This semiannual report includes references in future items in the Brookhaven National Labratory program as well as an account of progress in the post six months.

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The purpose of this report is to review the characteristics of particulate contamination which set it apart from the other phases of the radiation control program and make it necessary to apply to it different concepts, analytical procedures, and control measures. The program is treated as one in the appraisal and control of dusts and fumes. The fact that the material is radioactive introduces certain new details, but this does not make the problem basically different from others in the field of industrial dust control.

This study was undertaken to determine the maximum temperatures that may be expected in slugs under various operating power levels. Information of this nature is required to properly evaluate the effects on the slug of pile operation at power levels higher than those currently in use.

This report details events of importance reported by the Hanford Operations Office for the week ending January 5, 1949.

This report details events of importance reported by the Hanford Operations Office for the week ending January 12, 1949.

This progress report discusses activities at the P Division for the month of December 1948. All piles operated at 275 megawatts throughout the month except for the outages listed under Area activities in this report. An unscheduled power outage occurred in the 300 Area on December 2. No difficulties were encountered except for the lost operating time. A total of 103 tons of metal was discharged from the piles during the month. Operating schedules in the 300 Area were reduced from a six-day week to a five-day week on December 20 because of the favorable status of the inventory of canned slugs. All processes are now working one shift a day except Canning and Machining which work two shifts a day.

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N{sup 12} is shown to have a half life of 12.5 {+-} 1 milliseconds, and a positron upper limit of 16.6 {+-} 0.2 Mev. It is produced by the reaction C{sup 12}(p,n)N{sup 12}, and has a threshold proton energy of 20.0 Mev. This indicates that N{sup 12} is within about 200 Kev of being unstable against proton emission. The mass of N{sup 12} is 12.0228 {+-} 0.00015, and the beta transition is allowed.

Prior to April 1948 the generally accepted method of reducing the radioactive contamination of metal tools and laboratory apparatus was a series of rinses in aqua regia or various other concentrated acids. This method proved unsatisfactory for three reasons. (A) It was not a dependable method of removing activity. (B) It had a delecterious effect on tools in that it caused serious pitting, which resulted in weakened parts, and exposed a bare metal that was subject to very rapid corrosion. (C) Tools and apparatus once cleaned by this method could not readily be cleaned a second time. With the aforementioned limitations in mind, it became obvious that a new method was required. After considerable investigation into a electrochemical processes the present method was developed. Essentially, the new method is an electropolish bath to remove the activity lodged in the pores of the metal, and a ``follow-up`` chrome plate bath to render the surface impassive to corrosion.

The supersonic method of cleaning glassware is an outgrowth of the fact that it has been heretofore impossible to manually clean ground glass and quartz joints because the activity became lodged in the small pores of the ground surfaces. It has been theorized that the nature of the forces binding polonium to the glass is similar to that of the chemical bond but are less intense. The problem then becomes one of finding a force greater than this binding energy, capable of freeing the activity from the glass. This has been accomplished by using frequencies of 100 cycles to 20 kc at a power output from 2 to 20 watts, passing through a citric acid solution (pH-2) into which the contaminated article is placed. The optimum results, using a tank with the dimensions 7 in. {times} 7 in. {times} 7 in. and 3 liters of solution, has been found at 200 cycles or harmonics of 200 cycles. Citric acid was used because of the fact that it forms a soluble complex with polonium. The frequencies used have been kept within the sonic range until enough data has been obtained and correlated to warrant the design and construction of more costly …

This document details activities at the Hanford Engineer Works during the month of December 1948.

This is a report on Analytical Services of the Pile Area Laboratories at Hanford. Pertinent facts are listed regarding the analytical services currently provided by the Analytical Section in the pile areas. The work of the Analytical Section in the pile areas may be classified into five categories as follows: Analysis of pile process water, analysis of power plant (boiler) waters, analysis of drinking water, analysis of columbia (non-process) and Yakima River water, and preparation of reagents and standard solutions.

Redox operations and waste metal recovery are reported. Construction in the 100-H, 100-DR, P-10 area pile areas and in the 234-5, 241-BY waste storage, and redox areas, process areas and Richland village are described. Visitor information is given. And construction progress at Schenectady is reported.

This is the progress report for the University of California, Radiation Laboratory for December 15, 1948-January 15, 1949. It discusses the following: (1) Bevatron; (2) 184-inch Cyclotron Program; (3) 60-inch Cyclotron Program; (4) Synchrotron Operation; (5) Linear Accelerator and Van de Graaff Operation; (6) Experimental Physics; (7) Theoretical Physics, (8) Isotope Separation; (9) Chemistry Departments; (10) Medical Physics; and (11) Health Physics and Chemistry.

Considerable study has been given to the problem of a cathode-follower coupling circuit for matching a B-wall tube to a properly terminated coaxial cable. A matched circuit makes it possible to obtain faster counting rates independent of practical cable lengths. A breadboard circuit has been built and first results indicate that a two millivolt signal at the input of the cathode-follower will operate the Model 162 Instrument Development Laboratory Scaling Unit when adjusted for maximum gain. This is comparable to the voltage available when the B-wall tube is coupled to its amplifier through a coaxial cable. Shielded room measurements have been completed in the ``R`` Building. One log-amplifier (EL-257) was delivered to group 32, one scaler-multiplier (EL-252) to group 34, one four-input GM mixer (EL-247 to Group 24, and the plating control regulation checker (EL-258) plus the portable pulse generator (EL-261) to Group 12. The scaler-multiplier (EL-253)is 20 per cent complete and the motor-driven slide wire and the four-input gamma mixer (EL-262) are 95 per cent complete. The manufacturing specifications for plating controls and the instruction book for the portable pulse generator (EL-2561) have been submitted for duplication and should be completed by January 31, 1949. The two (2) 6 …

This report provides the regional radiation surveys for January through December 1949.

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This report details events of importance reported by the Hanford Operation Office for the week ending February 2, 1949.

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