Introduction: The present report summarizes pilot plant operations on the sulfuric acid digestion of -200 mesh leached zone and filtration of the digested slurry for the period May 5, 1952 through August 7, 1953.

Introduction: "The extensive use of uranium hexafluoride in the Nier-type mass spectrometers, where the ionization is produced by slow electrons, made a knowledge of the ionization potentials of the various ions desirable. This information was not available and work was accordingly begun to secure such data. The first measurement was made with a VGIA ion gauge and has been described in TEO report CD-310. With this apparatus it was not possible to identify the ionization products and it was presumed that the value reported was for the UF5 ion. When time and equipment became available, the work was continued and the critical potentials of the singly-charged ions determined."

This report follows experiments on K[infinity], measuring the element for several red sizes, enrichments, and water-to-uranium volume ratios-(1, 2), by making use of the relation k[infinity] = 0M-[2]B-[2] (M-2 = migration area, B = buckling). The purpose of this report is to compare the experimental data for k[infinity] with values calculated from the four-factor formula k[infinity] = [eta][epsilon]pf.