Authors:Sherrod Maxwell, Brian Culligan, and Gary Noyes
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.
Authors:Sherrod Maxwell, Brian Culligan, Angel Kelsey-Wall, and Patrick Shaw
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.
Influence of ionic liquids (ILs) addition (1–50 wt%) on extraction efficiency of actinides by diphenyl(dibutyl)carbamoylmethylphosphine
oxide (Ph2Bu2) from 3 M HNO3 has been studied. Am(III) distribution ratios in two-phase systems 0.1 M Ph2Bu2 in either DCE or CHCl3–3 M HNO3 depending on the nature of additional ionic liquids: imidazolium-based ILs: [C4mim][PF6], [C4mim][BF4] and phosphonium-based ILs: PPF6, PBF4 and PCl were determined. The highest value of Am(III) extraction ratio change (1040) was found on addition of PPF6 to Ph2Bu2 in CHCl3. Extraction of Pu(IV) and U(VI) by 0.001 M Ph2Bu2 in the presence of [C4mim][PF6] in DCE, CHCl3 or meta-nitrobenzotrifluoride (NBTF) have been investigated. The greatest enhancement of extraction efficiency was observed using
CHCl3, the least polar studied solvent. Using a mixture of conventional solvent and ionic liquid as a solvent for extractant enables
one to increase distribution ratios and reduce viscosity of organic phase as compared with ionic liquid viscosity. The marked
increase of Am(III), Pu(IV) and U(VI) extraction extent by Ph2Bu2 on addition of ionic liquids to the extent of 10 wt% permit one essentially to diminish amounts considerably more expensive
carbamoylmethylphosphine oxide(the general name is CMPO) used in TRUEX process.
The following paper covers a comparison of two new systems to traditional TEVA® resin systems for the analytical separation of actinides by immobilized liquid–liquid extraction using Aliquat-336. The new
systems are using expanded polytetrafluroethane (ePTFE) membrane or polyacrylonitrile (PAN) fibers as the solid support. The
systems are compared in two ways. First in how much Aliquat-336 they contain with the Vs, ratio of volume of Aliquat-336 to
volume of polymeric support, being 0.158, 0.483, and 0.590 for the TEVA® resin, PAN fibers, and the ePTFE systems, respectively. The second comparison is in their performance capacity of extraction
of uranyl chloride anion complex. The fiber and resins systems show similar capacities, and the membrane system being an order
of magnitude less than the other systems. A cost comparison demonstrates the savings advantages of using a fiber based support
compared with resin and membrane support systems.
Authors:C. Bouvier-Capely, A. Manoury, A. Legrand, J. Bonthonneau, F. Cuenot, and F. Rebière
In this work the applicability of calixarene columns for actinides analysis in urine samples and drinking water was investigated.
A radiochemical procedure has been developed for U, Pu, Am analysis in urine. A simple and effective method has also been
proposed on a specific column named AQUALIX, for the separation and preconcentration of U from drinking water. These procedures
are suitable for routine analysis and require a considerably reduced number of steps of sample treatment as compared to current
A concentrated ammonium nitrate solution (80 g L−1) generated during reprocessing of nuclear fuels was analysed for determining trace amounts of actinides present prior to
its reuse or disposal. A gamma spectrometric method using HPGe detector was developed for the assay of uranium (U), plutonium
(Pu) and americium (Am) using a suitable calibration sample. The results obtained were validated by liquid scintillation counting.
The presence of significant amounts of plutonium necessitated repeated purification of ammonium nitrate before its reuse.
Authors:Meng Wei, Qian’ge He, Xiaogui Feng, and Jing Chen
The crystal structure, melting range, decomposition temperature, solubilities in aqueous and organic phase, and distribution
ratio in biphase system of N,N,N′,N′-tetramethyl diglycolamide (TMDGA) have been studied in the present work. Water-soluble TMDGA with very low solubility in
kerosene or 30 % trialkyl phosphine (TRPO)/kerosene meets the primary requirement to act as the stripping agent in TRPO process
which has been developed for actinides partitioning from high level waste. Slope analysis, electrospray ionization mass spectrometry
(ESI–MS) and spectrophotometric titration indicate that in weak and moderate acidic aqueous solution, up to three TMDGA molecules
form complexes with Zr4+, trivalent lanthanides (Ln3+), trivalent actinides (An3+) or tetravalent actinides (An4+). Their complex formation constants determined by liquid–liquid extraction method follow the order predicted by the electrostatic
model of 4f and 5f elements and the covalent model of 4d transition elements: Ln3+ ~ An3+ < An4+ ≪ Zr4+. Hydrolysis of actinide cations, especially An4+, in the media of low acidity, reduces the complexation stability. In addition, the effect of aqueous acidity and temperature
has been investigated. No obvious influence of temperature on Np4+ complexes has been found. However, the influence on Am3+ and Pu4+, especially on their 1:1 or 1:2 complex species with TMDGA, is relatively considerable. Strong affinity of TMDGA to An3+ and An4+ implies that TMDGA has potential to strip An3+ and An4+ from TRPO.
The radioactivity concentration of 236Pu, 232U and 228Th in aqueous samples has been determined by means of alpha spectroscopy after chemical separation and pre-concentration of
the radionuclides by cation exchange and liquid–liquid extraction using the Chelex-100 resin and 30% TBP/dodecan, respectively.
Method calibration using a 236Pu standard solution containing the daughter radionuclides results in a detector efficiency of 18% and in a chemical recovery
for cation-exchange which is (30 ± 7)%, (90 ± 5)% and (20 ± 5)% for plutonium, uranium and thorium, respectively. The chemical
recovery for liquid–liquid extraction is found to be (60 ± 7)%, (50 ± 5)% and (70 ± 5)%, for plutonium, uranium and thorium,
respectively. The differences in the efficiencies can be ascribed to the oxidation states, the different actinides present
in solution. Taking into account that the electrodeposition of the radionuclides under study is quantitative, the total method
efficiency is calculated to be (18 ± 15)%, (46 ± 7)% and (15 ± 5)%, for plutonium, uranium and thorium, respectively, at the
mBq concentration range. The detection limit of the alpha spectrometric system has been found to be 0.2 mBq/L, suggesting
that the method could be successfully applied for the radiometric analysis of the studied radionuclides and particularly uranium
in aqueous samples.
Authors:K. Lieser, R. Hill, U. Mühlenweg, R. Singh, Tu Shu-De, and Th. Steinkoff
The influence of the following parameters is discussed: oxidation state (Eh), hydrolysis (pH), solubility, complex formation, colloid formation, sorption and filtration effects. The oxidation states of the actinides in neutral aqueous media are plotted as a function of the redox potential. Hydrolysis, stability of 11 carbonato complexes, of humic acid complexes and solubilities of the hydroxides in the various oxidation states are considered. Mobility is investigated as a function of pH by paper chromatography. Partition of the actinides in groundwaters on the molecular fraction, the fine particle (colloid) fraction and the coarse particle fraction is determined as a function of pH by filtration and ultrafiltration. Sorption ratios are measured as function of pH, salt concentration and of EDTA concentration. When the groundwaters are passed through the sediments, mainly the coarse particle fractions are retained by size filtration. The pronounced influence of the redox potential on sorption is demonstrated for Np.