Radioactive Residues Research Articles

Electron Beam on Fermentation Medium as an Alternative Disinfection Method for Ethanol Distilleries: A Comprehensive Review

Corn and sugarcane are the primary feedstocks for ethanol production, but microbial contamination hinders yeast fermentation efficiency. Current control methods include antibiotics and sulfuric acid, but they have limitations, resulting in dependence on external inputs and the risk of antibiotic-resistant bacteria. This review examines electron beam technology as an industrial-scale disinfection solution for both corn- and sugarcane-based ethanol production, highlighting its advantages, limitations and opportunities for adoption in Brazil. A critical evaluation highlights the importance of optimal operating conditions for scalability, cost effectiveness and sustainable implementation. Through a practical example, we demonstrate the effectiveness of electron beam treatment in improving fermentation efficiency and reducing contamination-related losses. Notably, the ionizing radiation from this process does not affect wort sugar content or generate radioactive residues. While acknowledging the potentially high energy input requirements, cogeneration in sugarcane mills can address this, making it a viable option; however, further technical and economic evaluation should be made. In addition, electron beam technology is a promising approach for the production of high-value products such as neutral alcohol, amino acids, animal feed and pharmaceuticals. Therefore, this comprehensive review provides valuable insights for researchers, industry stakeholders and policymakers to promote sustainable and efficient ethanol production practices.

Disposal Strategy of Ion-Adsorption Rare Earth Elements Low-Level Radioactive Residues: Reduction Emission and Recovery for Aluminum and Uranium by Alkaline and Alkalescent Media

Disposal Strategy of Ion-Adsorption Rare Earth Elements Low-Level Radioactive Residues: Reduction Emission and Recovery for Aluminum and Uranium by Alkaline and Alkalescent Media

Autonomous search investigation for radioactive leaked source based on an updated infotaxis method during nuclear emergency rescue

Identifying leakage locations is one of the key issues for off-site decision workers in nuclear accident conditions, especially for performing early emergency rescue. To rapidly reduce the environmental radiation level of serious accidents in nuclear facilities caused by external events and identify radioactive residues outside containment, an autonomous search method for residue leakage source in nuclear emergency rescue based on the updated Infotaxis method was proposed. It takes into account radioactive decay and wet settlement caused by high-pressure sprinkling or precipitation. The sampling rate function was updated by the radioactive decay term and washing factor in the Infotaxis method, which improves the dilution effect of environmental radiation and provides more accurate entropy information. The search trajectories were investigated under multiple scenarios, such as different source emission rates and wet deposition due to high-pressure sprinklers or precipitation. The results showed that the proposed method could improve search efficiency by adding a washing term, especially for improvement of the success rate in search of leakage source under higher source emission rates, and it helps nuclear emergency decision-makers trace the location of leakage source accurately during the rescue process to provide more scientific information for early emergency response and consequence assessment.

Stakeholder Model for Standard Operating Procedure of Radiation Safety Practice in Radiopharmaceutical Therapy

Using Xofigo procedure as an example of radiopharmaceutical therapy, to provide a quantitative analysis methodology for standard operating procedure development with binary stakeholder model. A Xofigo procedure was selected for this study. After nurse places the intravenous (IV) pole and start delivery of the saline liquid into the patients for required temporal period, calibrated Xofigo syringe will be transported into the treatment room by medical physicist and authorized radiation oncologist starts injecting the Xofigo liquid into the patient through the 3-way stopcock. During this process, the status of liquid path is from the syringe with Xofigo liquid to patient, and the saline liquid tube is shutoff. After about 1 minutes of injection, which most of the Xofigo radioactive liquid is injected into patient side, the 3-way stopcock will shut off the connection between the patient and syringe. The saline liquid then is abstracted into in the syringe from the saline bag hung on the IV pole, the liquid amount will be used for diluting the residual Xofigo liquid inside the syringe. Then the 3-way stopcock switch is switched off the connection between the saline bag and the syringe, and syringe is connected to the patient side again, then the saline liquid inside the syringe is injected into patient, and this process dilutes the residual Xofigo radioactive liquid at the inside surface of the syringe and the path to the patient. This dilution process could repeat a few times, depends on the estimation of residual amount. Then the syringe will be unscrewed from the 3-way stopcock by opening the path from the saline bag to the patient. At this moment, the saline is switched off from outside by cutting the tube with a scissor or unscrewed from the 3-way stopcock. A binary stakeholder quantitative model was used to evaluate the last step with a computational simulation program the tube cut-off process. Based on the numerical results from the simulation program, at the best situation, if the residual isotope liquid had been diluted completely, the radiative dose to both procedures would not be different, and the only difference is the tool used and workload dispatch to both medical physicist and radiation oncologist. And at the worst scenario, there were some radioactive residuals had gone into the IV-saline tube, then the radioactive contamination could be in the scissor, both side of cut off tube, and potential contacting point will increase to two stakeholders, one more tool(scissor), which could be treated as a stakeholder. The optimization principle could be simplified as to decrease the contacting point and contacting stakeholders by a computational simulation of a stakeholder model for a Xofigo radiopharmaceutical procedure. The analysis methodology could expand to all the steps in radiopharmaceutical therapy in developing a standard operating procedure and other complex radiation safety practice simulation system.

