X-ray photon correlation spectroscopy(XPCS)has emerged as a powerful tool for probing the nanoscale dynamics of soft condensed matter and strongly correlated materials owing to its high spatial resolution and penetrat...X-ray photon correlation spectroscopy(XPCS)has emerged as a powerful tool for probing the nanoscale dynamics of soft condensed matter and strongly correlated materials owing to its high spatial resolution and penetration capabilities.This technique requires high brilliance and beam coherence,which are not directly available at modern synchrotron beamlines in China.To facilitate future XPCS experiments,we modified the optical setup of the newly commissioned BL10U1 USAXS beamline at the Shanghai Synchrotron Radiation Facility(SSRF).Subsequently,we performed XPCS measurements on silica suspensions in glycerol,which were opaque owing to their high concentrations.Images were collected using a high frame rate area detector.A comprehensive analysis was performed,yielding correlation functions and several key dynamic parameters.All the results were consistent with the theory of Brownian motion and demonstrated the feasibility of XPCS at SSRF.Finally,by carefully optimizing the setup and analyzing the algorithms,we achieved a time resolution of 2 ms,which enabled the characterization of millisecond dynamics in opaque systems.展开更多
Electrocatalytic reduction of carbon dioxide(CO_(2))to carbon monoxide(CO)is an effective strategy to achieve carbon neutrality.High selective and low-cost catalysts for the electrocatalytic reduction of CO_(2)have re...Electrocatalytic reduction of carbon dioxide(CO_(2))to carbon monoxide(CO)is an effective strategy to achieve carbon neutrality.High selective and low-cost catalysts for the electrocatalytic reduction of CO_(2)have received increasing attention.In contrast to the conventional tube furnace method,the high-temperature shock(HTS)method enables ultra-fast thermal processing,superior atomic efficiency,and a streamlined synthesis protocol,offering a simplified method for the preparation of high-performance single-atom catalysts(SACs).The reports have shown that nickel-based SACs can be synthesized quickly and conveniently using the HTS method,making their application in CO_(2)reduction reactions(CO_(2)RR)a viable and promising avenue for further exploration.In this study,the effect of heating temperature,metal loading and different nitrogen(N)sources on the catalyst morphology,coordination environment and electrocatalytic performance were investigated.Under optimal conditions,0.05Ni-DCD-C-1050 showed excellent performance in reducing CO_(2)to CO,with CO selectivity close to 100%(−0.7 to−1.0 V vs RHE)and current density as high as 130 mA/cm^(2)(−1.1 V vs RHE)in a flow cell under alkaline environment.展开更多
In-situ TEM observation was conducted during Ni^(+)&He^(+)dual-beam irradiation to monitor the evolution of dislocation loops accompanied by He bubbles in the Ni-based alloy GH3535.Two distinct evolutions of dislo...In-situ TEM observation was conducted during Ni^(+)&He^(+)dual-beam irradiation to monitor the evolution of dislocation loops accompanied by He bubbles in the Ni-based alloy GH3535.Two distinct evolutions of dislocation loops,driven by residual stresses,were observed within the monitored grains.Hence,molec-ular dynamics(MD)simulations were employed to reveal the effects of stress magnitude and direction on loop evolution,including size,number density,type and variation.The simulations revealed that the presence of compressive stress reduced the formation energy of perfect dislocation loops,thus promoting their formation.Stress state was found to influence the preferential orientation of the loops,and com-pressive stress resulted in a decreased number density of dislocation loops but an increase in their size.This establishes a clear relationship between stress state and magnitude and the evolution of dislocation loops during ion beam irradiation.Additionally,the nature and characteristics of dislocation loops were quantified to explore the effects of He concentrations on their evolution.The higher He concentration not only promotes the nucleation of dislocation loops,leading to their higher number density,but also facil-itates the unfaulting evolution by increasing the stacking fault energy(SFE).Moreover,the accumulation of He in the lower-He-concentration sample led to the growth of dislocation loops in multiple stages,explaining their nearly identical average sizes when compared to the higher-He-concentration sample.展开更多
A comprehensive understanding of the dynamic processes at the catalyst/electrolyte interfaces is crucial for the development of advanced electrocatalysts for the oxygen evolution reaction(OER).However,the chemical pro...A comprehensive understanding of the dynamic processes at the catalyst/electrolyte interfaces is crucial for the development of advanced electrocatalysts for the oxygen evolution reaction(OER).However,the chemical processes related to surface corrosion and catalyst degradation have not been well understood so far.In this study,we employ LiCoO_(2) as a model catalyst and observe distinct OER activities and surface stabilities in different alkaline solutions.Operando X-ray diffraction(XRD)and online mass spectroscopy(OMS)measurements prove the selective intercalation of alkali cations into the layered structure of LiCoO_(2) during OER.It is proposed that the dynamic cation intercalations facilitate the chemical oxidation process between highly oxidative Co species and adsorbed water molecules,triggering the so-called electrochemical-chemical reaction mechanism(EC-mechanism).The results of this study emphasize the influence of cations on OER and provide insights into new strategies for achieving both high activity and stability in high-performance OER catalysts.展开更多
