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Maxwell S.L.,Savannah River Nuclear Solutions | Culligan B.K.,Savannah River Nuclear Solutions | Warren R.A.,Savannah River Nuclear Solutions | McAlister D.R.,PG Research Foundation Inc.
Journal of Radioanalytical and Nuclear Chemistry | Year: 2016

A new method that rapidly pre-concentrates and measures 226Ra from hydraulic fracturing wastewater samples was developed in the Savannah River Environmental Laboratory. The method improves the quality of 226Ra measurements using gamma spectrometry by providing up to 100 × pre-concentration of 226Ra from this difficult sample matrix, which contains very high levels of calcium, barium, strontium, magnesium and sodium. The high chemical yield, typically 80–90 %, facilitates a low detection limit, important for lower level samples, and indicates method ruggedness. Ba-133 tracer is used to determine chemical yield and correct for geometry-related counting issues. The 226Ra sample preparation takes <2 h. © 2016 Akadémiai Kiadó, Budapest, Hungary


Maxwell S.L.,Savannah River National Laboratory | Culligan B.K.,Savannah River National Laboratory | Hutchison J.B.,Savannah River National Laboratory | Utsey R.C.,Savannah River National Laboratory | McAlister D.R.,PG Research Foundation Inc.
Journal of Radioanalytical and Nuclear Chemistry | Year: 2013

A new rapid method for the determination of 210Po in water samples has been developed at the Savannah River National Laboratory (SRNL) that can be used for emergency response or routine water analyses. If a radiological dispersive device event or a radiological attack associated with drinking water supplies occurs, there will be an urgent need for rapid analyses of water samples, including drinking water, ground water and other water effluents. Current analytical methods for the assay of 210Po in water samples have typically involved spontaneous auto-deposition of 210Po onto silver or other metal disks followed by counting by alpha spectrometry. The auto-deposition times range from 90 min to 24 h or more, at times with yields that may be less than desirable. If sample interferences are present, decreased yields and degraded alpha spectrums can occur due to unpredictable thickening in the deposited layer. Separation methods have focused on the use of Sr Resin™, often in combination with 210Pb analysis. A new rapid method for 210Po in water samples has been developed at the SRNL that utilizes a rapid calcium phosphate co-precipitation method, separation using DGA Resin® (N,N,N′,N′ tetraoctyldiglycolamide extractant-coated resin, Eichrom Technologies or Triskem-International), followed by rapid microprecipitation of 210Po using bismuth phosphate for counting by alpha spectrometry. This new method can be performed quickly with excellent removal of interferences, high chemical yields and very good alpha peak resolution, eliminating any potential problems with the alpha source preparation for emergency or routine samples. A rapid sequential separation method to separate 210Po and actinide isotopes was also developed. This new approach, rapid separation with DGA resin plus microprecipitation for alpha source preparation, is a significant advance in radiochemistry for the rapid determination of 210Po. © 2013 Akadémiai Kiadó, Budapest, Hungary.


Maxwell S.L.,Savannah River National Laboratory | Culligan B.K.,Savannah River National Laboratory | Hutchison J.B.,Savannah River National Laboratory | Utsey R.C.,Savannah River National Laboratory | McAlister D.R.,PG Research Foundation Inc.
Journal of Radioanalytical and Nuclear Chemistry | Year: 2014

A new rapid method for the determination of actinides in seawater samples has been developed at the Savannah River National Laboratory. The actinides can be measured by alpha spectrometry or inductively-coupled plasma mass spectrometry. The new method employs novel pre-concentration steps to collect the actinide isotopes quickly from 80 L or more of seawater. Actinides are co-precipitated using an iron hydroxide co-precipitation step enhanced with Ti+3 reductant, followed by lanthanum fluoride co-precipitation. Stacked TEVA Resin and TRU Resin cartridges are used to rapidly separate Pu, U, and Np isotopes from seawater samples. TEVA Resin and DGA Resin were used to separate and measure Pu, Am and Cm isotopes in seawater volumes up to 80 L. This robust method is ideal for emergency seawater samples following a radiological incident. It can also be used, however, for the routine analysis of seawater samples for oceanographic studies to enhance efficiency and productivity. In contrast, many current methods to determine actinides in seawater can take 1-2 weeks and provide chemical yields of ∼30-60 %. This new sample preparation method can be performed in 4-8 h with tracer yields of ∼85-95 %. By employing a rapid, robust sample preparation method with high chemical yields, less seawater is needed to achieve lower or comparable detection limits for actinide isotopes with less time and effort. © 2014 Akadémiai Kiadó.


