Search Results (80)

We report on the study of the immobilization process of non-radioactive rhenium (Re), a chemical analogue of technetium-99 (⁹⁹Tc), in compounds based on magnesium potassium phosphate (MKP), as well as the possibility of enhancing their properties with iron-bearing additives/fillers. Powdered Re₂O₇ was used as the initial Re-containing source. Because of the solubility and high leachability of Tc (VII), which is also volatile at high temperatures, its immobilization for long-term storage and disposal poses a serious challenge to researchers. Taking this into account, low-temperature stabilization technology based on MKP, a cementitious material, is currently considered promising. We prepared experimental specimens based on Re-incorporated MKP matrices and analyzed their microstructure in detail using analytical methods of X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Considering that iron-bearing substances can reduce Tc (VII) to the lower-valence form Tc (IV), which is more stable, attention was also paid to evaluate the effect of fillers (Fe₂O₃, Fe₃O₄, Fe, FeS and blast furnace slag (BFS)) on strength, oxidation state, and water resistance (expressed as leaching cumulative concentration). The addition of fillers ensures the formation of denser compounds based on MKP after 28 days of curing under ambient conditions and increases their mechanical strength. The oxidation state of Re and the reduction from Re (VII) to Re (IV) was estimated using X-ray-absorption near-edge structure (XANES) analysis. Considering the Re leaching concentrations from tests using the ANS-16.1 standard in water, enhanced leachability indices (LI) for Re from MKP matrices were determined with the addition of iron-bearing fillers. Overall, the average LI values were greater than the minimum limit, indicating their acceptance for disposal recommended by the U.S. Nuclear Regulatory Commission. Full article

Airborne iodine-131 plays a pivotal role in both nuclear medicine and nuclear safety due to its radiotoxicity, volatility, and affinity for the thyroid gland. Although the total exhaled activity after medical I-131 therapy is minimal, over 95% of this activity appears in volatile organic forms, which evade standard filtration and reflect metabolic pathways of iodine turnover. Our experimental work in patients and mice confirms the metabolic origin of these species, modulated by thyroidal function. In nuclear reactor environments, both under routine operation and during accidents, organic iodides such as [¹³¹I]CH₃I have also been identified as major airborne components, often termed “penetrating iodine” due to their low adsorption to conventional filters. This review compares the molecular speciation, environmental persistence, and dosimetric impact of airborne I-131 across clinical, technical, and accidental release scenarios. While routine reactor emissions yield negligible doses (<0.1 µSv/year), severe nuclear incidents like Chernobyl and Fukushima have resulted in significant thyroid exposures. Doses from these events ranged from tens of millisieverts to several Sieverts, particularly in children. We argue that a deeper understanding of chemical forms is essential for effective risk assessment, filtration technology, and emergency preparedness. Iodine-131 exemplifies the dual nature of radioactive substances: in nuclear medicine its radiotoxicity is therapeutically harnessed, whereas in industrial or reactor contexts it represents an unwanted hazard. The same physicochemical properties that enable therapeutic efficacy also determine, in the event of uncontrolled release, the range, persistence, and the potential for unwanted radiotoxic exposure in the general population. In nuclear medicine, exhaled activity after radioiodine therapy is minute but largely organically bound, reflecting enzymatic and metabolic methylation processes. During normal reactor operation, airborne iodine levels are negligible and dominated by inorganic vapors efficiently captured by filtration systems. In contrast, major accidents released large fractions of volatile iodine, primarily as elemental [¹³¹I]I₂ and organically bound iodine species like [¹³¹I]CH₃I. The chemical nature of these compounds defined their atmospheric lifetime, transport distance, and deposition pattern, thereby governing the thyroid dose to exposed populations. Chemical speciation is the key determinant across all scenarios. Exhaled iodine in medicine is predominantly organic; routine reactor releases are negligible; severe accidents predominantly release elemental and organic iodine that drive environmental transport and exposure. Integrating these domains shows how chemical speciation governs volatility, mobility, and bioavailability. The novelty of this review lies not in introducing new iodine chemistry, but in the systematic comparative synthesis of airborne radioiodine speciation across medical therapy, routine nuclear operation, and severe accident scenarios, identifying chemical form as the unifying determinant of volatility, environmental transport, and dose. Full article

