Transpiration studies on the volatilities of PuO 3(g) and PuO 2(OH) 2(g) from PuO 2(s) in the presence of steam and oxygen and application to plutonium volatility in mixed-waste thermal oxidation processors

Abstract

Transpiration experiments have been carried out to study the volatility of PuO 2(s) in the presence of oxygen and steam. Vapor pressures have been measured for PuO 3(g) and PuO 2(OH) 2(g) and thermodynamic data established for them. Thus, Δ fH 298 0 is determined to be −(562.8 ± 5.0) kJ/mol for PuO 3(g) and −(1,018.2 ± 3.3) kJ/mol for PuO 2(OH) 2(g). In applying the Pu volatility data to a pilot scale mixed waste (containing both radioactive and hazardous constituents) incinerator with primary and secondary combustion chambers, it is found that Pu volatilization makes a negligible contribution to air emissions if the temperature in the secondary combustor is maintained at less than 1600 K. Chlorine- and fluorine-induced volatilities of plutonium are not considered in this analysis.