Ultra-effective modified clinoptilolite adsorbent for selective thorium removal from radioactive residue

This study investigated the efficacy of using phosphate-modified zeolite (PZ) as an adsorbent for removing thorium from aqueous solutions. The effects of various factors such as contact time, adsorbent mass, initial thorium concentration, and pH value of the solution on the removal efficiency were analyzed using the batch technique to obtain optimum adsorption condition. The results revealed that the optimal conditions for thorium adsorption were a contact time of 24 h, 0.03 g of PZ adsorbent, pH 3, and a temperature of 25 °C. Isotherm and kinetics parameters of the thorium adsorption on PZ were also determined, with equilibrium studies showing that the experimental data followed the Langmuir isotherm model. The maximum adsorption capacity (Qo) for thorium was found to be 17.3 mg/g with the Langmuir isotherm coefficient of 0.09 L/mg. Using phosphate anions to modify natural zeolite increased its adsorption capacity. Furthermore, adsorption kinetics studies demonstrated that the adsorption of thorium onto PZ adsorbent fitted well with the pseudo-second-order model. The applicability of the PZ adsorbent in removing thorium from real radioactive waste was also investigated, and nearly complete thorium removal was achieved (> 99%) from the leached solution obtained from cracking and leaching processes of rare earth industrial residue under optimized conditions. This study elucidates the potential of PZ adsorbent for efficient removal of thorium from rare earth residue via adsorption, leading to a reduction in waste volume for ultimate disposition.

A Preliminary Proposal for a Hybrid Lattice Confinement Fusion-Fission Reactor for Mobile Nuclear Power Plants

Scientists detected 2.45-MeV neutrons and in smaller yields 4- and 5-MeV neutrons in deuterated metals under a 2.9-MeV electron beam. Such discovery could allow the use of deuterated metals at temperatures below their melting point to provide nuclear fusion reactions. Such reactions could provide fast neutrons and energy in the form of heat. This work analyzed the results of some experiments to infer the neutron multiplication rate in such environments. It also considered the possible roles that such phenomena could play in a commercial nuclear power reactor under economic and compactness constraints. It seems the best way to promote nuclear fusion is the irradiation of deuterated metals by fast neutrons. This work presents the concept of a hybrid fission-fusion reactor using fissile or fertile fuel to generate heat and fast neutrons along deuterated metals providing excess neutrons (reactivity boost). Additionally, deuterated metals also may have a role in neutron moderation requiring less volume than other moderators (water or graphite). Such a reactor, given its reactivity boost, may burn radioactive residuals (transmutation) at affordable costs while generating power. Alternatively, this hybrid fission-fusion concept could also breed fissile fuel from fertile isotopes using natural uranium as seed.

