Abstract: "A titrimetric method for the determination of fluoride in plutonium is reported. Prior to a steam distillation of the fluoride, the bulk of the plutonium is separated by precipitation of the sulfate. The fluoride in the distillate is titrated at a pH of 3.2 with 0.001 M thorium nitrate, using chrome azurol-S indicator. Applied to samples containing 1 to 15 parts per million fluoride, the recovery is 87% and the precision on the 95% confidence level is +/- 0.65 ppm."

A small source model for neutron flux distribution in heterogeneous reactors is proposed. Such a model takes more explicit account of fuel lumping than has been customary in most pile calculations. The small source is applied to the cases of plate and rod fuel elements. The chief results are equations which give the pile buckling in terms of the distance between fuel elements and in terms of fuel element constants. (W.D.M.)

Handwritten report. This theoretical introduction to the anisotropic elastic properties of the orthorombic [sic] uranium crystal presents certain basic ideas which are useful in the study of experimental methods for determining preferred orientations in polycrystalline bodies. The method of analysis used to determine the elastic constants suggests explanations and correlations for the observations of sonic wave experiments on bars having preferred orientations and also serves as an introduction into the type of mathematical relations used in the study of anisotropic crystals.

The study of the flame photometric method for determining the concentration of tributylphosphate (TBP) in a hydrocarbon diluent was undertaken because it showed promise of being economically competitive and subject to fewer interferences than the existing methods. The determination of TBP in the hydrocarbon solutions throughout the range 0.01 to 80 per cent TBP may be performed using the flame photometer. The principal conclusions resulting from the study found a that there was higher precision in the one to two percent TBP rang than the 45 per cent TBP level due to error in reproducing narrow slit width in the higher range, 2) nitric acid, uranyl nitrate, and thorium nitrate all interfere if present but can be eliminated by contacting the solution with water or sodium carbonate solution. 3) a single determination may be made in 15 minutes, multiple determinations can be made at a rate of one to two minutes per determination, and 4) a modification of an existing method makes possible the application of this method to the determination of TBP dissolved in aqueous samples. A relative precision of plus of minus five per cent (95 per cent confidence level) is obtained.

The presence of large amounts of plutonium in high exposure uranium will give rise to a large, positive, graphite reactivity, temperature coefficient. This will create control problems in normal operation and also in the event of loss of cooling. Some general suggestions are given for the solution of these problems. The magnitude of the coefficient is probably known within ± 25% at present and a program is planned to reduce this uncertainty. The uncertainty is of minor importance in the operating control problem but of considerable significance in the disaster control problem.

The useful lifetimes of the phosphoric-hydrochloric anodic etching solution and the nitric acid stripping solutions were studied. Groups of uranium wafers of surface areas approximately 0.033 sq ft were anodically etched and stripped. From the losses in weight observed, it was concluded that at least three square feet of uranium may be anodized per liter of phosphoric-hydrochloric acid solution without regeneration. The nitric acid stripping solution was found to be satisfactory for at least one square foot of uranium per liter, but the reaction rate decreased rapidly after the treatment of two square feet per liter.

A presentation of the values for the Pu²³⁹ fission cross section f factor extended into a higher energy range than previously reported in BNL-250. The values were obtained by integrating the standard expression defining the f factor on the Hanford IBM-CPC equipment. The un-fit experimental data of Leonard, as corrected for resolution and doppler effect, was used above 0.03 ev being attached to an analytic fit applicable below this point. Results are shown on the accompanying graph.

A bibliography on the subject of air sample activity vs flow rate has been prepared. The findings in two documents reviewed have been applied directly to this problem. It is concluded that air sample activity is not dependent on flow rate when sampling particles whose average diameter in 0.06 micron or greater.

One of the distinguishing features of many chemical production processes is that the process variation is obscured by measurement errors which are of the same order of magnitude or greater. This paper will discuss some elementary means of estimating true product variability under these conditions.