Radioactive Waste Materials Research Articles

Радиологическая безопасность населения и персонала при двухкомпонентной ядерной энергетике

The Fundamentals of State Policy in the Field of Nuclear and Radiation Safety of the Russian Federation, approved by the President of the Russian Federation, indicate that the goal of state policy in this area is to ensure the protection of the population, considering modern requirements. The IAEA Fundamental Safety Principles emphasize the need to protect both current and future generations from radiation risks. The achievement of these safety goals is ensured by the development in Russia of new nuclear energy system based on a closed nuclear fuel cycle (CNFC) and fast neutron reactors (FNR). One of the objects of the new nuclear energy system is the Experimental Demonstration Energy Complex (EDEC) consisting of the BREST-OD-300 FNR, a reprocessing module and a fuel fabrication/refabrication module, located on the territory of JSC «SHK» in the Tomsk region. This article provides assessments of radiation carcinogenic risks for the population living in the 30-km zone of JSC «SHK» under normal operating conditions and for workers after potential emergency situations at EDEC facilities. The conditions for ensuring the protection of future generations of people are also justified. Radiation risk assessments are obtained directly from the dynamics of equivalent doses in human organs and tissues and modern risk models recommended by ICRP Publication 103. The predicted values of the risks of radiation carcinogenesis for the population and personnel are significantly lower than the current limits of NRB-99/2009 for both normal operation and potential exposure during accidents. It has been shown that transmutation of minor actinides during the development of CNFC based on FNR ensures the safety of future generations of people: it reduces the carcinogenic risk of americium by 213 times, neptunium by 101 times, and curium by 47 times. The effect of radiological equivalence of radioactive waste and natural uranium raw materials is achieved after 99 years of radioactive waste storage. Thus, the priority direction for the development of new nuclear power is the energy sector of the CNFC based on the FNR.

Glass-Containing Matrices Based on Borosilicate Glasses for the Immobilization of Radioactive Wastes

Glass-containing materials are widely considered among the most reliable materials for the immobilization of radioactive waste materials. The present work considers the synthesis of glass–ceramic and glass crystalline composite materials based on borosilicate glasses. The synthesis of glass–ceramic materials was carried out by a gradual temperature decrease, followed by crystallization for several hours. Sintering of crushed samples with crystalline components was carried out as an alternative procedure. Porous glasses were produced from glass melts by quenching. After impregnating the resulting porous materials with aqueous solutions of cesium nitrate, compaction of the glass was carried out to form glass crystalline composites. The thermochemical characteristics of the parent glasses were determined using the differential scanning calorimetry method. The phase composition and structure of the glass-containing materials were determined using X-ray phase analysis, X-ray spectral microanalysis, and Raman spectroscopy.

Diffusion of HTO, 36Cl and 22Na in the Mesozoic rocks of Northern Switzerland: III. Cross-lab comparison of diffusion measurements on argillaceous twin samples

In the past decades, there has been a high interest in evaluations of argillaceous rock formations to host repositories for spent fuel or radioactive waste material. One of the main reasons for this interest is that argillaceous rocks are dominated by clay minerals, resulting in a fine-grained sediment matrix with micropores, low pore connectivity and thus low permeability, and good self-sealing properties. This entails that diffusion is the prime mechanism for transport of gas, fission products and radionuclides in clay-rich rocks. The determination of diffusion parameters is therefore key to evaluate the quality of the rock from long-term safety perspectives. Cross-lab comparison of diffusion data is however often challenging as various methods, concepts and models are utilised in the different laboratories across the globe. Here, a direct cross-lab comparison study of through-diffusion experiments was performed to compare and assess the effect of experimental method (through-diffusion) and modelling uncertainties of the parameters by comparing results obtained by two independent laboratories. The R&D group ‘Disposal’ at SCK CEN (Belgium) and the PSI-LES group (Switzerland) both performed through-diffusion experiments on (nearly) the same sample material using their in-house experimental and modelling methodologies for through-diffusion experiments. Adjacent (twin) samples at five depths between 870 and 940 m in the Trüllikon1-1 borehole (Switzerland) were selected and each lab subjected these five clay rock samples to diffusion in synthetic pore water with three different tracers, HTO, 36Cl− and 22Na+, representative for neutral, anionic and cationic transport behaviour. The two labs used a similar design of diffusion cell and worked with similar experimental conditions, but there were small differences in the experimental set-up/conditions and in the modelling approach. The independently determined diffusion parameters from SCK CEN and PSI-LES for all three tracers confirmed previously observed uncertainties. For all three radionuclides, the variability of the effective diffusion coefficients estimated independently by both institutes was less than a factor 2 and in general much lower (deviations ranging between 0 and 73%). Besides, the parameter estimations of the capacity factor (or accessible porosity in case of HTO and 36Cl−) agreed well. Moreover, the experimental datasets of HTO and 36Cl− were also cross-fitted. The evaluation revealed that the minor deviations can be attributed predominantly to variations in temperature (experimental conditions) and to a lesser extent to minor distinctions in the modelling approach. It is important to acknowledge that local heterogeneity might also contribute to these differences.

