Radioactive Cesium Research Articles

Effect of calcium application on rice ears for suppressing cesium transfer from roots to brown rice.

Researchers have stressed that crops may absorb radioactive cesium (Cs) in the soil and translocate it to its edible parts. Therefore, a method was developed to suppress Cs absorption through high K fertilisation. However, this method is less effective for rice plants after ear emergence, thus demanding the application of a suppression method at this stage. In this study, we test whether immersion of ears in a Ca solution during its ripening period could suppress the translocation of Cs from roots to brown rice. The results show that the translocation of Cs absorbed from the hydroponic solution to brown rice is reduced based on the Ca concentration applied to the ears. In addition, differences in the inhibition of translocation were observed among the different Ca salts. In addition, the effect of immersion of ears in Ca solution on Cs translocation was effective at lower concentrations than that effective for K.

Behavior of radioactive cesium concentration for 13 years after FDNPP accident at Koriyama campus of Nihon University, Fukushima, Japan.

The concentration of the radioactive cesium (134Cs and 137Cs) in soils and in atmospheric fallouts has been measured at the Koriyama campus, Nihon University, after the Fukushima Dai-ichi Nuclear Power Plant accident for 13y, from October 2011 till September 2023 and now ongoing. The concentration of them decreased very rapidly due to decontamination activities and weathering effects, with an environmental half-life of 1.21 and 2.82y in soils, with those of 1.58 and 2.08y in atmospheric fallouts for 134Cs and 137Cs, respectively. The behavior of the decrease was not simple, due to particles raised from the surface soil in wooded areas that had not been thoroughly decontaminated or that had been accumulated due to the re-release of radioactive cesium by trees after decontaminated activity.

Rapid and efficient separation of radioactive cesium ion/other radioactive ions by reduced graphene oxide membrane

Separation of cesium ions from other radioactive ions is of great significance for recycling and utilization of radioactive sources, facilitating the management of highly radioactive liquid waste (HLW), as well as for environmental protection. We achieved a highly selective and efficient separation of binary mixtures of 137Cs/60Co, Cs+/Co2+, Cs+/Ni2+, and Cs+/Zn2+ using amino-hydrothermal reduced graphene oxide membranes. The separation factor for non-radioactive binary mixtures is up to 4290, with a water permeance of 50.8 L m−2 h−1 bar−1. The separation factor for radioactive 137Cs/60Co is 623, which is somewhat underestimated due to the detection limit of the high-purity germanium spectrometer. The rGO membranes has the high water permeance of 72.4 L m−2 h−1 bar−1, with a thickness of ∼300 nm. The rGO membrane achieved effective separation of cesium and cobalt ions over a wide range of cesium-to-cobalt ion concentration ratios, with the best results achieved at a concentration ratio of 100:1 for cesium and cobalt. In addition, the rGO membranes showed outstanding stability. The superior performance is attributed to the amino hydrothermal treatment, which reduced oxygen functional groups and directly inserted nitrogen atoms into the GO lattice, ultimately forming stable narrow nanochannels conducive to the size-sieving effect. The findings show that the rGO membranes have excellent separation performance due to their size-sieving effect, and this work has great potential for rapid and efficient treatment of radioactive liquid waste.

Enhanced adsorption of radioactive cesium from nuclear wastewater using ZIF-67 laminated 2D MXene Ti3C2

Development of nuclear industry has caused severe water pollution. Adsorptive removal of radionuclides from wastewater has been regarded as effective solution for environment. However, developing adsorbents with high adsorption capacity and selectivity for removal of radionuclides (such as 137Cs) is still a challenge. Herein, we adopted an in situ assemble strategy to construct a novel composite, in which zeolitic imidazolate framework (ZIF-67) was grafted into two-dimension (2D) layers of transition metal carbides/nitrides (MXenes) Ti3C2, and used it in adsorptive removal of Cs+ from wastewater. Laminated and pillaring effect of ZIF-67 increased interlayer spacing and specific surface area of Ti3C2, significantly enhancing Cs+ adsorption. MXenes matrix provided the main adsorptive sites and interaction to stabilize Cs+, while the hybrid ZIF-67 assisted adsorption. The adsorbent achieved 96.2 % removal for 5 mg·L-1 of Cs+ within 6 h, and 50.0 mg·g−1 of maximum adsorption capacity, with good recyclability for 4 times. Ion competition, kinetics and thermodynamics were studied in detail to obtain the behavior of Cs+ adsorption. Finally, adsorption mechanism was proposed that [Ti − O] − H+ and [Ti − O] groups of 2D Ti3C2 were main adsorptive sites to participate in ion exchange and complexation with Cs+, respectively, while 2-methylimidazole (2-MI) ligands in ZIF-67 were synergetic adsorption sites.

