A5036019929- Nuclear Materials and Properties
- Radioactive element chemistry and processing
- Nuclear reactor physics and engineering
- Fusion materials and technologies
- Nuclear and radioactivity studies
- Spectroscopy and Chemometric Analyses
- Radioactive contamination and transfer
- Nuclear Physics and Applications
- Extraction and Separation Processes
- Nuclear materials and radiation effects
- Chemical Synthesis and Characterization
- Electrochemical Analysis and Applications
- Surfactants and Colloidal Systems
- Spectroscopy and Quantum Chemical Studies
- Graphite, nuclear technology, radiation studies
- Enhanced Oil Recovery Techniques
- Microfluidic and Capillary Electrophoresis Applications
- Chemical and Physical Properties in Aqueous Solutions
- Water Quality Monitoring and Analysis
- Spectroscopy Techniques in Biomedical and Chemical Research
- Molten salt chemistry and electrochemical processes
- Advanced Chemical Sensor Technologies
- Groundwater flow and contamination studies
- Planetary Science and Exploration
- Electrostatics and Colloid Interactions
Pacific Northwest National Laboratory
2014-2024
Washington State University
2019
Analysis Group (United States)
2016-2018
Richland College
2017-2018
Battelle
2016
United States Department of Commerce
2009
Office of Scientific and Technical Information
2009
National Technical Information Service
2009
A distinct need exists for real time information on an acid concentration of industrial aqueous streams. Acid strength affects efficiency and selectivity many separation processes, including nuclear fuel reprocessing. Despite the seeming simplicity problem, no practical solution has been offered yet, particularly large-scale schemes involving toxic streams such as highly radioactive wastes. The classic potentiometric technique is not amiable online measurements due to requirements frequent...
This work explores the mechanisms of inter-conversions among various oxidation states neptunium in aqueous HNO<sub>3</sub>, and effect HNO<sub>3</sub>on their electronic structures.
Microfluidic devices are a growing field with significant potential for applications to small scale processing of solutions. Much like large processing, fast, reliable, and cost-effective means monitoring streams during needed. Here we apply novel micro-Raman probe the online within microfluidic device. For either macro- or microscale process via spectroscopic response, interfering confounded bands can obfuscate results. By utilizing chemometric analysis, form multivariate species be...
Microfluidic devices provide ideal environments to study solvent extraction. When droplets form and generate plug flow down the microfluidic channel, device acts as a microreactor in which kinetics of chemical reactions interfacial transfer can be examined. Here, we present methodology that combines chemometric analysis with online micro-Raman spectroscopy monitor biphasic extractions within device. Among many benefits microreactors is ability maintain small sample volumes, especially...
In nuclear fuel reprocessing, separating trivalent minor actinides and lanthanide fission products is extremely challenging often necessitates tight pH control in TALSPEAK (Trivalent Actinide-Lanthanide Separation by Phosphorus reagent Extraction from Aqueous Komplexes) separations. similar advanced processes, aqueous one of the most important factors governing partitioning lanthanides between an phase containing a polyaminopolycarboxylate complexing agent weak carboxylic acid buffer organic...
A method for separating the trivalent actinides and lanthanides is being developed using 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (HEH[EHP]) as extractant. The based on preferential binding of in aqueous phase by N-(2-hydroxyethyl)ethylenediamine-N,N',N'-triacetic (HEDTA), which serves to keep while are extracted into an organic containing HEH[EHP]. process very robust, showing little dependence upon pH or HEH[EHP], HEDTA, citrate concentrations over ranges that might be expected...
A solvent extraction system was developed for separating trivalent actinides from lanthanides. This "Advanced TALSPEAK" uses 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (HEH[EHP]) to extract the lanthanides into an n-dodecane-based solvent; are retained in a citrate-buffered aqueous phase by complexation polyaminocarboxylate ligand. Several aqueous-phase ligands were investigated, and N-(2-hydroxyethyl)ethylenediamine-N,N',N'-triacetic (HEDTA) chosen further study. Batch distribution...
In liquid–liquid extraction separation processes, accumulation of organic solvent degradation products is detrimental to the process robustness, and frequent analysis warranted. Our research explores feasibility online monitoring solvents relevant used nuclear fuel reprocessing. This paper describes first phase developing a system for tributyl phosphate (TBP)/n-dodecane commonly separate fuel. this investigation, effect nitric acid from aqueous solutions variable concentrations on...
To simplify and improve the safety of reprocessing nuclear fuel, Micro-Raman technique was applied at microfluidic scale with a view toward on-line spectroscopic measurement radioactive solutions.
Plutonium (Pu) exhibits a complex redox behavior in aqueous solutions. This is due to the ability of element adapt wide range oxidation states typically from +3 +6 and tendency for dynamic interconversion between that primarily depend upon acid concentration presence coordinating ligands. work interrogates Pu nitric via combination voltammetry situ vis-NIR spectroelectrochemistry under controlled potentials map various states. The NIR-spectroelectrochemistry studies used complement visible...
The degradation of the internal structure plutonium (IV) oxalate during calcination was investigated with Transmission Electron Microscopy (TEM), electron diffraction, Energy-Loss Spectroscopy (EELS), and 4D Scanning TEM (STEM). lift-outs were prepared from samples that had been calcined at 300°C, 450°C, 650°C 950°C. resulting phase all temperatures identified as PuO 2 diffraction. grain size range obtained high-resolution TEM. In addition, STEM images analyzed to provide distributions....
Treatment and reuse of used nuclear fuel is a key component in closing the cycle. Solvent extraction reprocessing methods that have been developed contain various steps tailored to separation specific radionuclides, which are highly dependent upon solution properties. The instrumentation monitor these processes must be robust, require little or no maintenance, able withstand harsh environments such as high radiation fields aggressive chemical matrices. Our group has investigating use optical...
Abstract The solution chemistry of Pu in nitric acid is explored via electrochemistry and spectroelectrochemistry. By utilizing comparing these techniques, an improved understanding behavior its dependence on concentration can be achieved. Here the (III/IV) couple characterized using cyclic voltammetry, square wave a spectroelectrochemical Nernst step. Results indicate formal reduction potential shifts negative with increasing reversible no longer attainable above 6 M HNO 3 ....