Kristy Long

In contrast to its aqueous chemistry, neptunium exhibits a highly complex redox behavior in the ionic liquid betaine bistriflimide, [Hbet][Tf2N]. Spectroscopic studies have shown for the first time that up to three oxidation states (iv, v and vi) and up to six neptunium species can exist simultaneously. Both redox reactions and coordination of betaine lead to an unprecedented stability of Np(iv) and Np(vi).

Project goals: Can used nuclear fuel be partitioned by dissolution in alkaline aqueous solution to give a solution of uranium, neptunium, plutonium, americium and curium and a filterable solid containing nearly all of the lanthanide fission products and certain other fission products? What is the chemistry of Am/Cm/Ln in oxidative carbonate solutions? Can higher oxidation states of Am be stabilized

Project goals: Can used nuclear fuel be partitioned by dissolution in alkaline aqueous solution to give a solution of uranium, neptunium, plutonium, americium and curium and a filterable solid containing nearly all of the lanthanide fission products and certain other fission products? What is the chemistry of Am/Cm/Ln in oxidative carbonate solutions? Can higher oxidation states of Am be stabilized

Previous work in Germany and Japan has indicated that crystallization of uranyl nitrate at low temperatures from nitric acid solution could be a useful process for removing most of the uranium from spent LWR fuel after the fuel is dissolved in nitric acid. The crystallization process potentially could reduce the cost of LWR fuel partitioning because it provides a selective

The mission of the Advanced Fuel Cycle Initiative (AFCI) of the Office of Nuclear Energy Science and Technology of the US DOE is to develop and demonstrate technologies that will enable the transition to a long-term and economically and politically viable advanced ...

In the context of the demonstration of the UREX (uranium extraction) process, a separation of uranium and technetium using an anion exchange resin was performed on a simulant solution containing 98.95 g/L of238U and 130.2 mg/L of99Tc. After sorption on the resin, TcO4−was eluted with NH4OH, the eluting stream was treated, and the technetium converted to Tc metal (yield=52.5%). The purity of the compound was analyzed: it contains less than 23.8 μg of238U per gram of99Tc. Tc metal was characterized by X-ray diffraction (XRD) and X-ray absorption fine structure (XAFS) spectroscopy; EXAFS analysis clearly confirms the hexagonal structure of the metal obtained after treatment. Uranium was converted to ammonium diuranate and to U3O8in a yield of 88.2%, analysis indicates that the compound contains less than 0.16 μg of99Tc per gram of ammonium diuaranate.

ABSTRACT A process to separate technetium from uranium in a simulated process solution resulting from the uranium extraction (UREX) process was demonstrated using a new extraction chromatographic (EC) resin from Eichrom Technologies. The Weak Base ECTM resin contains a tertiary amine incorporated into a macroporous resin bead support. The resin provided a good separation of pertechnetate from a 100 g/L uranyl(VI) nitrate solution representative of a UREX feed solution. The resin appeared quite stable to multiple uses. The elution of Tc from the resin was substantially improved over previous anion exchangers used. The eluted pertechnetate and ammonium nitrate solution was mixed with a reducing agent and gradually heated under an argon flow and then an argon/H2O flow to recover the Tc as the metal (96% yield). The U was precipitated with ammonium hydroxide and recovered as U3O8 (98% yield).

ABSTRACT In alkaline carbonate solutions both technetium and uranium exist as anionic species, TcO4– and UO2(CO3)34–, which makes separating Tc and U from each other more challenging compared to acidic PUREX type solutions where uranium forms neutral or cationic complexes. We tested the batch separation of 99Tc, 238U, and 239Pu from carbonate solutions using anion exchange resins with different properties, including Purolite A530E, Reillex HPQ, and Dowex Marathon WBA. Overall, the highest Kd values for pertechnetate were achieved using the strong base resins in solutions of the lowest carbonate concentration. Pretreating the resins in higher carbonate concentrations before use was shown to increase the Kd values for pertechnetate. The measured Kd values for uranium generally were low, resulting in high selectivity for the separation of pertechnetate from uranium in carbonate solutions.

For over forty years, NASA has relied on plutonium-238 in Radioisotope Thermoelectric Generator (RTG) units and Radioisotope Heater Units ( W s ) to provide power and heat for many space missions including Transit, Pioneer, Viking, Voyager, Galileo, Ulysses and Cassini. RHUs provide heat to keep key components warm in extremely cold environments found on planets, moons, or in deep