Separation of the minor actinides (Am, Cm) from lanthanides at an industrial scale remains a significant technical challenge for closing nuclear fuel cycle. To increase safety used (UNF) reprocessing, as well reduce associated costs, novel solvent extraction process has been developed. The allows partitioning actinides, lanthanides, and fission products following uranium/plutonium/neptunium removal, minimizing number separation steps, flowsheets, chemical consumption, waste. This new...

This Critical Review reviews the origin and chemical rheological complexity of radioactive waste at U.S. Department Energy Hanford Site. The waste, stored in underground tanks, was generated via three distinct processes over decades plutonium extraction operations. Although close records were kept original disposition, tank-to-tank transfers conditions that impede equilibrium complicate our understanding chemistry, phase composition, rheology waste. Tank slurries comprise particles...

Abstract The U.S. Department of Energy (DOE) is responsible for retrieving, immobilizing, and disposing radioactive waste generated during the production nuclear weapons in United States. general strategy treating tank consists pretreating wastes by separating them into high-level low-activity fractions. fraction will be immobilized a glass form suitable disposal geologic repository. on-site. This paper reviews recent developments application pretreatment technologies to processing DOE wastes.

The Actinide-Lanthanide SEParation (ALSEP) concept is described. This based on using an extractant phase consisting of either N,N,N’,N’-tetraoctyldiglycolamide (TODGA) or N,N,N’,N’-tetra(2-ethylhexyl)diglycolamide (T2EHDGA) combined with 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (HEH[EHP]) to separate Am and Cm from lanthanide other fission activation products in a single solvent extraction cycle. neutral TODGA T2EHDGA serves co-extract the trivalent actinide ions nitric media....

Abstract This paper is a review of recent publications that have focused on combined extractant systems for separating trivalent actinides from the lanthanides. These mixed solvent combine an acidic with neutral to achieve actinide/lanthanide separation. Depending used, three categorizations can be considered, including combinations extractants 1) diamides, 2) carbamoylmethylphosphine oxides, and 3) polydentate nitrogen-donor ligands. relevant indicates that, although there significant...

Evaluation of the malonamide substructure with respect to binding site preorganization and complementarity for lanthanide metal ions suggests a new ligand architecture specifically designed enhance ion affinity. Consideration conformational reorganization, restricted bond rotation, donor group orientation that typical structures, example, N,N,N‘N‘-tetrahexylpropane-1,3-diamide (1), N,N‘-dibutyl-N,N‘-dimethyl-2-tetradecylpropane-1,3-diamide (2), or N,N,N‘N‘-tetramethylpropane-1,3-diamide (6),...

Separation of the trivalent actinides from lanthanides relevant to used nuclear fuel reprocessing remains still a challenging task. One options currently being investigated is combination two extraction processes, TRUEX and TALSPEAK. However, extractants in individual when combined, result system with complex behavior. To better understand interactions this combined system, FT-IR spectroscopy was small-scale solvent tests. The data indicate that presence CMPO, HDEHP dimer cleaves interacts...

Abstract Combining octyl(phenyl)-N,N-diisobutyl-carbamoylmethyl-phosphine oxide (CMPO) and bis-(2-ethylhexyl) phosphoric acid (HDEHP) into a single process solvent for separating transuranic elements from liquid high-level waste is explored. Co-extraction of americium the lanthanide nitric solution possible with mixture consisting 0.1 M CMPO plus 1 HDEHP in n-dodecane. Switching aqueous-phase chemistry to citrate-buffered diethylene triamine pentaacetic (DTPA) allows selective stripping...

Abstract Expanded low-carbon baseload power production through the use of nuclear fission can be enabled by recycling long-lived actinide isotopes within fuel cycle. This approach provides benefits (a) more completely utilizing energy potential mined uranium, (b) reducing footprint geological repositories, and (c) time required for radiotoxicity disposed waste to decrease level uranium ore from one hundred thousand years a few years. A key step in achieving this goal is separation americium...

The mechanism by which high concentrations (1.5 M in n-dodecane) of N,N-di-2-ethylhexyl-isobutyramide (DEHiBA) extracts HNO3 and UO2(NO3)2 is under examination. Most prior studies have examined the extractant at a concentration 1.0 n-dodecane; however, higher loading conditions that can be achieved extractant, this could change. Increased extraction both nitric acid uranium observed with an increased DEHiBA. mechanisms are thermodynamic modeling distribution ratios, 15N nuclear magnetic...

