Uranium Waste Research Articles

Uranium Mill Tailings Generation and Management Challenges

Uranium mining has been ongoing for the past 200 years, yet managing uranium waste remains a significant challenge. This difficulty arises due to strict regulations imposed on uranium-related industries, driven by the assumed health risks associated with radiation. As a result, much of the waste generated by nuclear industries is currently stored. In India, uranium mining and milling waste is stored that require large tracts of land and continuous monitoring. Given the high value of land in India and the potential expansion of uranium mining to meet net-zero emission targets, an effective solution for managing uranium mill tailings is urgently needed. Meanwhile, India's construction sector is rapidly growing that require a huge quantity of materials. This paper reviewed the history of uranium mining and mill tailings generation and propose that the construction industry could effectively utilize these tailings. This approach not only addresses resource scarcity but also promotes environmental sustainability by conserving natural resources, reducing ecological imbalances, and advancing a circular economy.

Cancer Incidence in a Population Living Near Radioactive Waste Storage of Uranium Mining in Stepnogorsk Area, Northern Kazakhstan.

This study evaluates the impact of radioactive uranium waste storage facilities on cancer occurrence in nearby areas. Current research evaluates the effect of radioactive uranium waste storage facilities on cancer epidemiology in nearby areas. The critical area had Aqsu, Kvartsitka, Zavodskoy and Stepnogorsk cities, which are located at a less than 5 km distance to the south of the Hydrometallurgical Plant tailings dump while the control group had Akkol region in 90 km from the source. The majority of population had lived in this territory more than the 30 years. Data were obtained from the Electronic Register of Cancer Patients of the Republic of Kazakhstan from 2001-2015, and 2,271 incident cases of cancer were registered. The most frequent malignancies were observed in the digestive organs (646 cases, 28%) and respiratory and intrathoracic organs (376 cases, 17%). The proportion of digestive organ cancers was higher in the critical group (560 cases out of 1913, 29%) than in the control group (86 cases out of 358, 24%). Additionally, respiratory organ cancers were more common in men, but the cancer incidence rate ratio was higher in the critical area. Notably, the study found that the cancer incidence rate ratios decreased over time, specifically for digestive, respiratory and female genital organs and breast cancer. In conclusion, while our study highlights significant differences in cancer incidence rates and frequencies between the critical and control groups, further analytical research, incorporating age-adjustment, is needed to provide a more conclusive evaluation of the potential impact of residence in proximity to the uranium mining waste storage on cancer occurrence in the study area.

Analysis of Environmental Impact of Disposal of Uranium Waste in Surface Landfill Facilities

Analysis of Environmental Impact of Disposal of Uranium Waste in Surface Landfill Facilities

Unraveling the role of coordinated water in the capture of americium and toxic gases by an ultrastable uranyl phosphonate framework

The design and fabrication of uranium phosphonate frameworks (UPFs) pave a potential avenue to reduce the environmental risk of depleted uranium, transuranium waste, and toxic gases while adding to its waste to utility virtues. However, it remains unknown how the pervasive coordinated water of UPFs influences their performances in radionuclide and toxic gas separation. Toward this end, we prepared a new category of porous UPFs, namely UPF-205 with abundant coordinated water and resulting hydrogen bonding nanotraps. The coordinated water is synergistic in quantitatively removing trivalent f-elements (i.e., Am3+, Eu3+) from wide-ranging pH solutions together with proximal phosphonate groups at a low metal concentration. Most importantly, an unprecedented coordinated water-mediated Eu3+-UO22+ transmetalation had been verified at a relatively high metal concentration. The high-density open uranyl sites and optimal pore size triggered by the dehydration of coordinated water also contribute to the enhanced adsorption of toxic SO2 and NH3. Our work shows great relevance for the rational design of ultrastable UPFs as both depleted uranium waste forms and efficient adsorbents for radiological/nuclear protection.

Impact of chromium (VI) as a co-contaminant on the sorption and co-precipitation of uranium (VI) in sediments under mildly alkaline oxic conditions

