Critical mass measurements on graphite-tamped, heterogeneous oralloy-graphite systems have been made as a safety guide for certain oralloy casting procedures. Various concentrations were obtained by alternately stacking 10.5 in. diameter oralloy and graphite plates. In the relation Oralloy critical mass = constant x (fraction of oralloy in the core volume) -n values for the exponent, n, in the neighborhood of 0.70 were obtained.

Abstract: "A method for determining hydrogen in lithium hydride by heating samples with lead at 600 C, was developed. The hydrogen evolved during thermal decomposition of the hydride is purified and oxidized to water with cupric oxide at 400 C. The analysis is completed by collecting and weighing this water. Success in development of the analytical procedure has depended upon a careful design and assembly of equipment for handling samples in a dry, inert atmosphere. For seven pure hydride samples analyzed by the recommended method the estimates of the standard deviation varied between 0.12 and 0.41 percent lithium hydride (or 1.3 and 4.2 parts per thousand) for 8 to 18 determinations on each sample. The procedure is relatively insensitive to variations in certain conditions. For single-piece samples weighing 0.2 to 0.5 gram it was found to be more satisfactory than a method which uses mercury in place of lead for sample decomposition. For powdered lithium hydride samples the lead and mercury methods are equally satisfactory."

This paper is issued in two volumes: LA-1664 and LA-1665. In LA-1664, the fundamental properties of a shock in free air are described, including the reasons for failure of similarity scaling. The results of an analytic solution for strong shocks are presented, which permit a determination of the energy in a shock wave from its rate of growth without recourse to similarity assumptions; from it the scaling laws for both homogeneous and inhomogeneous atmospheres are explicitly shown. The total energy is evaluated in a machine calculation for the blast wave and from this evaluation, the free air wave form for all hydrodynamic variables is presented. The general nature of the laws governing thermal radiation from atomic bombs is deduced, a new figure of merit for thermal radiation is suggested to replace the concepts of “thermal energy” and “critical calories,” which are considered ambiguous. Partition of energy is considered negligible in most cases of interest; the waste heat concept is reconsidered and the failures of scaling to TNT are regarded primarily as a failure of the ideal gas law. LA-1665 is concerned with preparation of height of burst curves. In the reflection process over ideal surfaces, the usual subdivision into regions …

This paper is issued in two volumes: LA-1664 and LA-1665. In LA-1664, the fundamental properties of a shock in free air are described, including the reasons for failure of similarity scaling. The results of an analytic solution for strong shocks are presented, which permit a determination of the energy in a shock wave from its rate of growth without recourse to similarity assumptions; from it the scaling laws for both homogeneous and inhomogeneous atmospheres are explicitly shown. The total energy is evaluated in a machine calculation for the blast wave and from this evaluation, the free air wave form for all hydrodynamic variables is presented. The general nature of the laws governing thermal radiation from atomic bombs is deduced, a new figure of merit for thermal radiation is suggested to replace the concepts of “thermal energy” and “critical calories,” which are considered ambiguous. Partition of energy is considered negligible in most cases of interest; the waste heat concept is reconsidered and the failures of scaling to TNT are regarded primarily as a failure of the ideal gas law. LA-1665 is concerned with preparation of height of burst curves. In the reflection process over ideal surfaces, the usual subdivision into regions …

A glass vacuum manifold and ionization chamber are evacuated and filled to atmospheric pressure with hydrogen and tritium. The hydrogen and tritium are evolved by dropping liquid, urine or water, on calcium metal and dried by passing through a suitable freezing bath. The current produced by the beta activity due to tritium is measured with a vibrating reed electrometer. The method has a precision of +3 per cent between the ranges of 100 and 1500 pc of tritium per liter. From O to 100 pc of tritium per liter the precision is +-5 to 10 per cent. The glass vacuum manifold has been constructed to fit in an aluminum suitcase which contains all the auxiliary equipment for the determination except the vacuum pump, vibrating reed electrometer, and the freezing bath solutions. The apparatus is sturdy and readily transported. The procedure is simple and adapted for use by untrained personnel.

Report discussing a proposed electron probe that is connected to the discharge current from a device called the Perhapsatron. "The Perhapsatron is an apparatus for the study of the type of magnetic containment known as the 'pinch effect.'"

The capillary trap method for the determination of carbon in metals (LA-1128) has been modified to give a fivefold improvement in sensitivity (0.1 microgram of carbon per millimeter). Samples from pure uranium buttons gave standard deviations ranging from 1.4 to 3.2 p.p.m. Varying sample size, in the range from 100 to 250 milligrams, did not affect the results significantly. The time required for an analysis is about 13-14 minutes. The method should be equally useful for plutonium.

Abstract: A method for separating small amounts of scandium (1 to 10 mg.) from a gram of uranium depends upon formation of insoluble uranium peroxide while the scandium in solution is complexed with ethylenediamine-tetraacetic acid. The precipitated peroxide carries down less than 30 p.p.m. of scandium. Uranium left in solution, less than one milligram in amount, does not interfere when the scandium is precipitated as ammonium scandium tartrate and determined gravimetrically by ignition of the tartrate to the oxide.