This report addresses toxicity (largely chemical) of Manhattan Project materials from the point of worker protection. Known chemical toxicities of X material (uranium), nitrous fumes, fluorine, vanadium, magnesium, and lime are described followed by safe exposure levels, symptoms of exposure, and treatment recommendations. The report closes with an overview of general policy in a question and answer format.

The turnings have proved to be highly inflammable and subject to spontaneous ignition. Several experiments have been conducted at Herring-Hall-Marvin Safe Company, Hamilton, Ohio, and Baker Brothers, Inc., Toledo, Ohio, and in addition there have been a number of accidental fires, of which at least three were spontaneous. Fires of quantities ranging from several pounds to several hundred pounds have been experienced and a number of extinguishers have been tried. Records of this work are available in our files. While the work to date does not constitute an exhaustive survey of the problem, we believe that it is now safe to outline precautionary and protective measures.

Metal Hydrides Incorporated was a pioneer in the production of uranium metal on a commercial scale and supplied it to all the laboratories interested in the original research, before other methods for its production were developed. Metal Hydrides Inc. supplied the major part of the metal for the construction of the first experimental pile which, on December 2, 1942, demonstrated the feasibility of the self-sustaining chain reaction and the release of atomic energy.

Experiments were carried out for the purpose of increasing production, efficiency, and purity of uranium metal. The electrolytic method as described by Driggs and Lilliendahl for the preparation of uranium metal was followed with but little deviation. The yield of metal at the very best was only 50%. The metal powder produced, at times, was very pyrophoric. Methods were found whereby the metal, at least in part, can be made from the oxides with an average yield of about 90%. The small amounts of sludge and slag accumulated in this modified process can readily be re-used in the electrolysis pot and, therefore, an overall yield of 96% can be obtained. Information accumulated from these experiments has been compiled in such a manner as to be readily available for factory use, for patent purposes and for future publication.

Production of tetrafluoride for the month of April was 49,400. New equipment installed late in March operated smoothly and the production was slightly over the rated capacity of the plant. Nickel ends were welded on to the steel reactor tubes to prevent corrosion at the cover joint and possible contamination of the product with iron. The nickel ends will also save considerable repair work on the tube ends. The magnesium trays for some of the reactors are beginning to crack at the sides from frequent straightening. The trays are bent out of shape by the expansion of the product and are reshaped by hammering over a die. Some of the cracks have been repaired by welding but this is not very satisfactory because the welded trays are harder to straighten and often crack again.

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Measurements of the spectrum of the fission neutrons of 25 are described, in which the energy of the neutrons is determined from the ionization produced by individual hydrogen recoils. The slow neutrons producing fission are obtained by slowing down the fast neutrons from the Be-D reaction of the Stanford cyclotron. In order to distinguish between fission neutrons and the remaining fast cyclotron neutrons both the cyclotron current and the pusle amplifier are modulated. A hollow neutron container, in which slow neutrons have a lifetime of about 2 milliseconds, avoids the use of large distances. This method results in much higher intensities than the usual modulation arrangement. The results show a continuous distribution of neutrons with a rather wide maximum at about 0.8 MV falling off to half of its maximum value at 2.0 MV. The total number of netrons is determined by comparison with the number of fission fragments. The result seems to indicate that only about 30% of the neutrons have energies below .8 MV. Various tests are described which were performed in order to rule out modification of the spectrum by inelastic scattering.

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The objective of this report is to investigate the feasibility of obtaining uranium from the carnotite sludge in such a form as o permit its use in the brown oxide purification process.

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To find a process for successful photochemical separation of isotopes several conditions have to be fulfilled. First, the different isotopes have to show some differences in the spectrum. Secondly, and equally important, this difference must be capable of being exploited in a photochemical process. Parts A and B outline the physical and chemical conditions, and the extent to which one might expect to find them fulfilled. Part C deals with the applicability of the process.

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The report addresses the density of solid hex near the Triple and the expansivity of the liquid from the triple point.

Included in this semi-monthly report written in 1943 are progress with neutron beams, neutron absorption in enriched materials, equipment operation and maintenance reports of the cyclotron neutron source facility, and instrumentation maintenance activities of individuals in the cyclotron group. (GHT)

This report discusses effluent dilution of a retention basin at the Hanford Works in 1943. (JL)

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