Development of mechanistic models for the description of radionuclide retention onto calcareous gravels

The retention capacity of natural calcareous gravels used as a filling material between the packages containing radioactive waste materials in the disposal cells was evaluated for Sr, U, Ni, Ag, 14C, 99Tc, 239Pu, 228Th and 152Eu. The thermodynamic calculations performed considering repository conditions indicated that the chemistry of most of these elements was dominated by neutral or cationic species, this is the case of 238Pu 152Eu, 228Th, Ni and Ag. The studied gravels presented high sorption capacities for these cationic or neutral species, but they are not efficient on retaining anionic species as in the case of 99Tc or Sr, which is already present in the composition of the studied gravels. For those elements where the predominant species are carbonated (14C and U) low distribution coefficients were obtained. A preliminary mechanistic sorption model was developed for each radionuclide considering carbonate (>CO3H) and calcium hydroxide (>CaOH) sites. Our preliminary model allowed to successfully reproduce the experimental trend of the data obtained in this work.

Significance of induced magnetic field and thermal radiation: Dynamics of Newtonian fluids subject to viscous dissipation due to temperature gradient

This work is focused on Magneto hydrodynamic unsteady flow of Newtonian fluid flow over a perpendicular porous plate along with chemical reaction, heat, and mass transfer. The induced magnetic field and viscous and magnetic dissipation properties are considered throughout the porous plate. Heat source is the added effect in the model to observe the nature of flow in this work. This study finds its applications in understanding the storage of flues, disposal of radioactive waste materials, flow in water purifies, etc. The nonlinear behavior of the governing equation motivates us to use a finite difference approach for solving equations. The major resolution of this research is to work on how the physical elements affect velocity, temperature, concentration, and magnetic field. Fascinating facts are noticed as the unsteady fluid velocity rises with the heat source parameter because as the heat of a material increases, the movement of the fluid particle will be fast. Due to the presence of a magnetic field high thermal radiation is observed at high temperature and concentration. As the magnetic parameter and magnetic field are inversely proportional according to an induced magnetic field, it is noticed that their magnetic field declines for higher values of magnetic Prandtl number & magnetic parameter. This work has dynamic prominence in the field of medicine and engineering, which develops interest among young researchers.

Immobilization of radioactive waste material in concrete matrix–A study of leachability aspects

The biomass, Ganoderma Lucidum, is a naturally growing macro-fungus that grows in rubber plantations, and has been found to remove uranium from low level radioactive wastewaters. Subsequent to the sorption of uranium, the loaded biomass needs to be safely and scientifically disposed. This is done by first immobilizing the waste biomass material in a solid matrix such as concrete or resin, and then disposing it in deep sea or geological repositories after due enclosures for safety. Despite immobilization there remains a risk of leaching of radioactivity from the loaded biomass material. This requires to be verified by testing leachability in lab under varying pH conditions that mimic sea water and geological repository environments. Short terms desorption and leachability experiments were conducted at the materials lab at MANIT, Bhopal to determine the leachability of radioactivity from the concrete matrix enclosing the loaded biomass. It was found that leaching was rapid in acidic conditions (0.2 N HCl), with 27.2 % uranium leaching out within 8 days. This indicated the suitability of alkaline sea-waters for safer disposal of uranium laden immobilized biomass. Mathematical models were subsequently developed based on the laboratory data to predict the long-term leachability for assessing the safety of disposal mechanism, and indicated the prominence of diffusion as the leachability mechanism. This paper details the experiments conducted, the materials used, the lab observation results, and the mathematical models developed to determine safety aspects related to possible leaching from immobilized concrete matrix in which radioactive biomass has been loaded.