Uranium (U) waste, generated at a variety of mines and nuclear production sites, migrates in the subsurface, posing a serious threat to contaminate groundwater systems. In this study, batch equilibrium and kinetic experiments, geochemical modeling and solid phase characterization were conducted to investigate the impact of Cr(VI), a common co-contaminant, on the adsorption of U(VI) to quartz, plagioclase feldspar, and carbonate-dominated sediment (≤2 mm). Batch experiments were performed under slightly alkaline conditions (7.80 ± 0.18) and in the presence of major groundwater components (Ca2+, Mg2+, Na+, K+, carbonate, chloride, and sulfate) at different U(VI):Cr(VI) molar ratios 10:1, 1:1, and 1:10 at lower U(VI) concentration (10.5 μM [2.5 mg/L]) and at U(VI):Cr(VI) molar ratios of 168:1.05, 168:10.5, 168:105, 1:1, and 1:10 at higher U(VI) concentration (168 μM [40 mg/L]). At the low U(VI) concentration (10.5 μM [2.5 mg/L]), the distribution coefficients (Kd) were unchanged for the 10:1 and 1:1 U:Cr molar ratios indicating an excess of available U(VI) adsorption sites on the sediment. However, the U(VI) Kd values in the presence of Cr(VI) at the 1:10 M ratio decreased suggesting competition between U(VI) and Cr(VI) for adsorption sites. At the higher U(VI) concentration (168 μM [40 mg/L]), the Kd values were unaffected by U(VI):Cr(VI) molar ratios of 168:1.05, 168:10.5, 168:105, again indicating an excess of available sediment adsorption sites. At U:Cr molar ratios 1:1 and 1:10, there was a slight increase in Kd for U(VI) possibly reflecting an increase in inner-sphere binding of uranyl carbonate complexes. The adsorption process followed pseudo second-order kinetic parameters. These results indicate the sediment affinity for U(VI) adsorption appears to be largely independent of Cr(VI) under our experimental conditions. The intraparticle diffusion modeling of U(VI) adsorption to the sediment suggests a multi-step process, including film and intraparticle diffusion. The intraparticle diffusion stage remained constant in the presence of Cr(VI) suggesting the rate determining factors for overall equilibrium adsorption process for U(VI) was independent of Cr(VI). Understanding the mobility of U(VI) under natural conditions as simulated in our study is critical in developing effective remediation strategies and effective monitored natural attenuation (MNA) following the remediation of contaminated sites.

Source control on the acid mine drainage produced by the oxidation of pyrite and sulfur-containing uranium tailings based on the microbially induced carbonate precipitation technology

Large quantities of acid mine drainage (AMD) generated through the oxidation of sulfide-bearing minerals, particularly pyrite, pose a significant global environmental challenge. The implementation of efficient and fundamental governance methods is crucial as current conventional approaches fail to address the root cause of this problem. To investigate the technique of controlling AMD at its source, a 10-day static experiment was conducted in order to examine the inhibitory effect of Sporosarcina pasteurii (S. pasteurii) on oxidative acid production from pyrite under varying redox potentials (Eh) and Ca2+ concentrations. Additionally, a 180-day dynamic column experiment was carried out to assess the long-term stability of its inhibition and heavy metal fixation. The results of both short-term and long-term analysis indicate that the metabolic activity of S. pasteurii has beneficial effects on the control of AMD through sulfur oxidation, even in the presence of strong oxidants such as H2O2 and FeCl3. 1. It stabilizes pH within the neutral to alkaline range; 2. It maintains Eh at a low potential reducing environment; 3. It promotes an increase in SO42− concentration, followed by a decline and stabilization at lower concentrations; 4. It supplies carbonate for pyrite oxidation, maintaining a balance between acid production and consumption. Additionally, SEM, XRD, and XPS results demonstrated that the mineral surface appeared flat without prominent characteristic peaks of oxidation products, indicating effective inhibition of pyrite oxidation by S. pasteurii. The immobilization experiments for heavy metals showed that Cd exhibited the highest fixation effect with a rate of 94%; Mn, Cu, Zn, and Co had the second best fixation effect with ion concentrations decreasing by 82%, 83%, 87%, and 88% respectively; Ni and U(VI) decreased by rates of 75% and 69% respectively. These experimental findings suggest that S.pasteurii can effectively inhibit pyrite oxidation as well as sulfur-containing uranium waste rock oxidation while providing long-term stabilization for heavy metal immobilization.

Uranium surface processes with sandstone and volcanic rocks in acidic and alkaline solutions

