James C. Marra

Removal of cesium from alkaline waste solution. Part I - Batch ion exchange study

Summary Batch ion exchange tests have been employed to evaluate the ability of SuperLig® 644 resin to remove 137Cs from highly alkaline nuclear waste solution. The batch sorption data indicated the SuperLig® 644 resin has a relatively high sorption affinity for cesium with a predicted number of bed volumes required to reach 50% breakthrough in a column operation (generally known as λ value) of ∼400 based on an initial total cesium concentration of 12.1 μg/mL. The sorption data also obey the Freundlich and Dubinin–Radushkevich isotherms.

Multiple Ion Exchange Column Tests for Technetium Removal from Hanford Site Tank 241‐AW‐101 with Superlig® 639 Resin

Abstract Five cycles of loading, elution, and regeneration were performed to remove technetium in the form of pertechnetate from a Hanford waste sample retrieved from Tank 241‐AW‐101 using SuperLig® 639 resin. The waste sample was diluted to 4.95 M Na+ and then processed to remove 137Cs through dual ion exchange columns, each containing 15 mL of SuperLig® 644. To remove technetium, the cesium decontaminated solution was processed downwards through two ion exchange columns, each containing 12 mL of the SuperLig® 639 resin. The columns, designated as lead and lag, each had an inside diameter of 1.45 cm and a height of 30 cm. The columns were loaded in series, but were eluted and then regenerated separately. The average technetium loading for the cycles was 250 BV (bed volume) at 10% breakthrough. There was no significant difference in the loading performances among the five cycles. The percent removal of technetium in the pertechnetate form (TcO4 −) was >99.94% and the average de‐contamination factor (DF) was ∼1.7 × 103. Approximately 99% of the TcO4 − loaded on the resin was eluted with <15 BV of deionized water at 65°C.

SuperLig® 644 resin accelerated aging study

SuperLig® 644 resin was exposed to simulated Hanford waste solution under air atmosphere or in protated inert environment, and in 0.5M HNO3 solution for 15 days and 45 °C. The degradation was evaluated by cesium batch distribution measurement.

Effect of temperature on SuperLig® 644 cesium removal from simulated Hanford tank waste supernate

Batch kinetic and column experiments have been carried out at 25, 35, and 45 °C to examine the effect of temperature on SuperLig® 644 cesium (Cs) removal from simulated Hanford tank waste supernate. The simulated solution mimicked the composition of the low-activity waste supernate from tank 241-AN-105 in the U.S. DOE Hanford site. Small quantities of toxic metals, such as Cd, Cr, Fe, and Pb were spiked into the simulant to evaluate the metals competitiveness with Cs for sorption on SuperLig® 644 resin. The results indicated that the temperature affects the removal of Cs and metal ions, although the effect was not the same for all metal ions. The extent of Cs removal decreased with an increase in temperature. The Cs capacity at breakthrough point was 0.015, 0.013, and 0.011-mmole/g dry resin at 25, 35 and 45 °C, respectively. The column was effectively eluted to less than 1% (0.1 C/C0) of the feed concentration with approximately 10 BVs of 0.5M nitric acid. The resin showed limited affinity for toxic metal ions (Cr, Cd, Fe, and Pb) as compared to Cs. Based on the batch kinetic data, the Cs uptake of the resin was not hampered by the presence of the toxic metals in solution.

Adsorption decontamination of radioactive waste solvent by activated alumina and bauxites

An adsorption process utilizing activated alumina and activated bauxite adsorbents was evaluated as a function of operating parameters for the removal of low level radioactive contaminants from organic waste solvent generated in the fuel reprocessing facilities and support operations at Savannah River Site. The waste solvent, 30 vol% tributyl phosphate in n-paraffin diluent, was degraded due to hydrolysis and radiolysis reaction of tributyl phosphate and n-paraffin diluent, producing fission product binding degradation impurities. The process, which has the potential for removing these activity-binding degradation impurities from the solvent, was operated downflow through glass columns packed with activated alumina and activated bauxite adsorbents. Experimental breakthrough curves were obtained under various operating temperatures and flow rates. The results show that the adsorption capacities of activated alumina and activated bauxite were in the order of 10{sup 4} and 10{sup 5} dpm/g of adsorbent, respectively. The performance of the adsorption process was evaluated in terms of dynamic parameters (i.e., adsorption capacity, the height and the efficiency of adsorption zone) in such a way as to maximize the adsorption capacity and to minimize the height of the mass transfer or adsorption zone.