Subjects: Nuclear Science and Technology >> Nuclear Materials and Techniques submitted time 2024-06-11
Abstract: Experimental scratch tests and first-principles calculations were used to study the adhesion property of AlCrNbSiTi high-entropy alloy (HEA) coatings on zirconium substrate. AlCrNbSiTi HEA and Cr coatings were deposited on Zr alloy substrates using multi-arc ion plating technology and scratch tests were carried out to estimate adhesion property of the coatings. Scratch test results indicated that Cr coating have a better adhesion strength than HEA coatings, and HEA coatings showed brittleness. The Special quasi-random structure approach was used to build the HEA models, and the models of the Cr/Zr and HEA/Zr interfaces were employed to investigate the cohesion between the coatings and Zr substrate by first-principles calculations. The calculated interface energies showed that the cohesion between Cr coating and Zr substrate is stronger than HEA coatings. Cr, Nb, and Ti in HEA coating, not Al or Si, bind strongly with Zr. Judged by the calculated elastic constants, low Cr content and high Al content will decrease the mechanical performances of the HEA coatings. This work demonstrates the utility of the combined approach involving first-principles calculations and experimental studies for the development of new HEA coating.
Subjects: Nuclear Science and Technology >> Nuclear Materials and Techniques submitted time 2024-04-20
Abstract: After decades of research, the problems and behavior of the corrosion of reactor alloy materials are well known. However, some problems in corrosion of reactor materials have not been clarified, including the critical corrosion process of the reactor materials under operational conditions, the role of a single factor in the corrosion process, and the prediction of corrosion behaviors of new materials in extreme environments. The density functional theory, which is based on quantum mechanics, can accurately predict the motion process of atoms and the change in the relevant energy within a very short period. The density functional theory has become an important auxiliary method for investigating the corrosion process of reactor alloy materials in recent years and can help solve the above problems. In this paper, two parts are reviewed. The first part introduces the density functional theory and includes the theoretical basis, development process, and mainstream computing software. In the second part, the research status of the density functional theory in the corrosion of reactor alloy materials is reviewed, including the adsorption, separation, combination, and internal diffusion of the reactor alloy material surfaces in the environments of water-cooled reactor, liquid-metal-cooled reactor, and molten salt reactor.
Subjects: Nuclear Science and Technology >> Nuclear Materials and Techniques submitted time 2024-03-25
Abstract: Background : Uranium dioxide (UO2) has been broadly employed as nuclear fuel in nuclear reactors. The poor thermal conductivity of UO2, however, reduces the safety of the reactor due to possible sharp temperature gradients. Graphene oxide (GO) is a kind of promising additive to improve the thermal conductivity of UO2 for its excellent thermal performance. Purpose : This work aimed at achieving uniform distribution of GO in UO2 pellets, effectively controlling the doping amounts, and finally enhancing the thermal conductivity of UO2 pellets. Methods : GO-doped UO2 powders with different doping amounts were prepared by solid-liquid mixing method and ammonium diuranate (ADU) co-precipitation method. After selecting the optimized powdering process, the UO2-GO composite fuel pellets were prepared by spark plasma sintering (SPS). The properties of the UO2-GO composite fuel pellets, such as density, grain size, physical phase, thermal conductivity, etc., were examined and compared with that of the conventional pure UO2 pellets. Results : The results showed that the density of UO2-GO pellets could reach up to 97.6% T.D. The thermal conductivity of UO2-GO pellets with 1.5 wt. % doped GO was 85.9% higher than that of conventional UO2 pellets at 1000 ℃. The grain size of the UO2-GO pellets was uniform, and the GO was homogeneously distributed at the grain boundary to form a bridging thermal conduction network. Conclusions : The thermal conductivity of the UO2 pellets was successfully improved through GO doping.
