Showing papers in "Journal of Radioanalytical and Nuclear Chemistry in 2015"

Gamma radiation shielding efficiency of a new lead-free composite material

Abstract: The aim of the study is to produce a new metal-polymer composite in the form of disc and investigate shielding efficiencies against gamma radiation (137Cs and 131I and 241Am). The composite discs were produced from mixing polymer and different percentage tungsten carbide (50, 60, and 70 %). Compared with lead in same conditions the new material is more lightweight and flexible. Moreover the material’s shielding efficiency is higher than lead also.

Uranium sorption from aqueous solutions by activated biochar fibres investigated by FTIR spectroscopy and batch experiments

Abstract: The efficiency of activated biochar fibres obtained from Opuntia ficus indica regarding the sorption of hexavalent uranium (U(VI)) from aqueous solutions has been investigated by batch experiments, as a function of various physicochemical parameters, and FTIR spectroscopy prior and after U(VI) sorption. The experimental results show that the activated biochar fibres possess extraordinary sorption capacity for U(VI) even in acidic solutions (q max = 210 g kg−1), which is attributed to the formation of inner-sphere complexes with the surface carboxylic moieties, available in high density on the lamellar structures of the bio-sorbent. The adsorption process is described by a two-step exothermic reaction.

Development of a neutron generating target for compact neutron sources using low energy proton beams

Abstract: A neutron generating target using a Be(p,n) reaction was developed for a RIKEN compact accelerator-driven neutron source (RANS). The major problem of targets using a low energy proton beam is blistering, which is actually due to hydrogen embrittlement caused by injected hydrogen. To avoid this problem, the authors have proposed a new target design with a hydrogen diffusible backing and its design was modeled using finite-element analysis (FEM) and Monte-Carlo ion injection simulation. Also, the mechanical strength and heat removal capability of the target were considered by FEM. Based on those simulations, a new target was manufactured and applied to RANS and operated for 1 year without any problems. Also, the residual radioactivity of the target was investigated by experiment and simulation.

Behavior of technetium in nuclear waste vitrification processes

Abstract: Nearly 100 tests were performed with prototypical melters and off-gas system components to investigate the extents to which technetium is incorporated into the glass melt, partitioned to the off-gas stream, and captured by the off-gas treatment system components during waste vitrification. The tests employed several simulants, spiked with 99mTc and Re (a potential surrogate), of the low activity waste separated from nuclear wastes in storage in the Hanford tanks, which is planned for immobilization in borosilicate glass. Single-pass technetium retention averaged about 35 % and increased significantly with recycle of the off-gas treatment fluids. The fraction escaping the recycle loop was very small.

Recycle of U(VI) from aqueous solution by situ phosphorylation mesoporous carbon

Abstract: A new phosphorylated mesoporous carbon (CMK-3-PO4) was synthesized by situ phosphorylation of concentrated phosphoric acid (85 %) using mesoporous carbon (CMK-3) as a template. The maximum monolayer adsorption capacity of adsorbents increased from 133.5 mg g−1 (CMK-3) to 485.4 mg g−1 (CMK-3-PO4) due to the extended oxygen functional groups, and the U(VI) adsorption on CMK-3-PO4 was endothermic and spontaneous in nature. The selective sorption ability of U(VI) was significantly improved after phosphorylation. The U(VI) in the CMK-3-PO4 could been eluted by 1.0 mol L−1 HCl and also had good reusing property, and this may offer the CMK-3-PO4 very promising application prospects.

Removal of uranium(VI) from aqueous solution using graphene oxide and its amine-functionalized composite

Abstract: A new amine-functionalized graphene oxide (GO-NH2) nanosheet was prepared via covalently grafting reaction. The removal of U(VI) from aqueous solution with GO and GO-NH2 was compared using batch method. The adsorption of uranium ions could be well-described by the Langmuir isotherm and pseudo-second kinetic model. The adsorption capacities of GO and GO-NH2 were found to be 97.3 and 215.2 mg g−1 at 298.15 K, respectively. Results showed that adsorption capacity of GO was significantly improved by amine functionalization.

