We have studied a co-precipitation method to remove actinides from
radioactive liquid waste. Lanthanum phosphate was selected as a
co-precipitation material because actinides and lanthanides are among the
homology series in the periodic table. In this report, the conditions, under
which the lanthanum compound is precipitated was looked at, as well as, ways
to widen the pH range in which the precipitation occurrs in sodium nitrate
solution. The properties of the resulting precipitates were also
investigated. Further, we investigated the incorporation ratio of amerícium
(decontamination factor), one of the actinides, into the precipitate from
sodium nitrate solution. Lanthanum phosphate was found to be more effective
compared to ferric compounds as the co-precipitation material to remove
amerícium. The incorporation conditions for strontium using lanthanum
phosphate were also investigated. The removal of strontium, by this method,
was more effective when the pH is above 7.0.