Maxwell S.L.,Savannah River National Laboratory | Culligan B.K.,Savannah River National Laboratory | Hutchison J.B.,Savannah River National Laboratory | Utsey R.C.,Savannah River National Laboratory | McAlister D.R.,PG Research Foundation Inc.
Journal of Radioanalytical and Nuclear Chemistry | Year: 2014

A new method has been developed at the Savannah River National Laboratory (SRNL) that can be used for the rapid determination of 226Ra in emergency urine samples following a radiological incident. If a radiological dispersive device event or a nuclear accident occurs, there will be an urgent need for rapid analyses of radionuclides in urine samples to ensure the safety of the public. Large numbers of urine samples will have to be analyzed very quickly. This new SRNL method was applied to 100 mL urine aliquots, however this method can be applied to smaller or larger sample aliquots as needed. The method was optimized for rapid turnaround times; urine samples may be prepared for counting in <3 h. A rapid calcium phosphate precipitation method was used to pre-concentrate 226Ra from the urine sample matrix, followed by removal of calcium by cation exchange separation. A stacked elution method using DGA Resin was used to purify the 226Ra during the cation exchange elution step. This approach combines the cation resin elution step with the simultaneous purification of 226Ra with DGA Resin, saving time. 133Ba was used instead of 225Ra as tracer to allow immediate counting; however, 225Ra can still be used as an option. The rapid purification of 226Ra to remove interferences using DGA Resin was compared with a slightly longer Ln Resin approach. A final barium sulfate micro-precipitation step was used with isopropanol present to reduce solubility; producing alpha spectrometry sources with peaks typically <40 keV FWHM (full width half max). This new rapid method is fast, has very high tracer yield (>90 %), and removes interferences effectively. The sample preparation method can also be adapted to ICP-MS measurement of 226Ra, with rapid removal of isobaric interferences. © 2014 Akadémiai Kiadó.


Braley J.C.,Washington State University | Braley J.C.,Pacific Northwest National Laboratory | McAlister D.R.,PG Research Foundation Inc. | Philip Horwitz E.,PG Research Foundation Inc. | Nash K.L.,Washington State University
Solvent Extraction and Ion Exchange | Year: 2013

An advanced nuclear fuel cycle that aims to transmute the minor actinides (Am, Cm, Np) must include a separation of fission product lanthanides from the trivalent actinides. The TALSPEAK (Trivalent Actinide-Lanthanide Separation by Phosphorus reagent Extraction from Aqueous Komplexes) solvent extraction process provides an appropriate An3+/Ln3+ separation by matching the cation size-selective lanthanide extractant (bis-2-ethyl(hexyl) phosphoric acid, HDEHP) against the actinide-selective holdback reagent (diethylenetriamine-N,N,N',N'',N''-pentaacetic acid, DTPA) in a concentrated lactic acid buffer. This study examines the impact of TALSPEAK reagents (extractant, holdback complexant, carboxylate buffer, pH) on the chemistry of a TALSPEAK separation based on extraction chromatographic (EXC) materials as an alternative to the lipophilic extractant system. The dual purpose is to evaluate the practical potential of this alternative and to gain deeper understanding of this chemistry. The effectiveness of alternative reagents, 2-ethyl(hexyl) phosphonic acid mono-2-ethyl(hexyl) ester (HEH[EHP]) (immobilized on a support) and triethylenetetramine-N,N,N',N'',N''',N'''-hexaacetic acid (TTHA) (in the mobile phase) are also considered. Results indicate that the concentrated extractant in the EXC material behaves similarly to the lipophilic extractant system. It appears that lactate partitioning into the resin phase consumes resin capacity lowering extraction efficiency of the HDEHP EXC material, as is seen in conventional TALSPEAK-SX. The weaker hold-back reagent (under TALSPEAK aqueous conditions, pH ~ 3.6), TTHA, actually provides slightly improved Am3+/Ln3+ separations performance relative to DTPA. The decreased sensitivity to pH and improved extraction efficiency that was reported by substituting HEH[EHP] for HDEHP in earlier studies of the solvent extraction system is confirmed by similar observations in extraction chromatography. © 2013 Copyright Taylor & Francis Group, LLC.


Maxwell S.L.,Savannah River National Laboratory | Culligan B.,Savannah River National Laboratory | Hutchison J.B.,Savannah River National Laboratory | McAlister D.R.,PG Research Foundation Inc.
Journal of Radioanalytical and Nuclear Chemistry | Year: 2015

A new rapid sodium hydroxide fusion method for the preparation of 10–20 g soil samples has been developed by the Savannah River National Laboratory. The method enables lower detection limits for plutonium, neptunium, and americium in environmental soil samples. The method also significantly reduces sample processing time and acid fume generation compared to traditional soil digestion techniques using hydrofluoric acid. Ten gram soil aliquots can be ashed and fused using the new method in 1–2 h, completely dissolving samples, including refractory particles. Pu, Np and Am are separated using stacked 2 mL cartridges of TEVA and DGA resin and measured using alpha spectrometry. Total sample preparation time, including chromatographic separations and alpha spectrometry source preparation, is less than 8 h. © 2015, Akadémiai Kiadó, Budapest, Hungary.