Peer Review Status:Awaiting Review
Subjects: Nuclear Science and Technology >> Nuclear Materials and Techniques submitted time 2024-03-20
Abstract: Background Within GEN-IV reactors, nuclear graphite plays a crucial role as both a moderator and reflector in an environment characterized by high temperatures and intense fast neutron irradiation. The exposure to fast neutron irradiation induces the formation of numerous Frankel defects in the nuclear graphite. These defects undergo processes of annihilation and diffusion, ultimately giving rise to larger defect clusters. This transformation in the microstructure of nuclear graphite directly impacts its macroscopic properties, necessitating a thorough investigation. Purpose The paramount significance lies in comprehensively studying the evolution of defects in nuclear graphite under conditions of high-temperature irradiation. This research is essential for advancing reactor safety. Methods This study employed 30 MeV 107Ag5+ ions to irradiate IG-110 nuclear graphite at 420 ℃ to simulate the defect evolution behavior during fast neutron irradiation of nuclear graphite. The energy loss, defect distribution, and ion implantation profiles of 30 MeV 58Ni5+ and 107Ag5+ ion beams bombarding standard nuclear graphite ICRU-906 (density of 2.26 g/cm3, displacement energy of 28 eV) were calculated using the full cascade damage model in the SRIM (Stopping and Range of Ions in Matter) software. The cross-sectional structure of IG-110 nuclear graphite was characterized using micro-Raman spectroscopy. The relationship between the Raman spectroscopic features at various depths of IG-110 nuclear graphite and the irradiation damage dose was compared to investigate the evolution of IG-110 nuclear graphite microstructure with increasing irradiation damage dose (DPA, Displacements Per Atom). Results With the increase in particle fluence, the characteristic parameters of the Raman spectra of nuclear graphite, including the ID/IG ratio (the ratio of the D peak height to the G peak height), the Full Width at Half Maximum of the G peak (FWHM(G)), and the shift of the G peak, all show significant increments. When compared to samples irradiated with 58Ni5+ at the same irradiation damage dose, the graphite Raman spectra irradiated with 107Ag5+ demonstrate higher ID/IG ratios and FWHM(G). At the same FWHM(G) level, the ID/IG ratio of the graphite Raman spectra irradiated with 107Ag5+ is greater than that of the samples irradiated with 58Ni5+. Conclusion The results suggest that irradiation with heavier ions induces a higher rate of defect accumulation in nuclear graphite, leading to a more rapid reduction in graphite grain size and promoting the progression towards nanocrystallization.
Subjects: Nuclear Science and Technology >> Nuclear Materials and Techniques submitted time 2024-03-13
Abstract: Cs and I can migrate through the fuel-cladding interface and accelerate the cladding corrosion process induced by the Fuel Cladding Chemical Interaction. Cr coating is an important candidate in mitigating this chemical interaction. First-principles calculations were employed to investigate the diffusion behaviors of Cs and I in Cr bulk and Cr grain boundary, aiming to reveal the microscopic mechanisms for mitigating the interaction at fuel-cladding interface. The interactions between these two fission products and Cr coating were systematically studied, and the temperature-dependent diffusion coeffcients of Cs and I in Cr were obtained using Bocquet’s oversized solute atoms model and Le Claire’s nine-frequency model, respectively. The results show that the migration barriers of Cs and I are significantly lower compared to that of Cr, and the diffusion coeffcients of Cs and I are both more than 3 orders of magnitude larger than Cr self-diffusion coeffcient within the temperature range of Generation IV fast reactors (below 1000 K), which shows the strong penetration ability of Cs and I. Meanwhile, Cs and I are more likely to diffuse along the grain boundary because of the generally low migration barriers, indicating that grain boundary serves as a fast diffusion channel for Cs and I.
Subjects: Nuclear Science and Technology >> Nuclear Materials and Techniques submitted time 2024-02-20
Abstract: The synergistic damage effect of irradiation and corrosion of reactor structural materials has been a prominent research focus. This paper provides a comprehensive review of the synergistic effects on the third- and fourth-generation fission nuclear energy structural materials used in pressurized water reactors and molten salt reactors. The competitive mechanisms of multiple influencing factors, such as the irradiation dose, corrosion type, and environmental temperature, are summarized in this paper. Conceptual approaches are proposed to alleviate the synergistic damage caused by irradiation and corrosion, thereby promoting in-depth research in the future and solving this key challenge for the structural materials used in reactors.
