Radioactive Contamination Research Articles

Deep eutectic solvent microemulsions with abundant hydrogen ions in supercritical CO2 for decontamination of radioactive solid waste: Overcoming roadblocks to hydrogen ions deficiency

Deep eutectic solvents (DESs) dispersed in supercritical CO2 (SC-CO2) as microemulsions have shown promise for the removal of radioactive contaminants from solid surfaces. However, the current technology needs urgent improvement in terms of decontamination performance. This study reported a novel strategy to enhance the decontamination ability of DESs-in-CO2 systems by adding hydrogen ion (H+) supplemental reagents. The type and acidity of the added H+ reagents were found to be critical factors in dictating the decontamination performance. For instance, fluorinated carboxylic acids with higher acidity and higher CO2 affinity were more competitive for decontamination compared to other non-fluorinated carboxylic acids. Additionally, when nitric acid was used as the H+ supplemental reagent for microemulsions in SC-CO2, outstanding decontamination results were achieved. It could remove 99 % of UO3 contaminants on the specimen surfaces. The formation of microemulsions was demonstrated by molecular dynamics (MD) simulations. Meanwhile, low-cost nitric acid was more promising for scale-up applications. Remarkably, the versatility of the decontamination technology with the addition of nitric acid was demonstrated by its ability to completely decontaminate multiple radioactive wastes made of various materials, as well as different simulated radionuclides. Decontamination efficiency reached more than 99.0 %. More importantly, the DESs-in-CO2 systems with nitric acid also reduced the radioactivity of real radioactive metal waste to the clearance level with the decontamination efficiency reaching 99.0 %. Overall, this study provided valuable insights into the design of advanced decontamination technologies based on microemulsions of DESs in SC-CO2 and opened new avenues for the sustainable management of radioactive waste.

A new approach to determine abnormality of radioactive discharges from pressurized water reactors and to derive abnormality indicators correlated with a specific causal event

Abstract A novel methodology to analyze the trend of radioactive effluent data from nuclear power plants (NPPs) has been proposed to estimate the possibility of abnormal releases of radioactive materials, and to identify sensitive radionuclides with high correlation to specific events and abnormal releases. Actual discharge data including abnormal releases for 21 years (1,610 reactor-years) from 62 US and 22 Korean pressurized water reactors were collected. A release correlation factor (RCF) was newly proposed as a quantitative indicator of the abnormality of radioactive discharges based on annual discharge data from each NPP. The probability of correct estimation of abnormality using the RCF for a test case ranges 27–36 %, and such a modest estimation power was ascribed to the relatively low contribution (i.e., about 12 %) of a specific causal event to the annual radioactivity release. Through this, the feasibility of the RCF for estimating the abnormality of radioactive discharges was demonstrated. The RCF was derived for three types of causal events, and subsequently the sensitive radionuclides to each specific event were derived as 88Kr, 137Xe, and 138Xe for leakage from gas decay tank, 3H for leakage from steam generator’s power operated relief valve, and 85Kr, 88Kr, 133Xe, 133mXe, 3H and 14C for leakage from defected spent fuel during handling. The new approach proposed in this study is to be used to suppose the significant unreported abnormality in radioactive effluent data and the potential causal event, which may contribute to improving the safety and performance of radioactive effluent control as necessary.

"Exploring the role of lithium in Al2O3 tritium permeation barrier development: A crucial challenge for fusion reactor progress"

The development and application of robust tritium permeation barriers (TPBs) are crucial for a safe and economical fusion reactor operation because tritium permeation could cause serious safety problems, such as the brittleness of the structural material, fuel loss, and radioactive contamination. Coatings may effectively inhibit the permeation through the structural materials of tritium fuel generated inside the breeding blanket (BB) reducing the loss of lithium inventory contamination of the ancillary systems and the exposure of workers and the population. Al2O3 has been preliminary selected as the EU candidate for tritium permeation reduction of structural steels in the Water-cooled lithium–lead breeding blank (WCLL) concept, because of its very high permeation reduced factor (PRF). However, because of the chemical reactivity of lithium, several authors report the formation of Lithium aluminates after exposure to PbLi baths, based on different experimental techniques. In this contribution, we will show recent results about the quantification of the extent of the reaction and the thickness of the reacted layer and discuss the possible effects, that may happen under neutron irradiation based on the species produced (T and He) in the nuclear reactions (n, T) and (n, α) with 6Li and 7Li, with the Li atoms in the reacted layer To do that, the atomic density of produced T and He per second out of the transmutation reaction and the He/T ratio are calculated for diverse Li contents. Subsequently, we implant He into the coatings and characterize the desorption rate and the morphology. Finally, discussion and recommendations for further coating development will be presented.