The operational lifespan of nuclear graphite is significantly affected by irradiation creep,yet the microstructural mechanism underlying this creep phenomenon remains unclear.Some theories attempt to link microstructu...The operational lifespan of nuclear graphite is significantly affected by irradiation creep,yet the microstructural mechanism underlying this creep phenomenon remains unclear.Some theories attempt to link microstructural evolution with creep behavior,but the rapid migration rate of defects under irradiation and loading makes it difficult to capture the specific evolution process experimentally,resulting in a lack of direct structural evidence.Therefore,in this study,molecular dynamics simulations are employed to investigate the irradiation behavior and microstructural migration under external loading.The aim is to provide microstructural evidence for theories such as the dislocation pinning-unpinning and crystal yielding.The results demonstrate that high tensile loads can increase the potential energy and reduce threshold displacement energy of graphite crystals.Consequently,displacement damage probability and creep rate increase,which is not considered in previous theories.Meanwhile,different creep mechanisms are observed at different damage states and applied loads.In low-dose damage states dominated by interstitials and vacancies,the pinning-unpinning process at basal plane may be caused by a defect diffusion mode.Under high stress levels,direct breaking of pinning structures occurs,leading to rapid migration of basal planes,demonstrating the microstructural evolution process of irradiated crystal yielding and plastic flow.In high-dose damage states characterized significantly by amorphous components,short-range atomic diffusion can become the dominant creep mechanism,and diffusion along the c-axis of graphite crystals is no longer constrained.These findings provide a crucial reference for understanding the irradiation and creep behavior of nuclear graphite in reactors.展开更多
Molten salt reactors(MSRs)are a promising candidate for Generation IV reactor technologies,and the small modular molten salt reactor(SM-MSR),which utilizes low-enriched uranium and thorium fuels,is regarded as a wise ...Molten salt reactors(MSRs)are a promising candidate for Generation IV reactor technologies,and the small modular molten salt reactor(SM-MSR),which utilizes low-enriched uranium and thorium fuels,is regarded as a wise development path to accelerate deployment time.Uncertainty and sensitivity analyses of accidents guide nuclear reactor design and safety analyses.Uncertainty analysis can ascertain the safety margin,and sensitivity analysis can reveal the correlation between accident consequences and input parameters.Loss of forced cooling(LOFC)represents an accident scenario of the SM-MSR,and the study of LOFC could offer useful information to improve physical thermohydraulic and structural designs.Therefore,this study investigates the uncertainty of LOFC consequences and the sensitivity of related parameters.The uncertainty of the LOFC consequences was analyzed using the Monte Carlo method,and multiple linear regression was employed to analyze the sensitivity of the input parameters.The uncertainty and sensitivity analyses showed that the maximum reactor outlet fuel salt temperature was 725.5℃,which is lower than the acceptable criterion,and five important parameters influencing LOFC consequences were identified.展开更多
In this study,the corrosion and cracking behavior of the GH3535 alloy exposed to molten FLiNaK salts(46.5LiF-11.5NaF-42KF,mol%)with 0 and 0.1wt.%Cr_(3)Te_(4)and 0,1 and 3wt.%EuF_(3)additions at 700℃ for 250 h were in...In this study,the corrosion and cracking behavior of the GH3535 alloy exposed to molten FLiNaK salts(46.5LiF-11.5NaF-42KF,mol%)with 0 and 0.1wt.%Cr_(3)Te_(4)and 0,1 and 3wt.%EuF_(3)additions at 700℃ for 250 h were investigated.The results showed that all the samples exposed to tellurium containing salts exhibited intergranular corrosion and cracking,and the cracking severity increased with the increasing EuF_(3)concentration.Among them,the average and maximum cracking depths were 164 and 57.1μm,respectively.In contrast,the control sample exposed to salt without Te exhibited less evident intergranular corrosion and no intergranular cracking.These results demonstrate that the synergistic effect between EuF_(3) and Cr_(3)Te_(4) promotes grain boundary Te segregation and Cr depletion,resulting in more severe intergranular cracking.展开更多
High-loading Pt/C catalysts play an important role in the fabrication of membrane electrode assemblies with thin catalytic layer,which enhance mass transport and maintain the balance of water and heat.Unfortunately,as...High-loading Pt/C catalysts play an important role in the fabrication of membrane electrode assemblies with thin catalytic layer,which enhance mass transport and maintain the balance of water and heat.Unfortunately,as the loading increases,the agglomeration and growth of Pt nanoparticles(NPs)occur,causing unsatisfactory performance.Here,we present an efficient method for preparing of highly dispersed and small-sized Pt/C catalysts with Pt loadings varying from 39.01 wt%to 66.48 wt%through the high-temperature shock technique.The high density and ultrafine(~2.5 nm)Pt NPs are successfully anchored onto Vulcan XC-72R carbon black without the use of additional capping agents or surfactants.The modified carbon supports enhance the affinity for Pt precursors,contributing to loading efficiencies of 95%or more,while also providing abundant sites for the nucleation and fixation of Pt NPs,thus preventing agglomeration.In the context of the hydrogen evolution reaction in acidic media,the as-synthesized high-loading Pt/C catalysts show remarkable activity and stability,outperforming the state-of-the-art commercial Pt/C.This is mainly because the combined effects of ultrasmall and uniform Pt NPs,optimized electronic structure of Pt site,superhydrophilicity and effective anchoring of Pt NPs.The polymer electrolyte membrane electrolyzer integrated with Pt60/OX72R and commercial IrO2 reaches 1 A cm^(-2)at 1.77 V and operates stably for 120 hours with a negligible voltage decay.This new strategy is fast,scalable and cost-effective for large-scale production of metal-supported catalysts,especially for the high-loading ones.展开更多
In recent years,due to the scarcity of domestic radioisotopes,the Chinese government has strongly supported the development of dedicated radioisotope production facilities.This paper presents conceptual design simulat...In recent years,due to the scarcity of domestic radioisotopes,the Chinese government has strongly supported the development of dedicated radioisotope production facilities.This paper presents conceptual design simulations of an 11 MeV,50μA,H^(-) compact superconducting cyclotron for radioisotope production.This paper focuses primarily on four aspects:magnet system design,central region configuration,beam dynamics analysis,and extraction system design.This paper outlines the cyclotron's primary parameters and key steps in the development process.展开更多
Correction:Nuclear Science and Techniques(2025)36:4 https://doi.org/10.1007/s41365-024-01548-5 In this article,the caption for Fig(s)1,3,and 4 was inadvert-ently truncated.The incorrect and the corrected captions are ...Correction:Nuclear Science and Techniques(2025)36:4 https://doi.org/10.1007/s41365-024-01548-5 In this article,the caption for Fig(s)1,3,and 4 was inadvert-ently truncated.The incorrect and the corrected captions are given below.展开更多
