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Chemical stabilities of SrZrO3, BaZrO3, and Sr0.5Ba0.5ZrO3 in LiCl molten salt were investigated to evaluate dissolution properties of Sr and Ba in grey phases of spent nuclear fuels during oxide reduction. Sr in SrZrO3 was partially insoluble in LiCl, even in the presence of metallic Li, while Ba in BaZrO3 was almost extracted. In contrast, both Sr and Ba in solid-solution phase (Sr0.5Ba0.5ZrO3) well dissolved in LiCl. Pre-treatment of the spent nuclear fuels before the oxide reduction should be carefully designed to prevent formation of the insoluble Sr-based compounds for efficient Sr separation. [ABSTRACT FROM AUTHOR]

Sorption of iodine on Beishan granite was studied by batch method. Great difference exists in the sorption behaviors of I− and IO3−. Under acidic condition, the sorption of IO3− improves dramatically, and IO3− could partly convert to I−. However, the sorption of I− is close to zero at all studied pH. Humic acid can slight improve the sorption of IO3−, but greatly improve the sorption of I− in acidic condition. The postulated sorption mechanisms of IO3− are electrical interaction and followed by reduction. [ABSTRACT FROM AUTHOR]

U(VI)-containing wastewater has potential radiation hazard to the environment, but contains valuable uranium resource. Based on the reduction of U(VI) and the difference in solubility between U(VI) and U(IV), here we construct a TiO-based photoelectrochemical cell to remove U(VI) and recover uranium from aqueous solution. By irradiating TiO photoanode at E = 0.45 V versus SCE, U(VI) can be simultaneously removed from aqueous solution and recovered as solid uranium compounds on a FTO glass cathode. Since ethanol can act as hole scavenger to protect the formed U(IV) and provide CO as reductant, ethanol adding improved the U(VI) reduction efficiency of TiO-based photoelectrochemical cell. [ABSTRACT FROM AUTHOR]

The 3D structure of hydrazine derivatives was optimized and their energy was calculated by density functional theory with B3LYP method and 6-311 + (3 d, 3 p) basis set. The results show that the reaction relationship between the structure of hydrazine derivatives and Np(VI) could be explained by two quantitative structure-activity relationships equations. In Eq. 1, the lowest unoccupied molecular orbital energy is a major factor affecting the reduction rate, and it is negatively correlated with the reaction rate. In Eq. 2, the molecular dipole moment and hydrophobic parameters are the most important factors affecting the reduction rate. The molecular dipole moment is negatively correlated with the reaction rate, but the hydrophobic parameter is positively correlated with the reaction rate. [ABSTRACT FROM AUTHOR]

The process of plasma chemical conversion of isotopic enriched MoF in RF (13.56 MHz) capacitive-coupled and arc discharges was investigated. In both types of discharges the formation of metal (bulk) and powder nano-dispersed molybdenum as well as of fluoromolybdens of MoF fluorides was found. The mechanism of plasma chemical reduction of MoF by hydrogen under considered experimental conditions was suggested. The isotopic and impurity composition of prepared nano-powder and bulk samples of Mo as well as of their structure was determined. [ABSTRACT FROM AUTHOR]

Uncertainties associated with short lived (half-lives less than 1 day) fission product yields listed in databases such as the National Nuclear Data Center's ENDF/B-VII are large enough for certain isotopes to provide an opportunity for new precision measurements to offer significant uncertainty reductions. A series of experiments has begun where small samples of U are irradiated with a pulsed, fission neutron spectrum at the Nevada National Security Site and placed between two broad-energy germanium detectors. The amount of various isotopes present immediately following the irradiation can be determined given the total counts and the calibrated properties of the detector system. The uncertainty on the fission yields for multiple isotopes has been reduced by nearly an order of magnitude. [ABSTRACT FROM AUTHOR]

This project is focused on developing a geochronology tool enabling age dating of coastal marine sediments in the 100-1000 year age range. The technique employs the Si/P radio-chronometer with an ultra-low-background gas proportional beta detector with a background count rate approaching 10 counts per day (cpd), which will require significant decontamination of radiogenic nuclides present in the original sediment samples. This paper describes the multiple physical and chemical separation methods employed to maintain a high final chemical yield of P while reducing the radiogenic contributions. The final purified P samples had, on average 100 ± 7 % chemical yields with no quantifiable gamma emissions present. [ABSTRACT FROM AUTHOR]

Batch contact experiments with several porous carbon materials showed that carbon solids spontaneously reduce the oxidation state of plutonium in 1-1.5 M acid solutions, without significant adsorption. The final oxidation state and rate of Pu reduction varies with the solution matrix, and also depends on the surface chemistry and surface area of the carbon. It was demonstrated that acidic Pu(VI) solutions can be reduced to Pu(III) by passing through a column of porous carbon particles, offering an easy alternative to electrolysis with a potentiostat. [ABSTRACT FROM AUTHOR]

