Cs Isotopes Research Articles

Effects of climate warming and declining water quality on the eco-environmental evolution of Jinmucuo Lake: Evidence from sedimentary diatom assemblages

The problem of lake pollution on the Tibetan Plateau has become prominent in recent years because of the warming climate and increased human activity. However, it is difficult to obtain effective indicators to explain the long-term eco-environmental changes in plateau lakes. In this study, a sediment core from Jinmucuo Lake was taken as the research object, and the 210Pb and 137Cs isotopes, diatom assemblages, and climatic and environmental factors were analyzed. The results revealed that the lake had a sedimentation rate of 0.47 cm/a, and the age of the 30-cm sediment core was approximately 1876 AD. Diatom abundances at different ages tend to decrease. During 1876–1999, abundant diatom species, such as Cymbella lanceolata, Navicula sp., Surirella ovalis, Synedra sp., Epithemia adnata, Cymbella pusilla, Amphora ovalis and Tabularia tabulata, which included oligotrophic, mesotrophic, and eutrophic indicator species were detected, and the dominant species were Cymbella lanceolata, Navicula sp., Surirella ovalis and Synedra sp. After 2000, diatoms declined dramatically, and were undetected in most samples. Similarly, the species richness and Shannon‒Wiener index plummeted to 0 in approximately 2002. Canonical correspondence analysis revealed that total nitrogen and organic matter were the main influencing factors of diatom assemblages before 2000, whereas As and mean annual temperature were the main influencing factors after 2000. These findings indicate that diatom habitats have been rapidly destroyed by increasing temperatures and As inputs, even in the presence of abundant nutrients in the lake.

Composite based on Poly(ethylene-co-vinyl acetate) with lead-titanate for gamma attenuation

The radioprotective ability of composite materials based on a poly (ethylene-co-vinyl acetate) matrix with dispersed lead titanate filler has been estimated. The filler was obtained from the environmentally friendly synthesis based on exchanging potassium ions for lead in potassium titanates. The gamma ray protective composites have low density, good mechanical qualities and are able to be reprocessed by high-performance extrusion or injection molding techniques. The present work is dedicated to assess mechanical and gamma ray shielding properties of poly (ethylene-vinyl acetate) composites with different lead titanate content (70, 80 and 90 wt percent of lead titanate). The study was carried out for the emission of 137Cs, 60Co and 241Am isotopes with energies 0.6617 MeV, 1.332/1.173 MeV and 0.0595 MeV respectively. The study of radiation-protective properties showed that for 137Cs radiation half value layer for the composite containing 90 wt% of lead titanate is three times higher than for neat lead: 2.1 and 0.7 cm respectively. For the 60Co emission, these values are more close: 1.9 cm for 90 wt% composite and 1.2 cm for lead. The layer of 0.5 cm of composite with 70 % lead titanate almost fully diminishes the low-energetic 241Am radiation, and hence, is superior to lead foil of the same length. Mass attenuation coefficients of 70% composite for 0.6617 MeV, 1.332/1.173 MeV and 0.0595 MeV are 0.088, 0.046 and 2.487 cm2/g respectively. The tensile elongation at fracture decrease is 460% for 70/30 lead titanate/poly (ethylene-vinyl acetate) and is equal to 6% for 90/10 lead titanate/poly (ethylene-vinyl acetate).

Prediction of the 1st excitation energy of odd–odd nuclei with the Bayesian neural network approach

A Bayesian neural network (BNN) is developed to predict the 1st excitation energy of odd–odd nuclei. Aside from the proton number and neutron number, we introduce two empirical physical quantities into the input layer. δ=[−1N+−1Z]/2 is introduced to distinguish even–even, odd–odd and odd-A nuclei; and the so-called Casten factor P≡vpvnvp+vn is introduced to stand for collectivity. The BNN is trained with an experimental dataset of the 1st excitation energy for 434 odd–odd, 649 even–even and 1050 odd-A nuclei. After training, the BNN predicts the 1st excitation energy of odd–odd nuclei with a rms of 0.21 MeV. Examples of Dy, Gd, Eu and Cs isotopes are also shown. The BNN results show moderate predictive ability, in comparison with results from the projected Hartree–Fock method.