Understanding the behaviour of uranium waste, for disposal purposes, is crucial due to the correlation between pH values and the disposal of distinct types of waste, with low level waste typically associated with acidic pH values, and higher and intermediate level waste commonly related to alkaline pH values. We studied the adsorption of U(VI) on sandstone and volcanic rock surfaces at pH 5.5 and 11.5 in aqueous solutions with and without bicarbonate (2 mM HCO3–) using XAS and FTIR. In the sandstone system, U(VI) adsorbs as a bidentate complex to Si at pH 5.5 without bicarbonate and as uranyl carbonate species with bicarbonate. At pH 11.5 without bicarbonate, U(VI) adsorbs as monodentate complexes to Si and precipitates as uranophane. With bicarbonate at pH 11.5, U(VI) precipitated as a Na-clarkeite mineral or remained as a uranyl carbonate surface species. In the volcanic rock system, U(VI) adsorbed to Si as an outer sphere complex at pH 5.5, regardless of the presence of bicarbonate. At pH 11.5 without bicarbonate, U(VI) adsorbed as a monodentate complex to one Si atom and precipitated as a Na-clarkeite mineral. With bicarbonate at pH 11.5, U(VI) sorbed as a bidentate carbonate complex to one Si atom. These results provide insight into the behaviour of U(VI) in heterogeneous, real-world systems related to the disposal of radioactive waste.

Evolving radon diffusion through earthen barriers at uranium waste disposal sites

Field measurements of Rn-222 fluxes from the tops and bottoms of compacted clay radon barriers were used to calculate effective Rn diffusion coefficients (DRn) at four uranium waste disposal sites in the western United States to assess cover performance after more than 20 years of service. Values of DRn ranged from 7.4 × 10−7 to 6.0 × 10−9 m2/s, averaging 1.42 × 10−7. Water saturation (SW) from soil cores indicated that there was relatively little control of DRn by SW, especially at higher moisture levels, in contrast to estimates from most steady-state diffusion models. This is attributed to preferential pathways intrinsic to construction of the barriers or to natural process that have developed over time including desiccation cracks, root channels, and insect burrows in the engineered earthen barriers. A modification to some models in which fast and slow pathway DRn values are partitioned appears to give a good representation of the data; 4% of the fast pathway was needed to fit the data regression. For locations with high Sw and highest DRn (and fluxes) at each site, the proportion of fast pathway ranged from 1.7% to 34%, but for many locations with lower fluxes, little if any fast pathway was needed.

Efficient and clean release of uranium and zirconium in hazardous uranium purification waste by combined alkali decomposition and acid leaching process

Large amount of hazardous waste generated by the uranium purification process poses a potential threat to the environment. However, it also contains valuable metals like uranium and zirconium worth recovering. It is extremely difficult to extract uranium and zirconium and process such waste slag harmlessly by conventional methods because of its complex composition and a large amount of silicate coating. Therefore, this work proposed a new method for efficient and clean release of uranium and zirconium by alkali disaggregation coupled with acid leaching in hazardous uranium purification waste streams. NaOH was used to react with silicates to destroy the structure of the waste slag, then the target elements of uranium and zirconium were exposed. At the same time, NaOH reacted with ZrP2O7 in the waste residue to form acid soluble Zr(OH)4. Then, HNO3 was used to react with uranium and zirconium to produce soluble UO2(NO3)2 and ZrO(NO3)2. Under optimized conditions, i.e., NaOH concentration of 140 g/L, liquid-solid ratio of 4:1, reaction time of 1 h, and water washing dosage of 4 mL/g, the leaching rates of uranium and zirconium were enhanced to 99.12 % and 96.77 %, respectively. Meanwhile, the content of uranium and zirconium in the slags decreased from 13.325 g/kg and 133.392 g/kg to as low as 0.287 g/kg and 11.444 g/kg, respectively, which meets the internationally required clean release standard. This study will provide a viable way for secondary resource recycling and clean release of waste containing valued metals.

Research Progress on photocatalytic treatment of uranium waste liquid with ZnO Quantum Dots

Aiming at the difficult problem of radioactive nuclear waste liquid treatment, this paper summarizes the principle and development of a new photocatalytic technology for removing uranium waste liquid, several preparation methods of ZnO quantum dots and its applications in biomedicine, catalysis and light shielding, and summarizes its research on radioactive uranium waste liquid. In the future, it is expected that ZnO quantum dots with better properties can be modified and put into commercial production for the treatment of radioactive uranium-containing waste liquid.

The concept of a fast reactor with liquid metal fuel in tungsten capsules

The concept of a dual-purpose high-power nuclear reactor is proposed. One of the goals is the production of electricity, the other is the production of high-potential thermal energy. It is proposed to use liquid fuel based on waste uranium and plutonium extracted from the spent fuel of VVER reactors (purified from the 238Pu isotope). The fuel is in sealed tungsten capsules. Lead extracted from thorium ores is used to cool the reactor. The electrical power of the reactor is 3.3 GW. The layout of the reactor is identical to the BREST-OD-300 reactor under construction. The analysis of emergency modes from among ATWS (anticipated transients without scram) is carried out. The reactor is reliable and safe. The maximum temperature of a high-temperature reactor coolant is close to the boiling point of lead. By the nature of the change in the maximum temperatures of the core components, the reactor occupies an intermediate position between a reactor with solid metallic fuel and a reactor with cermets based on UN-PuN and metal uranium nanopowder.