The enrichment of rare earth from magnesium salt leaching solution of ion-adsorbed type deposit: A waste-free process for removing impurities

Due to the complex composition of ion-adsorbed type rare earth ore leaching solution, there are challenges in the process of rare earth (RE) separation, such as large RE loss rate, low product purity, radioactive residue and so on. In this article, 8-hydroxyquinoline modified silica gel (HQ-SiO2) and 2,2′-(1,4-phenylenebis(oxy)) dioctanoic acid (PPBOA) were used to form an efficient process for impurities removal and RE enrichment. Solid phase extraction successfully intercepted 96.7% of the radioactive element thorium. The concentration of aluminium was reduced to 2.14 ppm by frank chromatography. Rare earth elements were enriched from 336.35 mg/L to 237.75 g/L by extraction-precipitation, that is, the enrichment multiple reached more than 700 and the proportion of RE was increased from 21.85% to 96.62%. The loss rate of RE was controlled below 1.59%. Moreover, the magnesium salt leaching solution could be recycled for the leaching of RE ores. Although some liquid waste need to be treated in the processes of HQ-SiO2 production and regeneration, the integrated process helps to decrease volatile organic solvent, acid-base consumption, wastewater and waste residue. It is an environment-friendly RE enrichment and impurity removal process, which shows application potential in the production field of ion-adsorbed type rare earth mineral products.

Behavior and fate of a novel neonicotinoid cycloxaprid in water–sediment systems through position-specific C-14 labeling

Neonicotinoid insecticides are ubiquitous worldwide, are problematic for pollinators and other nontarget creatures and affect the stability of the environment. These negative impacts prompt the ongoing development of alternatives. Cycloxaprid, a novel cis-nitromethylene neonicotinoid, exhibits high efficacy against imidacloprid-resistant pests and is viewed as a promising alternative candidate. However, information about the fate of cycloxaprid in water–sediment systems is limited. To bridge this knowledge gap, radioactive isotope-labeled 14C-cycloxaprid was employed to determine the formation of residues, transformation products, and degradation pathways. First, the mass balance analysis of residue was investigated. The extractable residue of cycloxaprid accounted for 100–40% of the total radioactive residue; cycloxaprid could transform into bound residue (0–54%) and mineralization (0–0.015%). It was partitioned from the water phase to sediments with dissipation half-lives of 6.62 d in the Dianshan Lake sample and 4.61 d in the Jinhui Port sample. Three degradation products were then detected and identified by liquid chromatography coupled to mass spectrometry. Its main metabolite, 2-chloro-5-[(2-(nitromethylene)-1-imidazolidinyl)methyl]pyridine, was more toxic than the parent compound and should be given priority in monitoring. Ring opening, carboxylation, and reduction of nitro groups were confirmed as the primary degradation pathways. The present study assessed the fate of cycloxaprid in two different water–sediment systems for the first time, and this information could provide insight into the potential ecological impacts of cycloxaprid and more precisely into evaluating its environmental risks in the future.

RADIOACTIVE RESIDUE IN HONEY

The concentration of radioactive isotopes in honey is an important bioindicator of environmental contamination. For that purpose, a total of 66 samples of different types of honey (acacia, meadow, linden, sunflower, flower, forest, oilseed rape, chestnut) were examined. The samples were collected during 2020 and 2021 at different localities in the Republic of Serbia (Vojvodina, Central Serbia, Kosovo). Gamma spectrometric analysis was used to determine natural radionuclides 40K, 232Th, 226Ra, 238U, 235U and 22Na and anthropogenic radionuclide 137Cs. The obtained results indicate that the predominant radionuclide in all the analyzed honey samples is natural K-40, whose average activity was 74 Bq / kg. The activity of other tested radionuclides ranged as follows: Th-232: <1-2.0; Ra-226: 1.9-15.6; U-238: <1-31.4; U-235: <0.2-1.61 and Na-22: <0.2-2.4 Bq / kg. The activity of the artificial radionuclide Cs-137 was measured in 53% of the tested samples from the territory of Kosovo with the maximum value of 3.63 Bq / kg. Regarding the determined level of radioactive residues, it can be concluded that the honey produced in the Republic of Serbia is healthy and environmentally safe food.
 Key words: honey, natural radionuclides, artificial radionuclides

