Radioactive CO2 Research Articles

Modern and fossil seawater identification using ground- and pore-water dating from the western coast of the Miura Peninsula, Japan

Deep groundwater flow in coastal areas has attracted considerable attention in the context of radioactive waste disposal and CO2 storage from transportation point of view. It is important to show the stability of groundwater flow for a long time, which relates to identify modern and fossil seawater in coastal area. Borehole investigation was conducted at a coastal area along the west side of the Miura Peninsula in Japan, where is a typical of the accretionary wedge environments. As part of this investigation, groundwater ages have been evaluated based on dating ground- and pore-water samples (obtained by groundwater pumping and rock core squeezing, respectively) from three boreholes of up to 500 m deep. At the borehole locations, the Miura Group, which consists of sandstone and siltstone, is observed to depths of ∼200 m and the Hayama Group, which primarily consists of mudstone, is observed below ∼200 m. In the Miura Group, 14C was abundant; high-Cl samples showed high 14C and low 36Cl/Cl, equivalent to modern seawater. In the underlying Hayama Group, where the low hydraulic conductivity of the formation means that the assessment was based almost solely on porewater samples, the Cl concentration below a depth of 300 m was close to that of seawater and 36Cl/Cl was close to in situ secular equilibrium (as estimated from rock properties). Furthermore, 4He was abundant in the Hayama Group, and an observed shift in δ37Cl is inferred to have been controlled simply by diffusion. The results indicate that the groundwater in the Miura Group is modified modern seawater, while the porewater in the Hayama Group is fossil seawater. Thus, groundwater dating, using a combination of 14C, 36Cl, and 4He, is a useful tool for the identification of modern and fossil seawater in coastal areas.

Unexpectedly efficient ion desorption of graphene-based materials

Ion desorption is extremely challenging for adsorbents with superior performance, and widely used conventional desorption methods involve high acid or base concentrations and large consumption of reagents. Here, we experimentally demonstrate the rapid and efficient desorption of ions on magnetite-graphene oxide (M-GO) by adding low amounts of Al3+. The corresponding concentration of Al3+ used is reduced by at least a factor 250 compared to conventional desorption method. The desorption rate reaches ~97.0% for the typical radioactive and bivalent ions Co2+, Mn2+, and Sr2+ within ~1 min. We achieve effective enrichment of radioactive 60Co and reduce the volume of concentrated 60Co solution by approximately 10 times compared to the initial solution. The M-GO can be recycled and reused easily without compromising its adsorption efficiency and magnetic performance, based on the unique hydration anionic species of Al3+ under alkaline conditions. Density functional theory calculations show that the interaction of graphene with Al3+ is stronger than with divalent ions, and that the adsorption probability of Al3+ is superior than that of Co2+, Mn2+, and Sr2+ ions. This suggests that the proposed method could be used to enrich a wider range of ions in the fields of energy, biology, environmental technology, and materials science.

Slowing down x-ray photons in a vibrating recoilless resonant absorber

Recently, an observation of acoustically induced transparency (AIT) of a stainless-steel foil for resonant 14.4-keV photons from a radioactive 57Co Mössbauer source due to collective uniform oscillations of atomic nuclei was reported [Phys Rev Lett 124,163602, 2020]. In this paper, we propose to use the steep resonant dispersion of the absorber within the AIT spectral window to dramatically reduce a propagation velocity of γ-ray and x-ray photons. In particular, we show that a significant fraction (more than 40%) of a 97-ns γ-ray single-photon wave packet from a 57Co radioactive source can be slowed down up to 3 m/s and delayed by 144 ns in a 57Fe-enriched stainless-steel foil at room temperature. We also show that a similarly significant slowing down up to 24 m/s and a delay by 42 ns can be achieved for more than 70% of the 100-ns 14.4-keV x-ray single-photon pulse from a synchrotron Mössbauer source available at European Synchrotron Radiation Facility (ESRF) and Spring-8 facility. The propagation velocity can be widely controlled by changing the absorber vibration frequency. Achieving the propagation velocity on the order of 1–50 m/s would set a record in the hard x-ray range, comparable to what was obtained in the optical range.

Fabrication of a porous polyacrylonitrile nanofiber adsorbent for removing radioactive 60Co.