Metal mixture exposures and multiplexed autoantibody screening in Navajo communities exposed to uranium mine wastes

BackgroundEnvironmental exposures to metals in uranium mining wastes and drinking water were documented in more than half of the 1304 Navajo community members of the Diné Network for Environmental Health (DiNEH) Project, the first comprehensive assessment of exposures to these metals and community health on the Navajo Nation. ObjectiveEvaluate environmental exposures among participants who provided blood and urine samples using multiplexed autoantibody positivity as an early effect biomarker. MethodsSurvey and geospatial location data, well water quality, and metals biomonitoring were used to assess exposures to mixed-metal wastes from 100 abandoned uranium waste sites. ResultsWe observed that the prevalence of multiplexed autoantibody positivity in 239 participants was more than double that reported for the U.S. population (27.2% v. 13.8%) even though the national prevalence was generated using a different assay, the HEp-2 cell-based antinuclear antibody test. Increased risk of multiplexed autoantibody screening positivity (OR = 3.07,95%CI 1.15–8.22) was found among DiNEH study people who lived close to uranium mine and milling wastes and consumed metals in drinking water. Associations for females were even stronger when they lived closed to contaminated uranium mining and milling sites. Anti-U1-RNP antibodies were associated with water consumption of nickel. ConclusionProximity to waste sites and consumption of metals in water even below current drinking water standards were associated with perturbations of immune tolerance. These findings are consistent with previous studies of autoimmunity in the local population and demonstrate that multiplexed autoantibody screening method has a potential as sentinel indicator of exposures to environmental metals. Impact statementThis is the first, community-engaged environmental health study in exposed Navajo communities that applied clinical multiplexed testing in risk assessment of environmental metals associated with abandoned, unremediated uranium mining and milling waste sites. Routine clinical autoimmunity measures could be used as early effect biomarkers of environmental metal exposures.

Flux crystal growth of Ba2[(UO2)2Ti2O8]: Structures, spectroscopies and implications

AbstractWe report a flux crystal growth of Ba2[(UO2)2Ti2O8] and subsequent structural and spectroscopic studies using multiple techniques. The layered crystal structure, built up with sheets of edge‐sharing dimeric uranyl pentagonal bipyramids and dimeric TiO5 square pyramids with interlayer Ba(II) ions, was revealed by synchrotron single crystal x‐ray diffraction and confirmed with electron diffraction using a transmission electron microscope. The presence of only hexavalent uranium was confirmed by both diffuse reflectance and x‐ray absorption near‐edge structure spectroscopies, consistent with the bond valence sum calculations. Its vibrational modes were revealed by Raman spectroscopy. In addition, its implications as a potential hexavalent uranium waste form for the immobilization of uranium‐rich radioactive wastes were discussed.

The immunotoxicity of natural and depleted uranium: From cells to people

Uranium is a naturally occurring element found in the environment as a mixture of isotopes with differing radioactive properties. Enrichment of mined material results in depleted uranium waste with substantially reduced radioactivity but retains the capacity for chemical toxicity. Uranium mine and milling waste are dispersed by wind and rain leading to environmental exposures through soil, air, and water contamination. Uranium exposure is associated with numerous adverse health outcomes in humans, yet there is limited understanding of the effects of depleted uranium on the immune system. The purpose of this review is to summarize findings on uranium immunotoxicity obtained from cell, rodent and human population studies. We also highlight how each model contributes to an understanding of mechanisms that lead to immunotoxicity and limitations inherent within each system. Information from population, animal, and laboratory studies will be needed to significantly expand our knowledge of the contributions of depleted uranium to immune dysregulation, which may then inform prevention or intervention measures for exposed communities.