Maxwell S.L.,Savannah River National Laboratory | Hutchison J.B.,Savannah River National Laboratory | McAlister D.R.,PG Research Foundation Inc.
Journal of Radioanalytical and Nuclear Chemistry | Year: 2015

Recently, approximately 80 % of participating laboratories failed to accurately determine uranium isotopes in soil samples in the U. S Department of Energy Mixed Analyte Performance Evaluation Program Session 30, due to incomplete dissolution of refractory particles in the samples. Failing laboratories employed acid dissolution methods, including hydrofluoric acid, to recover uranium from the soil matrix. A new rapid fusion method has been developed by the Savannah River National Laboratory (SRNL) to prepare 1–2 g soil sample aliquots very quickly, with total dissolution of refractory particles. Soil samples are fused with sodium hydroxide at 600 °C in zirconium crucibles to enable complete dissolution of the sample. Uranium and thorium are separated on stacked TEVA and TRU extraction chromatographic resin cartridges, prior to isotopic measurements by alpha spectrometry on cerium fluoride microprecipitation sources. © 2015, Akadémiai Kiadó, Budapest, Hungary.


McAlister D.R.,PG Research Foundation Inc. | Horwitz E.P.,PG Research Foundation Inc. | Harvey J.T.,Northstar Engineered Technologies LLC
Health Physics | Year: 2011

Rapid methods for the isolation and analysis of individual actinides (Th, U, Pu, Am/Cm) and Sr, Tc and Po from small volumes of raw urine have been developed. The methods involve acidification of the sample and the addition of aluminum nitrate or aluminum chloride salting-out agent prior to isolation of the desired analyte using a tandem combination of prefilter material and extraction chromatographic resin. The method has been applied to the separation of individual analytes from spiked urine samples. Analytes were recovered in high yield and radionuclide purity with separation times as low as 30 min. The chemistry employed is compatible with automation on the ARSIIe instrument. © Copyright 2011 Health Physics Society.


Antonio M.R.,Argonne National Laboratory | McAlister D.R.,PG Research Foundation Inc. | Horwitz E.P.,PG Research Foundation Inc.
Dalton Transactions | Year: 2015

The synthesis, stoichiometry, and structural characterization of a homoleptic, cationic europium(iii) complex with three neutral tetraalkyldiglycolamide ligands are reported. The tri(bismuth tetrachloride)tris(N,N,N′,N′-tetra-n-octyldiglycolamide)Eu salt, [Eu(TODGA)3][(BiCl4)3] obtained from methanol was examined by Eu L3-edge X-ray absorption spectroscopy (XAS) to reveal an inner-sphere coordination of Eu3+ that arises from 9 O atoms and two next-nearest coordination spheres that arise from 6 carbon atoms each. A structural model is proposed in which each TODGA ligand with its OCa-Cb-O-Cb-CaO backbone acts as a tridentate O donor, where the two carbonyl O atoms and the one ether O atom bond to Eu3+. Given the structural rigidity of the tridentate coordination motif in [Eu(TODGA)3]3+ with six 5-membered chelate rings, the six Eu-Ca and six Eu-Cb interactions are readily resolved in the EXAFS (extended X-ray absorption fine structure) spectrum. The three charge balancing [BiCl4]- anions are beyond the cationic [Eu(TODGA)3]3+ cluster in an outer sphere environment that is too distant to be detected by XAS. Despite their sizeable length and propensity for entanglement, the four n-octyl groups of each TODGA (for a total of twelve) do not perturb the Eu3+ coordination environment over that seen from previously reported single-crystal structures of tripositive lanthanide (Ln3+) complexes with tetraalkyldiglycolamide ligands (of the same 1:3 metal-to-ligand ratio stoichiometry) but having shorter i-propyl and i-butyl groups. The present results set the foundation for understanding advanced solvent extraction processes for the separation of the minor, tripositive actinides (Am, Cm) from the Ln3+ ions in terms of the local structure of Eu3+ in a solid state coordination complex with TODGA. © The Royal Society of Chemistry 2015.


McAlister D.R.,PG Research Foundation Inc. | Horwitz E.P.,PG Research Foundation Inc.
Radiochimica Acta | Year: 2011

This work describes chromatographic radionuclide generator systems for the production of actinides and natural decay series elements. The generator systems begin with alpha emitting parent radioisotopes with half-lives (T 1/2) of greater than one year and produce alpha or beta emitting radioisotopes with half-lives of hours to days. Chromatographic systems were chosen to minimize radiolytic damage to chromatographic supports, preserve the parent activity for repeated use, provide high purity daughter radionuclide tracers, and to minimize or eliminate the need for evaporation of solutions of the parent or daughter nuclides. Useful secondary separations involving the daughters of the initial parent radionuclide are also described. Separation systems for 210Bi, 210Po, 211Pb, 212Pb, 223Ra, 224Ra, 225Ra, 225Ac, 227Th, 228Th, 231Th, 234Th, and 239Np are outlined in detail. © by Oldenbourg Wissenschaftsverlag,München.

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