Insight into the influence mechanism of chloride ions towards in-situ electric-induced uranium incorporation into magnetite

The application of electrochemical methods for incorporating uranium into the magnetite lattice has demonstrated efficacy and durability in remediating radioactive contamination. However, the impact of different ions, particularly electrolyte ions, on this process remains unclear. Herein, we successfully achieved simultaneous magnetite crystallization and uranium incorporation within an electrochemical system using an iron anode. Chloride ions have been identified as having a pivotal role in the generation of ferrous ions via pitting corrosion, thereby establishing an advantageous reducing environment that promotes the transformation of γ-FeOOH to magnetite. Unlike the surface adsorption process of γ-FeOOH, magnetite predominantly eradicates uranium through an incorporation mechanism. Consequently, the existence of chloride ions markedly boosts the effectiveness of uranium elimination and the stability of the resultant substance. Specifically, under conditions of a pH of 5 and a chloride ions concentration of 18 mM, uranium removal reaches nearly 100%. Additionally, findings from uranium leaching experiments indicate that γ-FeOOH removed 25.4% stable, 63.57% metastable, and 11.03% unstable uranium, while magnetite removed 60.35% stable, 24.81% metastable, and 14.84% unstable uranium. This research offers insight into the potential role of electrolyte ions in facilitating in-situ electric-induced uranium incorporation.

Polyamidoxime and graphene oxide synergistically stabilized foam decontaminant for removal of radioactive surface contaminants

Polyamidoxime and graphene oxide synergistically stabilized foam decontaminant for removal of radioactive surface contaminants

Assessment of the Radioactivity, Metals Content and Mineralogy of Granodiorite from Calabria, Southern Italy: A Case Study.

In this paper, an assessment of the natural radioactivity level, radon exhalation, metal contamination, and mineralogy of a granodiorite rock sample from Stilo, in the Calabria region, Southern Italy is presented as a case study. This rock was employed as a building material in the area under study. The specific activity of 226Ra, 232Th and 40K natural radioisotopes was assessed through high-purity germanium (HPGe) gamma-ray spectrometry. Then, several indices such as the absorbed gamma dose rate (D), the annual effective dose equivalent (AEDE), the activity concentration index (ACI) and the alpha index (Iα), were quantified to determine any potential radiological health risk related to radiation exposure from the analyzed rock. Furthermore, E-PERM electret ion chambers and inductively coupled plasma mass spectrometry (ICP-MS) measurements were carried out to properly quantify the radon exhalation rate and any possible metal pollution, respectively. In particular, to further address metal pollution factors, the geo-accumulation index (Igeo) was calculated to properly address the toxicity levels of the ecosystem originating from the detected metals. Finally, with the aim of successfully discriminating the provenance of such naturally occurring radionuclides, a combined approach involving X-ray diffraction (XRD) and µ-Raman spectroscopy was employed for the identification of the main radioisotope-bearing minerals characterizing the investigated granodiorite. The results achieved in this case study can be taken as the basis for further inquiries into background levels of radioactivity and chemical contamination in natural stone employed as building materials.

Radioactive elements in wastewater and potable water: Sources, effects, and methods of analysis and removal.

