One of the main issues in designing optimum tapered cascades for uranium enrichment for annual fuel production in a power reactor is whether to employ large(fat)or small(thin)cascades.What will be the permissible and ...One of the main issues in designing optimum tapered cascades for uranium enrichment for annual fuel production in a power reactor is whether to employ large(fat)or small(thin)cascades.What will be the permissible and optimal ranges of the number of machines that can be used in a cascade?For the first time,the permissible and optimal ranges of the number of gas centrifuges that can be utilized in a cascade were investigated using two types of centrifuges,and the performance of small and large tapered cascades was discussed.The particle swarm optimization algorithm(PSO)has been used to optimize tapered cascades.The results show:(1)For the first centrifuge,41 cascades(91≤n≤4897)and for the second centrifuge,49 cascades(18≤n≤3839)with small and large sizes can be used in enrichment facilities,and the best cascade for them has 530(with 23 stages)and 39(with 7 stages)centrifuges,respectively.(2)For both centrifuges,when 600≤n(number of centrifuges=n),the large cascade performance changes are relatively insignificant.(3)For both types of gas centrifuges,the annual los s of separation power in enrichment facilities is approximately 1.25%-4.82%of the total separation work required.展开更多
Amidst the growing global emphasis on nuclear safety,the integrity of nuclear reactor systems has garnered attention in the aftermath of consequential events.Moreover,the rapid development of artificial intelligence t...Amidst the growing global emphasis on nuclear safety,the integrity of nuclear reactor systems has garnered attention in the aftermath of consequential events.Moreover,the rapid development of artificial intelligence technology has provided immense opportunities to enhance the safety and economy of nuclear energy.However,data-driven deep learning techniques often lack interpretability,which hinders their applicability in the nuclear energy sector.To address this problem,this study proposes a hybrid data-driven and knowledge-driven artificial intelligence model based on physics-informed neural networks to accurately compute the neutron flux distribution inside a nuclear reactor core.Innovative techniques,such as regional decomposition,intelligent k_(eff)(effective multiplication factor)search,and k_(eff)inversion,have been introduced for the calculation.Furthermore,hyperparameters of the model are automatically optimized using a whale optimization algorithm.A series of computational examples are used to validate the proposed model,demonstrating its applicability,generality,and high accuracy in calculating the neutron flux within the nuclear reactor.The model offers a dependable strategy for computing the neutron flux distribution in nuclear reactors for advanced simulation techniques in the future,including reactor digital twinning.This approach is data-light,requires little to no training data,and still delivers remarkably precise output data.展开更多
The Monte Carlo(MC)method offers significant advantages in handling complex geometries and physical processes in particle transport problems and has become a widely used approach in reactor physics analysis,radiation ...The Monte Carlo(MC)method offers significant advantages in handling complex geometries and physical processes in particle transport problems and has become a widely used approach in reactor physics analysis,radiation shielding design,and medical physics.However,with the rapid advancement of new nuclear energy systems,the Monte Carlo method faces challenges in efficiency,accuracy,and adaptability,limiting its effectiveness in meeting modern design requirements.Overcoming technical obstacles related to high-fidelity coupling,high-resolution computation,and intelligent design is essential for using the Monte Carlo method as a reliable tool in numerical analysis for these new nuclear energy systems.To address these challenges,the Nuclear Energy and Application Laboratory(NEAL)team at the University of South China developed a multifunctional and generalized intelligent code platform called MagicMC,based on the Monte Carlo particle transport method.MagicMC is a developing tool dedicated to nuclear applications,incorporating intelligent methodologies.It consists of two primary components:a basic unit and a functional unit.The basic unit,which functions similarly to a standard Monte Carlo particle transport code,includes seven modules:geometry,source,transport,database,tally,output,and auxiliary.The functional unit builds on the basic unit by adding functional modules to address complex and diverse applications in nuclear analysis.MagicMC introduces a dynamic Monte Carlo particle transport algorithm to address time-space particle transport problems within emerging nuclear energy systems and incorporates a CPU-GPU heterogeneous parallel framework to enable high-efficiency,high-resolution simulations for large-scale computational problems.Anticipating future trends in intelligent design,MagicMC integrates several advanced features,including CAD-based geometry modeling,global variance reduction methods,multi-objective shielding optimization,high-resolution activation analysis,multi-physics coupling,and radiation therapy.In this paper,various numerical benchmarks-spanning reactor transient simulations,material activation analysis,radiation shielding optimization,and medical dosimetry analysis-are presented to validate MagicMC.The numerical results demonstrate MagicMC's efficiency,accuracy,and reliability in these preliminary applications,underscoring its potential to support technological advancements in developing high-fidelity,high-resolution,and high-intelligence MC-based tools for advanced nuclear applications.展开更多