Enhanced cesium removal from wastewater using a potassium hexacyanoferrate/gelatin aerogel composite

In the wake of the 2011 Fukushima nuclear disaster, the presence of radioactive cesium (137Cs) in nuclear wastewater has posed a critical and enduring health risk. Addressing this challenge, we have synthesized a gelatin aerogel, denoted as KCuFC/GA, immobilized with potassium cupric ferrocyanide (KCuFC) through an in situ approach, aiming for the efficient extraction of 137Cs from aqueous environments. This novel aerogel's rich porous structure enhances the accessibility of adsorption sites, thereby significantly promoting the capture of Cs+. The adsorption of cesium onto KCuFC/GA was investigated under various experimental conditions, including initial solution pH, contact time, initial cesium concentration, and the presence of coexisting ions (K+, Na+, Ca2+, Mg2+, Sr2+). The results indicated that the adsorption performance was largely independent of pH, achieving a high cesium removal rate of 93.4 % within the first 5 minutes. The cesium adsorption data were well-described by the Langmuir adsorption model, indicating a maximum adsorption capacity of 222.22 mg·L−1. Furthermore, in the presence of various competing ions, KCuFC/GA has demonstrated unparalleled selectivity for Cs+, with a partition coefficient (Kd) of 2.49 × 105 mL·g−1, and has sustained its adsorptive properties across five cycles of use. Through systematic investigation, including X-ray photoelectron spectroscopy (XPS) analysis, we have elucidated the adsorption mechanism, highlighting the pivotal role of ion exchange between lattice K+ and Cs+. The straightforward fabrication process and the aerogel's robust cesium removal capabilities from complex solutions indicate that KCuFC/GA is a promising candidate for real-world applications in the treatment of radioactive wastewater.

Fabrication of graphene oxide/ammonium molybdophosphate composite membrane for decontamination of cesium ions from seawater

Efficient separation of radioactive cesium ions (Cs+) from complicated aqueous environmental media has attracted considerable interest, especially seawater. Ammonium molybdophosphate (AMP) is regarded as a promising adsorbent for Cs+, but its fine powder dramatically inhibits the potential for practical applications. Herein, graphene oxide (GO) was utilized as a support for the in-situ growth of AMP, and after vacuum filtration, GO/AMP composite membrane was successfully fabricated. It was found that the GO/AMP membrane exhibited excellent adsorptive filtration performance (47.3 L m−2h−1 bar−1 water flux and 99.2 % rejection for Cs+ with 20 ppm initial concentration, 30 mL feed solution). Influent pH and coexisting metallic ions had scarcely effects on Cs+ rejection. Over five cycles, the water permeability and Cs+ rejection remained essentially unchanged. Moreover, the decontamination of Cs+ from real seawater was demonstrated with the rejection ratio as high as 87.4 % and a relatively inhibitory flux of 14 L m−2h−1 bar−1. Based on FT-IR, XPS, and EXAFS analyzes, the rejection of Cs+ was mainly ascribed to the exchange of NH4+ in AMP with Cs+ in solution, and an inner-sphere coordination of Cs+ rather than a weak outer-sphere interaction between hydrated Cs+ ions and adsorbent occurred.