A Survey on Various Methods of Extraction and Recovery of Thorium

In this survey, some methods of extraction of thorium such as selective extraction of thorium using phosphorodiamidate, selective cloud point extraction of thorium, extraction of thorium from sulfuric acid baking and leaching of monazite, extraction of thorium from chloride solution using Schiff base were discussed. The decomposition of monazite was manifested by sulfuric acid baking and leaching at an elated temperature. The recovery of thorium (Th) from various sources of rare earth and some selective extraction of thorium by using phosphorodiamidate as an extractant was also reported. Using a special synthesized surface-active ionic liquid extractant (SAIL), the cloud point extraction of thorium was analyzed. A synthesized Schiff base was applied for the extraction of thorium in the strategic solvent extraction method. Thorium, using α-amino phosphate extractant from bastnaesite, recovered by using Cyanex 572 and N1923, recovery of Th from industrial residues and recovery of Th from radioactive waste by using IREPO and monazite leached solution were discussed. In this study, the recovery of thorium from the industrial residue as well as from radioactive residue was also discussed.

Bioconcentration and Metabolism of the New Herbicide Methiozolin in Ricefish (Oryzias latipes).

Methiozolin is a novel herbicide used to control annual bluegrass. It has low vapor pressure and high hydrophobicity, which could result in persistence in water and bioaccumulation. We measured the bioconcentration factors (BCFs) of methiozolin in ricefish (Oryzias latipes). Two radiolabels were used to quantify the parent compound and identify its metabolites. Ricefish were exposed to 2.0 and 20.0 ng/L methiozolin for 28 days in the uptake phase with a 96-h LC50 of 2.2 mg/L(95% confidence limit: 2.1-2.5 mg/L) and water solubility of 4.2 mg/L after 48 h was observed. On the basis of total radioactivity residues (TRRs), BCFss and BCFk values of 797.0-851.9 and 992.9-1077.4 were observed, respectively, while BCFss values for methiozolin were 251.9-257.5. Several minor metabolites with TRR < 3.4% were detected. Among them, 4-(2,6-difluorobenzyloxy-methyl)-3-hydroxy-3-methyl-1-(3-methylthiophen-2-yl)butan-1-one, 2,6-difluorobenzyl alcohol, and 4,5-dihydro-5-methyl-3-(3-methylthiophen-2-yl)isoxazol-5-yl)methanol were identified. Methiozolin is metabolized into numerous minor metabolites with potentially low bioaccumulation capacity in ricefish. These findings can facilitate risk assessments regarding methiozolin use, particularly its movements and final stages in aquatic environments.

Shadow poles in the alternative parametrization of R -matrix theory

Nuclear data libraries (ENDF, JEFF, JENDL, CENDL, etc.) document our phenomenological knowledge of nuclear cross sections as interpreted by R-matrix theory. The R-matrix scattering model can parameterize the energy dependence of the scattering matrix in different ways. This article establishes new results on three such sets of parameters: the Wigner-Eisenbud, the Brune, and the Siegert-Humblet parameters. We show how the latter two arise from invariance to the arbitrary boundary condition, and how they can trade-off more complex parameters for a simpler energy dependence parameterization: the scattering matrix pole expansion of Humblet and Rosenfeld. We establish that the scattering matrix's invariance to channel radius sets a partial differential equation on the widths of the Kapur-Peierls operator, which enables us to derive an explicit transformation of the Siegert-Humblet radioactive residue widths under a change of channel radius. Considering the continuation of the scattering matrix to complex wavenumbers, several new results are established. We unveil there exist more Brune parameters than previously thought, depending on the way the scattering matrix is continued to complex energies. This points to a broader conundrum in the field: how to analytically continue the scattering matrix while closing sub-threshold channels. We argue that, contrary to the Lane and Thomas legacy of force-closing sub-threshold channels which introduces spurious poles, analytic continuation is the physically correct way of defining the scattering matrix for complex wave numbers. To back this claim we establish thee results: analytic continuation cancels spurious poles, enforces the generalized unitarity conditions of Eden and Taylor, and closes massive particle channels below threshold by both quantum tunneling and from the definition of the cross section as the ratio of probability currents.

