This technical report is the second of a series which concerns the separation of ions by solvent extraction with trialkyl phosphine oxides (TOPO). This investigation has consisted in the extraction of various ions from acidic solutions with extractants that are representative of these ore specific phosphine oxides - triphenylphosphine oxide (THPO) and tris-2-ethylhexylphosihine oxides (TEHPO). In general it is observed that: (a) the order of increasing capacity of extraction is THPO > TOPO >TEHPO. (b) No ion is extracted by THPO or TEHPO that is not extracted by TOPO under certain conditions. (c) The effect of hydrogen ion concentration is greater in TEHPO systems than it is in the other two, which indicated greater selectivity of extraction with TEHPO.

Techniques are described for determining U-235 abundance by measurement of the intensity of 0.18 Mev gamma radiation. One method involves measurement of the ratio of the intensity of 0.18-Mev radiation to that of 0.1 Mev radiation. The preferred technique consists of chemical separation of uranium followed by direct counting of 0.18-Mev photons. Application has been made in analysis of uranium samples of abundances in the range of 0.05% to 93%. Accuracy appears to be better than 3% if the abundance is between 0.7% and 100%. Findings in the self-absorption of 0.18 Mev radiation in uranium oxide are presented.