Screening diluents to optimize cesium contaminant separation using t-BAMBP extractant

The widespread use of nuclear energy has raised concerns about nuclear safety and radioactive waste management, particularly due to the release of radioactive cesium. This study investigates the use of t-BAMBP (4-tert-butyl-2-(α-methylbenzyl) phenol) for the extraction and separation of cesium from simulate high concentration cesium containing wastewater, focusing on the selection of suitable diluents to enhance the efficiency of the process. We performed a systematic study using density functional theory (DFT) calculations to evaluate the intrinsic properties and interactions of various common diluents with t-BAMBP. The diluents studied include aromatic hydrocarbons (benzene, toluene, xylene), alkanes (cyclohexane, hexane, heptane), and alcohols (hexanol, octanol). Our computational results revealed that cyclohexane is the most suitable diluent due to its moderate solvation-free energy, high nonpolarity, and optimal balance between solubility and reactivity. Experimental validation confirmed the computational findings. The cyclohexane-diluted t-BAMBP system achieved the highest cesium extraction efficiency of over 94 %, with a separation factor (βCs/K) of 767.67. Cyclohexane demonstrated the lowest toxicity and cost among the diluents evaluated, making it a safer and more economical choice for practical applications. The results of this study provide a comprehensive theoretical and experimental basis for the selection of diluents in the t-BAMBP extraction system, offering insights for the sustainable utilization of cesium resources and effective management of radioactive waste.

Improving the estimation of direct release rates and transport processes from the Fukushima Daiichi Nuclear Power Plant accident using higher-resolution oceanic dispersion model

A series of accidents at the Fukushima Daiichi Nuclear Power Station (F1NPS), following the 11 March 2011 earthquake and tsunami, resulted in the release of radioactive substances into the ocean. In particular, the release of large amounts of radioactive caesium has damaged the fishing industry, leading to voluntary restrictions on fishing and shipping. Oceanic dispersion simulations based on estimates of the pathways and fluxes of radioactive materials provide useful information for assessing the environmental impacts and formulating measures to mitigate the effects of the accident. For the direct release rate from the F1NPS site, an estimation method was developed using the results from nearby monitoring, and the seawater exchange rate was estimated in target volume using a numerical simulation. However, the influence of volume on the seawater exchange rate was not considered. Appropriate volumes must be considered when estimating the effects of future accidents. In addition, the directional coastal transport was underestimated in the simulations of the F1NPS accident because of the low resolution. To estimate the pathways and fluxes of radioactive material to the ocean and understand the distribution of the concentration of radioactive material based on ocean dispersion simulations, a study was conducted using a higher-resolution model. The horizontal resolution of the conventional ocean dispersion model Regional Ocean Modelling System (ROMS), was increased from 1 km to 200 m. The optimal settings of the seawater exchange rate were investigated, and the radioactive caesium transport process in the coastal direction was more accurately reflected. We found that the conventional volume for determining the seawater exchange rate, including the locations of release sources and observation points, is optimal. The validity of this finding was confirmed using experimental equations from previous oceanic tracer release experiments. To estimate future release rates, it an appropriate volume must be defined, for example, depending on the distance between the locations of the release sources and the observation point. In addition, improvements in the accuracy of the simulation of the coastal transport process were observed owing to the higher resolution, which increased reproducibility. However, with a horizontal resolution of 200 m, problems with repeatability near the harbours arose. A higher resolution, achieved using nesting or other methods, would be desirable to deal with releases smaller than those in the F1NPS accident.

Ion exchange selectivity for protons by sodium ion-form crystalline silicotitanate

ABSTRACT At the Fukushima Daiichi Nuclear Power Station site, crystalline silicotitanate (CST) ion exchangers containing sodium ions (Na+) as exchange ions are used as an adsorbent to remove radioactive cesium (Cs) and strontium (Sr) from groundwater and contaminated water. The ion exchange reactions to remove Cs+ and Sr2+ compete with the reactions with other cations in the water sources. Since the groundwater and contaminated water have low concentrations of metal cations, the influence of competitive ion exchange reactions with protons (H+) is relatively large in the removal of Cs+ and Sr2+ from the water. In this paper, the H+/Na+ ion exchange property of the aqueous solution-CST system was evaluated. Results of batch tests were used to draw the isotherm and Kielland plot for the H+/Na+ ion exchange. The thermodynamic equilibrium constant K and the standard Gibbs energy ΔG 0 of the H+/Na+ ion exchange reaction were evaluated from the Kielland plot. CST exhibited high H+ selectivity in the H+/Na+ ion exchange reaction. The values of K and ΔG 0 were determined to be 7.3 × 104 and − 28 kJ mol−1, respectively. The selectivity of CST for H+ decreased with increasing H+ concentration on the ion exchange sites in CST.