Natural radioactivity measurements in groundwater from Al-Jawa, Saudi Arabia

Abstract: Measurements of 222Rn, 226Ra and 228Ra concentration in a total of 19 different well waters sampled collected from Al-Jawa, Saudi Arabia were investigated. The concentrations of 222Rn were measured by RAD7 H2O technique. The concentration of 226 Ra and 228Ra were measured using gamma spectrometry preceded by ion exchange chromatography separation. It was found that the concentration of 222Rn ranged from 1.45 ± 1.19 to 9.15 ± 1.55 Bq L−1. These values are below 11 Bq L−1 the maximum contamination level recommended from the U.S. Environmental Protection Agency. The range of 226Ra concentration are 0.012 ± 0.001 to 0.59 ± 0.049 Bq L−1 with average value 0.29 ± 0.025 Bq L−1. The range of 228Ra concentration are 0.062 ± 0.007 to 2.12 ± 0.08 Bq L−1 with average value 0.86 ± 0.029 Bq L−1.

Adsorption of thorium (IV) ions from aqueous solution by magnetic chitosan resins modified with triethylene-tetramine.

Abstract: The triethylene-tetramine modified magnetic chitosan sorbents (TETA-MCS) were synthesized for the adsorption of Th(IV) ions from aqueous solution FTIR analysis indicated that the amine and hydroxyl groups of TETA-MCS were involved in the adsorption process for the formation of O, N–Th(IV) complex Th(IV) adsorption was pH dependent and the maximum adsorption was observed at pH 40 The adsorption kinetic data could be interpreted by pseudo-second-order kinetic model The equilibrium data were correlated with the Langmuir, Freundlich and Temkin models, and the maximum monolayer adsorption capacity obtained from the Langmuir model was 1333 mg Th(IV)/g at 25 °C Thermodynamic parameters revealed the feasibility, spontaneity and endothermic nature of adsorption The sorbents were successfully regenerated using 02 M HNO3−01 M EDTA and exhibited good reusability

Preparation and radiation attenuation performances of metal oxide filled polyethylene based composites for ionizing electromagnetic radiation shielding applications

Abstract: Linear low density polyethylene based and metal oxide (PbO and WO3) filled composites were prepared and characterized for ionizing electromagnetic radiation (IEMR) shielding applications. Density properties, microscopic structure and shielding performances of the composites with different filler loadings were investigated at three different IEMR energy regions as low (0–500 keV), intermediate (500–1100 keV) and high (>1100 keV). The prepared composites showed good IEMR attenuation performances especially for high filler loadings and some of them reached to or leave behind mass attenuation coefficients of elemental lead that is the most widely used shielding IEMR material.

Influences of planar source thickness on betavoltaics with different semiconductors

Abstract: Employing 63Ni and 147Pm with different thicknesses and apparent activity densities, we calculated the total efficiency (η total) and conversion efficiency (η) limits of betavoltaics by MCNP5 and Schottky equation. The apparent activity density, emitted average energy, and η limit increase and then reach their saturation levels with increasing source thickness. The increment rate of η limit increasingly smaller as the bandgap increases. Wide bandgap semiconductors lead η to reach saturation and η total to reach maximum more quickly than narrow ones. The limit of η for 147Pm is higher than that for 63Ni. Measurement results demonstrate that high apparent activity density can improve η as expected. This study can serve as a reference to evaluate the performance of betavoltaics.

Prospective carriers of 223Ra for targeted alpha particle therapy

Abstract: We report here on basic aspects that have to be addressed in TAT systems and describe our experiments with prospective carriers of 223Ra intended for bone therapy based on hydroxyapatite nanoparticles. Preparation, in vitro stability tests are described. Labelling yields were ranging between 60–99 % depending on the reaction conditions. Preliminary static stability tests of successfully 223Ra-labelled hydroxyapatite nanoparticles were performed in a physiological saline and showed relatively low activity washout within 24 h (<5 % of total sample activity).

Sorption of uranium from aqueous solutions with graphene oxide

Abstract: To explore the possible application of graphene oxide (GO) as a suitable adsorbent for the removal of U(VI) in solutions, sorption of uranium on GO was investigated as a function of pH, ionic strength, foreign ions and U(VI) concentrations using a batch technique. The results showed that the sorption of U(VI) was strongly pH-dependant and the influences of foreign ions were not significant. The sorption isotherm can be described by the Langmuir model, and the thermodynamic parameters indicated that the sorption process was endothermic and spontaneous. The results suggest that GO is a promising adsorbent for U(VI).

