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1.
Maxwell Sherrod L. Culligan Brian Hutchison Jay B. Utsey Robin C. Sudowe Ralf McAlister Daniel R. 《Journal of Radioanalytical and Nuclear Chemistry》2017,311(1):439-446
The sorption and diffusion behavior of cesium was studied to support the interpretation of the ongoing in-situ experiments in the Olkiluoto test site. The distribution coefficients of cesium in the Olkiluoto pegmatitic granite, veined gneiss and their main minerals were obtained by batch sorption experiments and the diffusion of cesium was studied in rock cubes. The results were modelled with PHREEQC and Comsol Multiphysics. The distribution coefficients of cesium were largest in biotite and veined gneiss. The effective diffusion coefficients of cesium from the diffusion model were 3 × 10−13 m2 s−1 for veined gneiss and 4 × 10−13 m2 s−1 for pegmatitic granite.
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The Savannah River Site Environmental Bioassay Lab participated in the 2008 NRIP Emergency Response program administered by
the National Institute for Standards and Technology (NIST) in May, 2008. A new rapid column separation method was used for
analysis of actinides and 90Sr in the NRIP 2008 emergency water and urine samples. Significant method improvements were applied to reduce analytical times.
As a result, much faster analysis times were achieved, less than 3 hours for determination of 90Sr and 3–4 hours for actinides. This represents a 25%–33% improvement in analysis times from NRIP 2007 and a ∼100% improvement
compared to NRIP 2006 report times. Column flow rates were increased by a factor of two, with no significant adverse impact
on the method performance. Larger sample aliquots, shorter count times, faster cerium fluoride microprecipitation and streamlined
calcium phosphate precipitation were also employed. Based on initial feedback from NIST, the SRS Environmental Bioassay Lab
had the most rapid analysis times for actinides and 90Sr analyses for NRIP 2008 emergency urine samples. High levels of potential matrix interferences may be present in emergency
samples and rugged methods are essential. Extremely high levels of 210Po were found to have an adverse effect on the uranium results for the NRIP-08 urine samples, while uranium results for NRIP-08
water samples were not affected. This problem, which was not observed for NRIP-06 or NRIP-07 urine samples, was resolved by
using an enhanced 210Po removal step, which will be described. 相似文献
4.
Sherrod L. MaxwellIII Brian K. Culligan Gary W. Noyes 《Journal of Radioanalytical and Nuclear Chemistry》2010,286(1):273-282
A new rapid method for the determination of actinides and radiostrontium in vegetation samples has been developed at the Savannah
River Site Environmental Lab (Aiken, SC, USA) that can be used in emergency response situations or for routine analysis. The
actinides in vegetation method utilizes a rapid sodium hydroxide fusion method, a lanthanum fluoride matrix removal step,
and a streamlined column separation process with stacked TEVA, TRU and DGA Resin cartridges. Lanthanum was separated rapidly
and effectively from Am and Cm on DGA Resin. Alpha emitters are prepared using rare earth microprecipitation for counting
by alpha spectrometry. The purified 90Sr fractions are mounted directly on planchets and counted by gas flow proportional counting. The method showed high chemical
recoveries and effective removal of interferences. The actinide and 90Sr in vegetation sample analysis can be performed in less than 8 h with excellent quality for emergency samples. The rapid
fusion technique is a rugged sample digestion method that ensures that any refractory actinide particles or vegetation residue
after furnace heating is effectively digested. 相似文献
5.
Sherrod L. Maxwell Brian A. Culligan Vernon D. Jones Sheldon T. Nichols Gary W. Noyes 《Journal of Radioanalytical and Nuclear Chemistry》2011,287(1):223-230
A new method that allows rapid preconcentration and separation of plutonium and neptunium in water samples was developed for the measurement of 237Np and Pu isotopes by inductively-coupled plasma mass spectrometry (ICP-MS) and alpha spectrometry. 238U can interfere with 239Pu measurement by ICP-MS as 238UH+ mass overlap and 237Np via peak tailing. The method provide enhanced removal of uranium by separating Pu and Np initially on TEVA Resin, then moving Pu to DGA resin for additional removal of uranium. The decontamination factor for uranium from Pu is almost 100,000 and the decontamination factor for U from Np is greater than 10,000. This method uses stacked extraction chromatography cartridges and vacuum box technology to facilitate rapid separations. Preconcentration is performed using a streamlined calcium phosphate precipitation method. Purified solutions are split between ICP-MS and alpha spectrometry so that long and short-lived Pu isotopes can be measured successfully. The method allows for simultaneous extraction of 20 samples (including QC samples) in 4?C6 h, and can also be used for emergency response. 239Pu, 242Pu and 237Np were measured by ICP-MS, while 236Pu, 238Pu, and 239Pu were measured by alpha spectrometry. 相似文献
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S. L. MaxwellIII B. K. Culligan 《Journal of Radioanalytical and Nuclear Chemistry》2009,279(3):757-760
A new rapid separation method for radiostrontium in emergency milk samples was developed at the Savannah River Site (SRS)
Environmental Bioassay Laboratory (Aiken, SC, USA) that will allow rapid separation and measurement of radiostrontium within
8 hours. The new method uses calcium phosphate precipitation, nitric acid dissolution of the precipitate to coagulate residual
fat/proteins and a rapid strontium separation using Sr Resin (Eichrom Technologies, Darien, IL, USA) with vacuum-assisted
flow rates. The method is much faster than the previous method that use calcination or cation-exchange pretreatment, has excellent
chemical recovery, and effectively removes beta-interferences. When a 100 mL sample aliquot is used with a 20 minute count
time, the method has a detection limit of 0.5 Bq·L−1, well below generic emergency action levels. 相似文献
8.