Migration of trace elements and radioisotopes to various fractions of solid wastes generated as a result of the sewage sludge incineration process

The research was aimed at providing new knowledge in the field of chemical characteristics of solid waste generated in the process of combustion of sewage sludge in fluidized bed furnaces. The research material consisted of disposed fluidized beds (DFB), sewage sludge ash (SSA) and air pollution control residues (APC) from three Polish installations for the thermal treatment of sewage sludge. Natural radionuclides as well as anthropogenic isotope 137Cs were determined in the tested materials and the migration of a wide spectrum of trace elements to various waste fractions generated in the process of sewage sludge combustion was examined. It was observed that both radioisotopes and most of the trace elements determined accumulate in SSA and DFB, while the APC fraction contains a much smaller amount of them. The exceptions are mercury and selenium, whose volatile compounds migrate to the exhaust gas dedusting system and accumulate in the APC fraction (up to 40 mg/kg and 13 mg/kg, respectively). A potential threat from the 226Ra isotope in SSA is identified in the context of the management of this waste in the production of building materials because the typical activity of 226Ra in SSA collected from areas with very low Ra content in natural environment exceeds 1.5–6 times the activity of this isotope in conventional cement mixtures. When managing SSA and DFB, special attention should be paid to the content of metalloids such as As, B and Se, due to the high content of mobile forms of these elements in the mentioned materials.

Long-term behaviour of Cs-137, Cs-133 and K in beech trees of French forests

In the long-term after atmospheric deposit onto a forest ecosystem, Cs-137 becomes incorporated into the biogeochemical cycle of stable elements and progressively reaches a quasi-equilibrium state. This study aimed at determining to what extent Cs-137 activity distribution in tree vegetation could be predicted from that of stable caesium (Cs-133) and potassium (K), which are known to be stable chemical analogues and competitors for Cs-137 intake in tree organs. Field campaigns that focused on beech trees (Fagus sylvatica L.) were conducted in 2021 in three French forest stands with contrasted characteristics regarding either the contribution of global vs. Chornobyl fallouts, soil or climatic conditions. Decades after Cs-137 fallouts, it was found that more than 80% of the total radioactive inventory in the system remained confined in the top 20 cm mineral layers, while organic layers and beech vegetation (including roots) contributed each to less than 1.5%. The enhanced downward migration of Cs-137 in cambisol than podzol forest sites was presumably due to migration of clay particles and bioturbation. The distribution of Cs-137 and Cs-133 inventories in beech trees was very similar among sites but differed from that of K due a higher accumulation of Cs isotopes in roots (40–50% vs. < 25% for K). The aggregated transfer factor (Tag) of Cs-137 calculated for aerial beech organs were all lower than those reported in literature more than 20 years ago, this suggesting a decrease of bioavailability in soil due to ageing processes. Regarding their variability, Tags were generally lower by a factor 5 at the cambisol site, which was fairly well explained by a much higher value of RIP (radiocesium immobilisation potential). Cs-137 concentrations in trees organs normalized by the soil exchangeable fractions were linearly correlated to those of Cs-133 and the best fit was found for the linear regression model without intercept indicating that no more contribution of the foliar uptake could be observed on long term. Provided that the vertical distribution of caesium concentrations and fine root density are properly measured or estimated, Cs-133 was shown to be a much better proxy than K to estimate the root transfer of Cs-137.

Growth Responses of Holcus lanatus L. (Velvet Grass) in Soils Contaminated with Cesium or Strontium