A hydrogen peroxide-based decontaminant, Decon Green, is efficacious for the decontamination of chemical agents VX (S-2-(diisopropylamino)ethyl O-ethyl methylphosphonothioate), GD (Soman, pinacolyl methylphosphonofluoridate), and HD (mustard, bis(2-chloroethyl) sulfide); biological agent anthrax (Bacillus anthracis); radiological isotopes 137Cs 60Co; thus demonstrating ability this approach to ameliorate aftermath all three types weapons mass destruction (WMD). Reaction mechanisms afforded...

Development of more effective, reliable, and fast methods for monitoring process streams is a growing opportunity analytical applications. Many fields can benefit from online monitoring, including the nuclear fuel cycle where improved radioactive materials will facilitate maintenance proper safeguards ensure safe efficient processing materials. Online with focus on optical spectroscopy provide fast, nondestructive method chemical species. However, identification quantification species be...

On-line monitoring based on optical spectroscopy provides unprecedented insight into the chemical composition of process streams or batches. Amplifying this approach through utilizing multiple forms in sensor fusion can greatly expand number and type species that be identified quantified. This is demonstrated herein, analysis used nuclear fuel recycling streams: highly complex processes with target interfering analytes. The techniques visible absorbance, near-infrared Raman were combined to...

Abstract A series of novel alkylphenoxy fluorinated alcohols were prepared and investigated for their effectiveness as modifiers in solvents containing calix[4]arene‐bis‐(tert‐octylbenzo)‐crown‐6 the extraction cesium from alkaline nitrate media. The structure portion modifier influences chemical stability, a that contained terminal 1,1,2,2‐tetrafluoroethoxy group was found to decompose following long‐term exposure warm solutions. However, replacement tetrafluoroethoxy with...

The complexes formed during the extraction of neodymium(III) into hydrophobic solvents containing acidic organophosphorus extractants were probed by single-crystal X-ray diffractometry, visible spectrophotometry, and Fourier-transform infrared spectroscopy. crystal structure compound Nd(DMP)3 (1, DMP = dimethyl phosphate) revealed a polymeric arrangement in which each Nd(III) center is surrounded six oxygen atoms pseudo-octahedral environment. Adjacent ions are bridged (MeO)2POO– anions,...

Liquid–liquid distribution behavior of nitric acid (HNO3) and water by a diglycolamide (DGA) ligand, N,N,N’,N’-tetra-2-ethylhexyldiglycolamide (T2EHDGA), into n-dodecane diluent was investigated. Spectroscopic Fourier transform infrared spectroscopy (FTIR) nuclear magnetic resonance (NMR) characterization the organic extraction solutions indicate T2EHDGA carbonyl coordinates with HNO3 progressively aggregates at high conditions. Water increases in presence HNO3. The experimentally observed...

Multiple tests of a co-decontamination (CoDCon) tributyl phosphate (TBP)-based solvent extraction flowsheet are being performed to determine the uncertainties associated with maintaining target U/Pu ratio in Pu-containing product. The first two used simple dissolved fuel simulants containing only U and Pu, but increasingly more complex will subsequent tests, ultimate goal performing irradiated fuel. is designed so as not create purified Pu stream, rather mixture mass 7/3. Uranium...

Nuclear energy is a promising low-carbon candidate to meet the increased demand for green energy, where integration of fuel recycling can have significant benefits material usage and waste reduction. Utilizing in situ monitoring tools provide ample opportunities better control safeguard nuclear recycle processes while also offering knowledge insight into real-time solution properties. The simultaneous measurement analytical targets multiple process locations enable mass balance accountancy...

The direct extraction of uranium from voloxidized nuclear fuel into an organic solvent offers several potential advantages over conventional hydrometallurgical reprocessing, including reducing the reprocessing plant footprint, providing initial degree decontamination fission products, and minimizing amount secondary waste nitric acid. In this work, oxides 1.5 M N,N-di(2-ethylhexyl)isobutyramide (DEHiBA) in n-dodecane is examined. UV-vis spectra distribution ratios HNO2 DEHiBA as well...

Nuclear fission is an energy source that can provide consistent power with very low associated carbon emissions. However, management of the used nuclear fuel important aspect application power. Recycling useful components from attractive option, but this involves chemical processing fuel. Possible separation technologies might be in regard are sensitive to solution pH. Raman spectroscopy a promising technique for monitoring pH solutions real time. Classical probes too fragile harsh...