Among the main man-made water pollutants that pose a danger to the environment are oil products, heavy metals, and radionuclides, as well as micro- and nanoplastics. To purify such waters, it is necessary to use advanced methods, with sorption being one of them. The aim of this work is to develop a nano-functionalized composite, comprising magnetically responsive, thermally expanded graphite (TEG) and the natural clay bentonite, and to assess its ability to purify man-made contaminated waters. Throughout the course of the research, the methods of scanning electron microscopy, optical microscopy, dynamic light scattering, radiometry, and atomic absorption spectrophotometry were used. The use of the TEG–bentonite composite for the purification of the model water, simulating radioactively contaminated nuclear power plant (NPP) effluent, reduced the content of organic substances by 10–15 times, and the degree of extraction of cesium, strontium, cobalt, and manganese was between 81.4% and 98.8%. The use of the TEG–bentonite composite for the purification of real radioactively contaminated water obtained from the object “Shelter” (“Ukryttya” in Ukrainian), in the Chernobyl Exclusion Zone, Ukraine, with high activity, containing organic substances, including micro- and nanoplastics, reduced the radioactivity by three orders of magnitude. The use of cesium-selective sorbents for additional purification of the filtrate allowed for further decontamination of radioactively contaminated water with an efficiency of 99.99%. Full article

This study presents long-term observations of tritium (³H) concentrations in the Neris River at monitoring sites located near the Belarus–Lithuania border and in the city of Vilnius. Since the commissioning of the Belarusian Nuclear Power Plant (BelNPP), ³H levels in the river have consistently exceeded natural background values, with pronounced temporal variations. These fluctuations are attributed to routine ³H releases from the BelNPP, with increased concentrations observed during scheduled maintenance periods. A ³H transport model was developed to estimate the downstream propagation of releases and to assess the time lag between upstream discharge events and their detection at downstream locations. The model reliably simulates ³H behavior in flowing water and can be adapted to future scenarios and other water-soluble radionuclides, provided that isotope-specific and hydrological data are available. These findings highlight the importance of continued monitoring and further research on the fate and transport of radioactive substances in transboundary river systems. Full article

Introduction: Night shift work (NSW) has been increasingly addressed in the scientific literature, as it is considered a probable carcinogen. In this study, we investigated the association of NSW with health problems, unhealthy behaviors, and occupational carcinogens. Methods: Cross-sectional study with a sample of 47,953 workers from the 2019 National Health Survey. NSW prevalence was estimated according to sociodemographic characteristics. To investigate the associations of NSW with all study variables, gender stratified logistic regression models were used. The odds-ratio and 95% confidence intervals were estimated. Results: Among men, there was a significant association of NSW with sleep disorders (OR = 1.39; 95% CI: 1.17–1.65), tiredness (OR = 1.68; 95% CI: 1.41–2.00), obesity (OR = 1.41; 95% CI: 1.20–1.66), unhealthy food consumption (OR = 1.28; 95% CI: 1.12–1.46), handling of radioactive material (OR = 2.45; 95% CI: 1.61–3.72), and biological material (OR = 3.18; 95% CI: 3.15–4.80). Among females, NSW was associated with the same variables except obesity, but depressive feelings (OR = 1.35 95% CI: 1.09–1.67), frequent alcohol intake (OR = 1.48; 95% CI: 1.23–1.78), handling of chemical substances (OR = 1.54; OR = 1.54; 95% CI: 1.20–1.97), and passive smoking at work (OR = 1.45; 95% CI: 1.12–1.86) were highly significant. Conclusion: Night shift workers are more vulnerable to occupational carcinogen exposure, experience greater impacts on their well-being, and are more likely to engage in unhealthy behaviors. These findings should be considered in managing and organizing night work in the workplace. Actions to promote healthy work environments should be encouraged to protect workers’ health. Full article