Justification of the economic and radiological advantages of a closed nuclear cycle with fast neutron reactors in view of IAEA radiation safety standards and equalization of carcinogenicity of the radioactive waste and natural uranium raw materials

Economic and radiological advantages of the closed nuclear fuel cycle with fast neutron reactors in view of radiological equivalence, i.e. the equalization of carcinogenicity of radioactive waste and the natural uranium ore materials are considered in the paper. Potential cancer risks of the spent nuclear fuel (SNF) from the WWER-1000 reactor and radioactive waste from the BR-1200 reactor generating 1 GW of electric power per year have been estimated. It is assumed that the SNF from WWER-1000 reactor will be sent to 10 or 30-year storage. In the closed nuclear fuel cycle radioactive wastes, the products of SNF reprocessing, consisting of 0.1% of Sr, Cs, Tc, I, U, Np, Pu, Am, Cm of their content in SNF and all other radionuclides are disposed. Over a period of 10,000 years, the total radiation detriment from SNF from the WWER-1000 reactor is more than 132 times higher than the radiation detriment from radioactive waste from the BR-1200 reactor. The time of radiological equivalence achievement was evaluated. It is assumed that if WWER-1000 and BR-1000 generate 1 GW of electricity per year, radiological equivalence of carcinogenicity of radioactive waste (BR-1200 reactor) and natural uranium ore material will be achieved in 100 years of radioactive waste storage. The equivalence of carcinogenicity of SNF storage and natural uranium ore materials will be achieved after 15,600 years storage. When disposing of spent fuel from a WWER-1000 reactor without achieving radiological equivalence, socio-economic losses due to excess mortality from cancer are estimated at 129 billion rubles/GW year.

Analysing the sustainability of renewable energy in France

In the study fifty seven years of time series data (1965 – 2021) was analysed to check the sustainability of renewable energy both in short run and long run using ARDL model as the data was stationary at the combination of I(0) and I(1). The results showed that CO2 emission negative relation with renewable energy. As CO2 emissions reduces with the increasing use of renewable energy. Renewable energy also has a very significant impact on agricultural as the electricity used for agricultural activity is more sustainable. The usage of renewable energy promotes green economy whereas, economic growth encourages environmental sustainability. However the waste and E-waste management needs to be promoted as nuclear energy has a highly radioactive waste materials which needs to be disposed properly as if it is leaked it will not only effect the country but also the neighbouring countries.

New Method for the Solidification of High-Concentration Radioactive Borate Solution by Cement-Based Materials

Cement is widely used for the solidification of low- and intermediate-level radioactive waste materials. Radioactive borate solution with a high concentration of boron is one of the main radioactive wastes produced in nuclear stations. It is difficult to solidify this solution by using cement because borate has a great inhibitory effect on the cement hydration process. In this study, the hydration kinetics, strength, durability, phase assemblage, and transportation and transformation of the silicon of the paste that blended Portland cement with 5 M borate solution were investigated. After the addition of sodium hydroxide and sodium metasilicate to the paste, the cement hydration process was restarted, and the 28-days strength of samples met the requirements of the Chinese standard. The mechanism of overcoming the retardation of cement hydration by the borate solution was attributed to the formation of calcium metaborate, ettringite, portlandite, and calcium silicate hydrate with the restarting of cement hydration, without the formation of ulexite.