Radioactive effluents, originating from nuclear power plants, medical-nuclear applications, and various extraction industries worldwide, present a significant and dangerous contamination challenge. The concentrations of radioactive substances in wastewater, surface water, and potable water vary widely depending on the source and location. For example, cesium-137 levels in wastewater from nuclear facilities can range from 0.1 to 10 Bq/L, while tritium concentrations in surface water near nuclear plants can reach up to 100 Bq/L. Regulatory guidelines, like the maximum contaminant level of 0.185 Bq/L for combined radium-226 and radium-228 in drinking water, are critical for ensuring safety and environmental protection. Specifically, in Fukushima, Japan, cesium-137 levels in surface water range from 0.1 to 10 Bq/L due to the nuclear accident. In contrast, regions with natural uranium deposits, like parts of the United States, have reported radium-226 concentrations in potable water up to 1 Bq/L. These variations highlight the necessity for focused monitoring and evaluation to protect water quality and community health. Among various methods, Gamma spectrometry and inductively coupled plasma mass spectrometry are precise for radionuclide quantification, scintillation detectors, and ion exchange, and adsorption techniques efficiently remove radioactive substances from water. This critical review examines the sources, adverse effects, and analysis and remediation strategies for various radioactive elements in wastewater. By thoroughly evaluating the origins and potential dangers associated with radioactive effluents, this report emphasizes the urgent need for rigorous monitoring and effective treatment practices to maintain the integrity of water resources and ecosystems. PRACTITIONER POINTS: Comprehensive analysis of the radioactive elements frequently found in wastewater and drinking water. Assess the negative effects of radioactive elements in water systems. Examine the treatment methods used to eliminate radioactive pollutants from water sources. Outline effective methods and tactics for addressing and controlling radioactive contamination occurrences. Analyze the latest advancements in technology, regulatory enhancements, and optimal methods to guarantee the safety of drinking water and the sustainable handling of radioactive substances in wastewater.

Comparison between the Baltic Sea and Irish Sea level of Cs-137 contamination on benthic, demersal and pelagic fish species

The Irish Sea and the Baltic Sea are nowadays still the two most Cs-137 contaminated Seas worldwide. However, the origins of this contaminations are completely different. While the Baltic Sea was unintentionally contaminated due to global fallout after the accident in the Chernobyl nuclear powerplant in 1986, the Irish sea was intentionally used for low level liquid radioactive waste discharges from the Sellafield nuclear reprocessing facility (called Windscale until 1981) between the 1950s and 1990s. Nowadays, more than 30 years later, it is still possible to detect these contaminations in fish, water and sediments of both seas. Since fish are an important part of the human diet, monitoring Cs-137 levels in fish is essential for assessing the potential radiation exposure to humans. In 2019 and 2020 two surveys were dedicated to study the current levels of radioactive contamination in fish species from both Seas. During both surveys, fish samples were collected and analysed by gamma spectrometry later on. The results show that the average Cs-137 activity in benthic, demersal and pelagic fish species from the Baltic Sea are 2.7, 4.6 and 4.2, respectively, times higher than the corresponding values of the Irish Sea. Based on this and two other comparisons, it is concluded that the Baltic Sea is the most contaminated with Cs-137.

ANALYSIS OF THE DESTRUCTION OF UKRAINIAN NUCLEAR FUEL CYCLE ENERGY FACILITIES AS A RESULT OF RUSSIAN MILITARY OPERATIONS

Problem statement. Due to Russia's ongoing terrorist attacks on Ukraine's energy facilities, the energy system was damaged, resulting in blackouts and rolling blackouts across the country. The destruction of power capacities resulted in the unstable operation of certain critical infrastructure units for electricity generation at thermal, nuclear and hydroelectric power plants and the introduction of forced hourly blackout schedules. Seizure of the Chornobyl Nuclear Power Plant, occupation and full control of the Zaporizhzhia Nuclear Power Plant and the Zaporizhzhia Thermal Power Plant (TPP). Complete destruction of the Kakhovka hydroelectric power station (HPP), partial destruction of the Dnipro HPP, Dniester HPP and Kaniv HPP. During the hostilities, Kryvyi Rih and Prydniprovia TPPs were damaged, Luhansk TPP (90–100 %), Vuhlehirsk TPP (90–100 %), Zmiiv TPP (up to 90 %) were completely destroyed, Burshtyn TPP (80–90 %) and Ladyzhyn TPP (70–95 %) were almost completely destroyed. The purpose of the article is to identify and analyse the damage to Ukrainian TPPs, HPPs and NPPs caused by the Russian military actions against Ukraine and to determine possible consequences for the nuclear fuel cycle of our country and possible prospects for the transition to new nuclear reactors of European and global fuel cell manufacturers, to improve equipment and stabilise the energy market in the context of military operations. Conclusion. In the course of the analysis of potential hazards at radiation hazardous facilities (RHF) in Ukraine, it was determined that the main threat is accidents at RHF with release of radiation into the atmosphere, lithosphere and hydrosphere. In the light of recent events regarding the military seizure of the Chornobyl NPP and Zaporizhzhya NPP, measurements using standard methods of research, screening and monitoring are not possible, and access of IAEA representatives is limited, which is why the latest measurement methods should be used with the use of autonomous remote-controlled ground, surface and air drones in automatic object or sample measurement of radiation parameters at RNS. It is the use of autonomous vehicles (drones) that is currently the most pressing issue of radiation safety not only in the nuclear power industry but also in the entire nuclear fuel cycle as part of the environmental safety of Ukraine. In case of seizure of a nuclear facility or limited access to it, research methods should be changed. If the facility is partially seized or access is available, then express methods of radiation contamination registration or sampling can be used and the method of laboratory research can be used in the future. However, if a nuclear power plant or a facility that is part of the nuclear fuel cycle of Ukraine is captured and access to it is impossible, then only methods of remote measurement of the radiation situation at and around nuclear facilities using ground and airborne autonomous vehicles remain. For further research, it is necessary to identify technical possibilities for using Ukraine's own mineral resources and switching from Soviet RBMK-1000, VVER-440 and VVER-1000 reactors with fuel elements supplied to us from the Russian Federation to newer types of European and American reactors with appropriate fuel elements.

