to be 0.02% except when the oxide source was uranyl sulfate. In this case, the moisture content was found to be 0.1%. Modifications of the procedure and apparatus are presented for improving the accuracy and shortening the time necessary for the determination."

Abstract. A fast-slow coincidence scintillation spectrometer for gamma-gamma cascade measurements following thermal neutron absorption in nuclei is now in operation at the Livermore 1-megawatt pool-type reactor. Design features of the spectrometer and experimental techniques in its use are discussed with particular emphasis on the application of the recently introduced sum-coincidence method for analysis of capture-gamma double cascades. A new technique for the determination of added neutron binding energy is presented and various types of coincidence data from appropriate experiments are illustrated.

The following report discusses the operation of the nuclear research reactor at the University of Michigan, as well as the maximum credible accident to the reactor.

Abstract: A simple process to recover the bulk of the uranium from ignited beta salvage residues was sought. In preliminary experiments a vapor phase chlorination with CCl₄ for about four hours followed by water and nitric acid leaching was found adequate. Recoveries are estimated at 60 to 90% of the total uranium content.

Abstract: The output signal of a linear accelerator may have a rise time of 1-2 x 10[minus]7 seconds. Therefore, the output of a pulse height selector operating on this signal has a variation of delay from the original signal of about this amount. In the instrument to be described in this technical report this difficulty is largely resolved.

The resonance absorption of uranium for neutrons has been investigated between 20 degree C and 1000 degree C. Experiments were caried out on both UO2, density 4.63, and metal. The resonance activity was measured with respect to that of an iodine monitor at several different temperatures and the ratio of activity at temperature T to that at 20 degree C was determined. The increase in activity is 0.9 per cent per 100 degree C for the oxide and 1.1 percent per 100 degree C for the metal. The period of U239 was found to be 23.54 +- 0.05 min.

When light propagates with the wave normal in the direction of an optic axis of a biaxial crystal, the usual ray theory breaks down. This phenomenon can be analyzed by means of an asymptotic solution of Maxwell's equations. The intensity is governed by a partial differential equation within the phase surfaces, instead of ordinary differential equations along rays. This example slows that light does not always propagate along rays. A similar phenomenon occurs in hydromagnetics.

A series of critical experiments with blocks of 2% U235-enriched UF4-C25H52 has been initiated at the ORNL Critical Experiments Facility. Thus far assemblies with H:U235 atomic ratios of 195 and 294 have been built in parallelepipedal and simulated cylindrical geometries, both reflected and unreflected. From the results the minimum critical masses for reflected spheres have been determined to be 16.3 and 8.5 kg of U235 for fuel mixtures with H:U235 atomic ratios of 195 and 294, respectively. The minimum critical masses for unreflected spheres of these two fuel mixtures are 24.3 and 12.7 kg of U235, respectively.

Technical report includes three reports of research progress: 1) Range Measurements on 190 Mev Deuterons, M. Stephan; 2) Meson measurements, C. Lattes; and 3) N-P Scattering, R. Christian.

A qualitative theory for cake formation in ThO2 slurries is presented. The sphere formation which occurs in "Standard" slurry can be explained on the same basis. The irregular and unpredictable yield strength is easily fitted into the theory. On the basis of this theory, the writer has been led to the conclusion that only colloidally stable slurries, or slurries with crystallites or comminution-resistant particles which are large enough to overcome colloidal effects (probably larger than 0.1u) can be used with assurance in the ThO2 reactor system. This conclusion holds for 300 gm/kg slurries as well as for more concentrated mixtures.

In analyzing stresses, deflections, and forces in piping and certain structural systems, it is useful to have a set of equations giving the deflections at any point of a curved beam in terms of the various loads acting on the beam. This technical report presents the deflection equations for a curved circular-arc beam of variable length. The cases treated include in-plane and out-of-plane bending due to forces and moments applied to the end of the beam in three principal directions, and uniformly distributed loads applied along the beam in these three directions. Deflections were calculated by the strain energy method using Castigliano's theorem.