A hybrid adsorption / ultrafiltration membrane process for removal of Cs-137 from radioactive wastewater using natural clay adsorbent

The removal of radioactive cesium element (Cs-137) from wastewater is relatively challenging due to its high diffusion coefficient, short hydration radius, and the similarity between its chemical behavior to other alkali metals having high background concentrations, leading to a competition that reduces the removal efficiency of cesium (Cs-137). This study introduces an innovative treatment process using a submerged membrane adsorption hybrid system (SMAHS) using natural Iraqi clay minerals as adsorbents. The operational conditions were studied using the (SMAHS) continuous flow operation in stirred filtration mode experiments. The maximum operational conditions were achieved for the initial radioactivity concentration of Cs-137 at 7201.8 Bq/L, clay dose 1 g/L, the stirring speed at 700 rpm, pH =6, the transmembrane pressure (TMP) under 2 bar, and temperature at 25 °C. The SMAHS rejection percentage of Cs-137 was 93.6 % and the permeate flux was 105.6 L/m2.h at the best operational conditions. This study demonstrates that utilizing raw bentonite which is both environmentally friendly and locally available as an adsorbent in the SMAHS has proven its effectiveness for removing Cs-137 from wastewater. The hybrid method effectively immobilizes radioactive waste by converting it from liquid to solid state, leading to an extended and safer storage time.

Distribution, risk evaluation, and source allocation of cesium and strontium in surface soil in a mining city.

Radioactive nuclides cesium (Cs) and strontium (Sr) possess long half-lives, with 135Cs at approximately 2.3 million years and 87Sr at about 49 billion years. Their persistent accumulation can result in long-lasting radioactive contamination of soil ecosystems. This study employed geo-accumulation index (Igeo), pollution load index (PLI), potential ecological risk index (PEPI), health risk assessment model (HRA), and Monte Carlo simulation to evaluate the pollution and health risks of Cs and Sr in the surface soil of different functional areas in a typical mining city in China. Positive matrix factorization (PMF) model was used to elucidate the potential sources of Cs and Sr and the respective contribution rates of natural and anthropogenic sources. The findings indicate that soils in the mining area exhibited significantly higher levels of Cs and Sr pollution compared to smelting factory area, agricultural area, and urban residential area. Strontium did not pose a potential ecological risk in any studied functional area. The non-carcinogenic health risk of Sr to the human body in the study area was relatively low. Because of the lack of parameters for Cs, the potential ecological and human health risks of Cs was not calculated. The primary source of Cs in the soil was identified as the parent material from which the soil developed, while Sr mainly originated from associated contamination caused by mining activities. This research provides data for the control of Cs and Sr pollution in the surface soil of mining city.

Synthesis of copper hexacyanoferrate from copper oxide catalyzed by trimesic acid for removal of radioactive cesium

Synthesis of copper hexacyanoferrate from copper oxide catalyzed by trimesic acid for removal of radioactive cesium

The Design of a Parameterization Scheme for 137Cs Based on the WRF-Chem Model and Its Application in Simulating the Fukushima Nuclear Accident

Based on the Weather Research and Forecasting Model Coupled with Chemistry (WRF-Chem) atmospheric chemistry model, a parameterization scheme for the radioactive isotope caesium (137Cs), considering processes such as advection, turbulent diffusion, dry deposition, and wet deposition, was constructed, enabling the spatial distribution simulation of the concentration and deposition of 137Cs. The experimental simulation studies were carried out during the high emission period of the Fukushima nuclear accident (from 11 to 17 March 2011). Two sets of comparison experiments, with or without deposition, were designed, the effects of wind field and precipitation on the spatial transport and ground deposition of 137Cs were analyzed, and the influence of wind field and precipitation on 137Cs vertical transport was analyzed in detail. The results indicate that the model can accurately simulate the meteorological and 137Cs variables. On 15 March, 137Cs dispersed towards the Kanto Plain in Japan under the influence of northeastern winds. In comparison to the experiment without deposition, the concentration of 137Cs in the Fukushima area decreased by approximately 286 Bq·m−3 in the deposition experiment. Under the influence of updrafts in the non-deposition experiment, a 137Cs cloud spread upward to a maximum height of 6 km, whereas in the deposition experiment, the highest dispersion of the 137Cs cloud only reach a height of 4 km. Affected by the wind field, dry deposition is mainly distributed in Fukushima, the Kanto Plain, and their eastern ocean areas, with a maximum dry deposition of 5004.5 kBq·m−2. Wet deposition is mainly influenced by the wind field and precipitation, distributed in the surrounding areas of Fukushima, with a maximum wet deposition of 725.3 kBq·m−2. The single-station test results from the deposition experiment were better than those for the non-deposition experiment: the percentage deviations of the Tokyo, Chiba, Maebashi, and Naraha stations decreased by 61%, 69%, 46%, and 51%, respectively, and the percentage root mean square error decreased by 46%, 25%, 38%, and 48%, respectively.