Partitioning of actinides from lanthanides is pivotal for advancing nuclear waste management and sustaining nuclear energy development,yet it remains a formidable challenge due to the intricate chemical behaviors of t...Partitioning of actinides from lanthanides is pivotal for advancing nuclear waste management and sustaining nuclear energy development,yet it remains a formidable challenge due to the intricate chemical behaviors of these f-block elements.In this study,we introduce 3,6-di-2-pyridyl-1,2,4,5-tetrazine(L1),whose hydrolysis product of pyridine-2-carbox-aldehyde(pyridine-2-carbonyl)-hydrazone(L2)can fractionally crystallize U(Ⅵ)ions over Ln(Ⅲ)cations with high selectivity and efficiency.Through hydrolysis-induced C–N bond cleavage,L2 acts as a tetradentate ligand,coordinating with two UO_(2)^(2+) ions in a planar arrangement to form a zerodimensional cluster,[(UO_(2))2(μ_(3)-O)(L2)(CH_(3)COO)]·DMF(U-L2),while lanthanide ions(Ln=La,Pr,Nd,Sm,Eu,Gd,Tb,Yb,and Lu)remain in solution due to their inability to achieve similar coordination.This selective crystallization strategy yields exceptional separation factors(SFs)between U(Ⅵ)and Ln(Ⅲ),with a value of 756276 between U(Ⅵ)and Sm(Ⅲ),the highest reported to date.Furthermore,this fractional crystallization separation process can be achieved under mild ambient conditions with high SFs,enabling the development of a rapid,safe and energy-efficient strategy for once-through separation of high oxidation state actinides from lanthanides.展开更多
Radio frequency(RF)cavities for advanced storage rings,also known as diffraction-limited storage rings,are under development.To this end,a competitive and promising approach involves normal-conducting continuous wave ...Radio frequency(RF)cavities for advanced storage rings,also known as diffraction-limited storage rings,are under development.To this end,a competitive and promising approach involves normal-conducting continuous wave technology.The design and preliminary test of a 499.654 MHz RF cavity for the Wuhan Advanced Light Source(WALS)based on specific beam parameters were conducted at the SSRF.Multi-objective evolutionary algorithms have been utilized to optimize RF properties,such as the power loss and power density,resulting in better performance in the continuous wave mode.Further improvements were made to suppress multipacting effects in the working area.To operate stably with the beam,higher-order mode dampers were applied to better address the coupling bunch instability than in previous designs,along with thermal analysis to achieve the desired RF performance.Comprehensive simulation studies demonstrated the stable operation of the RF cavity at the defined beam parameters in the WALS design.A prototype RF cavity was then developed,and the RF performance results in a low-power test showed good agreement with the design and simulation,exhibiting readiness for high-power experiments and operation.展开更多
The synergistic effects of irradiation and tensile deformation on the corrosion behavior of the GH3535 alloy in FLi-NaK molten salt were explored.Helium bubbles were introduced into the GH3535 alloy,followed by mechan...The synergistic effects of irradiation and tensile deformation on the corrosion behavior of the GH3535 alloy in FLi-NaK molten salt were explored.Helium bubbles were introduced into the GH3535 alloy,followed by mechanical loading with the plastic strain up to 10%.After immersion in molten salt for 300 h,all the samples exhibited a corrosion-induced Cr depletion layer.The depth of the Cr depletion layer increased by 40% for the alloy with helium ion irradiation and 10% plastic deformation,compared with that for the only corroded sample.Moreover,the proportion of large-sized helium bubbles increased with plastic deformation.These results indicate that the coupling effects of irradiation and tensile deformation accelerate the corrosion of the GH3535 alloy.In addition,in a molten salt environment,an unexpected outward migration behavior of helium bubbles was observed under different plastic deformation.Helium bubbles migrated closer to the surface as the strain increased up to 3%,while the migration depth declined when the strain reached 10%.This is ascribed to the interaction between deformation-induced dislocations and helium bubbles.展开更多
The stability of matrix graphite under neutron irradiation and in corrosive environments is crucial for the safe operation of molten salt reactors(MSRs).Raman spectroscopy and a slow positron beam were employed to inv...The stability of matrix graphite under neutron irradiation and in corrosive environments is crucial for the safe operation of molten salt reactors(MSRs).Raman spectroscopy and a slow positron beam were employed to investigate the effects of He ion irradiation fluences and subsequent annealing on the microstructure and defects of the matrix graphite.He ions with 500 keV energy and fluences ranging from 1.1×10^(15)ions∕cm^(2)to 3.5×10^(17)ions∕cm^(2)were used to simulate neutron irradiation at 300 K.The samples with an irradiation fluence of 3.5×10^(16)ions∕cm^(2)were subjected to isochronal annealing at different temperatures(573 K,873 K and 1173 K)for 3 h.The Raman results revealed that the D peak gradually increased,whereas the intrinsic G peak decreased with increasing irradiation fluence.At the same irradiation fluence,the D peak gradually decreased,whereas the intrinsic G peak increased with increasing annealing temperature.Slow positron beam analysis demonstrated that the density or size of irradiation defects(vacancy type)increased with higher irradiation fluence,but decreased rapidly with increasing annealing temperature.The Raman spectral analysis of sample cross sections subjected to high irradiation fluences revealed the emergence of amorphization precisely at the depth where ion damage was most pronounced,whereas the surface retained its crystalline structure.Raman and positron annihilation analyses indicated that the matrix graphite exhibited good irradiation resistance to He ions at 300 K.However,vacancy-type defects induced by He ion irradiation exhibit poor thermal stability and can be easily removed during annealing.展开更多