After the first release of synthalin B (dodecamethylenbiguanide) in 1928 and its later retraction in the 1940s in Germany, the retraction of phenformin (N-Phenethylbiguanide) and of Buformin in the USA (but not outside) because of the lethal complication of acidosis seemed to have put an end to the era of the biguanides as oral antidiabetics. The strongly hygroscopic metformin (1-1-dimethylbiguanide), first synthesized 1922 and resuscitated as an oral antidiabetic (type 2 of the elderly) compound first released in 1959 in France and in other European countries, was used in the first large multicenter prospective long-term trial in England in the UKPDS (1977–1997). It was then released in the USA after a short-term prospective trial in healthy overweight “young” type 2 diabetics (mean age 53 years) in 1995 for oral treatment of type 2 diabetes. It was, however, prescribed to mostly multimorbid older patients (above 60–65 years of age). Metformin is now the most used oral drug for type 2 diabetes worldwide. While intravenous administration of biguanides does not have any glucose-lowering effect, their oral administration leads to enormous increase in their intestinal concentration (up to 300-fold compared to that measured in the blood), to reduced absorption of glucose from the diet, to increased excretion of glucose through the stool, and to decrease in insulin serum level through increased hepatic uptake and decreased production. Intravenously injected F18-labeled glucose in metformin-treated type 2 diabetics accumulates in the small and even more in the large intestine. The densitometry picture observed in metformin-treated overweight diabetics is like that observed in patients after bowel-cleansing or chronically taking different types of laxatives, where the accumulated radioactivity can even reach values observed in colon cancer. The glucose-lowering mechanism of action of metformin is therefore not only due to inhibition of glucose uptake in the small intestine but also to “attraction” of glucose from the hepatocyte into the intestine, possibly through the insulin-mediated uptake in the hepatocyte and its secretion into the bile. Furthermore, these compounds have also a diuretic effect (loss of sodium and water in the urine) Acute gastrointestinal side effects accompanied by fluid loss often lead to the drugs’ dose reduction and strongly limit adherence to therapy. Main long-term consequences are “chronic” dehydration, deficiency of vitamin B12 and of iron, and, as observed for all the biguanides, to “chronic” increase in fasting and postprandial lactate plasma level as a laboratory marker of a clinical condition characterized by hypotension, oliguria, adynamia, and evident lactic acidosis. Metformin is not different from the other biguanides: synthalin B, buformin, and phenformin. The mechanism of action of the biguanides as antihyperglycemic substances and their side effects are comparable if not even stronger (abdominal pain, nausea, vomiting, diarrhea, fluid loss) to those of laxatives. Full article

Bis(2-ethylhexyl) phosphate (P204) is widely used in extraction processes in the nuclear and rare earth industries. However, its high solubility in water results in high levels of total organic carbon and phosphorus in aqueous environments, and may also lead to radioactive contamination when it is used to combine with radionuclides. In this paper, we characterized a coconut shell activated carbon (CSAC) and a coal-based activated carbon (CBAC) for the adsorption of P204 and then evaluated their adsorption performance through batch and column experiments. The results found that, except for the main carbon matrix, CSAC and CBAC carried rich oxygen-containing functional groups and a small amount of inorganic substances. Both adsorbents had porous structures with pore diameters less than 4 nm. CSAC and CBAC showed good removal performance for P204 under low pH conditions, with removal efficiencies significantly higher than those of commonly used adsorption resins (XAD-4 and IRA900). The adsorption kinetics of P204 conformed to the pseudo-second-order kinetic model, and the adsorption isotherms conformed to the Langmuir model, indicating a monolayer chemical reaction mechanism. Both adsorbents exhibited strong anti-interference capabilities; their adsorption performance for P204 did not change greatly with the ambient temperature or the concentrations of common interfering ions. Column experiments demonstrated that CSAC could effectively fix dissolved P204 with a removal efficiency exceeding 90%. The fixed P204 could be desorbed with acetone. The findings provide an effective method for the recovery of P204 and the regeneration of spent activated carbon, which shows promise for practical applications in the future. Full article

Nuclear accident-derived radionuclide dispersion poses critical challenges to marine ecological sustainability and human–ocean interdependence. While existing studies focus on hydrodynamic modeling of pollutant transport, the link between nuclear safety and sustainable ocean governance remains underexplored. This study investigates radionuclide diffusion patterns in semi-enclosed bays using a high-resolution coupled hydrodynamic particle-tracking model, explicitly addressing threats to marine ecosystem stability and coastal socioeconomic resilience. Simulations revealed that tidal oscillations and topographic constraints prolong pollutant retention by 40% compared to open seas, elevating local concentration peaks by 2–3× and intensifying bioaccumulation risks in benthic organisms. These findings directly inform sustainable marine resource management: the identified high-risk zones enable targeted monitoring of fishery resources, while diffusion pathways guide coastal zoning policies to decouple economic activities from contamination hotspots. Compared to Fukushima’s open-ocean dispersion models, our framework uniquely quantifies how semi-enclosed geomorphology exacerbates localized ecological degradation, providing actionable metrics for balancing nuclear energy development with UN Sustainable Development Goals (SDGs) 14 and 3. By integrating hydrodynamic specificity with ecosystem vulnerability thresholds, this work advances science-based protocols for sustainable nuclear facility siting and marine spatial planning. Full article

