The purpose of this memorandum is to present and analyze, in terms of the current status of knowledge of radiation damage to graphite, the data available at the present time on the expansion status of the graphite in the piles, and suggest, in terms of this analysis, several possibly feasible curative and preventive measures. The portion of the data to be covered in this memorandum consists of that obtained during the last four years from pile motion measurements and from tube bowing measurements, and particularly that from graphite mining operations during the last six months. The objective to be attained is twofold: (1) the information developed here should permit a better understanding of the need for and development of future corrective measures to be applied to the present piles, and (2) this summary will serve as a basis for further experimental work necessary to place the conclusions on a more firm foundation. This memorandum is being issued at this time, although present ideas and conclusions are in a somewhat uncertain state, in the hope that the currently most feasible preventive measure might be applied to the DR Pile before startup.

This is a progress report of the production reactors on the Hanford Reservation for the month of June 1950. This report takes each division (e.g., manufacturing, medical, accounting, occupational safety, security, reactor operations, etc.) of the site and summarizes its accomplishments and employee relations for that month.

The purpose of this manual is to present a Hazard Breakdown of all jobs normally encountered in the laboratory work of the three sections comprising the Analytic Section, Metallurgy and Control Division of the Technical Department. A Hazard Breakdown is a careful analysis of any job in which the source of possible dangers is clearly indicated for each particular step. The analysis is prepared by individuals who are thoroughly familiar with the specific job or procedure. It is felt that if the hazards herein outlined are recognized by the Laboratory personnel and the suggested safety cautions followed, the chance for injury will be minimized and the worker will become generally more safety conscious. The manual, which is prefaced by the general safety rules applying to all the laboratories, is divided into three main sections, one for each of the three sections into which the Laboratories Division is divided. These sections are as follows: Section 1 -- 200 Area Control; Section 2 -- 100 Area Control; Section 3 -- 300 Area Control, Essential Materials, and Methods Improvement.

This is the second of a series of Quarterly Progress Reports. While most of the departments have summarized their work or used a form comparable to abstracts, the Chemistry Department has given both abstracts and complete reports on its work. The major part of the progress in the Reactor Science and Engineering Department is being presented simultaneously in a separate classified report. There are reports from the following departments: (1) physics department; (2) instrumentation and health physics department; (3) accelerator project; (4) chemistry department; (5) reactor science and engineering department; (6) biology department; and (7) medical department.

Most methods of separating isotopes depend on the use of a large magnetic field. The isotron is an electromagnetic device for separating isotopes, but it effects the separation by the use of radiofrequency voltages instead of magnetic fields. It has the advantage that plane sources of large area can be used instead of the slit sources to which most magnetic methods are limited. Before entering into any discussion of the details, a simplified description of the principles of the method is given.

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A method for the paper chromatography of sterols involving impregnated paper has been developed.

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Uranium is recovered as an aqueous solution of uranyl nitrate and nitric acid in both the tributyl phosphate metal recovery process and the Redox separation process. The streams are designated as RCU and IIIEU in the respective processes. For metal recovery these streams are combined. The purpose of the nitric removal operation is to minimize equipment corrosion and to restrict contamination of the final uranium oxide with corrosion products which might be formed in the elevated temperature reactor employed for the decomposition of uranyl nitrate to the oxide. Because of the large quantities of uranium being processed it is desirable to conduct the concentration of the combined RCU and IIIEU streams in a continuous type process to reduce the operating and fixed charges. Determination of the physical and chemical properties of the dilute aqueous uranyl nitrate -- nitric acid system, as it progresses toward an essentially nitric acid free concentrated state, is necessary to define the optimum operating conditions.

The microgram scale isolation and preparation of pure compounds of americium is described. Data are presented to show that the alpha-half-life of the isotope Am{sup 241} is 490 {+-} 14 years. The absorption spectrum of Am(III) in 1M nitric acid in the range 3500-8000 mu is given. The wave lengths of 10 of the most prominent lines in the copper spark emission spectrum of americium are given to the nearest 0.01 {angstrom}. Evidence is presented to show that the potential for the Am(III)-Am(IV) couple in acid solution is more negative than -2v and that the potential for the Am(II)-Am(III) couple is more positive than +0.9v.

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