In this work, luminescent triangular silver nanoparticles were synthesized by radiolytic reduction method. The results showed that by variation of irradiation dose, morphology of silver nanoparticles can be converted from spherical to triangular. These shape variations mainly arise from competition between adsorption rate of polymer chains on (111) facets and reduction rate of the Ag ions along (110) facets during increasing dose. Furthermore, the dramatically enhanced photoluminescence spectra were observed from triangular Ag nanoparticles. This unusual behavior can be explained by excitation of dipolar and quadrupolar resonance in triangular nanoparticles which increase the electric fields at the surface. [ABSTRACT FROM AUTHOR]

We propose a method for the decontamination and waste volume reduction of cesium-contaminated soil. The soils were solidified with an interpolyelectrolyte complex solution and classified into several size fractions by wet sieving. Gamma-ray spectrometry of these fractions showed that the distribution ratio of the activity concentration of coarse soil particles decreased, whereas that of soil particles under 0.075 mm increased relative to reference samples. Results showed that the fine soil particles, on which radioactive cesium accumulates, were removed from the surface of the coarse soil particles during sieving and washing, and remained in the washing water. [ABSTRACT FROM AUTHOR]

The aim of this work is to find the optimal procedure for Po leaching from sediment samples. An improved method is described, the optimization consisting in a substantial reduction of leaching time. The method was tested on IAEA standard reference materials and compared with the classical procedure. The repeatability was estimated by analyzing seven duplicates of IAEA 385 Irish Sea sediment. However, the results are satisfactory only when the method is applied for sediments with high organic content. For silicates, a mixture of three acids was used for a complete digestion. [ABSTRACT FROM AUTHOR]

This work presented the electrochemical study of cerium(III) on the insert electrode (Mo) in NaCl-KCl molten salt in the temperature range 954-1,007 K. The electrochemical methods such as cyclic voltammetry and square wave voltammetry were used for investigating the reduction of Ce(III). The results obtained showed that CeCl could be reduced into cerium metal in a quasi-reversible one-step process exchanging three electrons (Ce(III)+3 e → Ce(0)) at the operating temperatures on a molybdenum cathode. The diffusion coefficients of Ce(III) ions at different temperatures were determined by cyclic voltammetry. The validity of the Arrhenius law was also verified and the activation energy for diffusion was found to be 46.0 kJ mol. The apparent standard potentials of the redox couple (Ce(III)/Ce(0)) at several temperatures was calculated. The thermodynamic properties of cerium trichloride have also been investigated. [ABSTRACT FROM AUTHOR]

The extraction and reduction behavior of Mo and W, lighter homologs of Sg, was studied in continuous on-line experiments at the JAEA tandem accelerator to develop a new chemistry assembly consisting of a membrane degasser (MDG), a flow electrolytic column (FEC), and the continuous liquid-liquid extraction apparatus (SISAK). Extraction yields of Mo and W from 0.1 M HCl/0.9 M LiCl into 4-isopropyltropolone (hinokitiol, HT) in toluene were investigated. In the reduction experiment, Mo(VI) was successfully reduced to a lower oxidation state while W(VI) showed no reduction under the given conditions. [ABSTRACT FROM AUTHOR]

Quench effects can cause a serious reduction in counting efficiency for a given sample/cocktail mixture in liquid scintillation counting (LSC) experiments. This paper presents a simple experiment performed in order to test the influence of quenching on the LSC efficiency of H. The aim of this study was to investigate the behavior of several quench agents with different quench strengths (nitromethane, nitric acid, acetone, dimethyl-sulfoxide) added in different amounts to tritiated water in order to obtain standard sets for quench calibration curves. The OptiPhase HiSafe 2 and OptiPhase HiSafe 3 scintillation cocktails were used in this study in order to compare their quench resistance. Measurements were performed using a low-level LS counter (Wallac, Quantulus 1220). [ABSTRACT FROM AUTHOR]

Solvent extraction of macro amounts of Mo(V) and Mo(VI) from HCl using Aliquat 336 in chloroform was performed for the electrochemistry of Sg. The extraction reaction attained equilibrium with a shaking time of 10 s in higher than 8 M HCl. The D values of Mo(V) obtained by the electrochemical reduction of Mo(VI) were in good agreement with those obtained by the extraction of MoCl, and the D values of Mo(V) were higher than those of Mo(VI). These results suggested that the reduction behavior of Sg might be studied by electrochemical reduction combined with the present solvent extraction. [ABSTRACT FROM AUTHOR]