Lead(Pb)plays a significant role in the nuclear industry and is extensively used in radiation shielding,radiation protection,neutron moderation,radiation measurements,and various other critical functions.Consequently,...Lead(Pb)plays a significant role in the nuclear industry and is extensively used in radiation shielding,radiation protection,neutron moderation,radiation measurements,and various other critical functions.Consequently,the measurement and evaluation of Pb nuclear data are highly regarded in nuclear scientific research,emphasizing its crucial role in the field.Using the time-of-flight(ToF)method,the neutron leakage spectra from three^(nat)Pb samples were measured at 60°and 120°based on the neutronics integral experimental facility at the China Institute of Atomic Energy(CIAE).The^(nat)Pb sample sizes were30 cm×30 cm×5 cm,30 cm×30 cm×10 cm,and 30 cm×30 cm×15 cm.Neutron sources were generated by the Cockcroft-Walton accelerator,producing approximately 14.5 MeV and 3.5 MeV neutrons through the T(d,n)^(4)He and D(d,n)^(3)He reactions,respectively.Leakage neutron spectra were also calculated by employing the Monte Carlo code of MCNP-4C,and the nuclear data of Pb isotopes from four libraries:CENDL-3.2,JEFF-3.3,JENDL-5,and ENDF/B-Ⅷ.0 were used individually.By comparing the simulation and experimental results,improvements and deficiencies in the evaluated nuclear data of the Pb isotopes were analyzed.Most of the calculated results were consistent with the experimental results;however,a few areas did not fit well.In the(n,el)energy range,the simulated results from CENDL-3.2 were significantly overestimated;in the(n,inl)D and the(n,inl)C energy regions,the results from CENDL-3.2 and ENDF/B-Ⅷ.0 were significantly overestimated at 120°,and the results from JENDL-5 and JEFF-3.3 are underestimated at 60°in the(n,inl)D energy region.The calculated spectra were analyzed by comparing them with the experimental spectra in terms of the neutron spectrum shape and C/E values.The results indicate that the theoretical simulations,using different data libraries,overestimated or underestimated the measured values in certain energy ranges.Secondary neutron energies and angular distributions in the data files have been presented to explain these discrepancies.展开更多
Nuclearβ-decay,a typical decay process for unstable nuclei,is a key mechanism for producing heavy elements in the Universe.In this study,neural networks were employed to predictβ-decay half-lives and,for the first t...Nuclearβ-decay,a typical decay process for unstable nuclei,is a key mechanism for producing heavy elements in the Universe.In this study,neural networks were employed to predictβ-decay half-lives and,for the first time,to identify abnormal trends in nuclearβ-decay half-lives based on deviations between experimental values and the predictions of neural networks.Nuclei exhibiting anomalous increases,abrupt peaks,sharp decreases,abnormal odd-even oscillations,and excessively large experimental errors in theirβ-decay half-lives,which deviate from systematic patterns,were identified through deviations.These anomalous phenomena may be associated with shell effects,shape coexistence,or discrepancies in the experimental data.The discovery and analysis of these abnormal nuclei provide a valuable reference for further investigations using sophisticated microscopic theories,potentially offering insights into new physics through studies of nuclearβ-decay half-lives.展开更多
Current sway test platforms for marine nuclear equipment face challenges in meeting the GJB 150.23A requirements.This is primarily because of the performance limitations of conventional actuators under extreme marine ...Current sway test platforms for marine nuclear equipment face challenges in meeting the GJB 150.23A requirements.This is primarily because of the performance limitations of conventional actuators under extreme marine conditions.This study aimed to overcome these constraints using an innovative parallel mechanism design.We developed a novel 6-PUS parallel platform featuring six kinematic chains with hybrid series-parallel actuators.Each chain combines(1)force-speed adaptive transmission,(2)redundant motor-driven dual-screw actuation,and(3)passive load-balancing mechanisms.Comprehensive kinematic/dynamic modeling and experimental validation were conducted.Tests demonstrated the capability of the platform to achieve cyclic speeds of±45°/7 s and±30°/3 s while supporting 10-ton loads.Successful sway tests on nuclear components(reactor pressurizer and control rod drive mechanism)confirmed the operational reliability.This work presented three key innovations:(1)a new parallel-platform architecture that overcomes the limitations of conventional actuators;(2)integrated hybrid actuation with adaptive transmission;and(3)high-speed,heavy-load performance that meets stringent marine testing standards.This solution significantly advances nuclear equipment qualification testing technology.展开更多