Multilateral evaluation of the effects of utilizing thorium oxide in the Bushehr VVER-1000 reactor

Abstract The use of thorium oxide in thermal reactors is currently being explored due to its promising outcomes. One primary concern is how to reduce the pollution of core components and nuclear waste. The inclusion of 232Th in the reactor leads to the production of 233U and decreases the formation of minor actinides. On the other hand, 238U increases the production of 239Pu, a toxic and strategically significant isotope, along with minor actinides. Therefore, the potential of thorium to reduce the production of 239Pu, one of the most harmful isotopes, can be assessed in the Bushehr VVER-1000 reactor. This study involved replacing some uranium in the Bushehr VVER-1000 reactor with 232Th. The research focused on examining the environmental impact of nuclear waste, including activity, chain reactions, and isotope levels, over a two-year period. The impact of the new fuel substitution was evaluated in the Bushehr reactor, which has a power of 3,000 MWth, in three scenarios: thorium addition to 1.6 % enriched assemblies, thorium addition to 2.4 % enriched assemblies, and thorium addition to 3.6 % enriched assemblies. These changes were analyzed in terms of nuclear waste contamination, plutonium production, fuel burn-up, and conversion ratio, and compared to the reactor using UO2 fuel. The simulation was conducted using the MCNPX 2.6.0 computational code and heterogeneous geometry. The results indicate that nuclear waste pollution decreased when thorium was added to the 1.6 % and 2.4 % enriched assemblies, but increased when added to the 3.6 % assemblies. Additionally, fuel burn-up increased with the addition of thorium in the 1.6 % and 2.4 % assemblies, but decreased in the 3.6 % assemblies. However, the conversion ratio increased in all cases. The fuel temperature coefficient (FTC), moderator temperature coefficient (MTC), and void coefficient (VC) were calculated and evaluated.

Quality and safety of products using GM soybeans in the diet of bulls

The production of high-quality and safe food products in areas contaminated by radiation due to the Chornobyl Nuclear Power Plant accident remains a pressing issue. The aim of this study was to determine the concentration and transfer factors of 137Cs, Pb, Cd, Cu, and Zn in bull products when including various high-protein feeds, such as narrow-leaved lupin and genetically modified soybean, in their diets. The study employed zootechnical methods (design and conduct of a scientific-economic experiment on animals), radiological and spectrometric methods (determination of the concentration of 137Cs, Pb, Cd, Cu, and Zn in feeds, longissimus dorsi muscle, liver, kidneys, and testes of bulls), and statistical methods. It was established that when using GM soybean in the grain mixture, the concentration of 137Cs in the muscle tissue of animals in Group II (experimental) decreased relative to the control by 2.57 Bq/kg, or by 40.5% with a statistically significant difference between groups (P > 0.99). Furthermore, the transfer factor of the radionuclide into the muscle tissue of animals in Group II compared to Group I also had 2.15% abs. lower. The content of Pb in the muscle tissue of bulls in both experimental groups exceeded the maximum permissible concentration by 2.52-2.78 times, while the concentration of Cd in the longissimus dorsi muscle and Cu in the liver of animals in Group II also exceeded sanitary-hygienic requirements by 10.0% and 2.0%, respectively. The introduction of 40% (by mass) of maize grain and 30% of GM soybean into the grain mixture instead of the same amount of wheat and lupin chop during the fattening of animals in the third zone of radioactive contamination contributed to significantly higher content and transfer of heavy metals into muscle tissue: Pb – by 10.3% and 0.10% abs., Cd – 10.0 and 0.03, Cu – 17.2 and 0.53, and Zn – by 17.2% and 2.40% abs. The results of the research can be used in agricultural enterprises and private households that produce livestock products in areas with a high anthropogenic load

Thorium Cluster Synthesized by a Solvent-Free Flux Approach: The Richest Coordination Diversity and Application Exploration.