RETRACTED: Sustainable utilization of red mud waste (bauxite residue) and slag for the production of geopolymer composites: A review

The production of cement results in the emission of much carbon dioxide, which contributes to ‎ ‎undesirable environmental impacts such as climate change and global warming. These ‎phenomena ‎have rekindled interest in utilizing a variety of industrial waste products to ‎produce geopolymer ‎‎(GP) composites and alkali-activated (AA) binders in order to reduce the ‎usage of ordinary ‎Portland cement in building construction. Waste red mud (RM), also known as bauxite residue, is one of these ‎hazardous radioactive ‎waste materials that is formed as a by-product of Bayer's aluminum ‎manufacturing process. This ‎paper conducts a systematic review of the literature on the use of ‎RM and slag in the production ‎of red mud-slag geopolymer (RM-SGP). An overview of the ‎economic and environmental ‎impacts, physical and chemical properties, production, ‎distribution, classification, and potential applications ‎of RM are presented. ‎Besides, recent advancements in the usage of RM and slag for geopolymer ‎production are ‎described in terms of physical, mechanical, durability, and microstructure ‎ properties. Moreover, this ‎study attempts to chart a route toward a realistic valorization that ‎reflects both real and perceived ‎concerns, such as radioactivity, leaching, and the life cycle ‎assessment of red mud geopolymer (RM-GP). The potential ‎use of RM-SGP production indicates the need for further studies into ‎the mixture proportion ‎and combination of these two raw ingredients with other cementitious materials ‎leading to new ‎energy-saving and affordable building products and processes. Also, it is ‎recommended that ‎research efforts be directed ‎toward economic, life cycle, and environmental ‎assessments.‎

Modelling of Radiological Health Risk in Water from Abstraction Well Close to a Hypothetical Radioactive Waste Repository in the Accra Plains

This study evaluated the integrity of the geosphere of the Accra Plains to host a radioactive waste disposal facility for Ghana’s radioactive waste materials. The study thus assessed the migration of radioactive contaminant from a hypothetical radioactive waste disposal facility through the geosphere to the biosphere in the Accra Plains. The Accra Plains is predominantly underlain by schist rocks, hence the hydrogeologic parameters of schist rock from literature were used as input data. AMBER software was used to develop a model to estimate the peak total annual effective dose from all the radionuclides at various receptor locations. The endpoint of interest was the dose received by a receptor for ingesting water from an abstraction well located at distance; 100 m, 200 m, 500 m, 1 km, 2 km, 3 km, 4 km and 5 km from the hypothetical repository. From the simulation, the annual effective dose values ranged from 2.07E-25 Sv/y to 6.45E-17 Sv/y which are all below the International Commission on Radiological Protection (ICRP) dose constraint of 0.3 mSv/y. The lifetime cancer risk for ingesting water from the abstraction wells were then calculated from the annual effective dose values. The resulting values ranged from 1.06E-24 to 3.30E-16 thus indicating that the potential cancer risk for ingesting water from the abstraction wells located within 100 m to 5 km from the hypothetical disposal facility is negligible. The model results demonstrate that, siting a disposal facility in the study area might not pose any significant risk to the sprawling population and the environment.

Novel thermometry approaches to facilitate safe and effective monitoring of nuclear material containers

Many established nuclear power producing countries are currently decommissioning first and increasingly second-generation power producing plants and fuel processing facilities. This has led to a growing inventory of different containers and packages containing radioactive waste and other nuclear materials, as well as storage of spent fuel. Here we describe research to establish in-situ yet remote health monitoring techniques based on novel temperature measurement methods for different containers and racks used to hold different nuclear waste forms, special nuclear materials and spent fuel.

Developing an Integrated Nuclear Waste Management Strategies on Aggregate Orphan Source Radioactive Materials in the Oil and Gas Sector.

Orphan sourced radioactive waste materials associated with oil and gas exploration, exploitation and production have been identified as causal factors in environmental health risks of operation personnel and the host communities in the Niger Delta. These Technologically Enhanced Radionuclides such as 14C, 40K, 87Rb, 232Th, 288U and some low frequency radioactive heavy metals constitute potential dangers to environmental health assay. Highly Sensitive Radiation Detection Tracers (HSRDT) were deployed for tracking and analysis of ionized leakages in the coastal marine offshore and shallow offshore areas in in a typical deltaic region. The inverse determination technique of the generalized half-life period was integrated into the model equations 1 – 12. Table 1 is a survey from 1992 t0 2015, showing that some identified radionuclides are reactive and contaminants to the surrounding environment from oil and gas processes. However, inadequate strategic decommissioning activities are responsible for severe occupational and environmental hazards to flora and fauna. This paper is fundamental to developing an integrated orphan waste management system as remedial techniques to minimize radiation waste burns and other harmful environmental effects on personnel and the environment. Its application is useful for decision-making on radioactive waste material management strategy. Furthermore, possible conceptual legal framework and standards for the disposal system of orphan sourced radionuclides in the petroleum sector could be explored. Keywords: Radioactive Waste Materials; Aggregate Orphan–Sourced Radionuclides; Environment Management; Waste Disposal Systems; Oil and Gas Sector etc.