A prototype system for the removal of 137Cs from liquid radioactive waste using reverse osmosis membrane

Cesium removal from aqueous solutions of radioactive waste streams is a challenge in the field of radioactive waste management; this is due to the small atomic radii of Cs+ metal ions and their high migration ability. So, the development of a withstand system for the removal of Cs+ is crucial. In the current study, the removal of radioactive cesium from aqueous solutions using an RO-TLC membrane was studied. Two modifications were conducted; the first is to enlarge the cesium metal ion radii by interacting with mono- and dibasic acids, namely, stearic acid, tartaric acid, citric acid, and EDTA, and the second is the modification of the RO membrane pore size via reaction with the same acids. The modification was confirmed using SEM, FTIR, and EDX analysis techniques. The Cs+ and K+ rejection capacities and water permeability across the membrane at 1.5 bars were evaluated. Along with using the above-mentioned acids, the Cs+ metal ion retention index (RCs) was also obtained. It was found that employing EDTA as a chelating agent in an amount of 1.5 g/L in conjunction with the variation of feed content since it provided the highest value of RCs ~ 98% when used. Moreover, the elution of Cs+ using water, EDTA, ammonia, and HCl is also investigated. The optimal value of the eluent concentration was (0.25 M) HCl. Finally, Langmuir and Freundlich isotherm models were applied for a better understanding of the sorption process. The results of the present work more closely match the Langmuir isotherm model to determine the dominance of the chemical sorption mechanism.

Better Harvest in the Treated Rice Fields and Rice-Husk Charcoals with the Water

We tried the rice plants to better harvest using the specially-processed water, and charcoal made of rice chaffs in Niigata prefecture for a few years and the results are more than twice harvest. Water must be essential to agriculture including soil and bacteria in it. Therefore, we discuss the pico-size water like an elementary particle fabricated with just higher pressure than 100MPa without any additives, so the plant can easily absorb the water leading to the chlorophyll resulting in more extensive roots. Another point is to emit more far-infrared to help the activated charcoals with the water. The result was more than twice the yield of the control. Furthermore, we report the water reduces radioactive cesium of the rice field in Fukushima, leading to stable elements like barium, lanthanum, and cerium. We discuss the basic idea of nuclear changes regardless of present theory.

Kapok fiber composites minimizing secondary waste and disposal costs for large-scale radioactive liquid treatment

Conventional liquid treatments for large-scale, low-level radioactive wastewater, such as ion exchange and waste solidification, face challenges due to the large amounts of secondary waste and high disposal costs. A new large-scale decontamination method is proposed that uses kapok fiber composites for rapid radionuclide adsorption and high volume reduction to minimize secondary waste. The composite consists of natural zeolite and kapok holocellulose, which has high water-soaking ability and low-temperature pyrolysis. The kapok composites, fabricated using a commercial wet-laid nonwoven manufacturing process, absorbs 99% of low-level radioactive cesium in 20 min, reducing the volume by 98% and the weight by 47% at 300 °C. The low-temperature pyrolysis process below 300 °C prevents cesium desorption and gasification by avoiding zeolite destruction. The mass-producible kapok composites can be used for adsorbing various radionuclides in large-scale wastewater by attaching specific adsorbents for target isotopes to the composites.