The renaissance of research interests in actinide oxo clusters in the past decade arises from both the concerns of radioactive contamination and their potential utility as nanoscale materials. Compared to the uranium cluster, the thorium (Th) cluster shows less coordination variation. Herein, we presented a unique Th cluster (ThC-1) that exhibits the most diverse coordination chemistry found within a single Th cluster via a solvent-free flux synthesis approach. The melt triazole not only offers a unique solvation environment that may be responsible for the coordination diversity in ThC-1 but also represents the first nitrogen-donor capping ligand in Th clusters. The potential utility of ThC-1 as a heterogeneous catalyst was also explored for a classical CO2 cycloaddition reaction. This work offers a novel approach in synthesizing Th clusters, broadening the realm of the structural diversity of Th.

Characterization of typical transuranic nuclides in a reference fallout material using SF-ICP-MS

For the quality control in determining transuranic nuclides in fallout samples, this work first reported the 237Np activity concentration in a reference fallout material and further calculated the activity ratios of 237Np/239+240Pu and 237Np/241Am, and the atom ratio of 237Np/239Pu in it. The reference fallout material prepared by the Meteorological Research Institute was collected at 14 stations throughout Japan in 1963–1979. The 237Np and Pu isotopes (239Pu and 240Pu) were separated and purified using AG MP-1M anion-exchange resin, quantified using 242Pu as an isotope dilution tracer, and determined by the SF-ICP-MS. The analytical method was validated by the analysis of 4 sediment reference materials. The activity concentrations of 237Np, 239Pu and 240Pu were (25.9 ± 0.6) × 10−3, 4.10 ± 0.01 and 2.89 ± 0.04 Bq/kg, respectively, in the investigated reference fallout material. The activity ratio of 237Np/239+240Pu (3.7 ± 0.1) × 10−3 was consistent with the global fallout evaluation value. The 237Np/239Pu atom ratio of 0.561 ± 0.014 was higher than the average global fallout value of 0.41 ± 0.010, indicating the necessity of establishing regional characteristic global fallout value of 237Np/239Pu atom ratio for assessment of radioactive contamination. Comparison of the 237Np/239+240Pu activity ratios between in the reference fallout material and in soils over several decades indicated that 237Np has stronger migration capability than Pu isotopes in soils because 237Np was depleted compared to reference fallout material.

N/O-Codoped Ultrathin Porous Biochar Derived from Casein for Fast Adsorption of Iodine.

The release of radioactive iodine into the environment poses a significant threat, as it can contaminate soil, water, and food chains, leading to detrimental effects on ecosystems and biodiversity. Hence, employing the adsorption method proves to be a simple yet effective approach for treating radioactive waste. N/O-codoped ultrathin porous biochar, synthesized from casein using NaHCO3 activation, emerges as a potential candidate for adsorption materials. The saturation level of I2 adsorption in 100 mg L-1 iodine-cyclohexane solution is 73 mg·g-1 at 20 min. The density functional theory (DFT) calculations and experiments attribute this phenomenon to the presence of graphite nitrogen (NG) and C-OH groups on the biochar surface. Furthermore, the pseudo-first-order model fits better with the experimental values, suggesting that the adsorption of iodine by the adsorbent is primarily physisorption-based. The Freundlich isotherm is suitable for iodine adsorption of biochar, owing to the abundance of adsorption sites within the porous structure, particularly at the edges, which enhance the adsorption activity. Significantly, the study highlights that NG adsorptive sites exhibit 1.5 times higher adsorption activity compared to C-OH adsorptive sites, underscoring the essential role of NG in iodine adsorption for electron transfer. Overall, these findings underscore the potential of N/O-codoped ultrathin porous biochar in effectively mitigating the presence of radioactive I2, showcasing its promise in addressing environmental challenges associated with radioactive contamination.

