A study was conducted to demonstrate the stripping and evaporation steps in a Purex-type uranium recovery process and to ascertain the operating behavior of the equipment under a range of conditions. The factors considered were control, effectiveness, and reliability of equipment and optimum feed point. Experimental procedures are described, and recommendations for equipment modifications are included. (J.R.D.)

A new and rapid method for the liquid-liquid extraction of uranium and plutonium from hydrochloric acid solution is based on the use of tri(iso-octyl)amine dissolved in xylene or methylisobutylketone. Uranium and/or plutonium are separated from thorium, alkalis, alkaline earths, rare earths, zirconium, niobium, ruthenium and other elements which do not form anionic species under the conditions described. The technique may be used for either tracer or macro quantities of uranium. Several practical applications of the method for the separations chemist are proposed.

On May 23, 1957, a visit was made by the writer to the Selas Corporation of American in Dresher, Pennsylvania. The purpose of the visit was to discuss further investigations into methods of tubesheet brazing by direct heating. Original work along these lines has been carried out at ORNL and is covered by a memo (CF-57-4-57) to W.D. Manly, dated April 16, 1957, and entitled : Investigation of Tubesheet Brazing by a Method of Direct Heating.

An estimate has been made of the critical fuel concentration in the HRT, taking into account the effect of the core corrosion sample assembly. The estimate is based on a number of previous calculations of critical concentration in an un-poisoned reactor and one calculation of critical concentration as a function of poison level. The makeup of the first core corrosion sample assembly was used in calculating equivalent neutron poisoning effects. Figure 1 shows the estimated critical concentration as a function of temperature with the corrosion sample assembly in place. At 280°C, the assembly raises the critical concentration by 0.6 g U-235/kg D2O. This effect is equivalent to a uniformly distributed poison equal to 4.1% of the fission cross section. The equivalent poison is greater at lower temperatures, where the uranium concentration is lower.