REMOVAL OF PU-239 AND AM-241 FROM ROCKY FLATS SOIL BY LEACHING

A proposed remediation technology to remove Pu and Am from Rocky Flats Plant (RFP) soil combines hot solution (80 degrees C) leach with comp lexing (e.g., citrate) and reducing (e.g., ascorbic acid or dithionite ) agents. The majority of the Pu and Am in the RFP soil was associated with soil size particles of <0.50 mm. The Pu and Am in the soil with particle sizes of <0.25 mm are generally associated with the soil iron oxides, while Pu and Am in the soil particles >0.25 mm are generally associated with soil organic matter (SOM). A laboratory column-leachin g process was used (1) to evaluate the teachability of Pu-239,Pu-240 a nd Am-241 from RFP soil using aqueous solutions of sodium chloride (Na Cl), sodium citrate (Cit), sodium citrate-ascorbic acid (CAA), and sod ium citrate-sodium dithionite (CD) and (2) to determine the effects of temperature and solution concentration to extract Pu-239,Pu-240 and A m-241 from soil. Additional batch experiments measured the influences of soil particle size, soil organic matter (SOM), and iron oxide on th e solubility of alpha active contaminants. Our results show that the c omplexing-reducing reagent of citrate-ascorbic acid and citrate-dithio nite removed at least 70% of alpha active contaminants from RFP site s oil. However, the effectiveness of each leaching scheme varies with th e particle size fractions. Our results also demonstrate that Pu and Am are effectively removed from RFP site soil at room temperature, and t hat the solution concentration of 0.1/0.1 or 0.05/0.05 is the optimum molar concentration.