The twelfth meeting of the Graphite Expansion Committee was held on December 6, 1946. A summary of the meeting is as follows. Recent laboratory studies suggest that the rate of graphite expansion decreases with exposure when the samples are exposed in an air atmosphere at ambient pile temperature, through the relative effects of atmosphere and temperature are not known. These observations are in qualitative agreement with the decreased rate of vertical expansion of the piles. The neoprene seal strips at the top of the near and far sides of the F Pile were removed during November. The cork seal in back of the Third Safety Tanks at the F Pile was also removed. Current estimates predict the general rupture of Van Stone flanges after 300,000--350,000 MD of pile operation if the rate of expansion is uniform. The working model of the split gun-barrel has been completed but is being modified to provide a key to prevent the gun-barrel flange from rotating. The proposal to replace a few tubes in operating piles, as discussed last month, has been modified in favor of more extensive work at the B Pile before moving to the D or F Piles.

This report divides the activities for November into three sections: D Pile; F Pile; and general physics. During November the D Pile was down twice for regularly scheduled shutdowns. Two scram occurred during the month, both of short duration. Five Special Request 15 tubes were discharged and recharged with Special Request 15. Some 13 inhour of reactivity were gained during the month. Vertical rod thimbles, 10 through 22, were tested. A Production Test was performed to determine the reactivity power coefficients of the F Pile at low power levels and with practically no xenon poison remaining. Additional experience in the use of temporary poison columns during an extended shutdown of the pile was obtained during the month. Four new bismuth columns were charged during the month and six tubes were charged with LiF. The F Pile had not yet returned to xenon equilibrium following the shutdown of November 27 at the end of the month, but conditions just prior to this shutdown indicate a loss of one inhour since October 31. Two sets of specimens were removed from the ``B`` Test Hole of the F Pile on November 4. Samples were also machined from graphite removed from the No. 9 …

The chelate process for the extraction and decontamination of plutonium has been investigated. The process is designed as an alternate process for ihe Hanford type operation. The basic chemical factors have been studied and two flowsheeis have been developed and tested for recovery of plutonium. An over-all yield of plutonium in excess of 99% is reported for one flowsheet using benzene as the organic solvent and 98.5% when toluene was substituted for benzene. The general factors involved in establishing all details of the flowsheets are thoroughly discussed and decontamination studies are indicated to complete the study in the present equipment. (auth)

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This technical progress report summarizes work at the Hanford Engineer Works` 100 Areas, 300 Area, 200 Areas for December 15, 1946 through December 21, 1946. (JL)

This document addresses radiation protection concerns for workers in the experimental laboratories and production plants where nuclear fission piles are being used. A broad in-depth discussion is provided based with the experiences gained in the Manhattan Project and being applied to contemporary activities. Discussion is thorough and encompasses control of external irradiations including alpha, beta, gamma, and neutron radiations; and control of radioactivity within the body by control of inhalation, ingestion, and entrance through skin or wounds. General measures for the control of radiation hazards is addressed by provision of clothing and waste disposal. An Appendix 1 is entitled General Rules and Procedures Concerning Activity Hazards.