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A portable beta and gamma radiation meter of exceedingly small dimensions and weight has been developed. User acceptance has been more enthusiastic than any previous instrument of its type. The circuit, using one Victoreen V-32 tube, is the simplest electronic circuit possible for radiation work and gives high sensitivity. Stability exceeds anything of comparable sensitivity which has come to our attention. The short term stability is due to a circuit which prevents emission before the cathode reaches operating temperature. Long term stability has been improved by evacuating the tube enclosure and switch. The complete, one unit instrument, weighs four pounds two ounces, and is carried with a pistol grip. Exclusive of chamber and handle, its dimensions are 3'' wide, 6 1/2'' long, and 5'' high. The case is formed of aluminum and is designed to give excellent visibility of the meter. Three ranges of approximately 50, 500 and 5000 mr/hr have been incorporated in the instruments. The instrument has been named ''Cutie Pie'' due to its diminutive size.

The fourteenth meeting of the Graphite Expansion Committee was held on February 7, 1947. Laboratory studies indicate that either the graphite thermocouples are reading low or that annealing effects at elevated temperatures within the pile are much greater than those encountered In the laboratory. Current difficulties with operation of some of the horizontal and vertical control rods seem to be attributable to graphite expansion, though no complete understanding of the phenomena has been obtained and one is unable to predict the time required for similar difficulties to develop in other rods. Changes in clearance between process tubes and pile graphite in the D Pile have been erratic in nature but have averaged much less than had been anticipated. The negligible decrease in clearance for central tubes indicates that the expanding cross-wise graphite layers are slipping with respect to the graphite layers which contain process tubes.

This report contains the calculation of the number and spacing of poison columns required to hold a 105 pile in the following cases: (1) complete failure of horizontal rods, (2) complete failure of all rods. Using 10% Cd 90% Pb poison columns of 1.44 inch diameter, it is found that 17 poison columns are required to hold the pile in case of complete failure of horizontal rods, and 65 poison columns are required to hold the pile in case of complete failure of all rods.

The excess reactivity available in an operating pile is absorbed in poison columns and horizontal rods. The temperature distribution of the pile is determined by the relative strengths and locations of the poison columns and the configuration of control rods used. A method for adjusting poison columns and rods to improve upon the pile`s temperature distribution is given in Document {number_sign}7-2654, ``Procedure for Improving Temperature Distribution via Rods and Columns,`` Wheeler and Menegus to Jordan, September 9, 1945. A relationship between poison moment (inhour lattice units) and temperature moments (per coat) was theoretically derived in the above document and has since been measured on several occasions on the basis of operating experience. A survey of recent operating data for the F Pile has been made by H. A. Gauper, Jr. with the intent of improving the method for obtaining the temperature and poison moments and relating changes in the two. This study was concerned with only the horizontal and vertical dipole moments. The results of Mr. Gauper`s investigation are summarized in this memorandum.