Sherrod L. Maxwell Brian K. Culligan Angel Kelsey-Wall Patrick J. Shaw 《Journal of Radioanalytical and Nuclear Chemistry》2012,292(1):339-347
A new rapid method for the determination of actinides in food samples has been developed at the Savannah River Site Environmental
Lab (Aiken, SC, USA) that can be used for emergency response or routine food samples. If a radiological dispersive device
or improvised nuclear device event occurs, there will be a urgent need for rapid analyzes of many different environmental
matrices, as well as food samples, to support dose mitigation and protect general populations from radioactivity that may
enter the food chain. The recent accident at Fukushima nuclear power plant in March, 2011 reinforces the need to have rapid
analyzes for radionuclides in environmental and food samples. The new method to determine actinides in food samples utilizes
a furnace ashing step, a rapid sodium hydroxide fusion method, a lanthanum fluoride matrix removal step, and a column separation
process with stacked TEVA, TRU, and DGA resin cartridges. The furnace ashing and rapid fusion steps are performed in relatively
inexpensive, reusable zirconium crucibles. Alpha emitters are prepared using rare earth micro precipitation for counting by
alpha spectrometry. The method showed high chemical recoveries and effective removal of interferences. The determination of
actinides in food samples can be performed in less than 8 h for 10 g samples with excellent quality for emergency samples
using short count times. Larger food samples (100 g) may be processed in 24 h or less. The rapid fusion technique is a rugged
sample digestion method that ensures that any refractory actinide particles are effectively digested. This method can be used
to meet the derived intervention level guidelines recommended by the U.S. Food and Drug Administrations. 相似文献
9.
Sherrod L. Maxwell Brian K. Culligan Jay B. Hutchison Robin C. Utsey Daniel R. McAlister 《Journal of Radioanalytical and Nuclear Chemistry》2014,300(3):1159-1166
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. 相似文献
10.
Sherrod L. Maxwell Brian K. Culligan Robin C. Utsey 《Journal of Radioanalytical and Nuclear Chemistry》2013,298(2):867-875
A new method for the determination of radiostrontium in seawater samples has been developed at the Savannah River National Laboratory (SRNL) that allows rapid pre-concentration and separation of strontium and yttrium isotopes in seawater samples for measurement. The new SRNL method employs a novel and effective pre-concentration step that utilizes a blend of calcium phosphate with iron hydroxide to collect both strontium and yttrium rapidly from the seawater matrix with enhanced chemical yields. The pre-concentration steps, in combination with rapid Sr Resin and DGA Resin cartridge separation options using vacuum box technology, allow seawater samples up to 10 L to be analyzed. The total 89Sr + 90Sr activity may be determined by gas flow proportional counting and recounted after ingrowth of 90Y to differentiate 89Sr from 90Sr. Gas flow proportional counting provides a lower method detection limit than liquid scintillation or Cerenkov counting and allows simultaneous counting of samples. Simultaneous counting allows for longer count times and lower method detection limits without handling very large aliquots of seawater. Seawater samples up to 6 L may be analyzed using Sr Resin for 89Sr and 90Sr with a minimum detectable activity (MDA) of 1–10 mBq/L, depending on count times. Seawater samples up to 10 L may be analyzed for 90Sr using a DGA Resin method via collection and purification of 90Y only. If 89Sr and other fission products are present, then 91Y (beta energy 1.55 MeV, 58.5 day half-life) is also likely to be present. 91Y interferes with attempts to collect 90Y directly from the seawater sample without initial purification of Sr isotopes first and 90Y ingrowth. The DGA Resin option can be used to determine 90Sr, and if 91Y is also present, an ingrowth option with using DGA Resin again to collect 90Y can be performed. An MDA for 90Sr of <1 mBq/L for an 8 h count may be obtained using 10 L seawater sample aliquots. 相似文献