Owing to the inherent limitation of the internal pulse ionization chamber within the AlphaGUARD PQ2000 radon monitor,that is,its inability to discriminate the energy levels of α particles,the ingress of^(220)Rn from ...Owing to the inherent limitation of the internal pulse ionization chamber within the AlphaGUARD PQ2000 radon monitor,that is,its inability to discriminate the energy levels of α particles,the ingress of^(220)Rn from the surrounding environment,along with its decay progeny,poses a substantive challenge in accurately determining the^(222)Rn concentration in the measurement outcomes.Among these,the protracted influence primarily stems from the two enduring decay progenies,namely^(212)Pb with a half-life of 10.64 h and^(212)Bi with a half-life of 60.54 min.This study explored the influence of^(220)Rn progeny on the measurement results of an AlphaGUARD PQ2000 radon monitor by developing a theoretical calculation model.The response coefficient related to the residual^(220)Rn progeny within the AlphaGUARD PQ2000 radon monitor was experimentally validated.In addition,this study investigated the effects of temperature and wind speed on the sensitivity of the instrument to^(220)Rn gas.The research findings revealed commendable agreement between the experimentally measured response coefficients of the residual^(220)Rn progeny and the corresponding values derived from the theoretical model.Notably,both the response coefficients of the AlphaGUARD PQ2000 radon monitor to^(220)Rn gas and its internal residual^(220)Rn progeny increased with elevated temperatures and increased wind speeds,providing a reference for correcting the impact of^(220)Rn and its progeny on the measurement results of^(222)Rn concentration obtained using the AlphaGUARD PQ2000 radon monitor.展开更多
Subcritical reactors(SCRs)or subcritical assemblies(SCAs)are the main infrastructure for designing power reactors.These reactors are widely used for training and research because of their high level of inherent safety...Subcritical reactors(SCRs)or subcritical assemblies(SCAs)are the main infrastructure for designing power reactors.These reactors are widely used for training and research because of their high level of inherent safety.The objective of this study is to design a subcritical reactor using a pressurized water reactor(PWR)conventional fuel following two safety points.In the first approach,deeply placed SCR cores with an infinite multiplication factor(k_(∞))of less than unity were identified using the DRAGON lattice code.In the second approach,subcritical reactor cores with an effective multiplication factor(k_(eff))of less than unity were determined by coupling the cell calculations of the DRAGON lattice code and core calculations of the DONJON code.For the deeply subcritical reactor design,it was found that the reactor would remain inherently subcritical while using fuel rods with ^(235)U enrichment of up to 0.9%,regardless of the pitch of the fuel rods.In the second approach,the optimal pitches(1.3 to 2.3 cm)were determined for different fuel enrichment values from 1 to 5%.Subsequently,the k_(eff) was obtained for a fuel rod arrangement of 8×8 to 80×80,and the states in which the reactor would be subcritical were determined for different fuel enrichments at the corresponding optimal pitch.To validate the models used in the DRAGON and DONJON codes,the k_(eff) of the Isfahan Light Water Subcritical Reactor(LWSCR)was experimentally measured and compared with the results of the calculations.Finally,the effects of fuel and moderator temperature changes were investigated to ensure that the designed assemblies remained in the subcritical state at all operational temperatures.展开更多
As the primary functional component of a fusion reactor,the fusion blanket pebble bed,composed of numerous particles,is crucial for tritium breeding,neutron multiplication,and radiation shielding.Particles within trit...As the primary functional component of a fusion reactor,the fusion blanket pebble bed,composed of numerous particles,is crucial for tritium breeding,neutron multiplication,and radiation shielding.Particles within tritium-breeding pebble beds are subjected to prolonged neutron irradiation,high thermal loads,and strong magnetic fields in fusion environments.Such conditions render them susceptible to pulverization and fragmentation.The resulting fragments and powders migrate and are deposited into the gas channel,driven by the purge gas.The reduction in the effective flow area of the gas increases the flow resistance,resulting in tritium retention,degraded heat transfer,and other adverse effects.These conditions impair the thermodynamic properties of the pebble beds and hinder the self-maintenance of tritium.Limited information exists on powder migration and clogging mechanisms in fusion blanket pebble beds,particularly under diverse physical conditions.The aim of this study was to use a computational fluid dynamics model coupled with the discrete element method(CFD-DEM)to numerically explore powder migration and clogging in pebble beds.The model considers factors such as breeder orientation,purge velocity,powder size distribution,and friction coefficient.We propose two migration and clogging mechanisms.One involves powder with a large particle size,and the other does not.The results indicate that the powder migration velocity progresses through three stages:rapid decay,linear decay,and stability.Pebble-bed clogging manifests in two forms:extensive superficial clogging and uniform internal clogging.Two fitted curves were used to depict the migration and clogging tendencies.The powder size distribution significantly influenced the powder migration.The breeder orientation,powder size,and friction coefficient affected the distribution of the clogging powders.However,the impact of the purge velocity on powder migration and clogging in pebble beds was limited,and this effect varied significantly with different particle size ratios.Based on the analysis,a formula is proposed to characterize the behavior of the powder in the pebble beds.The results of this study can aid in analyzing and predicting powder dynamics in pebble beds.展开更多