Identifying the damage and fracture properties of nuclear graphite materials and accurately simulating them are crucial when designing graphite core structures.To simulate the damage evolution and crack propagation of...Identifying the damage and fracture properties of nuclear graphite materials and accurately simulating them are crucial when designing graphite core structures.To simulate the damage evolution and crack propagation of graphite under stress in a finite element model,compression tests on disks and three-point bending tests on center-notched beams for fine-grained graphite(CDI-1D and IG11 graphite)were conducted.During these tests,digital image correlation and electronic speckle pattern interferometry techniques were utilized to observe the surface full-field displacements of the specimens.A segmented finite element inverse analysis method was developed to characterize the graphite’s damage evolution by quantifying the reduction in Young’s modulus with tensile and compressive strains in disk specimens.The fracture energy and bilinear tensile softening curve of the graphite were determined by comparing the load–displacement responses of the three-point bending tests and the finite element simulation.Finally,by combining the identified damage laws with a fracture criterion based on fracture energy,a damage–fracture model was established and used to simulate tensile tests on L-shaped specimens with different fillet radii.Simulations indicate that the damage area at the fillet expands with increasing radius,creating a blunting effect that enhances the load-bearing capacity of the specimens.This damage–fracture model can be applied to simulate graphite components in core structures.展开更多
Most synchrotron light storage rings are equipped with a higher harmonic cavity(HHC)and are currently predominantly used to increase beam life.With the enhancement of the beam current intensity,it is necessary to cons...Most synchrotron light storage rings are equipped with a higher harmonic cavity(HHC)and are currently predominantly used to increase beam life.With the enhancement of the beam current intensity,it is necessary to consider instability problems that may be caused by heavy beam loading effects.In this study,we incorporated a HHC into the small-signal Pedersen mathematical model and used system signal analysis to investigate the mode-zero Robinson instability driven by the passive superconducting harmonic cavity and active superconducting harmonic cavity fundamental modes.To further study and alleviate this instability,we introduced direct radio-frequency feedback,an automatic voltage control loop,and a phase-lock loop into the model,discussed the impact of the feedback loop parameter settings on the stability margin,and provided suggestions for parameter settings.展开更多
As a representative of non-evaporative getter,Zr-V-Fe has gained widespread attention due to its advantages including low activation temperatures and rapid hydrogen absorption rates.In this study,we investigated the i...As a representative of non-evaporative getter,Zr-V-Fe has gained widespread attention due to its advantages including low activation temperatures and rapid hydrogen absorption rates.In this study,we investigated the impact of La and Ce doping on the thermodynamic,kinetic,and activation properties of Zr_(7)V_(5)Fe alloy.X-ray diffraction analysis shows that rare earth doping causes a decrease in the cell volume of both the ZrV_(2) andα-Zr phases of Zr_(7)V_(5)Fe alloy,which results in an increase in the plateau pressure of the alloys.The kinetic curves illustrate that rare earth doping leads to a coarseα-Zr phases and a larger particle size after activation,resulting in a decrease in the hydrogen absorption kinetic properties.As for the activation process,the rare earth doped alloys exhibit excellent activation with shorter incubation periods.X-ray photoelectron spectroscopy investigations reveal that Zr and V are initially in a highly oxidized state.As the heating temperature increases,they undergo a transition from oxidation state to metal state.The content of metal Zr in rare earth doped alloys is higher than that in undoped alloys at 250℃,primarily due to rare earth elements'affinity for oxygen.展开更多
We present new data on the^(63)Cu(γ,n)cross-section studied using a quasi-monochromatic and energy-tunableγbeam produced at the Shanghai Laser Electron Gamma Source to resolve the long-standing discrepancy between e...We present new data on the^(63)Cu(γ,n)cross-section studied using a quasi-monochromatic and energy-tunableγbeam produced at the Shanghai Laser Electron Gamma Source to resolve the long-standing discrepancy between existing measurements and evaluations of this cross-section.Using an unfolding iteration method,^(63)Cu(γ,n)data were obtained with an uncertainty of less than 4%,and the inconsistencies between the available experimental data were discussed.Theγ-ray strength function of^(63)Cu(γ,n)was successfully extracted as an experimental constraint.We further calculated the cross-section of the radiative neutron capture reaction^(62)Cu(n,γ)using the TALYS code.Our calculation method enables the extraction of(n,γ)cross-sections for unstable nuclides.展开更多
Photonuclear data are increasingly used in fundamental nuclear research and technological applications.These data are generated using advanced γ-ray sources.The Shanghai laser electron gamma source(SLEGS)is a new las...Photonuclear data are increasingly used in fundamental nuclear research and technological applications.These data are generated using advanced γ-ray sources.The Shanghai laser electron gamma source(SLEGS)is a new laser Compton scattering γ-ray source at the Shanghai Synchrotron Radiation Facility.It delivers energy-tunable,quasi-monoenergetic gamma beams for high-precision photonuclear measurements.This paper presents the flat-efficiency detector(FED)array at SLEGS and its application in photoneutron cross-section measurements.Systematic uncertainties of the FED array were determined to be 3.02%through calibration with a ^(252)Cf neutron source.Using ^(197)Au and ^(159)Tb as representative nuclei,we demonstrate the format and processing methodology for raw photoneutron data.The results validate SLEGS’capability for high-precision photoneutron measurements.展开更多
The accurate photoneutron cross section of the^(27)Al nucleus has a significant impact on resolving differences in existing experimental data and enhancing the precision of nuclear reaction rate calculations for^(26)A...The accurate photoneutron cross section of the^(27)Al nucleus has a significant impact on resolving differences in existing experimental data and enhancing the precision of nuclear reaction rate calculations for^(26)Al in nuclear astrophysics.The photoneutron cross sections for the^(27)Al(γ,n)^(26)Al reaction,within the neutron separation energy range of 13.2-21.7 MeV,were meticulously measured using a new flat efficiency detector array at the Shanghai Laser-Electron Gamma Source.The uncertainty of the data was controlled to below 4%throughout the process,and inconsistencies between the present data and existing data from different gamma sources,as well as the TENDL-2021 data,are discussed in detail.These discussions provide a valuable reference for addressing discrepancies in the^(27)Al(γ,n)^(26)Al cross-section data and improving related theoretical calculations.展开更多
基金This work was supported by National Natural Science Foundation of China(No.12075304)Natural Science Foundation of Shanghai(No.22ZR1442100)National Key Research and Development Program of China(No.2022YFB3503904).
