Use of ozone for dissolving high-level plutonium dioxide in nitric acid in the presence of Am(V,VI) ions

• Published in: Radiochemistry (New York, N.Y.) Vol. 53; no. 6; pp. 612 - 618
• Main Authors: Gelis, V. M., Shumilova, Yu. B., Ershov, B. G., Maslennikov, A. G., Milyutin, V. V., Kharitonov, O. V., Logunov, M. V., Voroshilov, Yu. A., Bobritskii, A. V.
• Format: Journal Article
• Language: English
• Published: Dordrecht SP MAIK Nauka/Interperiodica 01.12.2011
• Subjects: Chemistry; Chemistry and Materials Science; Chemistry/Food Science; Nuclear Chemistry; nitric acid; americium; ozone; plutonium dioxide; dissolution
• ISSN: 1066-3622; 1608-3288
• DOI: 10.1134/S1066362211060087

Plutonium dioxide recovered in the course of reprocessing of SNF from WWER reactors (so-called high-level PuO 2 ) was subjected to dissolution in 0.6–3.0 M HNO 3 in the presence of Am(III) ions under ozonation with an ozone-oxygen mixture containing 30–180 mg l −1 O 3 . Measurements of the rate of the PuO 2 dissolution in 3 M HNO 3 in the temperature interval from 30 to 80°C showed that, with an increase in the ozone concentration in the ozone-oxygen mixture from 30 to 180 mg l −1 , the dissolution rate increases by a factor of 4–5. The acceleration of the PuO 2 dissolution is attributed to the formation of Am(V,VI) by homogeneous oxidation of Am(III) ions with ozone dissolved in HNO 3 . The Am dioxocations formed act as PuO 2 oxidants and are continuously regenerated by the oxidation of Am(III) with ozone. This assumption is confirmed by an additional increase in the dissolution rate, observed on introducing Am(III) into the initial electrolyte for the PuO 2 dissolution.