Radiocesium (r-Cs) and radiostrontium (r-Sr) released from nuclear accidents (e.g., Chornobyl, Fukushima) and routine operations (reactors, reprocessing) pose environmental and health concerns. Their primary pathway to humans is through plant uptake and subsequent bioaccumulation within the food chain. While soil amendments with potassium (K) and calcium (Ca) are known to mitigate r-Cs and r-Sr uptake, respectively, the impact on plant growth remains unclear. This study investigates the effects of Cs and Sr on the growth of Holcus lanatus L. seedlings under hydroponic and soil conditions with varying Cs and Sr concentrations. Stable isotopes of Cs and Sr served as non-radioactive analogs. Seedling growth was assessed across a range of Cs and Sr concentrations (≤1 and ≥4 mg L−1). The impact of the addition of K and Ca on Cs/Sr uptake in amended soils was also evaluated. Additionally, this study examined how Cs and Sr amendments affected the influx rates of other nutrients in H. lanatus. Higher Cs and Sr concentrations (≥4 mg L−1) significantly inhibited seedling growth, while lower concentrations had no effect. Notably, H. lanatus exhibited moderate Cs tolerance and strong Sr tolerance. Furthermore, K and Ca supplementation in Cs/Sr-amended soils demonstrably reduced plant uptake of these elements. This study also observed alterations in the uptake rates of other nutrients within H. lanatus due to Cs/Sr addition. This study suggests that H. lanatus exhibits moderate tolerance to Cs and Sr contamination, potentially making it suitable for revegetation efforts in contaminated grasslands. Additionally, K and Ca amendments show promise as a strategy to mitigate plant uptake of these radioisotopes further. These findings contribute to the development of safer revitalization strategies for areas impacted by nuclear accidents.

Advancing in Cesium Retention: Application of Magnesium Phosphate Cement Composites.

A serious risk that harms the safe use of water and affects aquatic ecosystems is water pollution. This occurs when the water's natural equilibrium is disrupted by an excessive amount of substances, both naturally occurring and as a byproduct of human activities, that have varied degrees of toxicity. Radiation from Cs isotopes, which are common components of radioactive waste and are known for their long half-lives (30 years), which are longer than the natural decay processes, is a major source of contamination. Adsorption is a commonly used technique for reducing this kind of contamination, and zeolite chabazite has been chosen as the best adsorbent for cesium in this particular situation. The purpose of this research is to investigate a composite material based on magnesium phosphate cement (MPC). Magnesium oxide (MgO), potassium dihydrogen phosphate (KH2PO4), and properly selected retarders are used to create the MPC. The optimal conditions for this composite material are investigated through the utilization of X-ray diffraction, scanning electron microscopy, BET surface area analysis, and atomic absorption spectroscopy. The principal aim is to enable innovations in the elimination of radioactive waste-contaminated water using effective cesium removal. The most promising results were obtained by using KH2PO4 as an acid, and MgO as a base, and aiming for an M/P ratio of two or four. Furthermore, we chose zeolite chabazite as a crucial component. The best adsorption abilities for Cs were found at Qads = 106.997 mg/g for S2 and Qads = 122.108 mg/g for S1. As a result, zeolite is an eco-friendly material that is a potential usage option, with many benefits, such as low prices, stability, and ease of regeneration and use.

Radioactivity of the atmospheric aerosols detected by CTBTO stations in Africa following the accident at the Fukushima Daiichi nuclear power plant

Radionuclides from the reactor accident Fukushima Daiichi nuclear power plant were observed in the airborne aerosols at CTBT International Monitoring System (IMS) stations (MRP43, CMP13) in Africa. The maximum activity concentrations in the air measured in Mauritania were 186.44 10−6 Bq.m−3, 264.16 10−6 Bq.m−3 and 1269.94 10−6 Bq.m−3 for 134Cs, 137Cs and 131I respectively, and in Cameroon 16.42 10−6 Bq.m−3, 25.53 10−6 and 37.58 10−6 Bq.m−3 respectively for 134Cs, 137Cs and 131I. The activity ratio of 134Cs/137Cs is almost constant throughout the period of time relevant to this study due to their long half-lives of 30.2 years for 137Cs and 2.06 years for 134Cs. Whereas the 131I/137Cs activity ratio varies in time according to the radioactive decay with a half-live of 8.06 days for 131I and different removal rates of both radionuclides from the atmosphere during transport. The EMAC atmospheric chemistry-general circulation was used to simulate the emission and transport of the isotope 137Cs and map the deposition of the 137Cs deposition over Africa.