文摘X-ray photon correlation spectroscopy(XPCS)has emerged as a powerful tool for probing the nanoscale dynamics of soft condensed matter and strongly correlated materials owing to its high spatial resolution and penetration capabilities.This technique requires high brilliance and beam coherence,which are not directly available at modern synchrotron beamlines in China.To facilitate future XPCS experiments,we modified the optical setup of the newly commissioned BL10U1 USAXS beamline at the Shanghai Synchrotron Radiation Facility(SSRF).Subsequently,we performed XPCS measurements on silica suspensions in glycerol,which were opaque owing to their high concentrations.Images were collected using a high frame rate area detector.A comprehensive analysis was performed,yielding correlation functions and several key dynamic parameters.All the results were consistent with the theory of Brownian motion and demonstrated the feasibility of XPCS at SSRF.Finally,by carefully optimizing the setup and analyzing the algorithms,we achieved a time resolution of 2 ms,which enabled the characterization of millisecond dynamics in opaque systems.
基金supported by the National Key R&D Program of China(2024YFB4106400)National Natural Science Foundation of China(22209200,52302331)。
文摘Electrocatalytic reduction of carbon dioxide(CO_(2))to carbon monoxide(CO)is an effective strategy to achieve carbon neutrality.High selective and low-cost catalysts for the electrocatalytic reduction of CO_(2)have received increasing attention.In contrast to the conventional tube furnace method,the high-temperature shock(HTS)method enables ultra-fast thermal processing,superior atomic efficiency,and a streamlined synthesis protocol,offering a simplified method for the preparation of high-performance single-atom catalysts(SACs).The reports have shown that nickel-based SACs can be synthesized quickly and conveniently using the HTS method,making their application in CO_(2)reduction reactions(CO_(2)RR)a viable and promising avenue for further exploration.In this study,the effect of heating temperature,metal loading and different nitrogen(N)sources on the catalyst morphology,coordination environment and electrocatalytic performance were investigated.Under optimal conditions,0.05Ni-DCD-C-1050 showed excellent performance in reducing CO_(2)to CO,with CO selectivity close to 100%(−0.7 to−1.0 V vs RHE)and current density as high as 130 mA/cm^(2)(−1.1 V vs RHE)in a flow cell under alkaline environment.
基金supported by the National Natural Science Foundation of China(Nos.U2341261 and 12375280)the Young Potential Program of Shanghai Institute of Applied Physics,Chinese Academy of Sciences(No.YXJH-2022002)the National MCF Energy R&D Program(No.2022YFE03110000).
文摘In-situ TEM observation was conducted during Ni^(+)&He^(+)dual-beam irradiation to monitor the evolution of dislocation loops accompanied by He bubbles in the Ni-based alloy GH3535.Two distinct evolutions of dislocation loops,driven by residual stresses,were observed within the monitored grains.Hence,molec-ular dynamics(MD)simulations were employed to reveal the effects of stress magnitude and direction on loop evolution,including size,number density,type and variation.The simulations revealed that the presence of compressive stress reduced the formation energy of perfect dislocation loops,thus promoting their formation.Stress state was found to influence the preferential orientation of the loops,and com-pressive stress resulted in a decreased number density of dislocation loops but an increase in their size.This establishes a clear relationship between stress state and magnitude and the evolution of dislocation loops during ion beam irradiation.Additionally,the nature and characteristics of dislocation loops were quantified to explore the effects of He concentrations on their evolution.The higher He concentration not only promotes the nucleation of dislocation loops,leading to their higher number density,but also facil-itates the unfaulting evolution by increasing the stacking fault energy(SFE).Moreover,the accumulation of He in the lower-He-concentration sample led to the growth of dislocation loops in multiple stages,explaining their nearly identical average sizes when compared to the higher-He-concentration sample.
基金financially supported by the Shenzhen Science and Technology Innovation Program(Grant No.JCYJ20220530150011024)。
文摘A comprehensive understanding of the dynamic processes at the catalyst/electrolyte interfaces is crucial for the development of advanced electrocatalysts for the oxygen evolution reaction(OER).However,the chemical processes related to surface corrosion and catalyst degradation have not been well understood so far.In this study,we employ LiCoO_(2) as a model catalyst and observe distinct OER activities and surface stabilities in different alkaline solutions.Operando X-ray diffraction(XRD)and online mass spectroscopy(OMS)measurements prove the selective intercalation of alkali cations into the layered structure of LiCoO_(2) during OER.It is proposed that the dynamic cation intercalations facilitate the chemical oxidation process between highly oxidative Co species and adsorbed water molecules,triggering the so-called electrochemical-chemical reaction mechanism(EC-mechanism).The results of this study emphasize the influence of cations on OER and provide insights into new strategies for achieving both high activity and stability in high-performance OER catalysts.
