Entrained solids have in the past been one of the major factors limiting solvent extraction fission product decontamination. These solids are known to be surface active, to absorb fission products, and to form interfacial films or "cruds". A major step in eliminating these cruds was taken when the Purex columns were modified to operate with the interfaces at the waste ends of the columns rather than the product ends. This type of operation tended to flush the solids out with the waste rather than the product streams.

In the Columbia River downstream from Richland, Washington there is a gradual decrease in concentration of radioactive isotope. At any one location there are fluctuations due to factors such as dilution and decay time. During this period at all locations the concentration of alpha particle emitters in water averaged below the detection limit. Beta particle emitters in water upstream of McNary Dam decreased slightly due to increased river flow this quarter, with averages at various locations. Downstream from McNary Dam, beta particle emitter average concentrations in water were about the same as the past three quarters.

Hydrogen peroxide has been used to reduce plutonium (VI) in nitric acid solution to the (IV) valence state. However, reduction of plutonium (VI) solutions containing iron has often been incomplete when hydrogen peroxide was used as the reducing agent. Since reduction of plutonium (VI) has been applied in plant solutions containing iron, a study of the plutonium (VI) reduction with hydrogen peroxide was undertaken. Variables tested included plutonium, nitric acid, and iron concentrations.