Uranium releasing behavior from a uranium waste rock heap in southern China: indication from sink

Uranium releasing behavior from a uranium waste rock heap in southern China: indication from sink

Adsorptive sequestration of noxious uranium (VI) from water resources: A comprehensive review

Groundwater is usually utilized as a drinking water asset everywhere. Therefore, groundwater defilement by poisonous radioactive metals such as uranium (VI) is a major concern due to the increase in nuclear power plants as well as their by-products which are released into the watercourses. Waste Uranium (VI) can be regarded as a by-product of the enrichment method used to produce atomic energy, and the hazard associated with this is due to the uranium radioactivity causing toxicity. To manage these confronts, there are so many techniques that have been introduced but among those adsorptions is recognized as a straightforward, successful, and monetary innovation, which has gotten major interest nowadays, despite specific drawbacks regarding operational as well as functional applications. This review summarizes the various adsorbents such as Bio-adsorbent/green materials, metal oxide-based adsorbent, polymer based adsorbent, graphene oxide based adsorbent, and magnetic nanomaterials and discuss their synthesis methods. Furthermore, this paper emphasis on adsorption process by various adsorbents or modified forms under different physicochemical conditions. In addition to this adsorption mechanism of uranium (VI) onto different adsorbent is studied in this article. Finally, from the literature reviewed conclusion have been drawn and also proposed few future research suggestions.

Geophysical Diagnosis of Diversion Channel Infiltration in a Uranium Waste Rock Pile

Geophysical Diagnosis of Diversion Channel Infiltration in a Uranium Waste Rock Pile

Effect of EDTA Complexation on the Kinetics and Thermodynamics of Uranium Redox Reactions Catalyzed by Pyrite: A Combined Electrochemical and Quantum-Mechanical Approach

Ethylenediaminetetraacetic acid (EDTA), a strong complexing agent, is a common constituent of liquid nuclear waste streams. The interaction of EDTA or other organic or inorganic ligands with uranyl enhances the mobilization of uranium and therefore significantly influences the disposal and remediation of uranium waste. Although numerous studies have focused on the effect of EDTA on the mobilization of environmental uranium, including the adsorption and redox reactions of uranium on mineral surfaces, few studies have differentiated the reaction-controlling steps (diffusion, adsorption, and chemical reaction/electron transfer) occurring at heterogeneous interfaces to assess the effect of EDTA complexation on each of these processes. Here, a combination of in situ electrochemical methods and quantum-mechanical calculations was used to study the effect of EDTA complexation on the kinetics and thermodynamics of redox reactions of uranium at the pyrite-solution interface. Experiments indicate a potential shift of U(VI)/U(V) on the pyrite surface of ∼0.04 V due to surface adsorption and −0.21 V due to EDTA complexation, with similar results from the calculations. The oxidation of the U(IV) reaction is more sensitive to EDTA complexation in solution than that of U(V). Disproportionation, affecting 2/3 of the intermediate pentavalent state, is the rate-limiting step of the overall redox cycle of uranyl. The charge transfer was controlled by diffusion and adsorption processes. EDTA can promote the delivery of free uranyl from the bulk solution to the pyrite–water interface where the reaction takes place, making the electron-transfer process less diffusion-limited. Adsorption of uranyl onto pyrite surfaces in the gradient electric field is multimolecular layer adsorption, through which electron transfer can occur.

Remediation of the uranium industry in the Czech Republic: regulation aspects and main technologies

There is a long history of uranium mining and milling in what is now the Czech Republic, with the main exploitation beginning in the second half of the 19th century. The greatest expansion was during the Cold War, which was then reduced after political changes in eastern Europe in the 1990s. Thereafter, almost all uranium work was stopped, the mines and mills were closed, and plans for decommissioning and remediation of sites and facilities were initiated. The paper describes the application of the regulatory framework for the decommissioning and remediation of the uranium waste sites and facilities in the Czech Republic, illustrated by examples of deep and surface mining, in-situ leaching sites, and ore processing facilities. It builds on information provided as a case study for the Nuclear Energy Agency’s Expert Group on Legacy Management. Some practical experience and lessons learned are presented. The sharing of the lessons and experience is noted as an important mechanism for avoiding the creation of future legacies.

Study of migration of radioactive elements in clay layers during the burial of radioactive waste

In 2015, Kazakhstan and the International Atomic Energy Agency (IAEA) signed an agreement to host a low-enriched uranium bank in Ust-Kamenogorsk. In 2019, several batches of enriched uranium were delivered to Kazakhstan and the bank began operations at the Ulba Metallurgical Plant. When transporting and disposing of radioactive elements, there is a need to reduce this possibility by limiting the transfer of uranium from underground storage to underground water. Therefore, in this article, a study was conducted on the migration of radioactive elements in clay layers during the disposal of radioactive uranium waste. There are now many underground repositories (for some types of radioactive waste). These systems are based on different underground container structures for different geological formations. For underground repositories located in geological environments where enriched uranium can migrate, other system components must reduce this possibility by preventing or limiting uranium mobility. This work investigates the process of convective transport of radioactive elements, in a moist soil layer through the installation of an additional natural clay barrier layer, the migration of radioactive elements during safe disposal, the effect of diffusion and convection through the solid waste layer.