Distribution coefficient prediction using multimodal machine learning based on soil adsorption factors, XRF, and XRD spectrum data

The distribution coefficient (Kd) plays a crucial role in predicting the migration behavior of radionuclides in the soil environment. However, Kd depends on the complexities of geological and environmental factors, and existing models often do not reflect the unique soil properties. We propose a multimodal technique to predict Kd values for radionuclide adsorption in soils surrounding nuclear facilities in Republic of Korea. We integrated and trained three sub-networks reflecting different data domains: soil adsorption factors for physicochemical conditions, X-ray fluorescence (XRF) data, and X-ray diffraction (XRD) spectra for inherent soil properties. Our multimodal model achieved high performance, with a coefficient of determination (R2) of 0.84 and root mean squared error (RMSE) of 0.89 for natural log-transformed Kd. This is the first study to develop a multimodal model that simultaneously incorporates inherent soil properties and adsorption factors to predict Kd. We investigated influential peaks in XRD spectra and also revealed that pH and calcium oxide (CaO) were significant variables in soil adsorption factors and XRF data, respectively. These results promote the use of a multimodal model to predict Kd values by integrating data from different domains, providing a cost-effective and novel approach to elucidate the mechanisms of radionuclide adsorption in soil.

Proposal of database of radiological characterization for decommissioning nuclear power plants

AbstractIn Korea, Kori Unit 1 was permanently closed in 2017 and scheduled for decommissioning. Kori Unit 1 is currently scheduled to undergo system decontamination and to be decommissioned by December 2038. Measures to properly control and remove radiological hazards must be established to go through decommissioning a nuclear power plant (NPP). Radiological characterization must precede NPP decommissioning. Radiological characterization generates a lot of data during this process. The consistency of radiological characterization data is important for systematically decommissioning NPPs. However, the data generated from radiological characterization may not be systematically managed because a database of radiological characterizations for Kori Unit 1 has not been properly established. Therefore, this study has proposed a database to be filled during radiological characterization in terms of occupational radiation exposure of personnel and decommissioning waste safety using key performance indicators presented by the International Atomic Energy Agency. From the perspective of occupational exposure, databases have been proposed for operational history investigations, decommissioning source term calculations, and investigation of the level of radiological contamination. From the perspective of the safety of decommissioning waste, databases were proposed for operational history investigation, decommissioning source term calculation, investigation of the level of radiological contamination, and investigation of radiological characteristics of decommissioning waste.

Technologies for retrospective radiation dosimetry.

Radiation dosimetry is an important task for assessing the biological damages created in human being due to ionising radiation exposure. Ionising radiation being invisible and beyond the perception of human natural sensors, the dosimetry equipments/systems are the utmost requirement for its measurement. Retrospective measurement of radiation doses is a challenging task as conventional radiation dosemeters are not available at the exposure site. The material/s in close proximity of exposed individual or individuals' biological samples may be used as retrospective radiation sensor for dosimetry purpose. Environment materials such as sand, bricks, ceramics, sand stones, quartz, feldspar, glasses and electronic chips have been utilised using TL (Thermoluminescence) techniques for retrospective gamma dose (min 10cGy) measurement. Electron Spin Resonance techniques have been employed to human biological samples such as tooth enamel, bones, nails, hair, etc. and reported for dosimetry for ~20cGymin dose measurement. Some commercial glasses have been found sensitive enough to measure the minimum gamma doses of the order of 100cGy using TL techniques. For internal retrospective dosimetry, the radioactivity contamination assessment in food items, water, other edible product and ambient air are the prerequisites. The radioactivity concentration vis-à-vis their consumption rate may help in controlling the internal contamination and estimation of dose absorption in human body. Defence Laboratory, Jodhpur has been working extensively on the dosimetry techniques for external dose measurement using environmental material and developed portable contamination monitoring systems for food and water radioactivity measurement in the range of 50Bq kg-1 to 1000kBq kg-1 in 60s measurement time. The recent research and development in the methodologies, equipments and systems undertaken towards capacity building and self-reliance in retrospective radiation dosimetry is reported in this paper.

C─H Activation Enables the Construction of New Bis-Polyaryl Phenylpyridine Ruthenium Complexes: Conjugation and Rigidity Synergistic Effect for Advanced Electrochemiluminescence.