Multi-element characterization and source identification of trace metal in road dust from an industrial city in semi-humid area of Northwest China

Abstract: Concentrations and sources of multi-elements in road dusts from an industrial city of northwest China were determined. Dust samples have elevated concentrations of Co, Cr, Cu, Pb, Zn, Sr and Ba. The dusts were mainly moderate enrichment by Co and Pb, minimal enrichment to moderate enrichment by Sr and Zn, and deficiency to minimal enrichment by other trace metals. Mn, V, Y, La, Hf, Th and U originated from soil. Cu, Pb, Cr, Ba and Sr mainly derived from traffic. Co, Zr, Ni, Ga, As and Zn have mixed sources of nature, industry and traffic.

Development of synthetic nuclear melt glass for forensic analysis

Abstract: A method for producing synthetic debris similar to the melt glass produced by nuclear surface testing is demonstrated. Melt glass from the first nuclear weapon test (commonly referred to as trinitite) is used as the benchmark for this study. These surrogates can be used to simulate a variety of scenarios and will serve as a tool for developing and validating forensic analysis methods.

Measurement of natural radioactivity and radiation hazard assessment in the soil samples of Ramanagara and Tumkur districts, Karnataka, India

Abstract: The activity concentration of primordial radionuclides, 226Ra, 232Th and 40K in soil samples of Ramanagara and Tumkur districts were determined by gamma spectrometry using HPGe detector. The average activity concentrations of 226Ra, 232Th and 40K were found to be 33.78 ± 1.99, 77.44 ± 2.37 and 791.58 ± 5.78 Bq Kg−1 respectively. The measured activity concentrations of these radionuclides were compared with world average activity concentration of soil. The radiological hazard indices of the natural radioactivity have been calculated and compared with the internationally approved values. The concentration of these radionuclides with different size and depth of the soil samples was studied.

U(VI) sorption on illite: effect of pH, ionic strength, humic acid and temperature

Abstract: In this work, the effect of various environmental factors on U(VI) sorption to illite was investigated,such as pH, ionic strength, humic acid (HA) and temperature. U(VI) sorption to illite strongly depended on pH values, ionic strength and temperature. At pH 6.0. The thermodynamic parameters (ΔH°, ΔS° and ΔG°) calculated from the temperature dependent sorption isotherms indicated that U(VI) sorption on illite was endothermic and spontaneous. Desorption investigation indicated that U(VI) sorption on illite was reversible in the absence of HA. However, in the presence of HA, U(VI) sorption on illite was irreversible due to the strong complexation between HA and U(VI). U(VI) sorption on illite was mainly dominated by ion-exchange and outer-sphere complexation. The results are very important for estimating the uptake and transfer of U(VI) in the natural environment.

Application of Fe 3 O 4 /graphene oxide composite for the separation of Cs(I) and Sr(II) from aqueous solution

Abstract: The composite of Fe3O4 and graphene oxide (denoted as Fe3O4/GO) with excellent adsorption capacity of Cs(I) and Sr(II) was prepared by chemical coprecipitation method. The characterization results Fe3O4/GO confirmed the successful preparation of Fe3O4/GO. Fe3O4/GO was applied as adsorbent for the separation of Cs(I) and Sr(II) from aqueous solution. At pH 5.0 and 293 K, the maximum adsorption capacities of Cs(I) and Sr(II) on Fe3O4/GO can achieve to 15.8 and 38.4 mg/g, respectively. Adsorptions of Cs(I) and Sr(II) on Fe3O4/GO surface were an endothermic and spontaneous process, and were enhanced at high pH and low ionic strength. Fe3O4/GO can be separated from aqueous solution by a simple magnetic process. The results of this work highlight the application of Fe3O4/GO as an adsorbent for the separation of Cs(I) and Sr(II) from radionuclide waste water.

Nuclear data for medical radionuclides

Abstract: Radionuclides are used in medicine both for diagnosis and therapy. The radioactive decay data play a key role in the choice of a radionuclide for a certain application. The nuclear reaction data, on the other hand, allow to optimise the production route of a chosen radionuclide. The status of nuclear data of the commonly used diagnostic and therapeutic radionuclides is reviewed and the recent efforts to standardise those data are described. The expected specific activity of the cyclotron produced 99mTc is briefly discussed. The present efforts are devoted to development of non-standard positron emitters (e.g. 64Cu, 86Y, etc.) and low-range highly-ionising therapeutic radionuclides (e.g. 67Cu, 225Ac, etc.). The need of intermediate-energy multiple-particle accelerating cyclotrons is pointed out.