A Co2+ adsorbent was prepared using electrospun porous polyacrylonitrile (PAN) nanofibers, featuring easy recovery for reuse compared with a nanoparticle-based adsorbent. As an efficient ligand for Co2+, ethylenediaminetetraacetic acid (EDTA) was introduced on the surface of porous PAN nanofibers with the aid of a branched polyethyleneimine (PEI) linker to obtain an adsorbent with carboxylic acid groups. On the adsorbent surface, the carboxylic acid and amine groups from EDTA could adsorb Co2+ via ion exchange and chelation, and amine groups from PEI that remained after EDTA functionalization played a role in coordinating Co2+. The amine and carboxylic acid groups were simultaneously involved in the adsorption on the surface, making it possible to remove Co2+ over a wide pH range. An investigation of the adsorption isotherms and kinetics of the nanofibrous adsorbent indicated that monolayer chemisorption was achieved with a maximum Co2+ adsorption capacity of 8.32mg/g. In addition, radioactive 60Co was efficiently removed by the adsorbent with a removal extent of more than 98%. Considering the easy separation from Co2+ solution and regeneration of the nanofibrous adsorbent and its availability in a wide pH range, the adsorbent has great advantages in practical applications.

THROUGHOING FLUID-CONDUCTING STRUCTURES: MORPHOGENETIC CLASSIFICATION AND CHARACTERIZATION OF TYPES

Throughgoing fluid-conducting structures are the main elements of the plumbing system of the sedimentary cover and play an important role in fluid migration, evolution of sedimentary basins and lithogenesis, formation of fluidogenic deposits (including hydrocarbons and metals), use of geothermal energy sources, risk assessment for geological depositories of radioactive wastes, CO2 and other materials. They are widespread and characterized by a variety of morphology and origins, but are poorly systematized by these attributes, which complicates identification and interpretation of these structures. In this article, based on the analysis and generalization of literature sources and data from own field studies, morphogenetic classification of throughgoing fluid-conducting structures is developed and the characteristics of the defined types are given. At the first level, such structures are divided into four groups according to the nature of the dominant formation processes: tectonic, fluidodynamic, karstic (dissolution) and karstic-gravitational. At the second and third levels, groups and types of the structures are distinguished by structural-morphological and material features, taking into account the peculiarities of mechanisms and conditions of formation. The mechanisms of formation of structures of some types are clarified. It is shown that karstification, particularly hypogenic, is the leading process of formation of the most permeable structures and, accordingly, of the most contrasting hydrogeological anomalies and their geological consequences. Structures of relatively small vertical dimensions and stratigraphic coverage (bed-crossing, suite-crossing) can be elementary and of unambiguous origins, although they frequently show signs of superimposed changes that significantly affect their fluid-exchange function. The proposed classification is applicable mainly to small and elementary structures, while large (cross-formational, cross-sedimentary cover) are usually of complex origin, potentially involving the combined or sequential action of tectonic or hydraulic rupture, fluidization, metasomatism, dissolution / karstification and collapsing. This polygenetic nature is due to the material and mechanical heterogeneity of sections of host strata and changes in the properties of fluids during their upward migration, as well as over time. However, the assignment of structures to certain genetic categories can be carried out by the nature of the dominant formation processes.

Determination of Gamma-Ray Abundance in Photopeaks with Analytic and Numeric Approaches via CERN’s ROOT Analysis Framework

For years in gamma-ray spectrometry, there has been numerious numeric methods implemented and dedicated to integrate the photopeak areas. With the advance of new technology and softwares, determination of peak areas have been digitized. In addition, new statistical approaches have given diverse perspectives in analysing the experimental data. In this case study, Maestro software was used to extract the experimental gamma-ray data from radioactive 60Co source. In general, analysts have been challenged by the calculation of background area under certain gamma-ray peaks when there is especially low counts. For instance, this problem lead them to find different net area values in various accuracies for the same peak. Therefore the precision of determination based on different statistics might affect the results. The systematic error, which is caused by the shapes and models of the background estimation, has been investigated by CERN’s ROOT software. This detailed analysis of digital data from NaI(Tl) scintaillation detector has been tabulated with its comparisons in various modern analytic methods and numeric approaches dated back to 1960s and 1970s.

