Contributions to the analysis of nuclear raw materials

A procedure to determine mg amounts of uranium in sodium diuranate samples was described. In this method the sample is dissolved in mineral acids and the uranium then determined titrimetrically after its reduction by means of ferrous sulfate in phosphoric acid solution. The titration was performed with standard potassium dichromate solution in the presence of barium diphenylamine sulphonate as indicator. This titration procedure is also very suitable for determination of uranium after its separation by means of anion exchange in a mixed aqueous-organic solvent system of 50 vol % tetrahydrofuran, 40 vol % methylglycol and 10 vol % 6 M hydrochloric acid. The method was used to determine the uranium in numerous yellow-cake samples from Mexico, uranium contents between 57 % and 71 % U3O8 were found. (author)