Specific surface area determinations of U and Pu oxide particles

Abstract

Important factors that can influence the dissolution rate of a particle deposited in the lung include chemical composition of the particle, crystalline structure, and amount of surface interacting with body fluids. Specific surface area determinations were made on samples of mixed uranium and plutonium oxides from industrial facilities and on samples of depleted uranium oxide, using a 85Kr adsorption technique. Samples of respirable particles collected on filters during aerosolization of these materials for animal exposures, as well as the starting materials, were examined. Specific surface areas ranged from 3 to 40 m 2 g −1. Results were used to determine shape factors used in a simulation model of the retention, distribution, and excretion of particles deposited in the lungs of animals during an inhalation exposure. For two aerosol samples, the specific surface area increased with each overnight heat treatment; this suggests that heat transformed the samples. Measurements made before and after a 30-day dissolution study of uranium oxides in lung serum simulant demonstrated a decrease in specific surface area (∼50%). This suggests that particle size or surface roughness changes as dissolution proceeds.