The nuclear accident at Chernobyl: Immediate and further consequences

The accident at Chernobyl occurred in April 1986 at the Chernobyl Nuclear Power Plant in Soviet Union. The incident occurred during a scheduled safety test. A combination of inherent reactor design flaws and operators’ mistakes resulted in reactor’s No.4 disaster and the emission of a large quantity of radiation. The immediate actions involved the fire extinguishing, the cleanup of radioactive residues and the prevention of a new explosion. For this purpose, plenty of people worked with self-sacrifice. The people who lived nearby were removed. As far as the socio-economic impact for the Soviet Union is concerned, it was quite serious. Moreover, the environmental and human health consequences were also alarming with thyroid cancer being the most studied. Useful conclusions, especially for the safety both of reactors and nuclear power, as well as for the impact of radiation at ecosystems have been drawn. The debate about the use of nuclear power has remained open ever since.

Investigation of thorium separation from rare-earth extraction residue via electrosorption with carbon based electrode toward reducing waste volume

Rare-earth (RE) industries generate a massive amount of radioactive residue containing high thorium concentrations. Due to the fact that thorium is considered a non-economic element, large volume of these RE processed residues are commonly disposed of without treatment. It is essential to study an appropriate treatment that could reduce the volume of waste for final disposition. To this end, this research investigates the applicability of carbon-based adsorbent in separating thorium from aqueous phase sulphate is obtained from the cracking and leaching process of solid rare-earth by-product residue. Adsorption of thorium from the aqueous phase sulphate by carbon-based electrodes was investigated through electrosorption experiments conducted at a duration of 180 minutes with a positive potential variable range of +0.2V to +0.6V (vs. Ag/AgCl). Through this research, the specific capacity obtained was equivalent to 1.0 to 5.14 mg-Th/g-Carbon. Furthermore, electrosorption of thorium ions from aqueous phase sulphate is found to be most favorable at a higher positive potential of +0.6V (vs. Ag/AgCl). This study's findings elucidate the removal of thorium from the rare-earth residue by carbon-based electrodes and simultaneously its potential to reduce disposal waste of untreated residue.

Impacts of TENORM from fertilizers on soil and vegetables and the effective dose rate due to ingestion of vegetables at the agricultural zone in Vietnam

In this work, the impacts of TENORM (Technologically Enhanced Naturally Occurring Radioactive Materials) from fertilizers on soil and vegetables were estimated. We investigated both the activity concentration of the natural radionuclides and the annual effective dose rate due to the ingestion of vegetables in the crops using fertilizers at the agricultural zone of Hoc Mon, Ho Chi Minh City, Vietnam. The results show that there have not yet been signs of radioactive residues from using conventional fertilizers in agricultural land after a crop at the surveyed area and time. The radiological impact of surveyed vegetables was negligible to the public health.

Recovery of thorium and rare earths from leachate of ion-absorbed rare earth radioactive residues with N1923 and Cyanex® 572

Ion-absorbed rare earth ores radioactive residues (IREORR) are a class of waste residue from the production of rare earth elements (REEs). Because of its radioactive dose, IREORR are usually stored in waste warehouses. IREORR are difficult to be disposed of. However, it contains relatively high concentrations of REEs, which can be considered as a valuable secondary resource. In this paper, a novel process is developed for the separation of thorium (Th) and recovery of REEs from IREORR hydrochloric acid leachate with primary amine N1923 and Cyanex® 572, respectively. The effects of sulfate concentration, extractant concentration and pH on N1923 extraction in hydrochloric acid solution were investigated in detail. The results show that the extraction capacity of N1923 can be improved by adding sulfate to the solution and increasing the concentration of N1923. Acidity has little effect on the extraction of Th when pH is higher than 1. As for the stripping, REEs are more easily stripped from loaded organic phase than Th, and nitric acid is a better stripping agent than hydrochloric acid. Combined with the extraction of Cyanex® 572 for REEs, a fractional extraction experiment for separating Th and enriching of REEs was performed. The yield of Th is higher than 99.9% and the concentration of REEs is enriched to 183.84 g/L.

Metabolism of esfenvalerate in tomato plants (Solanum lycopersicum).

