Results of tracer studies suggest that, in tributyl phosphate extraction processes designed to recover and purify fissionable material, minimum ruthenium extraction should be obtained from feeds at least 2 M in nitric acid or at least 1 M acid-deficient. Ruthenium decontamination was decreased by preheating the feed and increased by pretreatment with reducing agents. A pretreatment using 0.06 M ferrous ion and 0.5 M urea with 1 hr simmering at 85°C should increase ruthenium decontamination about 10-fold in the 25 process. If other process considerations dictate the use of a low-acid feed, decontamination from ruthenium may be improved by using 3 M nitric acid as the scrubbing solution. Apparently, the scrubbing process is quite time-dependent; a solvent holdup time of about 15 min may be needed in the scrub section for maximum decontamination.

In some recent experiments the ion density in a plasma was measured as a function of radial distance from a d-c arc source of ions for the magnetic field intensities from 2500 to 14000 oersted. The diffusion coefficient appeared to very inversely as the square of the magnetic field strength, D~1/H2. The absolute value of D was shown to be approximately that which would be predicted by the collision diffusion theory when account is taken of the shorting effect of the end walls. The purpose of this report is to continue the examination of ion diffusion in a plasma and field experimentally the relation between the diffusion coefficient and the neutral gas pressure for a constant magnetic field.

The Aircraft Reactor Experiment (ARE)was successfully concluded in November of 1954, and a detailed report of the operation was published the following year. At that time it was thought that an extensive examination of the reactor and system components after disassembly was warranted. It was realized, of course, that the level of radioactivity of the components would necessitate extensive delays in the examinations. Since examination of a few critical ARE samples showed nothing unexpected, much of the planned hot-cell inspection was postponed and complete examination of all but a few specimens was indefinitely suspended. The few examinations that were completed are described in this report, along with a description of the disassembly of the ARE system. Diagrams of the fuel system, sodium system, and off-gas system are presented in Figs. 1, 2, and 3 for reference use in visualizing the disassembly process.