On the particle size distribution of hydrolyzed plutonium(IV) polymer

Colloid-borne forms of tetravalent actinides: a brief review

Tetravalent actinides, An(IV), are usually assumed to be little mobile in near-neutral environmental waters because of their low solubility. However, there are certain geochemical scenarios during which mobilization of An(IV) in a colloid-borne (waterborne) form cannot be ruled out. A compilation of colloid-borne forms of tetravalent actinides described so far for laboratory experiments together with several examples of An(IV) colloids observed in field experiments and real-world scenarios are given. They are intended to be a knowledge base and a tool for those who have to interpret actinide behavior under environmental conditions. Synthetic colloids containing structural An(IV) and synthetic colloids carrying adsorbed An(IV) are considered. Their behavior is compared with the behavior of An(IV) colloids observed after the intentional or unintentional release of actinides into the environment. A list of knowledge gaps as to the behavior of An(IV) colloids is provided and items which need further research are highlighted.

Size and Density of A 242Pu Colloid

The size and density of a 242Pu colloid has been measured by autocorrelation photon spectrometry. The sedimentation rate of the colloid was determined by ultraspeed centrifugation. From the concentration profiles of 242Pu in the centrifuged test tubes, a standard sedimentation formula was used to calculate the density; the size of the colloid was known from the light scattering experiments. The determined density of the 242Pu colloid was only slightly lower than the estimated density of crystalline PuO2.