Carbon-Sulfur isotope and major and trace element variations across the Permian–Triassic boundary on a shallow platform setting (Xiejiacao, South China)

We examined microbialites deposited near the Permian–Triassic boundary (PTB) at the Xiejiacao section of South China, including the size and morphology of pyrite framboids, carbonate carbon isotopes (δ13Ccarb), carbonate associated sulfur isotope (δ34SCAS), major and trace elements, and total organic carbon (TOC) concentrations. The microbialite unit is much thicker than the PTB beds in deeper water sections, providing more detailed geochemical records from that time. A prominent negative δ13Ccarb excursion was recognized in association with the second phase of the Permian–Triassic mass extinction (PTME), comparable with that of several other shallow platform facies sections worldwide. δ34SCAS stratigraphic profiles also show a negative excursion, with minimum values occurring slightly later than those of δ13Ccarb. The minimum peak can be calibrated to the middle part of the conodont Isarcicella staeschei Zone, corresponding to the second phase of PTME. Over all, the carbon and sulfur isotopes demonstrate a coupled long-term relationship with large negative excursions during the Permian–Triassic transition followed by gradual recovery in the lowest Triassic, represented an extremely low concentration of sulfate in the ocean during this period. In contrast, the CS isotopes are strongly decoupled within the microbialite unit, which could be linked with the oxygen-poor conditions and microbial sulfate reduction (MSR: Sulfate reducing microorganisms facilitated the precipitation of sulfide and carbonate, such as SO42− + 2CH2O → H2S + 2HCO3−). The second phase of PTME was calibrated to the top of the microbialite unit, which was marked by the second δ13Ccarb-δ34SCAS negative excursions. The distinct marine oxygen deficiency was indicated by the small pyrite framboids, relatively high values of UEF (>1) and Ce/Ce* (>0.8). Combined with the previous biostratigraphic work, we propose that continuous volcanic activity induced intensified marine anoxia, leading to biotic mortality in the second phase of the PTME. Overall, our isotopic and geochemical data, integrated with results of previous studies, provided a new explanation for the carbon and sulfur isotope variations and additional evidences into the concurrent environmental changes during the Permian–Triassic transition.

Effective dose evaluation for external exposure from surface soil by using resrad-onsite code

An annual effective dose evaluation from Dong Nai surface soil (45 samples) to humans was carried out in this work. ResRad-Onsite software has been applied to estimate the maximum exposure dose by considering different exposure levels across an area of ​​5905.7 km2 with a topsoil thickness of 20 cm. The calculation grid used in ResRad Onsite software is divided in the form of a circle of radius 3, 5, 10, 20, and 30 km, respectively, calculated from the circle center in terms of 16 wind directions. A high-purity germanium detector (HPGe) was used to determine 238U, 232Th, 226Ra, 137Cs, and 40K isotopes. The range activity concentrations of them were found to be 6.46 ÷ 48.11; 13.95 ÷ 58.75; 5.71 ÷ 35.27; 0.15 ÷ 1.23 and 6.7 ÷ 222; mBq/g, respectively. The isotope 239,240Pu was determined by the radiochemical separation method, measured on the alpha spectrometer system, and the calculated value range is 0.009 ÷ 0.073 mBq/g. The activity of 90Sr was determined by separation technique, measured on a low-background alpha/beta total counting system (MPC 9300) with a calculated value range of 0.10 ÷ 0.83 mBq/g. By ResRad-Onsite code, the external effective dose derived from the ground (excluding Radon’s contribution) is calculated to be 170 ÷ 658 µSv/year with an average value is 368.6 µSv/year. The external dose from the soil is 136.5 µSv/year (accounting for 37%). The results showed that the annual radiation dose distribution derived from the ground equivalent to the average of some different regions in the territory of Vietnam and the world. In addition, the external effective dose from the ResRad-Onsite code tended to be about 1.36 times smaller than the practical measured due to the library’s different dose conversion coefficients.

Highly selective capture of cesium using an electrochemically renewable molybdenum-based crystalline adsorbent

The development of highly efficient adsorbents for the capture of 133Cs and the removal of radioactive isotope 137Cs from complex aqueous solutions is crucial for the chemical production and environmental remediation. Herein, Mo-based crystalline adsorbent with sub-nanometer (5.76 Å) channels was successfully prepared and used in electrochemically controlled Cs+ separation process. Crystalline structures of MoIC (HNO3) before and after adsorption of Cs+ were clearly elucidated using powder X-ray diffractometer (PXRD). A more environmentally friendly electrochemical method was employed to achieve easy release and recapture of Cs+. Adsorption comparison experiments revealed that our material clearly outperforms the reported adsorbents for the removal or recovery of trace amount of Cs+ (< 10 mg L−1). Furthermore, MoIC (HNO3) also exhibited excellent selectivity for low concentration of Cs+ over highly excess of competitive cations, such as Mg2+, Ca2+ and K+, which are commonly distributed in brines. The maximum separation factors of Cs+/Mg2+, Cs+/Ca2+ and Cs+/K+ are 1.2 × 105, 1.3 × 104 and 66, respectively. The remarkable selectivity can be attributed to the outstanding ion-sieving ability of sub-nanometer channels based on the differences in ionic radius and hydration energy of these cations. A real brine was introduced to further prove that one complete cycle of electrochemical adsorption and desorption can dramatically reduce the competing ions concentrations up to 980 times. We anticipate that our findings may give the prospect of opening up new path for the efficient separation of Cs+ from brines using molybdenum-based adsorbent via electrochemically controlled process as a green and sustainable way.

