分类: 核科学技术 >> 核材料与工艺技术 提交时间: 2024-06-11
摘要: 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.
分类: 核科学技术 >> 核材料与工艺技术 提交时间: 2024-04-20
摘要: 经过几十年的研究,对现有反应堆合金材料服役工况下的腐蚀问题及规律已经有了较为清晰的认识,但是依然存在一些待解决的问题,如反应堆合金材料腐蚀中本质过程的理解,单一因素在腐蚀过程中所起的作用,新材料以及极端环境下的腐蚀行为预测等。基于量子力学的密度泛函理论计算可以精确地预测极短时间内原子的运动过程以及相关能量的变化,近年来逐渐成为反应堆合金材料腐蚀过程研究的重要辅助手段,这将有助于解决上述问题。本文首先介绍了密度泛函理论方法,主要包括理论基础、发展过程与主流计算软件。之后,综述了密度泛函理论在反应堆合金材料腐蚀领域应用的研究现状,包括水冷堆、液态金属冷却堆、熔盐堆介质环境中反应堆合金材料表面的吸附、解离、结合、内部扩散等腐蚀行为。
分类: 核科学技术 >> 核材料与工艺技术 提交时间: 2024-03-25
摘要: 氧化石墨烯(Graphene Oxide,GO)掺杂改性二氧化铀(UO2)芯块是高性能核燃料研究的重点方向之一。为实现GO在UO2芯块中的均匀分布及掺杂量控制,利用固-液混合法和ADU(Ammonium diuranate)共沉淀法制备了不同GO掺杂量的UO2粉末,研究了制粉方法及GO掺杂量对GO在UO2中混合均匀性的影响。采用放电等离子烧结制备了不同GO掺杂量的UO2-GO芯块,探索了不同烧结参数的影响,并对燃料芯块的性能进行测试。结果表明,固-液混合法制备的GO掺杂UO2粉末混合均匀度更好;放电等离子烧结得到的UO2-GO芯块密度最高可达97.6% T.D.;GO掺杂量为1.5 wt.%的芯块在1000 ℃下的热导率较常规UO2芯块提高了85.9%;制备的UO2-GO芯块晶粒尺寸较为均匀,GO均匀分布在晶界处并形成了桥联导热网络,有效提升了掺杂芯块的热导率。
分类: 核科学技术 >> 核材料与工艺技术 提交时间: 2024-03-20
摘要: 在第四代反应堆中,核石墨作为慢化体和反射体材料服役于高温和高通量的快中子辐照环境中。快中子辐照会在核石墨中产生大量的弗伦克尔缺陷对。这些缺陷经过湮灭、扩散、最终形成更大的缺陷团簇,从而改变核石墨的微观结构,进而改变核石墨的宏观性能。因此,研究核石墨在高温辐照条件下的缺陷演化行为和机理对提高反应堆安全性具有重要意义。本研究采用30 MeV的107Ag5+离子在420 ℃下辐照IG-110核石墨来模拟核石墨在快中子辐照过程中的缺陷演化行为。通过微区拉曼光谱对IG-110核石墨截面结构进行表征,并对比IG-110核石墨不同深度处的拉曼光谱特征参数和辐照损伤剂量之间的关系,研究IG-110微观结构随辐照损伤剂量(DPA, Displacements Per Atom)的演化行为。研究结果表明,随着注量的增加,核石墨拉曼光谱的特征参数D峰高度与G峰高度比值(ID/IG)、G峰半高宽(FWHM(G), Full Width at Half Maximum of the G peak)以及G峰的偏移量都显著增加。与58Ni5+辐照样品相比,相同辐照损伤剂量下, 107Ag5+辐照的石墨拉曼光谱的ID/IG和FWHM(G)更大。相同的FWHM(G)下,107Ag5+辐照的石墨拉曼光谱的ID/IG比58Ni5+辐照样品大。这些结果说明更重的重离子辐照会在核石墨中引起更高速率的缺陷积累,从而更快地导致石墨晶粒尺寸变小,并促进纳米晶化进程。
分类: 核科学技术 >> 核材料与工艺技术 提交时间: 2024-03-13
摘要: 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.
分类: 核科学技术 >> 核材料与工艺技术 提交时间: 2024-02-20
摘要: 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.
分类: 核科学技术 >> 核材料与工艺技术 提交时间: 2023-08-14
摘要: 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 -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 2* 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.
分类: 核科学技术 >> 核材料与工艺技术 提交时间: 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要: 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.
分类: 核科学技术 >> 核材料与工艺技术 提交时间: 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要: 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 (PP>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.
分类: 核科学技术 >> 核材料与工艺技术 提交时间: 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要: 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.
分类: 核科学技术 >> 核材料与工艺技术 提交时间: 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要: 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 2728 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.
分类: 核科学技术 >> 核材料与工艺技术 提交时间: 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要: 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 50125 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 (m) and cell membrane integrity were evaluated. We conclude that X-ray irradiation results in DNA lesions, ROS accumulation and m 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.
分类: 核科学技术 >> 核材料与工艺技术 提交时间: 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要: 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.
分类: 核科学技术 >> 核材料与工艺技术 提交时间: 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要: 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 0200 kGy by 60Co -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 -radiation was proposed.
分类: 核科学技术 >> 核材料与工艺技术 提交时间: 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要: 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.
分类: 核科学技术 >> 核材料与工艺技术 提交时间: 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要: 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 (2.65.3)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= (0.817.0)10-11 m2/s for Se(IV) and De= (1.44.4)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.
分类: 核科学技术 >> 核材料与工艺技术 提交时间: 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要: 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 0.326.36 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.
分类: 核科学技术 >> 核材料与工艺技术 提交时间: 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要: 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.
分类: 核科学技术 >> 核材料与工艺技术 提交时间: 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要: 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.
分类: 核科学技术 >> 核材料与工艺技术 提交时间: 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要: 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.