基金supported the Science and Technology Commission of Shanghai Municipality(No.21DZ2206900)。
文摘The operational lifespan of nuclear graphite is significantly affected by irradiation creep,yet the microstructural mechanism underlying this creep phenomenon remains unclear.Some theories attempt to link microstructural evolution with creep behavior,but the rapid migration rate of defects under irradiation and loading makes it difficult to capture the specific evolution process experimentally,resulting in a lack of direct structural evidence.Therefore,in this study,molecular dynamics simulations are employed to investigate the irradiation behavior and microstructural migration under external loading.The aim is to provide microstructural evidence for theories such as the dislocation pinning-unpinning and crystal yielding.The results demonstrate that high tensile loads can increase the potential energy and reduce threshold displacement energy of graphite crystals.Consequently,displacement damage probability and creep rate increase,which is not considered in previous theories.Meanwhile,different creep mechanisms are observed at different damage states and applied loads.In low-dose damage states dominated by interstitials and vacancies,the pinning-unpinning process at basal plane may be caused by a defect diffusion mode.Under high stress levels,direct breaking of pinning structures occurs,leading to rapid migration of basal planes,demonstrating the microstructural evolution process of irradiated crystal yielding and plastic flow.In high-dose damage states characterized significantly by amorphous components,short-range atomic diffusion can become the dominant creep mechanism,and diffusion along the c-axis of graphite crystals is no longer constrained.These findings provide a crucial reference for understanding the irradiation and creep behavior of nuclear graphite in reactors.
基金supported by the Youth Innovation Promotion Association(YIPA)(No.E329290101)of the Chinese Academy of Sciences。
文摘Molten salt reactors(MSRs)are a promising candidate for Generation IV reactor technologies,and the small modular molten salt reactor(SM-MSR),which utilizes low-enriched uranium and thorium fuels,is regarded as a wise development path to accelerate deployment time.Uncertainty and sensitivity analyses of accidents guide nuclear reactor design and safety analyses.Uncertainty analysis can ascertain the safety margin,and sensitivity analysis can reveal the correlation between accident consequences and input parameters.Loss of forced cooling(LOFC)represents an accident scenario of the SM-MSR,and the study of LOFC could offer useful information to improve physical thermohydraulic and structural designs.Therefore,this study investigates the uncertainty of LOFC consequences and the sensitivity of related parameters.The uncertainty of the LOFC consequences was analyzed using the Monte Carlo method,and multiple linear regression was employed to analyze the sensitivity of the input parameters.The uncertainty and sensitivity analyses showed that the maximum reactor outlet fuel salt temperature was 725.5℃,which is lower than the acceptable criterion,and five important parameters influencing LOFC consequences were identified.
基金financially supported by the National Natural Science Foundation of China(Nos.12425511 and 12375280).
文摘In this study,the corrosion and cracking behavior of the GH3535 alloy exposed to molten FLiNaK salts(46.5LiF-11.5NaF-42KF,mol%)with 0 and 0.1wt.%Cr_(3)Te_(4)and 0,1 and 3wt.%EuF_(3)additions at 700℃ for 250 h were investigated.The results showed that all the samples exposed to tellurium containing salts exhibited intergranular corrosion and cracking,and the cracking severity increased with the increasing EuF_(3)concentration.Among them,the average and maximum cracking depths were 164 and 57.1μm,respectively.In contrast,the control sample exposed to salt without Te exhibited less evident intergranular corrosion and no intergranular cracking.These results demonstrate that the synergistic effect between EuF_(3) and Cr_(3)Te_(4) promotes grain boundary Te segregation and Cr depletion,resulting in more severe intergranular cracking.
文摘High-loading Pt/C catalysts play an important role in the fabrication of membrane electrode assemblies with thin catalytic layer,which enhance mass transport and maintain the balance of water and heat.Unfortunately,as the loading increases,the agglomeration and growth of Pt nanoparticles(NPs)occur,causing unsatisfactory performance.Here,we present an efficient method for preparing of highly dispersed and small-sized Pt/C catalysts with Pt loadings varying from 39.01 wt%to 66.48 wt%through the high-temperature shock technique.The high density and ultrafine(~2.5 nm)Pt NPs are successfully anchored onto Vulcan XC-72R carbon black without the use of additional capping agents or surfactants.The modified carbon supports enhance the affinity for Pt precursors,contributing to loading efficiencies of 95%or more,while also providing abundant sites for the nucleation and fixation of Pt NPs,thus preventing agglomeration.In the context of the hydrogen evolution reaction in acidic media,the as-synthesized high-loading Pt/C catalysts show remarkable activity and stability,outperforming the state-of-the-art commercial Pt/C.This is mainly because the combined effects of ultrasmall and uniform Pt NPs,optimized electronic structure of Pt site,superhydrophilicity and effective anchoring of Pt NPs.The polymer electrolyte membrane electrolyzer integrated with Pt60/OX72R and commercial IrO2 reaches 1 A cm^(-2)at 1.77 V and operates stably for 120 hours with a negligible voltage decay.This new strategy is fast,scalable and cost-effective for large-scale production of metal-supported catalysts,especially for the high-loading ones.
文摘In recent years,due to the scarcity of domestic radioisotopes,the Chinese government has strongly supported the development of dedicated radioisotope production facilities.This paper presents conceptual design simulations of an 11 MeV,50μA,H^(-) compact superconducting cyclotron for radioisotope production.This paper focuses primarily on four aspects:magnet system design,central region configuration,beam dynamics analysis,and extraction system design.This paper outlines the cyclotron's primary parameters and key steps in the development process.
文摘Correction:Nuclear Science and Techniques(2025)36:4 https://doi.org/10.1007/s41365-024-01548-5 In this article,the caption for Fig(s)1,3,and 4 was inadvert-ently truncated.The incorrect and the corrected captions are given below.
基金supported by the National Natural Science Foundation of China(U22B20139,22322609,22076152,and 22476158).
