The bibliography provided investigates the following sources: Chemical Abstracts 1947-1950., Metallurgical Abstracts Vols. 1-18., ASM Review of Metals Literature Vols. 1-6., J. Institute of Metals Vols. 78-80 (No. 7)., Physics Abstracts 1937-1950.

"This report contains information on the following topics related to the radiation shielding at test cell "C". (1) Calculation of wall and roof thicknesses. (2) Calculation of radiation heating of front wall by gamma and neutron absorption. (3) Calculation of neutron activation in front face of test cell. (4) Calculation of γ-dose rates both direct and behind shadow shields at various distances. (5) Dose produced by a reactor catastrophe."

A sphere of LiD 2 feet in diameter was irradiated by 2 x 10<sup>15 14 Mev neutrons. Samples of Li<sup>7 metal were positioned at various radii for the irradiation. An analysis of these samples for tritium led to a determination of the number of tritons produced by 14 Mev neutrons acting on Li<sup>7 in a LiD system.

A measurement of the [Lithium-7] reaction cross section by absolute counting of the tritium betas is described. The cross section was measured at several neutron energies between 4 Mev and 15 Mev. A comparison with results by emulsion techniques is given.

This report describes the construction, operation, and typical uses of Topsy, the versatile, remotely controlled, critical assembly machine at Pajarito. Section 1 covers the mechanical design of the machine, and the hydraulic and electrical operation of the various components. Section 2 describes how Topsy is used for investigating reacting metal assemblies. Procedures for establishing a delayed critical configuration and operation at delayed critical are illustrated for the oralloy-tuballoy system. Also included are brief descriptions of oralloy-nickel, plutonium-tuballoy, and low density and concentration assemblies that have been made on the machine.

The production yields of hydrazine by various ionization methods are compared. The maximum value of M/N (number of molecules reacting per ion pairs) for electric discharge was 0.25 and for beta particles on liquid ammonia, M/N = 0.31. A 1-Mev reactor could produce 1.6 kg of hydrazine per hour if M/N = 0.04 as determined by alpha particles on liquid ammonia. About 300 ev of energy were needed to form a hydrazine molecule. (C.J.G.)

This report brings together an extensive accumulation of material replacement (danger coefficient) data for the various oralloy critical assemblies at Pajarito. Corresponding values of effective absorption and transport cross sections are derived. In certain favorable cases, inelastic scattering contributions to the effective absorption cross sections are estimated. Special applications of material replacement data include computation of the relationship between oralloy critical mass and concentration of a diluent and hydrogen isotopic analysis of heavy water and heavy polythene.

Optical and morphological properties of 28 compounds of uranium, plutonium, americium and some related elements, belonging to 21 isomorphous groups, are described. Additional data are given on 5 compounds of similar type described in the National Nuclear Energy Series, Division IV, Volume w, Chapter 19, “Actinide Elements.”

Neutron detector traverses of the untamped Oy (Godiva) and the Tu- or Ni-tamped Oy (Topsy) metal critical assemblies have been obtained by counting the following types of radiation : 1) y-activity of U 235 and U238 fission products; 2) fission fragments of Np 237 in a spiral chamber; 3) and Beta -activity of Au and S. At a few positions within the assemblies, and for the U235 fission spectrum, cross section ratios of a number of pairs of fissionable isotopes were determined by means of a comparison fission chamber. At the center of Godiva, af(25)\af(28) = 6.2, and this ratio for the Topsy Oy-Tu assembly ranges from 6.8 at the center to 76 at a radius of 8-1/4”. Results of radiochemical analyses for fission and other reaction products, by Group J-11, are listed in an appendix.

The increased use of tritium monitoring devices has made it necessary to devise a scheme for the calibration of such instruments. Several methods for setting up known concentrations of tritium were considered. A dynamic system containing tritium as HTO vapor or gaseous HT was selected because of the ease of control of variables. The variables that have been considered are: ,1. The effect of rate of air flow through the instruments. 2. The effect of humidity on instrument response. 3. The effect of ion collection ahead of the ion chamber. 4. The variation of “hold time” from the generation of tritium to its passage through the ion chamber. 5. The instrument response to several concentrations of tritium as HTO vapor and gaseous HT. The following three types of monitoring devices have been calibrated:1. Model 101 Sniffer of Group P-1. 2. Cl-1 Vibrating Reed Electrometer of Group CMR-7. 3. Modified TIB of Group H-6.

The development of sampling methods and some field results of the off- site air sampling stations at the Nevada Proving Ground are reviewed. A technique of radioautography is presented which yields information about the activities of individual fall-out particles. This technique gives a comparison of particle activities from air drops and tower shots and a reason for the greater contamination associated with the latter. It also indicates that air samplers do not capture the most active fall-out particles, presumably because of their large size.

The work of the Laboratory has greatly expanded into applications of nuclear energy which are significant for national defense and security, but are not directly connected with weapons development. It was felt, therefore, that a description of the non weapons activities of the Laboratory would serve a useful purpose at this time. For classification reasons, it has been necessary to issue the report in three parts; the third part concerns power reactor experiments.

The work of the Laboratory has expanded into applications of nuclear energy which are significant for natural defense and security, but are not directly connected with weapons development. It was felt, therefore, that a description of the nonweapons activities of the Laboratory would serve a useful purpose at this time.. For classification reasons, it has been necessary to issue the report in three parts; this is the first and is concerned with controlled thermonuclear reactions.

The experiments described in this report were designed to explore the feasibility of precipitating plutonium from 35 percent TBP in Gulf BT using peroxide, fluoride, sulfide, sulfite, sulfate, cocalate, hydroxide, iodate and phosphate ions from anhydrous, dilute and concentrated aqueous sources.

Thorium is determined in uranium alloys by means of a fluoride separation followed by a complexometric titration. A nitric of hydrochloric acid solution of the alloy is neutralized to a pH of 2.0 to 3.0 and the thorium precipitated as thorium fluoride by the addition of hydrofluoric acid and ammonium fluoride using lanthanum as a carrier.