Fabrication of Alkaline Earth Oxide-Containing Glass Adsorbents for Capturing Carbon Dioxide under Mild Conditions

With growing global concern on radiological hazards, there has been strong interest in the adsorbents for the treatment of radioactive carbon dioxide (CO2) containing C-14, which should be removed under mild operating conditions. In this study, we fabricated a new class of alkaline earth oxide-containing glass adsorbents with high CO2 adsorption capacity and good adsorption rate under mild aqueous conditions, which is not feasible with alkaline earth oxide-containing natural minerals. The glass adsorbents were fabricated by incorporating alkaline earth oxides (SrO or CaO) into an amorphous glass framework using network modifiers (Na2O or K2O). The comprehensive characterization of the structure and adsorption and dissolution properties of the fabricated glass adsorbents revealed that CO2 was adsorbed via the dissolution of alkaline earth metal ions and their subsequent carbonation through heterogeneous surface nucleation. Variation in the type of alkaline earth metals and network modifiers significantly affected the CO2 adsorption performance and kinetics of the glass adsorbents by altering the dissolution behavior of the alkaline earth metal ions. The best fabricated glass adsorbent exhibited a high maximum CO2 capacity of 5.56 mmol g−1 and a fast carbonation rate of 5.31 mmol g−1 h−1 in deionized water under ambient conditions, demonstrating its potential application in treating radioactive CO2.

The essential role of the microstructure and composition in the corrosion resistance of laser-decontaminated surfaces

Metal equipment in nuclear facilities produces a wide range of radioactive wastes during the long-term service of reactors. Simulated specimens with non-radioactive isotopes Co were used instead of extremely radioactive 60Co to improve the analysis feasibility. Herein, laser decontamination was performed on 304 stainless steel with a stable isotope Co contamination layer. The microstructure and composition were characterized by transmission electron microscopy to investigate the effect of laser decontamination on the outermost surface. The results showed that laser decontamination altered the surface morphology and microstructure. The high-energy laser instantly melted and vaporized the surface, thereby removing the contaminants. Molten pool craters and corrugated protuberances were formed on the surface through the ejection of metal vapors and droplets, and the dual-phase microstructure containing γ-Fe and strain-induced martensite transformed into δ-Fe and γ-Fe phases in the recast layer. Corrosion resistance measurements showed that laser decontamination decreased the corrosion current density and the corrosion rate, whereas increased the passivation film resistance and charge transfer resistance. This indicates a remarkable improvement in comparison with the as-received specimens, mainly due to the formation of a chromium-rich oxide layer (Fe2CrO4), which acted as a separator, thereby isolating the solution from the substrate.

Influence of radiation on the stability of electrical filters characteristics as components for overvoltage protection

The paper represents the results of testing the effect of neutron and gamma radiation of radioactive 60Co on electrical filters. Neutron and gamma radiation was chosen because of its conductivity. The analysis of the standard structure of the electric filter found that neutron and gamma radiation can affect the value of the capacitance as the most important component of the filter. The presented results are a contribution to the wider research of the radiation resistance of elements for the coordination of insulation at the low-voltage level. The experiments were performed on commercial capacitors that are installed in electric filters. Measurements were made with professional equipment under well-controlled laboratory conditions. The combined measurement uncertainty of the experimental procedure was less than 5%.

Biomass base membrane with phenol hydroxy-amino group for ultraselective adsorption of radioactive Co(II) in trace concentration

60Co is widely utilized in industries and can emit high gamma energy. The removal radioactive 60Co in trace concentration from wastewater is important for human health and environment protection. Here, we designed a biomass base membrane with phenol hydroxyl-amino group for ultraselective enriching of trace concentration of Co2+ from radioactive wastewater. This novel membrane adsorbent (PAM–PBWT), that is, the immobilized black wattle tannin (BWT) modified with polyethylenimine onto the polyamide microporous membrane (PAM), utilizes phenolic hydroxyl and amino group can form a coordinated coordination with Co2+, exhibiting high selectivity adsorption to Co2+ even in the presence of other ions. A maximal adsorption capacity (0.39 mmol g−1) was reached at pH 8.0 and 323 K. The continuous adsorption experiments showed that the PAM–PBWT can enrich the trace concentration of Co2+ (60 ng L−1) from radioactive wastewater in the presence of other coexisting ions (K+, Ca2+, Na+, Mg2+, Zn2+, Mn2+, Fe3+). Moreover, the processing capacity of three-layer PAM–PBWT for simulated 60Co-containing wastewater can reach 80 L m−2. Notably, PAM–PBWT can be easily regenerated with 0.1 M HNO3 without the loss of adsorption capacity. Our work might introduce a new strategy for realizing selectivity adsorption of trace concentration irradiation contaminants from radioactive wastewater.