Effect of competing anions on pertechnetate adsorption by activated carbon

Abstract: Activated carbon (AC) has a relatively high efficiency for retaining TcO4 − compared to other materials. AC is used on a vast scale in gas and water purification, metal extraction, medicine and many other applications. The TcO4 − adsorption mechanism on AC is not fully known, however there are assumptions of ion-exchange reaction between AC surface and TcO4 − anions. Adsorption and anion competitive investigation have shown that perchlorate anions have most influence on TcO4 − adsorption. Adsorption properties depend on standard absolute molar enthalpies of hydration. Anion competitiveness was investigated with five samples that were prepared in different ways (this was already published in previous article), we used several anions Cl−, Br−, ClO4 −, CH3COO−, NO3 −, HCOO− and SO4 2− at different concentrations. In general, the adsorption of TcO4 − is influenced mostly by ClO4 −, what is explained by its similar structure with TcO4 −; however the co-existence of Fe3+ cations in the AC structure decreases TcO4 − adsorption.

FTIR spectroscopy in the characterization of the mixture of nuclear grade cation and anion exchange resins

Abstract: The practice of using the mixed bed resin (mixture of cation and anion exchange resin) in removing the ionic impurities is widely adopted in various plants including the nuclear reactors The determination of the mixing ratio by the conventional method exhibits several disadvantages (while the ratio is far from unity, poor color difference between the components and low sample volume etc) A FTIR based spectroscopic method has been proposed here for the rapid analysis (semi-quantitative) of the mixing ratio and applied on the mixture of nuclear grade cation and anion resin to overcome the difficulties faced by the conventional procedure The possibility of quantification has also been proposed by extending the present methodology

Adsorption and photocatalytic reduction of U(VI) in aqueous TiO2 suspensions enhanced with sodium formate

Abstract: In this work, the effects of sodium formate on adsorption and photocatalytic reduction of U(VI) on the TiO2 surface were investigated. The results showed that sodium formate may enhance the adsorption of U(VI) on the TiO2 surface, the maximum adsorption capacity of U(VI) in the presence of sodium formate increased by 44 mg g−1. In addition, the photocatalytic reduction of U(VI) can be also enhanced, the reduction rate constant of U(VI) in the presence of sodium formate increased 17-fold. Results from XPS analysis clearly indicated the reduction of U(VI) to U(IV) on the TiO2 surface.

Migration behavior of 134 Cs and 137 Cs in the Niida River water in Fukushima Prefecture, Japan during 2011-2012

Abstract: Total radioactivity of 137Cs in water samples from the Niida River was 0.025–4.18 Bq/L during May 2011–November 2012. Higher radioactivity was found during May–September 2011 and after a high flow condition caused by a rain event in 2012. The particulate phase of 134Cs and 137Cs was 47–48 % for May–September 2011, 75–93 % in normal flow conditions and 86–91 % in high flow conditions after December 2011. These results indicate that the supply of 134Cs and 137Cs from the watershed differs from the early stage up to September 2011 and from the last stage.

Preparation and characterization of adsorbent based on carbon for pertechnetate adsorption

Abstract: Activated carbon can potentially be used as an adsorbent for removing Tc from aqueous solutions. Five carbon materials were prepared by soaking of fibrous cellulose with different solutions containing inorganic compounds suitable for creation of micropores. After drying, materials were carbonized at 500–800 °C, characterized by BET, acid–base titration, HRTEM and SAXRD methods and tested on their adsorption capabilities for pertechnetate. Adsorption kinetics of the pertechnetate ion on these materials is relatively fast and depends on pH. For some sorbents, a 99 %-adsorption within 1 min was found. One of the variables used to characterize of pertechnetate adsorption is distribution coefficient Kd. Maximum Kd of about 7 × 104 mL g−1 was measured for acidic pH (pH 2–3). In general, Kd was decreasing with increasing pH; however, the sample treated with zinc chloride sorbed TcO4 − very well even at pH 8 (Kd = 5 × 103 mL g−1).

Rapid fusion method for the determination of Pu, Np, and Am in large soil samples

Abstract: 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.

