Showing papers on "Curium published in 2024"
TL;DR: Researchers develop a new diglycolamide extractant, iPDdDGA, with improved separation between Americium and Curium, achieving up to 3.0 SFCm/Am values, a small but significant improvement over existing TODGA-based processes.
Abstract: Partitioning and transmutation are important strategies for closing the nuclear fuel cycle. The diglycolamide extractant TODGA has played a major role in the development of solvent extraction processes for nuclear fuel reprocessing due to its good extraction performance, its hydrolytic and radiolytic stability, and its compliance with the CHON principle. However, due to drawbacks such as the tendency to form a third phase during extraction if no phase modifiers are used, continued research on diglycolamide-type extractants has led to the development of diglycolamides with decreased symmetry. In this study, it is shown that the recently developed diglycolamide, N,N-diisopropyl-N′,N′-didodecyldiglycolamide (iPDdDGA), is a potential alternative to TODGA with improved separation between Am and Cm or the Ln. Using the AmSel system as a reference, the extraction kinetics, influence of the acid concentration, influence of the iPDdDGA concentration, and influence of temperature were evaluated. Slope analysis indicates similar average stoichiometries for iPDdDGA and TODGA complexes, but the extraction efficiency of iPDdDGA is orders of magnitude higher. The feasibility of selective americium stripping in combination with the hydrophilic sulfonated bis-triazinyl bipyridine SO3-Ph-BTBP complexant was demonstrated. Selective stripping of americium was found to be possible, and the use of iPDdDGA gave an unexpected improvement in Am/Cm separation, with SFCm/Am values of up to 3.0. This represents a small but significant improvement compared to the 2.5 value typically found for TODGA, and it demonstrates the potential of this solvent extraction system to improve existing processes based on diglycolamide-type extractants.
TL;DR: A consolidated reprocessing procedure for curium enables milligram-scale recovery, facilitating spectroscopic studies and industrial safeguards through targeted ligand design, leveraging curium's stable redox chemistry and strong metal-based luminescence.
Abstract: Curium's stable redox chemistry and ability to emit strong metal-based luminescence make it uniquely suitable for spectroscopic studies among the actinide series. Targeted ligand and coordination compound design can support both fundamental electronic structure studies and industrial safeguards with the identification of unique spectroscopic signatures. However, limited availability, inherent radioactive hazards, and arduous purifications have long inhibited such investigations of this element. A consolidated reprocessing procedure for curium has been developed for the milligram scale. The recovery of not only standard legacy curium samples but also hazardous legacy perchlorate containing curium samples was achieved, culminating in column chromatography utilizing the extraction resin DGA (
TL;DR: This study investigates the separation of Americium (Am) and Curium (Cm) using Cyanex301 and carboxylic acids as stripping chelates, achieving improved separation factors of 5.87 and 5.26 with formic and glycolic acid, respectively.
Abstract: The distribution equilibria of Am(III) and Cm(III) between the organic phase of bis(2,4,4-trimethylpentyl)dithiophosphonic acid (purified Cyanex301, HA) in xylene and aqueous solutions containing varying concentrations of formic acid or glycolic acid have been investigated aiming at the separation of the two actinides from each other after the groups separation of Am(III)/Cm(III) from Ln(III) ions. The apparent extraction constants for Am(III) and Cm(III) in the Cyanex301-xylene system are determined to be −8.84 and −9.37, respectively, at 0.01 M ionic strength. The specific ion interaction method (SIT) is used to obtain the stability constants of Am(III) and Cm(III) with nitrate and glycolate for calculating the speciation of the ions in extraction at 25°C and I = 0.01 M. The separation of Cm(III) from Am(III) loaded in 0.5 M HA in xylene can be considerably improved by emplying 0.01 to 0.05 M formic acid or glycolic acid as selective stripping reagents favoring complexation with Cm(III). Specifically, with 0.01 M formic acid or glycolic acid in the aqueous phase, the separation factor (SF) for Am(III) over Cm(III) is improved from 3.61 to 5.87 and 5.26, respectively. Hence, both separations of An(III) from Ln(III) and then Am(III) from Cm(III) are achieved by a selective extraction process at first and then a selective stripping process in one simple efficient system using purified Cyanex301 as extractant in organic phase and carboxylic acids as stripping chelates in aqueous.
31 Dec 2024
TL;DR: Density functional theory calculations reveal the binding of cerium, americium, and curium cations to 18-crown-6 ether, demonstrating the potential for crown ethers in radionuclide sequestration and separation.