The access to bench-stable organometallic compounds unfolds new chemical space for medicinal and material sciences. In particular, stable organoruthenium compounds with constitutional and stereoisomeric forms for subtle regulation of electrochemiluminescence are intriguing and challenging. Here, coordination of polycyclic aromatic hydrocarbons on (2-phenylpyridine)2(CO)2Ru complex allows access to bis-polyaryl phenylpyridine (BPP) Ruthenium complex through C─H activation strategy and coupling reactions for installation of the functionalities with steric and electronic purposes. The photoluminescence and electrochemiluminescence of BPP Ru complexes are affected by the actual polycyclic aromatic hydrocarbons inherent properties. The anthracene derivatized BPP Ru complex (BPP-Ant) shows the best ECL performance and reveals an enormous ECL quantum efficiency of 1.6-fold higher than the golden standard Ru(bpy)3 2+. The unprecedentedly high efficiency is due to the best compromise between the structural conjugation and molecular rigidity from BPP-Ant providing a providential energy gap that facilitated the feasibility of electron transfer and favored the radiative energy release by experimentally and DFT calculations. Moreover, PL and spooling ECL spectroscopies are used to track and link multiple emission peaks of BPP-Ant at 445, 645, and 845nm to different emissive species. These discoveries will add a new member to the efficient ECL ruthenium complex family and bring more potentials.

Modeling Fallout from Nuclear Weapon Detonations: Efficient Activity and Dose Calculation of Radionuclides and Their Progeny.

The purpose of this paper is to present a practical method for quick determination of potential radiological doses and contaminations by fallout from nuclear detonations, or other releases, that includes the contributions from all nuclides. We precalculate individual (total) activities of all radionuclides from any initial cocktail and all their ingrowing progeny at a set of pinpoints in time with a logarithmic time-spacing. This is combined with the set of dose conversion factors (DCC) for any exposure pathway to obtain a time-dependent cocktail for the whole release as if it is one substance. An atmospheric dispersion model then provides the thinning coefficient of the released material to give local concentrations and dose rates. Progeny ingrowth is illustrated for pure 238 U and for a nuclear reactor that has been shut down. Efficient dose assessment is demonstrated for fallout from nuclear detonations and compared with the traditional approach of preselecting nuclides for specific endpoints and periods-of-interest. The compound cocktail DCC reduces the assessment of contaminations and potential dose-effects from fallout after a nuclear detonation to (the atmospheric dispersion of) only one tracer substance, representing any cocktail of nuclides and their progeny. This removes the need to follow all separate nuclides or an endpoint-specific preselection of "most important nuclides." As the cocktail DCCs can be precalculated and the atmospheric dispersion of only one tracer substance has to be modelled, our method is fast. The model for calculating cocktail DCCs is freely available, easily coupled to any regular atmospheric dispersion model, and therefore ready for operational use by others.

МИГРАЦИИОННАЯ АКТИВНОСТЬ 137CS В АГРОПРОДУКЦИЮ БИОГЕОЦЕНОЗОВ КРАСНОЯРСКОГО КРАЯ

The purpose of the study is to determine the intensity of 137Cs movement along the trophic chain “soil – diet – livestock products” in the agricultural landscapes of the Krasnoyarsk Region with additional radiation load. A literature review of scientific data characterizing the features of the migration activity of 137Cs in the links “soil – feed – livestock products” in agrobiocenoses with radioactive contamination above established standards is given. Based on the results of a radioecological survey of agricultural landscapes in the central regions of the Krasnoyarsk Region and calculation of absorbed doses, the author identified agricultural landscapes with additional technogenic pollution and determined the specific activity of 137Cs in feed and cow's milk in agricultural landscapes with additional technogenic load. The specific activity values of 137Cs in agricultural landscape feeds with doses of 1.33 and 1.55 mGy/year are higher than the background va¬lue for the Krasnoyarsk Region. The content of 137Cs in livestock products produced in farm biogeocenoses with additional technogenic load is higher than the average for the region, but does not exceed the criterion of regulatory documents; accordingly, radiation-safe agricultural products are produced on the territory of the Krasnoyarsk Region. For agricultural landscapes with absorbed doses of 1.33 and 1.55 mGy/year, a KP for the link “feed – livestock products” has been established. When the radioecological situation changes, the established Kp values can be used to predict the migration of 137Cs in the chain “soil – feed – livestock products”. A direct linear moderate Spearman rank correlation was identified between the specific activity of 137Cs in feed and the concentration of 137Cs in cow's milk. Linear regression equations have been determined to determine the specific activity of cow's milk based on data on the specific activity of 137Cs in feed. The revealed direct linear relationship indicates that even a slight increase in the 137Cs activity of the diet leads to an equivalent increase in the specific activity of technogenic cesium in cow's milk.