Acoustically induced transparency for synchrotron hard x-ray photons

The induced transparency of opaque medium for resonant electromagnetic radiation is a powerful tool for manipulating the field-matter interaction. Various techniques to make different physical systems transparent for radiation from microwaves to x-rays were implemented. Most of them are based on the modification of the quantum-optical properties of the medium under the action of an external coherent electromagnetic field. Recently, an observation of acoustically induced transparency (AIT) of the 57Fe absorber for resonant 14.4-keV photons from the radioactive 57Co source was reported. About 150-fold suppression of the resonant absorption of photons due to collective acoustic oscillations of the nuclei was demonstrated. In this paper, we extend the AIT phenomenon to a novel phase-locked regime, when the transmitted photons are synchronized with the absorber vibration. We show that the advantages of synchrotron Mössbauer sources such as the deterministic periodic emission of radiation and controlled spectral-temporal characteristics of the emitted photons along with high-intensity photon flux in a tightly focused beam, make it possible to efficiently implement this regime, paving the way for the development of the acoustically controlled interface between hard x-ray photons and nuclear ensembles.

Calibration of imaging plates sensitivity to high energy photons and ions for laser-plasma interaction sources

Imaging plates are widely used in laser-plasma interaction experiments for detection of electrons, x-ray, gamma-ray, ions, and neutrons, therefore, the calibration of imaging plates to different types of ionizing and non-ionizing radiation is vital. In this paper, a universal response function of FUJI BAS-TR imaging plate is presented using experiment and Monte-Carlo simulation with respect to high-energy photons and ions. The sensitivity of imaging plate sensitivity to x-ray radiation was examined using radioactive Co-60 isotope. Furthermore, the fading and decay mechanism affected by phosphor stimulated process were also investigated by employing the high energy gamma-rays produced in laser-plasma experiment. Finally, an ion spectrometer was designed to examine the IP response to different ion energies during a laser-driven plasma experiment. The universal relation given, can be used to evaluate the response of the imaging plate against any other types of radiation.

Effective removal of radioactive cobalt from aqueous solution by a layered metal sulfide adsorbent: Mechanism, adsorption performance, and practical application

The removal of radioactive Co2+ from aqueous solutions is a critical issue because it is highly toxic and hazardous to humans. Metal sulfides are promising materials for the removal of toxic ions; however, studies on the adsorption of Co2+ by this class of adsorbents as well as their adsorption mechanisms and practical application in complex natural water matrixes are limited. To fill this knowledge gap, in this study, a layered K/Zn/Sn/S metal sulfide nanosheet (KZTS-NS) was employed as an adsorbent for Co2+ removal from aqueous solutions. Besides ion exchange, the mechanism of surface adsorption by forming a Zn0.76Co0.24S composite was found when initial Co2+ concentration was higher than 20 mg/L, which was reported for the first time in layered metal sulfides. The Co2+ adsorption performance of KZTS-NS was systematically studied using batch methods in deionized water, including isotherms, kinetics, influential factors, and selectivity. The results indicated that KZTS-NS exhibited a high adsorption capacity, rapid kinetics, and strong selectivity in a wide pH range. Furthermore, tap water was used as a complex natural water matrix, and the practical application of KZTS-NS in a bench-scale countercurrent two-stage adsorption-flocculation-microfiltration (CTA-F-MF) process for Co2+ removal from tap water matrix was demonstrated. The CTA-F-MF process significantly enhanced the performance of the adsorbent, thereby achieving ultrahigh Co2+ removal (decontamination factor of up to 1176). This study not only provides a new insight into the adsorption of Co2+ by layered metal sulfides, but also forms the basis to enable the practical application of metal sulfides in the field of radioactive wastewater treatment.

