In the treatment of carnotite concentrates, sodium diuranate was prepared by acidifying tricarbonate liquors to eliminate carbon dioxide, and then precipitating the sodium salt by the addition of caustic. Direct precipitation of uranium by the addition of caustic to tricarbonate liquors was used when pitchblende ores were processed, because this procedure was more effective in giving a product with a low molybdenum content. Tests of this method in the laboratory and Pilot Plant indicated that low uranium losses (0.2 to 0.3%) would be encountered with typical liquors if 1.7 to 2.0 lbs of caustic were added for every pound of uranosic oxide in solution. Since losses as high as 3% were incurred in plant operations, further work was undertaken, in an effort to reduce the uranium concentration in the waste liquors.

In the ether extraction process, as originally developed, purified uranium dioxide was obtained by evaporation and calcination of the uranyl nitrate solution, followed by calcination of the resultant UO{sub 3}. It was suggested that an alternate procedure might be developed, involving the precipitation of uranium from the nitrate solution as ammonium diuranate. This material could then be calcined to uranosic acid, or reduced directly to the dioxide. It had already been established that ammonium diuranate could be precipitated completely from uranyl nitrate solutions. Experiments were carried out to determine whether a basic nitrate, analogous to a known sulfate salt, would be formed in the process. Both direct reduction of the diuranate to UO{sub 2} and calcination to uranosic acid were investigated to determine the physical characteristics and residual nitrogen of the resultant brown oxide.

This technical progress letter contains reports from six Technical Department divisions at the Hanford Engineer Works for February 9, through February 15, 1947. The six reporting divisions are: 100 Areas, 300 Area, 200 Areas, Chemical Development, Laboratories, and Statistical Studies.

This technical progress letter contains reports from six Technical Department divisions at the Hanford Engineer Works for February 16 through February 22, 1947. The six reporting divisions are: 100 Areas, 300 Area, 200 Areas, Chemical Development, Laboratories, and Statistical Studies. (JL)

Four routine shutdowns were experienced during the month. A measurable amount of the excess reactivity held in the control rods at the first of the month has been lost in the decrease in the average accumulated exposure of all the metal in the pile. The vertical safety rod guides have been measured for vertical alignment by the Maintenance Dept. A definite pattern has been found in the misalignment of the guides. The horizontal rod thimbles were borrowed on January 2, 1947 to see if any leaks were present. No leaks were observed but No. 2 Rod and No. 8 Rod had heavy gouge marks along the longitudinal axes. Several thimbles contained white corrosion. During the month two new bismuth tubes were established, 2871-D and 2877-D. This now gives the desired pattern of ten bismuth tubes.

None

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.