Supplementary cementitious materials (SCMs) may be prepared using industrial byproduct streams, aiding in the development of a more environmentally sustainable circular economy. However, these byproducts may carry a risk of exhibiting elevated levels of radioactivity because of the preceding processing that may have concentrated the radionuclides naturally occurring in the raw material. This processing causes the byproducts to be considered technologically enhanced naturally occurring radioactive material (NORM). Thus, the safe use of such SCMs requires robust data on the activity concentrations of three main radionuclides (²²⁶Ra, ²³²Th, ⁴⁰K) represented by the activity concentration index (ACI) used as a radiological suitability indicator. In this work, candidate SCMs derived from the alumina industry byproduct processed bauxite (PB), also referred to as bauxite residue, were assessed by measuring the activity of all available samples, including input raw materials and intermediate substances, through gamma spectrometry. PB was found to significantly impact the final ACI value of the building material. As a key analysis outcome applicable to the substances assessed in this work, no additional dose assessment is required, given the low ACI value of the building materials. This result indicates that, from a radiological perspective, the PB samples studied are suitable precursors for SCMs. In addition, a generalized approach was found to provide good estimations of the ACI value of building materials, which is useful to screen materials for regulatory compliance, without needing to prepare samples of the materials in question. Full article

Many studies have examined the ability of polymer-based gels or hydrogels to serve various purposes, particularly as absorbents. Several studies have reported that polyvinyl alcohol (PVA), with specific compositions and additives, is an absorbent and a decontamination material usable for heavy metals and radioactive substances. PVA has a high cost and is slowly degradable under anaerobic conditions. This study investigated the potential of natural materials, namely cassava starch, which is an environmentally friendly, non-toxic, and readily available gel-forming polymer that, notably, is inexpensive in Indonesia. The FTIR analysis showed a bond and polymer formation between cassava starch and glycerol. The cassava starch–glycerol–water mixture was applied to media such as glass, aluminum plates, and ceramics contaminated with heavy-metal stable ions which correspond to a radionuclide. The media, stored at room temperature for 24 h, becomes a film. According to the SEM and XRF results, the gel becomes a film that binds and absorbs metals when dried. The SEM results showed the presence of metals corresponding with the sources of contamination, and the XRF results showed that the quantity of metals absorbed was large. The cassava starch gel absorption results indicated the formation of an amorphous compound, as indicated by the XRF results. Based on all the analyses, the cassava starch–glycerol gel has enormous potential. It is almost equivalent to a PVA gel as an absorbent material and heavy-metal decontamination material, when used for radioactive decontamination on the material’s surface. Full article

Mushrooms are a significant component of human diets but can bioaccumulate hazardous substances, including both anthropogenic (¹³⁷Cs) and naturally occurring (²³⁸U, ²³²Th, and ⁴⁰K) radionuclides. This study quantified these radionuclides in 24 commonly consumed mushroom species collected in Amasya and Tekirdağ, provinces of Türkiye. Using a high-purity germanium (HPGe) detector, we found ¹³⁷Cs activity in the Tekirdağ samples ranging from 3.9 to 127.8 Bq/kg, while the ¹³⁷Cs activity in the Amasya samples ranged from 3.1 to 63.7 Bq/kg. In particular, Tricholoma terreum (Tekirdağ) and Tricholoma imbricatum (Amasya) exhibited notably higher ¹³⁷Cs concentrations. The concentration of ²³⁸U varied between 4.8 and 17.5 Bq/kg in the Tekirdağ samples and 6.5 and 16 Bq/kg in the Amasya samples, whereas the ²³²Th and ⁴⁰K values fluctuated across species and regions, with ⁴⁰K sometimes exceeding 1900 Bq/kg. These results highlight that mushrooms can serve as effective bioindicators for residual radioactive contamination and underline the need for periodic monitoring to assess potential public health risks associated with wild mushroom consumption. These findings also offer a valuable dataset for understanding post-Chernobyl fallout dynamics in the forest ecosystems of Türkiye. Full article

Urea level determination in biological fluids provides nutritional information regarding the body metabolism and/or the renal condition. In order to propose a rapid determination of this biomarker at low levels in biological fluid samples, the present work developed an electrochemical sensor based on a simple arrangement of a nickel-nanoparticle-modified glassy carbon electrode (GCE/NiNPs). Under optimal conditions for selective urea detection, a linear response was obtained in the range of 0.085 to 3.10 mmol L⁻¹ (R = 0.9993), with a limit of detection of 60.0 µmol L⁻¹ and limit of quantification of 198.0 µmol L⁻¹. The GCE/NiNPs sensor showed recovery rates from samples from 105 ± 0.2% (hemodialysis wastewater) to 111 ± 0.3% (dialysate) for urea determination in biological fluid samples. The results obtained showed that the proposed method is relatively easy to operate and has a good degree of reliability and the satisfactory sensitivity required for monitoring urea, as well as exhibiting excellent detection capacity in the presence of possible interferents in both samples. Full article