Subjects: Nuclear Science and Technology >> Nuclear Materials and Techniques submitted time 2023-08-14
Abstract: Alloys of uranium and molybdenum are considered as the future of nuclear fuel and defense materials. However, surface corrosion is a fundamental problem in practical applications and storage. In this study, the static and dynamic evolution of carbon monoxide (CO) adsorption and dissociation on γ-U (1 0 0) surface with different Mo doping levels was investigated based on density functional theory and ab initio molecular dynamics. During the static calculation phase, parameters, such as adsorption energy, configuration, and Bader charge, were evaluated at all adsorption sites. Furthermore, the time-dependent behavior of CO molecule adsorption were investigated at the most favorable sites. The minimum energy paths for CO molecular dissociation and atom migration were investigated using the transition state search method. The results demonstrated that the CO on the uranium surface mainly manifests as chemical adsorption before dissociation of the CO molecule. The CO molecule exhibited a tendency to rotate and tilt upright adsorption. However, it is difficult for CO adsorption on the surface in one of the configurations with CO molecule in vertical direction but oxygen (O) is closer to the surface. Bader charge illustrates that the charge transfers from slab atoms to the 2π* antibonding orbital of CO molecule and particularly occurs in carbon (C) atoms. The time is less than 100 fs for the adsorptions that forms embryos with tilt upright in dynamics evolution. The density of states elucidates that the overlapping hybridization of C and O 2p orbitals is mainly formed via the d orbitals of uranium and molybdenum (Mo) atoms in the dissociation and re-adsorption of CO molecule. In conclusion, Mo-doping of the surface can decelerate the adsorption and dissociation of CO molecules. A Mo-doped surface, created through ion injection, enhanced the resistance to uranium-induced surface corrosion.
Peer Review Status:Awaiting Review
Subjects: Nuclear Science and Technology >> Nuclear Materials and Techniques submitted time 2023-06-18 Cooperative journals: 《Nuclear Science and Techniques》
Abstract: Polyvinyl alcohol (PVA) is a well-known friendly polymer for paper-making, textiles, and a variety of coatings, biomedical applications such as artificial pancreas, synthetic vitreous body, wound dressing, artificial skin, and cardiovascular device. In this paper, ion/electron beam is employed to get insight into the irradiation effect on surface morphology and optical properties of PVA polymer. UV-Vis spectra are recorded to investigate the effect of induced defects on the optical band gap and the formed carbon clusters size. Scanning electron microscopy (SEM) is used to relate and investigate surface morphology and optical properties of the target polymer with different doses (15, 30 and 60 min). Also, PVA polymer is subjected to theoretical studies by using semi-empirical PM7 quantum chemical method.
Subjects: Nuclear Science and Technology >> Nuclear Materials and Techniques submitted time 2023-06-18 Cooperative journals: 《Nuclear Science and Techniques》
Abstract: This study was to evaluate effect of 125I brachytherapy combined with chemotherapy on advanced non-small cell lung cancer (NSCLC). Patients with NSCLC in stages III to IV were divided into two groups: Group A (n=27) received 125I brachytherapy combined with gemcitabine and cisplatin (GP) chemotherapy, and Group B (n=27) received GP chemotherapy only. The results showed that the overall response rate and median progression-free survival time were 78% and 11.5 months in Group A, 41% and 8 months in Group B, respectively (P<0.05). For Group A, the 1- and 2-years survival rates were 67% and 37%, respectively, with the median survival time of 16 months, whereas the corresponding data of Group B were 48%, 22% and 11.5 months (P>0.05). The interventional complications in Group A included 5 patients with postoperative pneumothorax and 4 patients with hemoptysis. No patients had radiation pneumonia, radiation esophagitis or esophagotracheal fistula. Chemotherapy treatment-related toxicities were not significantly different between the two groups. The relief of tumor-associated symptoms including cough, hemoptysis, chest pain, and short breath was found in both groups, without statistical difference in remission rates between Groups A and B (P>0.05). In conclusion, 125I brachytherapy combined with chemotherapy proved to be safe and effective for treating advanced NSCLC with few complications. It improves local control rate and prolongs the progression-free survival time.
