Chemical and engineering data were obtained for the feed digestion system and the extraction-scrub step of the Monex tributyl phosphate solvent-extraction process for recovering thorium and uranium from nitric acid-digested unclarified monasite sludge. Tests of the recommended conditions in a 2-in.-dia pulsed column demonstrated that thorium losses were approximately 1.2% and uranium losses, 1.5%. The flowsheet is workable but is not necessarily optimum.

It was suggested that radon concentrations in air and potassium fertilizers on the ground contribute appreciably to natural background radiation levels. The effect on natural background gamma radiation from radon and its associated daughters in equilibrium and from potassium in fertilizers has been calculated and found to be negligible. Background radiation intensities have been assumed to be on the order of 10 [mu]rad/hr.

Accurate knowledge of the lattice parameters comprised in the four factor formula k∞=η∈Pi are required for optimum designing of reactors. In the special case of cluster fuel elements conventional handbook formulas are of little use. It is the intent of this paper to report the results of some recent improvements in the calculation of these parameters. By the addition of certain refinements in the calculation of these parameters. By the addition of certain refinements to the conventional calculational methods considerable success has been obtained in the correlation of theory with experiment.

This report supersedes the similarly titled report dated December 31, 1958. It describes briefly features of the Dresden plant and proposes technical specifications.