Optical and radiation shielding characteristics of Dy2O3 doped B2O3–TeO2–BaO glasses

Glass samples with varying compositions was prepared by standard approach. The composition of the samples was (50-x) B2O3–25TeO2–25BaO-xDy2O3, with x ranging from 0 to 1.25 mol%. XRD profiles confirmed that the samples were amorphous, as there were no long-range lattice arrangements observed. The successful preparation of amorphous samples was further confirmed by the absence of sharp lines &amp; peaks. The optical properties of the obtained samples were analyzed. That a decrease in Eopt values resulted in a higher value of the refractive index (n) for the glasses. However, when the concentration of Dy2O3 exceeded certain levels (0.75, 1, and 1.25 mol%), the refractive index (n) decreased due to an increase in Eopt values. Experimental measurements using a NaI(Tl) detector were conducted to determine the radiation shielding parameters (LAC and MAC), as well as the (HVL), (TVL), &amp; (MFP) of the glasses against gamma rays emitted by 137Cs and 60Co isotopes at energies of 0.662, 1.173, and 1.333 MeV. Excellent agreement was observed when comparing the experimental results with theoretical calculations using Phy-x/PSD software program. This suggests that the fabricated glasses have great potential for various applications in the field of optics and can effectively shield against radiation.

Investigation of bentonite clay minerals as a natural adsorbents for Cs-137 real radioactive wastewater treatment

In this work, the removal of the radioactive element Cs-137 from actual radioactive wastewater was studied by batch adsorption studies. To lower the dangers of radioactive contamination, bentonite, a naturally occurring clay mineral, was used as an adsorbent. The bentonite clay mineral was characterized using chemical composition analyses, (XRD), (SEM), (EDX), (BET) surface area analysis, and (FT-IR). Experiments of batch adsorption were conducted to determine the optimal adsorbent. After two hours, equilibrium was attained with a bentonite Cs-137 removal effectiveness of 98%. The kinetics of Cs-137 adsorption on the bentonite clay surfaces was investigated. A good match was obtained for the bentonite kinetic data using the pseudo 2nd order kinetic model. As a result, it was found that bentonite was the good medium for adsorption. The findings provide helpful details on the ways in which bentonite clays adsorb radioactive Cs-137 and remediate pollution. The chosen of bentonite clay adsorbents was displayed to be hopeful adsorbent for the adsorption of the radioactive Cs-137 isotope because of effective material, very cheap, and available.

Effects of Cesium on Physiological Traits of the Catherine's Moss Atrichum undulatum Hedw.

Mosses are proven bioindicators of living environments. It is known that mosses accumulate pollutants from precipitates and, to some lesser extent, from the substrate. In this study, the effects of cesium (Cs) on the physiological traits of acrocarp polytrichaceous Catherine's moss (Atrichum undulatum Hedw.) were studied under controlled, in vitro conditions. Cesium can be found in the environment in a stable form (133Cs) and as a radioactive isotope (134Cs and 137Cs). Belonging to the same group of elements, Cs and potassium (K) share various similarities, due to which Cs can interfere with this essential element and thus possibly alter the plant's metabolism. Results have shown that Cs affects the measured physiological characteristics of A. undulatum, although the changes to antioxidative enzyme activities were not drastic following Cs treatments. Therefore, the activities of antioxidative enzymes at lower pH values are more the consequence of pH effects on enzymatic conformation than simply the harmful effects of Cs. Moreover, Cs did not affect the survival of plants grown on the solid substrate nor plants grown in conditions of light and heavy rain simulation using Cs with variable pH, indicating that Cs is not harmful in this form for the studied species A. undulatum.