Abstract: We use density functional theory to investigate the interactions of cerium, americium, and curium cations with crown ethers. Our calculations reveal that the modeled structure of cerium integrated within the crown ether is in good agreement with experimental data, with the negative binding energy indicating that capturing the cerium nitrates is thermodynamically favorable. Our results demonstrate that crown ethers can also bind americium and curium, providing insights into the potential applications of crown ether in radionuclide sequestration. Finally, we explore the impact of the skeleton modification of different crown ethers through by substitution of nitrogen atoms in the core of the crown ether for oxygen atoms and find that this structural modification significantly increases the radionuclide binding energies. These findings provide insights on the potential for the use of organic linkers such as crown ethers to address the urgent needs in radionuclide sequestration, separation and sensing.
TL;DR: This study investigates the potential biological hazard of Curium isotopes in deep burial, estimating the effects of radionuclide toxicity and cancer risk from oral consumption, and finds that processing and removal of Pu isotopes reduces radiation risk and waste danger.
Abstract: The potential biological hazard (PBH) of radionuclides from the decay chains of Curium (Cm) isotopes in the pore water of sandy rocks has been investigated. The effect of the Pu isotopes from the Cm fraction after reprocessing spent nuclear fuel (SNF) and storage during 70 years on the PBH has been estimated. The effects of radionuclides toxicity and malignant neoplasms development in people were estimated as lifetime attributable radiation risk of cancer caused by oral consumption of radionuclides. It was found that, according to the fraction isolated from SNF with isotopes, Cm decreases by 10 times after the removal of Pu isotopes with a 0.1% residue in radioactive waste. It is shown that the processing of Cm with the release of Pu allows to reduce the time of occurrence of the radiation-migration balance with uranium raw materials for nuclear fuel, as well as to reduce the amount and danger of radioactive waste for deep burial.
TL;DR: This study presents cross-section data for fission reactions of curium isotopes (243Cm to 248Cm) induced by neutrons below 100 keV, utilizing the high-luminosity SVZ-100 neutron spectrometer, complementing international nuclear databases and indicating potential adjustments to recommended values.
Abstract: The possibilities of lead slowing-down neutron spectrometry have been demonstrated. We present a review of the results of a series of works on measuring the fission cross-sections of curium isotopes 243Cm, 244Cm, 245Cm, 246Cm, 247Cm, 248Cm by neutrons with energies below 100 keV, performed by a joint group of researchers of INR RAS and SSC RF IPPE on the SVZ-100 neutron spectrometer. This third-generation spectrometer has a high luminosity, which made it possible to study neutron-nuclear processes in microgram samples of radioactive nuclides, which is not available in experiments using time-of-flight spectrometry. The results of work at the INR RAS–SSC RF IPPE are reflected in international nuclear databases, complement the known experimental data and in some cases indicate the need to adjust the recommended values.
8 Oct 2024
Abstract: Curium’s stable redox chemistry and ability to
emit strong
metal-based luminescence make it uniquely suitable for spectroscopic
studies among the actinide series. Targeted ligand and coordination
compound design can support both fundamental electronic structure
studies and industrial safeguards with the identification of unique
spectroscopic signatures. However, limited availability, inherent
radioactive hazards, and arduous purifications have long inhibited
such investigations of this element. A consolidated reprocessing procedure
for curium has been developed for the milligram scale. The recovery
of not only standard legacy curium samples but also hazardous legacy
perchlorate containing curium samples was achieved, culminating in
column chromatography utilizing the extraction resin DGA (<i>N</i>,<i>N</i>,<i>N</i>′,<i>N</i>′-tetra-2-ethylhexyldiglycolamide, branched). Surprisingly,
controlled elution of the Cm band from the extraction resin was followed
through bright pink luminescence triggered by an inexpensive hand-held
UV–vis lamp (380–400 nm). This observation inspired
the design of an enantiopure, <i>C</i><sub>2</sub>-symmetrical
ligand bearing a chiral (<i>trans</i>-1,2-diaminocyclohexane)
backbone with achiral DGA moieties (<i>N</i>,<i>N</i>,<i>N</i>′,<i>N</i>′-tetra-<i>n</i>-octylacetamide), that enabled rarely observed curium circularly
polarized luminescence upon metal chelation. These combined achievements
should unlock more luminescence and circularly polarized luminescence
studies of curium, and enable the recovery of many curium and other
trivalent actinide samples.