Subjects: Nuclear Science and Technology >> Nuclear Materials and Techniques submitted time 2023-06-18 Cooperative journals: 《Nuclear Science and Techniques》
Abstract: Bleomycins (BLMs), as tumor-seeking antibiotics, have been used for over 20 years in treatment of several types of cancers. Several radioisotopes are used in radiolabeling of BLMs for therapeutic and diagnostic purposes. An important points in developing new radiopharmaceuticals, especially therapeutic agents, is the absorbed dose delivered in critical organs. In this work, absorbed dose to organs after injection of 153Sm-, 177Lu- and 166Ho-labeled BLM was investigated by radiation dose assessment resource (RADAR) method based on biodistribution data in wild-type rats. The absorbed dose effect of the radionuclides was evaluated. The maximum absorbed dose for the complexes was observed in the kidneys, liver and lungs. For all the radiolabeled BLMs, bone and red marrow received considerable absorbed dose. Due to the high energy beta particles emitted by 166Ho, higher absorbed dose is observed for 166Ho-BLM in the most organs. The reported data can be useful for the determination of the maximum permissible injected activity of the radiolabeled BLMs in the treatment planning programs.
Subjects: Nuclear Science and Technology >> Nuclear Materials and Techniques submitted time 2023-06-18 Cooperative journals: 《Nuclear Science and Techniques》
Abstract: To isolate and separate thorium from nitric acid solutions, three silica-based anion exchange resins were synthesized. Batch experiments were carried out to investigate adsorption behavior of thorium in nitric acid solutions. Adsorption at different concentrations of nitric acid and thorium, influence of contact time and coexisting metal ions, and effect of NO3- were investigated in detail. It was found that at high HNO3 concentrations, the resins exhibited higher adsorption capacity and better affinity towards thorium. The adsorption kinetics could be described by the pseudo-second order model equation, while the adsorption isotherms were well correlated by the Langmuir model. The maximum capacity towards thorium species on SiPyR-N4 was evaluated at 27–28 mg/g-resin. The thermodynamic parameters indicated the adsorption was an exothermic reaction. The presence of NO3- was found to promote the retention of the thorium species.
Subjects: Nuclear Science and Technology >> Nuclear Materials and Techniques submitted time 2023-06-18 Cooperative journals: 《Nuclear Science and Techniques》
Abstract: In this paper, the growth curves of yeast cells exposed to X-rays were detected, and then fitted by Gompertz equation. The yeast cells treated with 50–125 Gy showed an increased exponential growth rate, and lower total biomass at plateau. At doses 150 Gy, cells showed a decreased exponential growth rate and higher total biomass at plateau. DNA lesions were detected by comet assay. Meanwhile, intracellular accumulation of reactive oxygen species (ROS), reduction of mitochondrial membrane potential (ΔΨm) and cell membrane integrity were evaluated. We conclude that X-ray irradiation results in DNA lesions, ROS accumulation and ΔΨm decline in a dose-dependent manner, and that these changes may be one of causes of X-rays-induced apoptosis in yeast. Furthermore, yeast cell membrane integrity appeared compromised following irradiation, suggesting that membrane damage may also have a role in the biological effects of radiation.
Subjects: Nuclear Science and Technology >> Nuclear Materials and Techniques submitted time 2023-06-18 Cooperative journals: 《Nuclear Science and Techniques》
Abstract: To develop a microbe-based bioremediation strategy for cleaning up thorium-contaminated sites, we have investigated the biosorption behavior and mechanism of thorium on Bacillus sp. dwc-2, one of the dominant species of bacterial groups isolated from soils in Southwest China. Thorium biosorption depended on the pH of environment, and its rapid biosorption reached a maximum of up to 10.75 mg Th per gram of the bacteria (wet wt.) at pH 3.0. The biosorption agreed bettter with Langmuir isotherm model than Freundlich model, indicating that thorium biosorption was a monolayer adsorption. The thermodynamic parameters, negative change in Gibbs free energy and positive value in enthalpy and entropy, suggested that the biosorption was spontaneous, more favorable at higher temperature and endothermic process with an increase of entropy. Scanning electron microscopy (SEM) indicated that thorium initially binded with the cell surface, while transmission electron microscopy (TEM) revealed that Th deposited in the cytoplasm and served as cores for growth of element precipitation (e.g., phosphate minerals) or by self-precipitation of hydroxides, which is probably controlled by ion-exchange, as evidenced by particle induced X-ray emission (PIXE) and enhanced proton backscattering spectrometry (EPBS). Fourier Transform Infrared (FTIR) further indicated that thorium biosorption involved carboxyl and phosphate groups and protein in complexation or electrostatic interaction. Overall results indicated that a combined electrostatic interaction-complexation-ion exchange mechanism could be involved in thorium biosorption by Bacillus sp. dwc-2.
