Dissolver solution samples were analyzed for neptunium, and the data are plotted as g Np/t U vs g Pu/t U.

BS>The average energy required to form an ion pair, W, when alpha particles are absorbed in mixtures of argon with other gases is studied. The other gases were selected on the basis of their ionization potentials. One group consists of representative gases that have ionization potentials below that of Ar (15.77 ev) and above the doublet metastable state of Ar (11.49 and 11.66 ev). This list includes methane, carbon dioxide, nitrous oxide, xenon, and krypton. The other group of special interest consists of some gases with ionization potentials below the metastable state of Ar. All gases tested in these two groups cause an increase in ionization, i e., a decrease in W, when added to argon. As an illustration of this effect, the addition of 1/2% of acetylene to Ar will increase the ionization by 23% The experimental data, i.e., W as a function of relative concentration of the two gases, were fitted to a model in which it is assumed that energy is transferred from two excited levels in argon to the additive gases in collision processes. Good agreement between the experimental data and calculations based on the model is taken as additional evidence that the excited state notion …

The Zirflex and Sulfex processes for chemical decladding Zircaloy or stainless-steel-clad UO/sub 2/ power reactor fuels were successfully demonstrated at irradiation levels as high as 28,200 Mwd/t. The Zircaloy jackets were dissolved in boiling 6 M NH/sub 4/F-- 1 M NH/sub 4/NO/sub 3/, and the stainless steel jackets were dissolved in refluxing 4 M H/sub 2/SO/sub 4/. Both processes gave average soluble losses of uranium and plutonium to the decladding reagents of about 0.05%. Centrifugation or filtration of the highly radioactive decladding waste solutions was required to recover UO/sub 2/ fines produced by fracture of the UO/sub 2/. The fines were recycled and dissolved with the UO/sub 2/ cores in boiling 4 M HNO/sub 3/ solution. About 5 to 6 hr were required for complete dissolution of the UO/sub 2/ core to produce terminal concentrations of 100 g of uranium per liter and 3 M HNO/sub 3/. The core solution was a suitable solvent extraction feed after clarification and adjustment of plutonium valence with sodium nitrite. One cycle of the modified Purex process, in Mini mixersettlers, using 100-g-uranium-per-liter feed solutions, gave losses of uranium and plutonium to the raffinate of less than 0.1%, and gross gamma decontamination factors of about …