Environmental behaviour of radioactive particles from chernobyl

Long-term environmental behaviour of radioactive particles released during the Chernobyl accident and deposited in sandy topsoil in Ivankiv district of Kyiv Region (Ukraine), in radioactive trench waste materials from the Red forest, and in bottom sediments from the Cooling pond has been assessed. The efficiency of the models describing the dissolution/weathering rates of U fuel particles developed 15–20 years ago was tested, and their predictions for the dynamics of remobilization, mobility and plants uptake of 90Sr were confirmed.It was found that at present in the topsoil and in radioactive trench waste material, total dissolution of fuel particles of low chemical stability (UO2+x) has occurred and about half of the non-oxidized chemically stable fuel particles (UO2) has also dissolved, indicating radiological stabilization of the environment and that the mobile fraction of radionuclides would be reduced in the future. The biological availability of 90Sr in topsoil due to fuel particles dissolution has reached maximum values and further decrease is expected.The presence of chemically extra-stable fuel particles (U-Zry-Ox) in environments should be taken into account when the total radionuclides activity concentrations are assessed during radioactive materials management.It was shown that nearly half of the 90Sr activity remained as part of the non-dissolved UO2 fuel particles at the time of the study. Taking into consideration that 31 ± 4% of the radionuclide activities were still associated with non-dissolved chemically extra-stable particles (U-Zry-Ox) in radioactive trench waste materials from the Red forest, increased dissolution should not be expected in the near future.The physico-chemical form of radionuclides in air exposed sediments from the Cooling pond were determined, and results showed that about 70–80% of total 90Sr, 241Am and plutonium isotopes activity were associated with U fuel particles. The low dissolution rate of radionuclides from the pond sediments is attributed to prolonged slightly alkaline pH in the medium due to zebra mussel residues.According to new data, the emission value of 238Pu associated with fuel particles released during the Chernobyl accident amounted to 1.8 × 1013Bq (1.2% of the activity in the reactor) and 90Sr amounted to 2.6 × 1015Bq (1.5% of the activity in the reactor).

HUMAN ADAPTATION TO RADIOACTIVE CONTAMINATION OF A TERRITORY

The aim was to study effects of radioactive contamination of a territory on human adaptive mechanisms with special emphasis on cardiovascular risk factors. The adaptive reactions of the human body as a result of long radiation exposure were studied by analyzing heart rate variability and blood pressure. Methods: A sample consisted of 944 residents of the Urals region. Of them, 223 lived in the Techa River basin, into which liquid radioactive waste materials were released, 587 lived in the zone of the East Ural Radioactive Trace (EURT), and 134 residents lived in a non-polluted area. Short electrocardiograms (100 R-R intervals) were recorded. Continuous data were analyzed using Scheffe test two-way analysis of variance. Proportions were analyzed using tests assuming binomial distribution. Results: Heart rate variability and blood pressure were chosen as indicators of adaptive reactions of the human body. Substantial proportion of the population living in radioactive contaminated areas is in the state of the stress, as expressed by the deviation from the normal values of SI (at 52.2 % of the sample), SDNN (at 58.1 % of the sample), and from the normal values of VBI (at 42.7 % of the sample). Mean values of SI among residents of the Techa River basin were significantly different from the corresponding values among study participants from other territories. Conclusions: We observed significant effect of radioactive pollution on the state of adaptation mechanisms of the Urals region population. It is shown that regulatory system is in stress at significant part of population living in radioactive contaminated territories.

The Properties and Latest Application of Geopolymers

With unique and favorable performances, geopolymer have attracted extensive attention in recent years. It combines some characteristics of organic polymers,cements and ceramics for its special poly-condensed network structure. This paper introduced the synthesis and performance of geopolymer, and mainly reviewed its application in recent years.We can see that the geopolymer has a great development future in many fields like civil engineering,innovative geopolymer binder, rapidly-repair and dealing with poisonous and radioactive waste material, geopolymer-type coatings, novel ceramic materials and so on. In addition, the existing problems and several suggestions according to personal researches are put forward.

