PNNL

Abstract

This paper summarizes the results-to-date of the Battelle, Stoller, and WASTREN (BSW) team’s efforts supporting the United States Department of Energy’s plans to remove uranium and technetium deposits before decommissioning the Portsmouth gaseous diffusion uranium enrichment plant. The BSW team investigated nitrogen trifluoride as a safer yet effective alternative gaseous treatment to the chlorine trifluoride (ClF3)-elemental fluorine (F2) treatment currently used to remove uranium and technetium deposits from the uranium enrichment cascade. Both ClF3 and F2 are highly reactive, toxic, and hazardous gases while NF3, although toxic [14], is “ no more harmful than moth balls”1]. BSW’s laboratory thermoanalytical and laboratory-scale prototype studies with NF3 established that thermal NF3 can effectively remove likely and potential uranium (UO2F2 and UF4) and technetium deposits (a surrogate deposit material, TcO2, and pertechnetates) by conversion to volatile compounds. Our engineering evaluations suggest that NF3’s effectiveness could be enhanced by combining with a lesser concentration of ClF3. BSW’s and other’s studies indicated compatibility with Portsmouth materials of construction (aluminum, copper, and nickel).