Suitability of 210Pbex, 137Cs and 239+240Pu as soil erosion tracers in western Kenya

Land degradation resulting from soil erosion is a global concern, with the greatest risk in developing countries where food and land resources can be limited. The use of fallout radionuclides (FRNs) is a proven method for determining short and medium-term rates of soil erosion, to help improve our understanding of soil erosion processes. There has been limited use of these methods in tropical Africa due to the analytical challenges associated with 137Cs, where inventories are an order of magnitude lower than in the Europe. This research aimed to demonstrate the usability of 239+240Pu as a soil erosion tracer in western Kenya compared to conventional isotopes 210Pbex and 137Cs through the determination of FRN depth profiles at reference sites. Across six reference sites 239+240Pu showed the greatest potential, with the lowest coefficient of variation and the greatest peak-to-detection limit ratio of 640 compared to 5 and 1 for 210Pbex and 137Cs respectively. Additionally, 239+240Pu was the only radionuclide to meet the ‘allowable error’ threshold, demonstrating applicability to large scale studies in Western Kenya where the selection of suitable reference sites presents a significant challenge. The depth profile of 239+240Pu followed a polynomial function, with the maximum areal activities found between depths 3 and 12 cm, where thereafter areal activities decreased exponentially. As a result, 239+240Pu is presented as a robust tracer to evaluate soil erosion patterns and amounts in western Kenya, providing a powerful tool to inform and validate mitigation strategies with improved understanding of land degradation.

Stable and Radioactive Cesium in Natural Environment

Cesium is the heaviest stable alkali metal (with only one stable isotope – 133Cs) and it occurs mainly as a potassium-substituting cation. It is an important trace element in rocks typical for the Earth crust, and its content in biomass is also relatively high compared to those abiogenic elements which are little soluble. Low-cost analytical methods like X-Ray Fluorescence are inadequate to quantify cesium in typical natural samples, so that the usage of ICP-MS (Inductively-Coupled-Plasma Mass Spectrometry) or INAA (Instrumental Neutron Activation Analysis) is necessary. Nevertheless, investigation of the pollution with the radioactive isotope 137Cs, which is an important fission product and can be measured with gamma-ray spectrometry, also contributed to the knowledge of biogeochemistry of cesium. It has been shown that Cs is usually strongly retained in humus (thank to clay minerals), or is cycling intensely within the soil-biomass system, being only slowly removed (at least, this is valid for ecosystems in temperate climate). The results of extensive biomonitoring in Czech coniferous forests (with prevailing spruce) also show that Cs is concentrated in humus (relatively to all other alkali elements) by natural processes.

Internal organ dose rate conversion coefficients of Japanese macaques to 134Cs,137Cs and 131I†.

The purpose of this study was to estimate the internal dose of radiation in Japanese macaques (aka Nihonzaru or snow monkey) due to the Fukushima nuclear power plant accident. Images of a male Japanese macaque weighing ~10kg were acquired using a multi-slice computed tomography (CT) scan with a 64-row segment detector. The CT images were used to create voxel phantoms of the bones, bone marrow, brain, eyes, heart, lungs, stomach, liver, spleen, pancreas, kidneys, intestines, bladder, testes, thyroid and miscellaneous tissue. The Particle and Heavy Ion Transport System (PHITS) Monte Carlo code was used to calculate the internal exposure rate conversion factors for 134Cs, 137Cs and 131I isotopes for the created voxel phantoms with a statistical precision higher than 1%. The PHITS-calculated energy deposits were compared with those for rhesus monkeys. The results showed that the fractions of energy deposits for β-radiation in different organs were almost identical between the two species. For γ-radiation, there was excellent agreement in the self-absorption rate with the approximate curve of the Japanese macaque, with an average deviation of 2%. The maximum deviation of 12% was for the kidney, which has two organs, so the error with the approximate curve is slightly larger due to the energy loss created between organs.

