The critical mass of 94-239 and the corresponding critical dimensions of homogeneous mixtures of 94-239 with various moderating media been calculated as a function of the concentration of 94. A simple transformation makes the figures applicated to92-235. the results are in essential agreement with the preliminary estimated made independently by Oppenheimer and Serber. The problem of the stability of a chain reaction in solution and questions of protection are discussed.

Part 1. The neutron fission cross section of U237 has been measured in a thermal neutron spectrum and in a somewhat degraded fission spectrum. The fission cross section for thermal neutrons is found to be <2 barns; the ratio of the fission cross section of U237 to that of U235 in the degraded fission spectrum is found to be 0.476 +- 15% which corresponds to [formula] in this spectrum equal to 0.66 +- 0.10 barns. Part 2. The average neutron fission cross section of U237 has been measured in a neutron energy range extending from approximately 100 ev to fission spectrum. the average fission cross section in this spectrum is found to be 0.70 +- 0.07 barns. Part 3. The low thermal fission cross section for U237 (<2 barns) indicated that the excitation function for fission probably shows an effective threshold. If the excitation function is like all other heavy element (Z > 90) neutron fission excitation functions, it will exhibit a region of approximate constancy starting at a neutron energy of 0.5 to 1 Mev above its effective threshold and extending to a neutron energy in the neighborhood of 5.5 Mev. A hypothetical excitation function for neutron fission of …

The need for thermal and fast neutron fluxes in the range of 1 to 5 x l0/ sup 15/ neutrons/cm/sup 2/(sec) for the production of heavy elements such as Cf/ sup 252/ and other special isotopes and for improving the quality of beam experiments, reactor materials testing work, and solid state research has led to plans for the construction of three ultra high flux research reactors. The designs of these and other high flux research reactors are based on the general technology of enriched tank-type reactors; however, they utilize the principle of separate fuel and moderator regions to achieve flux peaking in these regions. Thus, proposed designs take the form of an annular fuel region with internal and external moderating regions or an under moderated core with an external moderator or reflector. In such arrangements, the thermal flux peaks in the moderating regions and the fast flux peaks in the fuel region, which results in maximum fast and thermal fluxes per unit of power. Since most of the moderation of fast neutrons takes place outside of the fuel region, the thermal flux peaking depends on the number of fast neutrons leaking from the reactor core, which in turn depends on …

"Several multiplier phototubes produced by England, Russia, or Switzerland were evaluated for amplification, photocathode sensitivity, photo-electron collection efficiency, cathode uniformity, and dark current. A description of the various tubes by designation numbers is given, along nth a description of techniques and equipment used in testing."

This report describes and evaluates the Hanford 105 reactor building structures' ability to withstand an internal pressure increase. The means by which their roof and wall surface would contain a pressure buildup 0.3 psi, and prevent contaminant release which might accompany a nuclear incident are discussed. Prototypes of the B, D, DR, F, and H reactor block wall configuration, the corrugated transite roof of the K reactors, and the corrugated transite walls of the K and C reactors are evaluated. Methods of securing certain building components are described, and a comparison of several candidate sealant coatings presented for consideration. These tests were performed at the request of the Design Operation, as part of CG-791, an existing reactor containment program. This series of tests represents only a part of the overall modifications program. A study of the reactor building containment design criteria is available in a Hanford document, HW-59236, by T. O. Brown.

Abstract. thorium can be precipitated as a salt of p-dimethylaminoazophenylarsonic acid at a pH of about 1.5. the precipitate, collected on a sintered glass filter is washed with dilute ammonium hydroxide to dissolve the dye. the amount of thorium is determined by measuring the concentration of the dye spectrophotometrically at a wavelength of 450 millimicrons. Zirconium, which interferes, can be separated and determined using the same reagent in strong hydrochloric. the behavior of thorium metal upon treatment with various acids and upon fusion withKHSO4 is described. three satisfactory procedures are given for dissolving the metal with sulfuric acid, phosphoric acid, and by a potassium hydrogen sulfate fusion. The laboratory was presented with the problem of analyzing for a large number of elements in O2 metal. the results of a systematic study of methods for effecting solution of the metal are offered here since they may be of some interest and use to other laboratories. The four methods which effected complete solution of the metal are (1) Sulfuric acid method; (2) Fusion method; (3) Phosphoric acid method; and (4) Nitric acid-hydrofluoric acid method.

A report about the properties of dilute uranium alloys. The mechanical properties of cold worked sirconium and zircaloy 2 at temperatures up to 500 C ore being determined.

A report about thermal conductivity measurements which are made on uranium, uranium-1.5 w/o zirconium, and zircaloy 2 for a program that aims to determine the feasibility of using clad specimens. Results from the measurements indicate that the difference in thermal conductivity values between uranium and uranium-1.5 w/o zirconium is less than the anticipated 5 percent.

Purpose of this research is twofold:: (1) to uncover new principles or techniques from which a CW source of electromagnetic radiation for the low millimeter and submillimeter wavelength range can be developed; and (2) to develop suitable detectors, components, and measuring techniques for evaluating and using the radiation as a diagnostic tool for plasma physics

"This paper deals with the Riemann function for linear hyperbolic systems of first-order equations. the leading term in the singularity of the Riemann function is determined and interpreted. In addition to equations with distinct characteristics, certain equations with multiple characteristics are treated."