This quarterly progress report of the Aircraft Nuclear Propulsion Project at ORNL records the technical progress of the research on circulating-fuel reactors and ether ANP research at the Laboratory under its Contract W-7405-eng-26. The report is divided into three major parts: I. Reactor Theory, Component Development, and Construction, II. Materials Research, and III. Shielding Research.

Report issued by the Oak Ridge National Laboratory discussing the development of a closed-loop control system. As stated in the statement, "the purpose of this thesis was to design and build a closed-loop control system to be used as an indicator of the level of high temperature liquids contained in a tank" (p. 1). This report includes tables, illustrations, and photographs.

Changes made in the Thorex process flowsheet were a decrease in the extraction column acidity to decrease thorium losses and the addition of a second thorium solvent-extraction cycle to provide the increased decontamination required when thorium irradiated to 2000-4000 g of U233 per ton is processed. Bonded slugs could not be dissolved by the Thorex flowsheet procedure. Various laboratory scale studies on feed preparation, first-cycle variables, and radiation damage to the solvent are reported.

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.