A new analysis workflow for discrimination of nuclear grade graphite using laser-induced breakdown spectroscopy

Stand-off, in-situ, laser induced breakdown spectroscopy (LIBS) offers a rapid, safe, and cost-effective method for discrimination of radioactive waste materials arising during the operation of nuclear plants and from decommissioning activities. Characterisation of waste materials is a critical activity in understanding the nature of the waste, ensuring hazardous material is managed safely and that waste can be segregated for reuse, recycle or sentenced for appropriate disposal. Characterisation of materials, often in hostile environments, requires the ability to remotely differentiate between materials in terms of their chemical composition and radioactivity.This proposition was tested using a case study on nuclear grade graphite. Graphite has been used extensively as a moderator material in many nuclear reactors. Internationally, over 250,000 tons of various nuclear-grade graphite, and graphite-bearing, materials exist. These are a major issue for nuclear decommissioning and radioactive waste management, due to the long half-lives of the associated 14C and 36Cl isotopes. LIBS offers a method for discrimination of nuclear grade graphites and other carbon and non-carbon-bearing wastes. This paper describes the development of a workflow method, including LIBS measurement analysis, for the discrimination of pre-irradiated nuclear ‘Pile Grade A’ (PGA) graphite moderator rod and domestic lumpwood charcoal, which act as surrogates for nuclear grade graphite and other carbon-bearing wastes. A new analysis workflow comprising the examination of spectral characteristics, multivariate analysis and molecular isotopic spectroscopy is proposed to enable rapid segregation of graphite from a heterogeneous waste stream. Enhanced characterisation techniques have the potential to significantly reduce the cost of decommissioning large parts of legacy nuclear generation plants.

Numerical Study of Mixed Convection in a Channel Filled with a Porous Medium

The heat transfer of mixed convection in a horizontal channel filled with a porous medium has been studied in this article, given that it plays an extensive role in various technical applications, such as flow of fluid in geothermal resources, formations in chemical industries, the storage of radioactive nuclear waste material, and cooling. Those equations written in a dimensionless form have been solved using the finite difference method for different values of the parameters. The results obtained from the study have been presented through streamlines, isotherms, and both local and average Nusselt numbers. It has been observed that parameters such as the Rayleigh and Peclet numbers have an effect on flow and temperature fields.

Overview of CAST project

ABSTRACTThe European Commission CAST project (CArbon-14 Source Term) aimed to develop understanding of the potential release mechanisms of carbon-14 (radiocarbon, 14C) from radioactive waste materials under conditions relevant to waste packaging and disposal to underground geological disposal facilities. The project focused on the release of carbon-14 as dissolved and gaseous species from irradiated metals (steels, Zircaloys), from spent ion-exchange materials and from irradiated graphites. This paper provides an overview of the CAST project and its output. It also acts as an introduction and scene-setter to the other papers in this special edition of Radiocarbon.

Comparison of solvent extraction and extraction chromatography resin techniques for uranium isotopic characterization in high-level radioactive waste and barrier materials

The development of Deep Geological Repositories (DGP) to the storage of high-level radioactive waste (HLRW) is mainly focused in systems of multiple barriers based on the use of clays, and particularly bentonites, as natural and engineered barriers in nuclear waste isolation due to their remarkable properties.Due to the fact that uranium is the major component of HLRW, it is required to go in depth in the analysis of the chemistry of the reaction of this element within bentonites. The determination of uranium under the conditions of HLRW, including the analysis of silicate matrices before and after the uranium-bentonite reaction, was investigated. The performances of a state-of-the-art and widespread radiochemical method based on chromatographic UTEVA resins, and a well-known and traditional method based on solvent extraction with tri-n-butyl phosphate (TBP), for the analysis of uranium and thorium isotopes in solid matrices with high concentrations of uranium were analysed in detail.In the development of this comparison, both radiochemical approaches have an overall excellent performance in order to analyse uranium concentration in HLRW samples. However, due to the high uranium concentration in the samples, the chromatographic resin is not able to avoid completely the uranium contamination in the thorium fraction.