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.

The most important source of radioactivity at the exit manifold of the pile will be due to O19, formed by neutron absorption of O18. A recent measurement of Fermi and Weil permits to estimate that it will be safe to stay about 80 minutes daily close to the exit manifolds without any shield. Estimates are given for the radioactivities from other sources -- both in the neighborhood and farther away from the pile.

The following sources of contamination in cooling water of the P-9 plant are considered: (1) Fission recoils, (2) Corrosion of metal, (3) Recoil from aluminum, (4) Induced activity in the water. It is found that for a P-9 plant of 3.5 x 10(4) KW contamination of the river at "X" should not exceed the .1 r criterion unless coating failure occurs. Tables of the amount of coating failure permissible are given as a function of holdup time.

Fermi, Anderson, and Nagle's experimental distribution of Indium resonance neutrons around a point source of fission neutrons in water has been fitted by analytic expressions which are source functions in the two-group, three-group, Fermi and Christy-Wheeler pile theory. The Christy-Wheeler function (exponential followed by a Gaussian) is the best fit; the two-group function (exponential) is slightly better than the Fermi Gaussian.

Various experimenters have shown (H.H. Gersman U.S. Patent 2,335,590, Nov. 30, 1943; Aluminum Co. of America, various technical papers; also CT-482) that when a billet is extruded by proper technique into a rod (or tube by a floating mandril) that flow of material is streamline and and the extruded article is essentially a space replica of the billet, with linearly distorted coordinates. Advantage is taken of this fact in the manufacture of alclad tubing in which a billet containing an inner core of one alloy with the outer part of another alloy cast around it is extruded together into an integral tube, e.g., to combine high corrosion resistance with high strength. The following experiments were carried out because of the desirability of obtaining a control rod which can be water cooled (or immersed in P9) and which contains boron. For some pile structures it may be desirable to have the major portion of the energy released by the neutron absorption of the control rod be spend in the rod itself by the nuclear reactions [formula] rather than in the surrounding media as is the case when absorption of neutrons is by cadmium according to the reaction [formula]. In the later …

Prior to operating a chain reacting, graphite moderated, water cooled uranium pile at Hanford, the corrosive action of water on uranium was studied. It was necessary to enclose the uranium cylinders in Al jackets. Preliminary data were available which indicated Al jacket corrosion might be influenced by the water temperature. Therefore, in order to specify safe operating conditions, it was desirable to know the temperature at any position on the Al jacket of a slug in the tube. Because of the experimental difficulties encountered in the measurement of the correct surface temperature, the problem has been attacked primarily from a mathematical standpoint. Mathematical formulae have been developed for most of the proposed Hanford designs. The purpose of this report was to evaluate and summarize the theoretical and experimental information for calculation of Al jackets surface temperatures for the design now installed at Hanford. Also, the summarized results were to be put into a form suitable for use in routine calculations. As a result of this survey, the Al surface temperature for the Hanford tube and slug design may be calculated with 15 degrees C by employing routine methods and certain simple factors and equations contained in this report. The factors …

Technical report with short reports from the (1) Physics Section I; (2) Physics Section II ; and (3) Physics Section III.