Subjects: Nuclear Science and Technology >> Nuclear Materials and Techniques submitted time 2023-06-18 Cooperative journals: 《Nuclear Science and Techniques》
Abstract: As a potential matrix of three-dimensional gel dosimeter, agarose hydrogels will be used for measuring radiation doses, hence the importance of studying their radiation resistance and radiolysis mechanism. Physical property and chemical structure of physically cross-linked agarose hydrogel samples irradiated to 0–200 kGy by 60Co γ-rays were analyzed by universal testing machine, gel permeation chromatography, fourier transform infrared spectrometer, ultraviolet visible spectroscopy, nuclear magnetic resonance, and gas chromatography. The results showed that agarose hydrogels had good radiation stability below 25 kGy, and the maximum compression strength of sample was ca. 0.1 MPa at 25 kGy. The irradiated samples degraded obviously and liquefied gradually with increasing doses. Compared with unirradiated sample, carbonyl groups, which generated from the molecular chains of agarose hydrogels, were observed at 25 kGy and increased gradually with dose. The main gas products evolved from irradiated agarose hydrogels were H2, CO2, CO and CH4. Based on the analysis of radiolytic products, the radiolysis mechanism of agarose hydrogels under γ-radiation was proposed.
Subjects: Nuclear Science and Technology >> Nuclear Materials and Techniques submitted time 2023-06-18 Cooperative journals: 《Nuclear Science and Techniques》
Abstract: Understanding uranium-protein interaction is important for revealing the mechanism of uranyl ion (UO22+) toxicity. In this study, we investigated the interaction between UO22+ and a quadruple mutant of cytochrome b5 (E44/48/56A/D60A cyt b5, namely 4A cyt b5) by spectroscopic approaches. The four mutated negatively-charged surface residues of cyt b5 have been considered to be the interactive sites with cytochrome c (cyt c). Also, we studied the interaction between UO22+ and the protein-protein complex of 4A cyt b5-cyt c. The results were compared to the interaction between UO22+ and cyt b5, and the interaction between cyt c and cyt b5-cyt c complex, from previous studies. It was found that the interaction of UO22+-cyt b5, i.e., uranyl ion binding to cyt b5 surface at Glu37 and Glu43 as previously proposed by molecular modeling, is regulated by both surface mutations of cyt b5 and its interacting protein partner cyt c. These provide valuable information on metal-protein-protein interactions and clues for understanding the mechanism of uranyl toxicity.
Subjects: Nuclear Science and Technology >> Nuclear Materials and Techniques submitted time 2023-06-18 Cooperative journals: 《Nuclear Science and Techniques》
Abstract: Diffusion behaviors of Se(IV) and Re(VII) in bentonite were investigated by a through-diffusion method in nitrate, sulfate, carbonate and silicate solutions. SEM-EDS analysis showed that Se(IV) was reduced to red precipitate Se(0) by sulfite. Se(IV) was sorbed on bentonite with distribution coefficient Kd of (2.6–5.3)×10-4 m3/kg in sulfite, nitrate and sulfate solutions, whereas it was hardly sorbed in carbonate and silicate solutions. The effective diffusion coefficients were De= (0.81–7.0)×10-11 m2/s for Se(IV) and De= (1.4–4.4)×10-11 m2/s for Re(VII). The De value of Se(IV) exhibited a dependence on the inorganic salts in the order of sulfite ≈ nitrate ≈ sulfate > silicate > carbonate, whereas the salts had insignificant effect on Re(VII) diffusion. The results suggest that the discrepancy in diffusion mechanism may lead to the different impact of the salts on the diffusion of Se(IV) and Re(VII) in GMZ bentonite.