Magnetic hierarchical titanium ferrocyanide for the highly efficient and selective removal of radioactive cesium from water

Selective adsorption is the most suitable technique for eliminating trace amounts of 137Cs from various volumes of 137Cs-contaminated water, including seawater. Although various metal ferrocyanide (MFC)-functionalized magnetic adsorbents have been developed for the selective removal of 137Cs and magnetic recovery of adsorbents, their adsorption capacity for Cs remains low. Here, magnetic hierarchical titanium ferrocyanide (mh-TiFC) was synthesized for the first time for enhanced Cs adsorption. Hierarchical TiFC, comprising 2-dimensional TiFC flakes, was synthesized on SiO2-coated magnetic Fe3O4 particles using a sacrificial TiO2 shell as a source of Ti4+ via a reaction with ferrocyanide under acidic conditions. The resultant mh-TiFC exhibited the highest maximum adsorption capacity (434.8 mg g−1) and enhanced Cs selectivity with an excellent Kd value (6,850,000 mL g−1) compared to those of previously reported magnetic Cs adsorbents. This enhancement was attributed to the hierarchical structure, which reduced intracrystalline diffusion and increased the surface area available for direct Cs adsorption. Additionally, mh-TiFC (0.1 g L−1) demonstrated an excellent removal efficiency of 137Cs exceeding 99.85% for groundwater and seawater containing approximately 22 ppt 137Cs. Therefore, mh-TiFC offers promising applications for the treatment of 137Cs-contaminated water.

Quantitative evaluation of radioactive cesium concentration in leachate and landfill waste at a municipal waste final disposal site in Fukushima prefecture

Quantitative evaluation of radioactive cesium concentration in leachate and landfill waste at a municipal waste final disposal site in Fukushima prefecture

Temporal Trends and Spatial Relationships of Radioactive Isotopes (I-131, Cs-134, and Cs-137) in Response to Nuclear Events: A Comprehensive Analysis Using Time Series Graphs, Regression, and Multivariate Techniques

This research aims to comprehend the evolution of radioactive isotopes Iodine-131 (I-131), Cesium-134 (Cs-134), and Cesium-137 (Cs-137) over time in diverse locations and analyze their relationships with the independent variables Longitude and Latitude using Linear Regression, Principal Component Analysis (PCA), and Canonical Correlation Analysis (CCA). The data used in this study were processed from the "DE.xlsx" file, including the imputation of missing values with 0 and column transformation into factors. The results of the Linear Regression analysis indicate a significant association between these isotopes and Longitude and Latitude. Additionally, PCA and CCA analyses reveal complex relationships between the isotopes and independent variables. This research provides valuable insights into the historical trends of radioactive isotopes Iodine-131 (I-131), Cesium-134 (Cs-134), and Cesium-137 (Cs-137) in various locations. The novel aspect and uniqueness of this study lie in the utilization of a comprehensive analytical approach, combining Linear Regression, PCA, and CCA to comprehend the relationships between isotopes and specific environmental factors. Moreover, this study significantly contributes to understanding the phenomena of radioactive isotopes and can serve as a foundation for further research in this field. The findings of this research are expected to support efforts in preventing and managing potential environmental and human health impacts of radioactive isotopes in the future.

Magnetic Prussian blue nanoshells are controllable anchored on the surface of molybdenum disulfide nanosheets for efficient separation of radioactive cesium from water

The rapid development of nuclear energy in China has led to increased attention to the treatment of radioactive wastewaters. Herein, a novel magnetic adsorbent, magnetic Prussian blue‑molybdenum disulfide (PB/Fe3O4/MoS2) nanocomposite, was prepared by a simple in-situ fixation of ferric oxide nanoparticles (Fe3O4 NPs) and Prussian Blue (PB) shell layers on the surface of molybdenum disulfide (MoS2) nanosheets carrier. The prepared PB/Fe3O4/MoS2 nanocomposites adsorbent displayed excellent fast magnetic separation and adsorption capacity of Cs+ (Qm = 80.51 mg/g) from water. The adsorption behavior of Cs+ by PB/Fe3O4/MoS2 conformed to Langmuir isothermal and second-order kinetic model, which belonged to chemical adsorption and endothermic reaction. The equilibrium adsorption capacity of PB/Fe3O4/MoS2 to Cs+ has reached 90 % in less than 110 min. Moreover, the adsorption properties of PB/Fe3O4/MoS2 remained good in the pH range of 2–7. Based on this, PB/Fe3O4/MoS2 complex was a fast and high selectivity adsorption material for Cs+, which was expected to be used in the practical treatment of cesium-containing radioactive wastewater.