Accelerator-based photoproduction of promising beta-emitters 67Cu and 47Sc

Abstract: In this paper we discuss our experimental work in photoproducing two medically-useful radioisotopes (68Zn(γ,p) 67Cu and 48Ca(γ,n)47Ca → 47Sc) using an electron linear accelerator. We further address the issues of production and separation of medical isotopes arising from photoneutron (γ,n) and photoproton (γ,p) reactions. While (γ,n) reactions typically result in greater yields, separating product nuclides from the target is challenging since the chemical properties of both nuclides are identical. Although the yields of (γ,p) reactions are typically lower than for (γ,n), these proton-rich isotopes have the advantage that target and product nuclides belong to different chemical species allowing for more straightforward chemical separation. We conclude the paper by touching upon the dire necessity of experimentally revisiting a broad swath of photonuclear reactions in the 10- to 50-MeV regime. The very paucity of empirical cross-sectional data makes it altogether impossible to realistically predict accelerator-based photoproduction of many promising radiopharmaceuticals.

The nature of the volatile technetium species formed during vitrification of borosilicate glass

Abstract: Vitrification of sodium pertechnetate into borosilicate glass was performed in air at 1100 °C. A glass with a composition similar to the one developed for vitrification of the low activity waste at the Hanford site was used. A red volatile species was observed above 600 °C. The extended X-ray absorption fine structure results indicate the environment of the absorbing Tc atom consists of 2.9(6) O atoms at 1.73(2) A, 2.2(4) O atoms at 2.02(2) A, and 0.8(2) O atoms at 2.18(2) A. The results are consistent with the presence of a mononuclear species with a structure closely related to TcO3(OH)(H2O)2.

Three-dimensional graphene oxide/phytic acid composite for uranium(VI) sorption

Abstract: In this work, a novel three dimensional graphene oxide sponge composite material was synthesized by functionalized GO sheets with phytic acid (PA). The as-synthesized samples were characterized and employed to investigate the removal of U(VI) from aqueous solution. Results show that higher pH favored the sorption of uranium on PA–GO. Ionic strength puts insignificant influence on the sorption. The maximum adsorption capacity is 124.3 mg g−1 at pH 5.5. The adsorption isotherms can be well described by Langmuir isotherm model and the sorption kinetics has been successfully modeled by pseudo-second-order kinetic model.

Radiolytic hydrogen generation from aluminum oxyhydroxide solids: theory and experiment

Abstract: Exploratory work on gamma exposure to dried solids with chemically-bound water that are typical of those produced on aluminum-clad nuclear fuel in reactor and post-discharge storage has shown a profound production of hydrogen (as the sole gaseous species) from dry boehmite (γ-AlOOH or Al2O3·H2O) powders and barely observable hydrogen from dry gibbsite (γ-Al(OH)3 or Al2O3·3H2O) under gamma irradiation from cobalt-60. A computational investigation of hydrogen bond energies was performed to provide insights to explain the experimental observations. A gas phase or single-molecule model, and a solid phase model were used. For all model reactions, computations indicate hydrogen loss is more favorable for boehmite than for gibbsite, in qualitative agreement with the experimental findings.

Mineralogy and uranium leaching of ores from Triassic Peribaltic sandstones.

Abstract: The recovery of uranium and other valuable metals from Polish Peribaltic sandstones were examined. The solid–liquid extraction is the first stage of the technology of uranium production and it is crucial for the next stages of processing. In the laboratory experiments uranium was leached with efficiencies 71–100 % by acidic lixiviants. Satisfactory results were obtained for the alkaline leaching process. Almost 100 % of uranium was leached with alkaline carbonate solution. In post leaching solutions only uranium and small amounts of vanadium were present.

Thermoluminescence characteristics of zinc lithium borate glass activated with Cu + (ZnO–Li 2 O–B 2 O 3 :Cu + ) for radiation dosimetry

Abstract: Copper doped zinc lithium borate glass was prepared by solid state melt quenching method and characterized using X-ray diffractometry. The effect of varying concentration of dopant CuO on thermoluminescence (TL) properties of zinc lithium borate is reported in this paper. The best annealing temperature and time were found to be 300 °C and 30 min respectively. While the optimal heating rate was 3 °C. Glow curves with single peaks for all concentrations were obtained. The TL intensity increases with the increase of dopant concentration and radiation dose from 0.5 to 4 Gy. Time-base thermal fading was stable. Attractive reusability and kinetic parameters of the phosphor were also achieved. These outstanding features show that our dosimeter has the potential ability to use for radiation processing dosimetry.