Subjects: Nuclear Science and Technology >> Nuclear Materials and Techniques submitted time 2023-06-18 Cooperative journals: 《Nuclear Science and Techniques》
Abstract: The gel dosimeter has the uniquely capacity in recording radiation dose distribution in three dimensions (3D), which has the specific advantages in dosimetry measurements where steep dose gradients exist. In this study, a novel radiochromic gel dosimeter was developed by dispersing nanovesicles self-assembled by 10, 12-pentacosadiynoic acid (PCDA) into the tissue equivalence gel matrix. The characteristics of radiochromic PCDA vesicle gel dosimeters were evaluated. Results indicate that these radiochromic gel dosimeters have good linear response to 1.7 MeV electron beam irradiation in the dose range of 0.32–6.36 kGy. In addition, the radiochromic gel dosimeters overcome the limitations of the existing gel dosimeters such as diffusion effect, post-radiation effect, and poor forming ability. Hence, the radiochromic PCDA vesicle gel dosimeters developed could be generally applied to 3D dose distribution measurement with optical readout.
Subjects: Nuclear Science and Technology >> Nuclear Materials and Techniques submitted time 2023-06-18 Cooperative journals: 《Nuclear Science and Techniques》
Abstract: Instrumental neutron activation analysis (INAA) has been used to determine some chemical element contents (K, Ca, Na, Fe, Zn, Co, Eu, Sb, and Sc) in Traganum nudatum Del (Chenopodiaceae family) consumed in North African rangelands by sheep livestock. Samples were collected from the area of Djelfa in an arid steppe of Algeria. Results show that pasture halophyte had sufficient levels of K, Ca, Zn, and Co to meet the requirements of ruminants. However, it seems that this halophyte shrub had substantial amounts of Na, higher than the critical level established by the National Research Council (NRC). Eu, Sb, and Sc were within the safety baseline of all the assayed elements recommended by the NRC. The high Na content (∼ 10 g/kg) in this halophytic species requires elevated intake of water by livestock.
Subjects: Nuclear Science and Technology >> Nuclear Materials and Techniques submitted time 2023-06-18 Cooperative journals: 《Nuclear Science and Techniques》
Abstract: To prevent radioactive iodides from releasing into the environment in an accident of a nuclear power plant, silver-impregnated alumina (Ag/Al2O3) was fabricated, and its performance of radioactive iodine adsorption from high-temperature gas was tested. The silver loadings on alumina were obtained by ICP-OES and the texture properties of Ag/Al2O3 were characterized by N2 adsorption-desorption. The Ag/Al2O3 was of reduced specific surface (107.2 m2/g at 650 ℃). Crystalline phases of Ag/Al2O3 were confirmed through XRD characterization. After calcination at 650 ℃ for 2 h, the crystalline phase of Ag/Al2O3 changed. The 131I- removal efficiency of Ag/Al2O3 was tested at 100, 250, 350, 450 and 650 ℃, with good decontamination factor values for the radioactive iodine. Silver-impregnated alumina can be applied as adsorbents to remove radioactive iodine at high temperatures in nuclear accident.
Subjects: Nuclear Science and Technology >> Nuclear Materials and Techniques submitted time 2023-06-18 Cooperative journals: 《Nuclear Science and Techniques》
Abstract: Uranium removal efficacy of fullerence multi-macrocyclic polyamine derivatives (C60-MMP), a novel chelating agent, was evaluated in mice. C60-MMP was administrated intravenously into mice at 30 min after the uranium contamination. The molar ratio of chelating ligand/uranium was about 1:1. The results indicate that C60-MMP can effectively prevent accumulation of uranium in liver at 8 h after C60-MMP injection. At 48 h after the last injection, uranium deposition in liver of C60-MMP treated mice is approximately 65% less than that of the control group. C60-MMP reacted positively in promoting the removal of uranium from kidney, and the urinary uranium excretion increased significantly, compared with the control and DTPA-treated mice. However, repeated administration of C60-MMP, and combined injection of DTPA and C60-MMP, did not show desirable effects on uranium removal from mice. It implies that more investigations are needed for the treatment protocols and clinical applications of C60-MMP.