文摘Partitioning of actinides from lanthanides is pivotal for advancing nuclear waste management and sustaining nuclear energy development,yet it remains a formidable challenge due to the intricate chemical behaviors of these f-block elements.In this study,we introduce 3,6-di-2-pyridyl-1,2,4,5-tetrazine(L1),whose hydrolysis product of pyridine-2-carbox-aldehyde(pyridine-2-carbonyl)-hydrazone(L2)can fractionally crystallize U(Ⅵ)ions over Ln(Ⅲ)cations with high selectivity and efficiency.Through hydrolysis-induced C–N bond cleavage,L2 acts as a tetradentate ligand,coordinating with two UO_(2)^(2+) ions in a planar arrangement to form a zerodimensional cluster,[(UO_(2))2(μ_(3)-O)(L2)(CH_(3)COO)]·DMF(U-L2),while lanthanide ions(Ln=La,Pr,Nd,Sm,Eu,Gd,Tb,Yb,and Lu)remain in solution due to their inability to achieve similar coordination.This selective crystallization strategy yields exceptional separation factors(SFs)between U(Ⅵ)and Ln(Ⅲ),with a value of 756276 between U(Ⅵ)and Sm(Ⅲ),the highest reported to date.Furthermore,this fractional crystallization separation process can be achieved under mild ambient conditions with high SFs,enabling the development of a rapid,safe and energy-efficient strategy for once-through separation of high oxidation state actinides from lanthanides.
基金supported by National Natural Science Foundation of China(Nos.12222513,12105345,12175292,and No.12405178)。
文摘Radio frequency(RF)cavities for advanced storage rings,also known as diffraction-limited storage rings,are under development.To this end,a competitive and promising approach involves normal-conducting continuous wave technology.The design and preliminary test of a 499.654 MHz RF cavity for the Wuhan Advanced Light Source(WALS)based on specific beam parameters were conducted at the SSRF.Multi-objective evolutionary algorithms have been utilized to optimize RF properties,such as the power loss and power density,resulting in better performance in the continuous wave mode.Further improvements were made to suppress multipacting effects in the working area.To operate stably with the beam,higher-order mode dampers were applied to better address the coupling bunch instability than in previous designs,along with thermal analysis to achieve the desired RF performance.Comprehensive simulation studies demonstrated the stable operation of the RF cavity at the defined beam parameters in the WALS design.A prototype RF cavity was then developed,and the RF performance results in a low-power test showed good agreement with the design and simulation,exhibiting readiness for high-power experiments and operation.
基金supported by the National Natural Science Foundation of China(Nos.12425511,12375280,U2341261,U23B2072 and 12305293).
文摘The synergistic effects of irradiation and tensile deformation on the corrosion behavior of the GH3535 alloy in FLi-NaK molten salt were explored.Helium bubbles were introduced into the GH3535 alloy,followed by mechanical loading with the plastic strain up to 10%.After immersion in molten salt for 300 h,all the samples exhibited a corrosion-induced Cr depletion layer.The depth of the Cr depletion layer increased by 40% for the alloy with helium ion irradiation and 10% plastic deformation,compared with that for the only corroded sample.Moreover,the proportion of large-sized helium bubbles increased with plastic deformation.These results indicate that the coupling effects of irradiation and tensile deformation accelerate the corrosion of the GH3535 alloy.In addition,in a molten salt environment,an unexpected outward migration behavior of helium bubbles was observed under different plastic deformation.Helium bubbles migrated closer to the surface as the strain increased up to 3%,while the migration depth declined when the strain reached 10%.This is ascribed to the interaction between deformation-induced dislocations and helium bubbles.
基金supported by the National Natural Science Foundation of China(Nos.12005289,52072397)State Key Laboratory of Nuclear Detection and Electronics,University of Science and Technology of China(SKLPDE-KF-202316).
文摘The stability of matrix graphite under neutron irradiation and in corrosive environments is crucial for the safe operation of molten salt reactors(MSRs).Raman spectroscopy and a slow positron beam were employed to investigate the effects of He ion irradiation fluences and subsequent annealing on the microstructure and defects of the matrix graphite.He ions with 500 keV energy and fluences ranging from 1.1×10^(15)ions∕cm^(2)to 3.5×10^(17)ions∕cm^(2)were used to simulate neutron irradiation at 300 K.The samples with an irradiation fluence of 3.5×10^(16)ions∕cm^(2)were subjected to isochronal annealing at different temperatures(573 K,873 K and 1173 K)for 3 h.The Raman results revealed that the D peak gradually increased,whereas the intrinsic G peak decreased with increasing irradiation fluence.At the same irradiation fluence,the D peak gradually decreased,whereas the intrinsic G peak increased with increasing annealing temperature.Slow positron beam analysis demonstrated that the density or size of irradiation defects(vacancy type)increased with higher irradiation fluence,but decreased rapidly with increasing annealing temperature.The Raman spectral analysis of sample cross sections subjected to high irradiation fluences revealed the emergence of amorphization precisely at the depth where ion damage was most pronounced,whereas the surface retained its crystalline structure.Raman and positron annihilation analyses indicated that the matrix graphite exhibited good irradiation resistance to He ions at 300 K.However,vacancy-type defects induced by He ion irradiation exhibit poor thermal stability and can be easily removed during annealing.
基金supported by the National Natural Science Foundation of China(No.52278251)Guizhou Provincial Sciences and Technology Projects(ZK[2022]Key 007).