Study on (n, α) reactions for the production of 51Cr, 89Sr, 99Tc, 131I, 133Xe, 137Cs and 153Sm radioisotopes used in nuclear medicine

Nuclear medicine seems to be a decent choice of medicine in the recent decade. The radioactive isotopes 51Cr, 89Sr, 99Tc, 131I, 133Xe, 137Cs and 153Sm are extremely essential in nuclear medicine. The excitation functions of the 54Fe (n, α) 51Cr, 92Zr (n, α) 89Sr, 102Rh (n, α) 99Tc, 134Cs (n, α) 131I, 136Ba (n, α) 133Xe, 140La (n, α) 137Cs and 156Gd (n, α) 153Sm reactions were calculated in this study using the EMPIRE 3.2.3 and TALYS 1.95 nuclear codes. Additionally, the cross sections at 14–15 MeV were calculated using empirical formulae and the experimental data. The computer codes were compared to the experimental data and Empirical formulas as well as the evaluated data (TENDL 2021, JENDL 3.3, JENDL 5, JEFF 3.3, EAF 2010, CENDL 3.1, CENDL 3.2, ROSFOND 2010, FENDL 3.2 b, and BROND 3.1).

A close look for the γ-ray attenuation capacity and equivalent dose rate form composites based epoxy resin: An experimental study

The present work aims to develop new epoxy-based composites with halloysite, basalt, PbO, CuO, and Bi2O3 fillers. The role of the utilized fillers in the structural properties of the fabricated composites was studied using the Fourier transform infrared spectrometer and scanning electron microscope. Additionally, the role of utilized fillers in reducing the equivalent dose rates from Co-60 and Cs-137 isotopes were experimentally examined where the equivalent dose rate values ranged between 1.95 μSv/h–1.36 μSv/h (for E@PbO), 1.88 μSv/h–1.31 μSv/h (for E@Bi2O3 composite), 1.97 μSv/h–1.43 μSv/h (for E@CuO composite), 1.96 μSv/h–1.46 μSv/h (for E@Halloysite composite), and between 1.94 μSv/h–1.47 μSv/h (for E@ Basalt composite), raising the composites’ thickness between 1.0 and 4.65 cm, at gamma-ray energy of 0.662 MeV. Based on the examined equivalent dose rate, the shielding parameters of the fabricated composites were evaluated where the radiation protection efficiency f reaches 36.4%, 33.2%, 31.8%, 38.8%, and 31.3% for epoxy resin reinforced by 25 wt% of PbO, CuO, halloysite, Bi2O3, and basalt, respectively, at gamma-ray energy of 0.662 MeV. The observed outcomes demonstrated that the radiation shielding parameters of low-cost epoxy resin with natural fillers (halloysite and basalt) are marginally inferior to those of CuO, PbO, and Bi2O3 fillers. These results support the feasibility of creating shielding polymer composites using natural fillers rather than expensive and hazardous heavy-weight fillers.

A comparison of 210Pbxs, 137Cs, and Pu isotopes as proxies of soil redistribution in South Spain under severe erosion conditions

PurposeThe use of fallout radionuclides as proxies for the study of soil redistribution processes in semiarid environments of Southern Spain has been restricted to 137Cs. The potential and limitations of alternative proxies such as 239+240Pu and 210Pbxs should be explored given the expected constrains imposed by the features of the study area.Materials and methodsFour soil and one sediment cores were collected in a highly eroded area to test the feasibility of these proxies under demanding conditions. The use of gamma spectrometry and ICP-MS did allow exploring the potential of 210Pbxs and Pu isotopes against the well-established tracer, 137Cs. The activity ratios 239+240Pu/137Cs were explored to evaluate the previous evolution of the sampling sites. Soil redistribution rates were estimated using the model MODERN.Results and discussionDespite all the profiles showed intense perturbation, Pu isotopes showed the highest potential thanks to higher sensitivity and sample throughput. The deviations of 239+240Pu/137Cs inventory ratios (0.012–0.158) from the global fallout average (0.026 ± 0.003) suggest that the sediment core was a deposition site involving alternate episodes of topsoil removal and incorporation from different sources. The calculated erosion rates ranged 34–43 t ha−1 year−1, being in good agreement for 137Cs and 239+240Pu. 210Pbxs was not used due to low-quality data.ConclusionsThe use of Pu as a tracer of soil redistribution processes in semiarid areas seems to be promising even under severe erosion conditions. The use of 210Pbxs is not recommended in this area due to its low concentration.Graphical