About this title - Integrated Fault Seal Analysis

Faults commonly trap fluids such as hydrocarbons and water and therefore are of economic significance. During hydrocarbon field development, smaller faults can provide baffles and/or conduits to flow. There are relatively simple, well established workflows to carry out a fault seal analysis for siliciclastic rocks based primarily on clay content. There are, however, outstanding challenges related to other rock types, to calibrating fault seal models (with static and dynamic data) and to handling uncertainty. The variety of studies presented here demonstrate the types of data required and workflows followed in today's environment in order to understand the uncertainties, risks and upsides associated with fault-related fluid flow. These studies span all parts of the hydrocarbon value chain from exploration to production but are also of relevance for other industries such as radioactive waste and CO 2 containment.

Integrated Fault Seal Analysis: An Introduction

Abstract Faults commonly trap and impact the flow of fluids such as hydrocarbons and water over a range of timescales and therefore are of economic significance. During hydrocarbon exploration, analysis of the sealing capacity of faults can impact both the assessment of the probability of finding hydrocarbons and also the estimate of the likely resource range. During hydrocarbon field development, smaller faults can provide seals, baffles and/or conduits to flow. There are relatively simple, well-established workflows to carry out a fault seal analysis for siliciclastic rocks based primarily on clay content. There are, however, outstanding challenges related to other rock types, to calibrating fault seal models (with static and dynamic data) and to handling uncertainty. The variety of studies presented here demonstrate the types of data required and workflows followed in today's environment in order to understand the uncertainties, risks and upsides associated with fault-related fluid flow. These studies span all parts of the hydrocarbon value chain from exploration to production but are also of relevance for other industries such as radioactive waste and CO 2 containment.

Advanced oxidation process based on water radiolysis to degrade and mineralize diclofenac in aqueous solutions

Residual pharmaceutical compounds (PCs) are among the emerging organic contaminants detected in our water cycle. Diclofenac (Dic) is one of the commonly detected pharmaceutical contaminant in aquatic systems. This study was designed to investigate the degradation and mineralization of Dic in aqueous solutions by ionizing radiation emitted from radioactive Co60 under several conditions. Ultra-performance liquid chromatography, ion chromatography and TOC measurements confirmed the radiolytic degradation of Dic. The absorbed doses needed to degrade 99% Dic at 25, 50, 100, 190, 280, and 480 μM were 0.560, 0.950, 1.950, 4.000, 5.400, and 7.400 kGy, respectively. This process follows pseudo-first-order kinetics. The γ-ray/N2O system decreased the dose required to degrade 99% to 1.47 kGy. The presence of bromide anions inhibits degradation. Remarkably, adding H2O2, S2O82−, or N2O promotes mineralization. Conversely, the absence of dissolved oxygen hinders mineralization. This study provides a viable finding that ionizing radiation are useful tolls to remedy water containing pharmaceutical organic compounds.

Arginine and lysine-functionalized layered double hydroxides as efficient sorbents for radioactive Co2+ removal by chelate-facilitated immobilization

An increase in heavy metal contamination in aquatic environments require an efficient sorbent for the removal and reuse of toxic elements. We attempted to synthesize arginine/lysine-functionalized MgAl LDHs in one-pot without using any hazardous alkaline reagents. The LDHs produced at lower temperatures showed larger numbers of amino acids on their surfaces, while these are exchanged with CO32− at higher temperatures. The arginine/lysine present on the surface of LDH enhanced the adsorption of Co2+ and showed the highest adsorption capacity of 1.159 and 1.170 mmol/g for the LDHs functionalized with lysine and arginine, respectively. Kinetics studies indicated that the adsorption of Co2+ occurred by multiple mechanisms. The Co2+ adsorption on these amino acid functionalized LDHs occurs by the formation chelation complex with amino acid, which provide better vicinity of Co2+ to basic LDH that facilitating the enhanced immobilization. The sorption of other divalent metal ions on these arginine/lysine functionalized LDHs followed the order of Co2+ > Ni2+ > Mn2+ > Fe3+. The Co2+ forms diamine-like coordination that is stable on the surface of LDH and causes higher sorption densities, while other metals form partial glycine-like coordination that detaches the amino acid from the surface of LDH, thereby leading to lesser sorption capacity. The conversion of anionic LDH in to a cationic sorbent was successfully fabricated by these arginine/lysine-assisted methods and explored for the remediation of Co2+ from aqueous solution.