State-of-the-art hydrogeological investigations use transient calibrated numerical flow and transport models for multiple scenario analyses. However, the transient calibration of numerical flow and transport models still requires consistent long-term groundwater time series, which are often not available or contain data gaps, thus reducing the robustness and confidence of the numerical model. This study presents a data-driven approach for the reconstruction and prediction of gaps in a discontinuous groundwater level time series at a monitoring station in the Allertal (Saxony-Anhalt, Germany). Deep Learning and classical machine learning (ML) approaches (artificial neural networks (TensorFlow, PyTorch), the ensemble method (Random Forest), boosting method (eXtreme gradient boosting (XGBoost)), and Multiple Linear Regression) are used. Precipitation and groundwater level time series from two neighboring monitoring stations serve as input data for the prediction and reconstruction. A comparative analysis shows that the input data from one measuring station enable the reconstruction and prediction of the missing groundwater levels with good to satisfactory accuracy. Due to a higher correlation between this station and the station to be predicted, its input data lead to better adapted models than those of the second station. If the time series of the second station are used as model inputs, the results show slightly lower correlations for training, testing and, prediction. All machine learning models show a similar qualitative behavior with lower fluctuations during the hydrological summer months. The successfully reconstructed and predicted time series can be used for transient calibration of numerical flow and transport models in the Allertal (e.g., for the overlying rocks of the Morsleben Nuclear Waste Repository). This could lead to greater acceptance, reliability, and confidence in further numerical studies, potentially addressing the influence of the overburden acting as a barrier to radioactive substances. Full article

Multidrug resistance proteins (MRPs) are transporters for metabolic waste and xenobiotics and are known to export a wide range of substances from renal tubular cells. This study aimed to define and characterize the transport of mercuric conjugates of glutathione (GSH-Hg-GSH) in inside-out membrane vesicles containing MRP3 and MPR5. The functionality of the MRP3 and MRP5 vesicles was confirmed by measuring the uptake of [³H]-estradiol and 5-6-carboxy-2′,7′-dichloro-fluorescein (CDCF) over time (at 1, 5, 15, and 30 min). The uptake of GSH-Hg-GSH, containing radioactive mercury ([²⁰³Hg]), was measured in each set of membrane vesicles over time, and the findings suggest that GSH-Hg-GSH is a substrate of MRP3 and MRP5. The saturation kinetics were also analyzed by measuring the uptake of 10 µM GSH-[²⁰³Hg]-GSH in the presence of 25, 50, or 100 µM unlabeled GSH-Hg-GSH for 5 min at 37 °C. The transport of GSH-Hg-GSH by MRP3 (V_max = 25.6 µM; K_m = 2.8 µM) and MRP5 (V_max = 32.9 µM; K_m = 4.9 µM) was saturable. These findings are the first to show that MRP3 and MRP5 are capable of mediating the export of any form of mercury. Full article

This study addresses the operational degradation of reinforced concrete structures of buildings and facilities where radioactive materials and waste are handled, if degradation is caused by the joint effect of ionizing radiation from materials (substances) handled and factors affecting the overall aging of concrete, reinforcement bars, and their combination. The research focuses on gamma radiation and its physical, chemical, and mechanical effects, triggering corrosion processes in reinforcement bars during the operation of reinforced concrete structures. Changes in the structural behavior of existing and newly built facilities, where radioactive materials and waste (with a focus on highly and moderately radioactive waste) are handled, must be predictable during the extended period of operation. Prognostication methods and assessment models must be accessible to various specialists, including design engineers. Available software packages and numerical analysis tools are used to devise these methods and models. This research project demonstrates the numerical modeling of electrochemical corrosion triggered by oxygen diffusion in concrete. The COMSOL Multiphysics software package was used to develop a model of a reinforced concrete wall segment. This model was used to analyze and prognosticate electrochemical processes in a structure during its future operation. Results of numerical modeling show that corrosion-triggered changes in the original diameter of reinforcement do not exceed tenths (11.2–12.4%) for the predicted service life of 100 years. Studies should be continued in this direction because such factors as radiolysis, carbonization, radiation heating, and changes in the aggregate can have an adverse effect on structures during their operation. Full article