文摘Identifying the damage and fracture properties of nuclear graphite materials and accurately simulating them are crucial when designing graphite core structures.To simulate the damage evolution and crack propagation of graphite under stress in a finite element model,compression tests on disks and three-point bending tests on center-notched beams for fine-grained graphite(CDI-1D and IG11 graphite)were conducted.During these tests,digital image correlation and electronic speckle pattern interferometry techniques were utilized to observe the surface full-field displacements of the specimens.A segmented finite element inverse analysis method was developed to characterize the graphite’s damage evolution by quantifying the reduction in Young’s modulus with tensile and compressive strains in disk specimens.The fracture energy and bilinear tensile softening curve of the graphite were determined by comparing the load–displacement responses of the three-point bending tests and the finite element simulation.Finally,by combining the identified damage laws with a fracture criterion based on fracture energy,a damage–fracture model was established and used to simulate tensile tests on L-shaped specimens with different fillet radii.Simulations indicate that the damage area at the fillet expands with increasing radius,creating a blunting effect that enhances the load-bearing capacity of the specimens.This damage–fracture model can be applied to simulate graphite components in core structures.
文摘Most synchrotron light storage rings are equipped with a higher harmonic cavity(HHC)and are currently predominantly used to increase beam life.With the enhancement of the beam current intensity,it is necessary to consider instability problems that may be caused by heavy beam loading effects.In this study,we incorporated a HHC into the small-signal Pedersen mathematical model and used system signal analysis to investigate the mode-zero Robinson instability driven by the passive superconducting harmonic cavity and active superconducting harmonic cavity fundamental modes.To further study and alleviate this instability,we introduced direct radio-frequency feedback,an automatic voltage control loop,and a phase-lock loop into the model,discussed the impact of the feedback loop parameter settings on the stability margin,and provided suggestions for parameter settings.
基金Project supported by the National Key R&D Program of China(2022YFB3504701)National Natural Science Foundation of China(51971126,12105355)Youth Innovation Promotion Association,Chinese Academy of Sciences(2019263)。
文摘As a representative of non-evaporative getter,Zr-V-Fe has gained widespread attention due to its advantages including low activation temperatures and rapid hydrogen absorption rates.In this study,we investigated the impact of La and Ce doping on the thermodynamic,kinetic,and activation properties of Zr_(7)V_(5)Fe alloy.X-ray diffraction analysis shows that rare earth doping causes a decrease in the cell volume of both the ZrV_(2) andα-Zr phases of Zr_(7)V_(5)Fe alloy,which results in an increase in the plateau pressure of the alloys.The kinetic curves illustrate that rare earth doping leads to a coarseα-Zr phases and a larger particle size after activation,resulting in a decrease in the hydrogen absorption kinetic properties.As for the activation process,the rare earth doped alloys exhibit excellent activation with shorter incubation periods.X-ray photoelectron spectroscopy investigations reveal that Zr and V are initially in a highly oxidized state.As the heating temperature increases,they undergo a transition from oxidation state to metal state.The content of metal Zr in rare earth doped alloys is higher than that in undoped alloys at 250℃,primarily due to rare earth elements'affinity for oxygen.
基金supported by the National Key Research and Development Program(Nos.2023YFA1606901 and 2022YFA1602400)National Natural Science Foundation of China(Nos.U2230133,12275338,and 12388102)Open Fund of the CIAE Key Laboratory of Nuclear Data(No.JCKY2022201C152).
文摘We present new data on the^(63)Cu(γ,n)cross-section studied using a quasi-monochromatic and energy-tunableγbeam produced at the Shanghai Laser Electron Gamma Source to resolve the long-standing discrepancy between existing measurements and evaluations of this cross-section.Using an unfolding iteration method,^(63)Cu(γ,n)data were obtained with an uncertainty of less than 4%,and the inconsistencies between the available experimental data were discussed.Theγ-ray strength function of^(63)Cu(γ,n)was successfully extracted as an experimental constraint.We further calculated the cross-section of the radiative neutron capture reaction^(62)Cu(n,γ)using the TALYS code.Our calculation method enables the extraction of(n,γ)cross-sections for unstable nuclides.
基金supported by National Key Research and Development Program of China(Nos.2022YFA1602404 and 2023YFA1606901)the National Natural Science Foundation of China(Nos.12275338,12388102,and U2441221)the Key Laboratory of Nuclear Data Foundation(JCKY2022201C152).
文摘Photonuclear data are increasingly used in fundamental nuclear research and technological applications.These data are generated using advanced γ-ray sources.The Shanghai laser electron gamma source(SLEGS)is a new laser Compton scattering γ-ray source at the Shanghai Synchrotron Radiation Facility.It delivers energy-tunable,quasi-monoenergetic gamma beams for high-precision photonuclear measurements.This paper presents the flat-efficiency detector(FED)array at SLEGS and its application in photoneutron cross-section measurements.Systematic uncertainties of the FED array were determined to be 3.02%through calibration with a ^(252)Cf neutron source.Using ^(197)Au and ^(159)Tb as representative nuclei,we demonstrate the format and processing methodology for raw photoneutron data.The results validate SLEGS’capability for high-precision photoneutron measurements.
基金supported by the National key R&D program(Nos.2023YFA1606901 and 2022YFA1602404)the National Natural Science Foundation of China(Nos.12375123 and 12388102)the Natural Science Foundation of Henan Province(No.242300422048)。
文摘The accurate photoneutron cross section of the^(27)Al nucleus has a significant impact on resolving differences in existing experimental data and enhancing the precision of nuclear reaction rate calculations for^(26)Al in nuclear astrophysics.The photoneutron cross sections for the^(27)Al(γ,n)^(26)Al reaction,within the neutron separation energy range of 13.2-21.7 MeV,were meticulously measured using a new flat efficiency detector array at the Shanghai Laser-Electron Gamma Source.The uncertainty of the data was controlled to below 4%throughout the process,and inconsistencies between the present data and existing data from different gamma sources,as well as the TENDL-2021 data,are discussed in detail.These discussions provide a valuable reference for addressing discrepancies in the^(27)Al(γ,n)^(26)Al cross-section data and improving related theoretical calculations.