Quantitative evaluation and leaching behavior of cobalt immobilized in sulfur polymer concrete composites based on lignite fly ash, slag and phosphogypsum

Combined method coupling problematic industrial waste utilization with immobilization of hazardous radioactive waste is proposed. Nine different sulfur polymer composites (SPC) containing radioactive Co-60 were prepared by hot mixing and pressing in order to determine possibility of radioactive cobalt immobilization in SPC matrix. For matrix preparation three different industrial wastes fillers were used: phosphogypsum (PG), lignite slag (SL) and lignite fly ash (FA) and three different compositions of sulfur modified with styrene, dicyclopentadiene and decene. Formulations of SPC were tested against Co-60 immobilization efficiency according to the slightly modified ANSI/ANS 16.1 leaching test. Results indicate for very good immobilization efficiency for SL and FA based SPC formulations, and worse parameters regarding phosphogypsum based matrices. Effective diffusion coefficients determined for slag and fly ash based composites were determined to be within the range of 1.41·10−10-1.85·10−10 cm2 s−1 and 1.37·10−11-4.33·10−11 cm2 s−1, whereas for phosphogypsum based samples between 6.22·10−8-1.60·10−7 cm2 s−1. Measured leaching rates from SPC after 28 days were determined to be between 1.28·10−4-2.61·10−4 g cm−2·d−1 (PG), 5.84·10−6-7.65·10−6 g cm−2·d−1 (SL) and 2.53·10−6-4.50·10−6 g cm−2·d−1 (FA). Immobilization, as well as release mechanisms for Co-60 radionuclide in sulfur polymer composite matrices were proposed to be physical adsorption-dissolution for phosphogypsum based composites, and silicate/aluminate binding-dissolution-re-immobilization in case of fly ash based matrices.

Strongly Bipolar Inner Ejecta of the Normal Type IIP Supernova ASASSN-16at

Abstract We report distinctly double-peaked Hα and Hβ emission lines in the late-time, nebular-phase spectra (≳200 days) of the otherwise normal at early phases (≲100 days) type IIP supernova ASASSN-16at (SN 2016X). Such distinctly double-peaked nebular Balmer lines have never been observed for a type II SN. The nebular-phase Balmer emission is driven by the radioactive 56Co decay, so the observed line profile bifurcation suggests a strong bipolarity in the 56Ni distribution or in the line-forming region of the inner ejecta. The strongly bifurcated blueshifted and redshifted peaks are separated by ∼3 × 103 km s−1 and are roughly symmetrically positioned with respect to the host-galaxy rest frame, implying that the inner ejecta are composed of two almost-detached blobs. The red peak progressively weakens relative to the blue peak, and disappears in the 740 days spectrum. One possible reason for the line-ratio evolution is increasing differential extinction from continuous formation of dust within the envelope, which is also supported by the near-infrared flux excess that develops after ∼100 days.

Detailed study of water radiolysis-based degradation of chloroorganic pollutants in aqueous solutions.

Water radiolysis-induced destruction, dechlorination and mineralization of harmful chlorophenols, i.e., 2,4,6-trichlorophenol (2,4,6-tCPH), 4-chlorophenol (4-CPH) and 4-chlorocatechol (4-CC), using radioactive Co-60 have been investigated as individual and combination methods (2,4,6-tCPH+4-CPH+4-CC) with an initial concentration of 100 μM of each pollutant. The kinetic efficiencies of chlorophenol destruction were compared. The individual destruction percentages of 2,4,6-tCPH, 4-CPH and 4-CC reached at least 99% with absorbed doses (D99%) of 1.44, 1.73 and 1.85 kGy, respectively. Substantially higher absorbed doses were required to destroy each chlorophenol when they were all present in the treated. HCO3- anions inhibit the elimination efficiency of chlorophenols. The effects of S2O82- anions, N2O and N2 on destruction and mineralization were elaborated. O2 was crucial for the mineralization. Except for the γ-ray/N2 system, full mineralization was achieved for both individual and combined chlorophenols. The results indicate that hydrated electrons (eaq-) do not have a direct effect on the destruction of these chlorophenols. The study main goals were to show the successful application of ionizing radiation as a useful tool for environmental remediation, to continue scientific research on ionizing radiation as an advanced oxidation technology (AOT) and to provide a new, economic, practical and efficient solution to remove pollutants from aqueous media.