The metabolic fate of esfenvalerate (1), 14C-labeled at the chlorophenyl or phenoxyphenyl ring, in tomato plants was investigated by spraying it three times at 15 g/ha. The overall metabolic trend of 1 was similar in foliage and fruit. The applied 1 gradually penetrated into the foliage/fruit, and approximately 30% of the total radioactive residue (TRR) distributed within the plant. The applied radioactivity remained mostly intact on the plant surface, while its degradation proceeded via ester cleavage to produce two corresponding acids derived from the chlorophenyl and phenoxyphenyl moieties, followed by saccharide conjugation at the inner tissues (each <5%TRR). While 1 retained its optical configuration (2S,αS) on the plant surface and in the fruit, a very slight isomerization at the α-cyanobenzyl carbon occurred to form a (2S,αR) isomer in the foliage (≤1%TRR). The isomerization at another asymmetric carbon C2 in the isovaleric acid moiety did not proceed on/in the plant for 1 or its metabolite.

Distribution and Chemical Fate of [36Cl]Chlorine Dioxide Gas on Avocados, Eggs, Onions, and Sweet Potatoes.

Fate and distribution studies were conducted with [36Cl]-chlorine dioxide in avocados, eggs, onions, and sweet potatoes. Experiments utilized sealed, darkened chambers, 5 mg of 36ClO2 (g), and two-hour exposure periods. Total radioactive residues were quantitated in gas purges, tank rinses, reaction chambers, and on fractions specific to each food. Deposition of the radioactive residue was mostly a surface phenomenon; transfer of radioactivity into albumen occurred in egg, but radioactivity did not penetrate the onion tunic and only small amounts of activity were present in avocado flesh. Potato skin contained essentially all the potato radiochlorine. Regardless of the food product, nearly all radioactive residue was present in edible tissues as chloride ions; the chlorite ion was present only in egg-rinse water. Small amounts (10% or less) of radioactivity were present as chlorate ions, which would be a useful marker compound for chlorine dioxide sanitation.

Degradation of Spent Radioactive Ion Exchange Resins and Its Mechanisms by Fenton Process

Spent IERs are released during the operation and decommissioning of nuclear facilities. The safe and efficient treatment of spent IERs is an emergent problem in nuclear industry. IRN77 is a typical ion exchange resin widely used in many nuclear power plants. Fenton process can degrade organic resins and reduce the radioactive residues volume and the disposal cost significantly. In this work, the IRN77 resin was selected as a model ion exchange resin and its treatment via Fenton process was investigated. The influencing factors for resin degradation, including catalyst dosage, reaction time, initial pH, temperature and oxidant dosage were investigated and optimized via the single-factor experimental method. Under the reaction temperature of 100°C and reaction time of 120 min at initial pH of 2, more than 97% COD was removed with 1.66 g H2O2 and 32 mg FeSO4·7H2O added to per gram of wet resin. The catalyst dosage and H2O2 dosage can decrease 78% and 50% respectively compared to previous results. SEM, FT-IR and ion chromatograph were employed to characterize the resin beads, soluble organics and intermediates during the degradation reaction. Based on the characterization results, the resin degradation pathway was discussed in detail and it is proposed to three stages including beads dissociation, styrene and divinylbenzene decomposition and carboxylic acids mineralization. During the IERs degradation, formic acid, acetic acid, propionic acid and oxalic acid were quantitatively monitored as main intermediates, and oxalic acid accounted for over 90% of COD in the final residue solution. Fenton process is suggested as a promising resin degradation method.

A cost-effective process for recovering thorium and rare earths from radioactive residues

Ion-adsorbed rare earth ores radioactive residues (IREORR) are low-level radioactive wastes generated by the production processes of ion-adsorbed rare earth ores (IREO). IREORR were difficult to be managed due to their radioactivity and larger volume. The wastes have caused environmental concerns. In addition, IREORR were rich in rare earth elements (REEs). The contents of REEs in IREORR were much higher than those in IREO. In this study, a separation process based on 2-(4-(2,4,4-trimethylpentan-2-yl) phenoxy) acetic acid (POAA) for the recoveries of REEs and radioactive element Th from IREORR leachate have been developed. The extraction mechanism of POAA for Th was indicated to be cation exchange mechanism. Unsaponified POAA revealed a better selectivity for the separation of Th from mixed REEs. The separation of Th and enrichment of REEs from IREORR leachate were achieved by liquid-liquid extraction and extraction-precipitation, showing that this process may be cost-effective used to deal with IREORR leachate for environmental concerns and resource utilizations.