This study aimed to integrate Monte Carlo(MC)simulation with deep learning(DL)-based denoising techniques to achieve fast and accurate prediction of high-quality electronic portal imaging device(EPID)transmission dose...This study aimed to integrate Monte Carlo(MC)simulation with deep learning(DL)-based denoising techniques to achieve fast and accurate prediction of high-quality electronic portal imaging device(EPID)transmission dose(TD)for patientspecific quality assurance(PSQA).A total of 100 lung cases were used to obtain the noisy EPID TD by the ARCHER MC code under four kinds of particle numbers(1×10^(6),1×10^(7),1×10^(8)and 1×10^(9)),and the original EPID TD was denoised by the SUNet neural network.The denoised EPID TD was assessed both qualitatively and quantitatively using the structural similarity(SSIM),peak signal-to-noise ratio(PSNR),and gamma passing rate(GPR)with respect to 1×10^(9)as a reference.The computation times for both the MC simulation and DL-based denoising were recorded.As the number of particles increased,both the quality of the noisy EPID TD and computation time increased significantly(1×10^(6):1.12 s,1×10^(7):1.72 s,1×10^(8):8.62 s,and 1×10^(9):73.89 s).In contrast,the DL-based denoising time remained at 0.13-0.16 s.The denoised EPID TD shows a smoother visual appearance and profile curves,but differences between 1×10^(6)and 1×10^(9)still remain.SSIM improves from 0.61 to 0.95 for 1×10^(6),0.70 to 0.96 for 1×10^(7),and 0.90 to 0.97 for 1×10^(8).PSNR increases by>20%for 1×10^(6)and 1×10^(7),and>10%for 1×10^(8).GPR improves from 48.47%to 89.10%for 1×10^(6),61.04%to 94.35%for 1×10^(7),and 91.88%to 99.55%for 1×10^(8).The method that combines MC simulation with DL-based denoising for EPID TD generation can accelerate TD prediction and maintain high accuracy,offering a promising solution for efficient PSQA.展开更多
The effects of the in-medium nucleon-nucleon(NN) elastic cross section on the observables in heavy ion collisions in the Fermi energy domain are investigated within the framework of the ultrarelativistic quantum molec...The effects of the in-medium nucleon-nucleon(NN) elastic cross section on the observables in heavy ion collisions in the Fermi energy domain are investigated within the framework of the ultrarelativistic quantum molecular dynamics model. The results simulated using medium correction factors of F=σ_(NN)^(in-medium)/σ_(NN)^(free)=0.2,0.3,0.5,and the density-and momentum-dependent factor obtained from the FU3 FP1 parametrization are compared with the FOPI and INDRA experimental data. It is found that the calculations using the correction factors F=0.2 and 0.5 reproduce the experimental data(i.e.,collective flow and nuclear stopping) at 40 and 150 MeV/nucleon, respectively. Calculations with the FU3 FP1 parametrization can best fit these experimental data. These conclusions can be confirmed in both^(197)Au+^(197)Au and^(129)Xe+^(120)Sn.展开更多
“A Craftsman Must Sharpen His Tools to Do His Job,”said Confucius.Nuclear detection and readout techniques are the foundation of particle physics,nuclear physics,and particle astrophysics to reveal the nature of the...“A Craftsman Must Sharpen His Tools to Do His Job,”said Confucius.Nuclear detection and readout techniques are the foundation of particle physics,nuclear physics,and particle astrophysics to reveal the nature of the universe.Also,they are being increasingly used in other disciplines like nuclear power generation,life sciences,environmental sciences,medical sciences,etc.The article reviews the short history,recent development,and trend of nuclear detection and readout techniques,covering Semiconductor Detector,Gaseous Detector,Scintillation Detector,Cherenkov Detector,Transition Radiation Detector,and Readout Techniques.By explaining the principle and using examples,we hope to help the interested reader underst and this research field and bring exciting information to the community.展开更多
To benefit from recent advances in modeling and computational algorithms,as well as the availability of new covariance data,sensitivity and uncertainty analyses are needed to quantify the impact of uncertain sources o...To benefit from recent advances in modeling and computational algorithms,as well as the availability of new covariance data,sensitivity and uncertainty analyses are needed to quantify the impact of uncertain sources on the design parameters of small prismatic high-temperature gascooled reactors(HTGRs).In particular,the contribution of nuclear data to the k_(eff)uncertainty is an important part of the uncertainty analysis of small-sized HTGR physical calculations.In this study,a small-sized HTGR designed by China Nuclear Power Engineering Co.,Ltd.was selected for k_(eff)uncertainty analysis during full lifetime burnup calculations.Models of the cold zero power(CZP)condition and full lifetime burnup process were constructed using the Reactor Monte Carlo Code RMC for neutron transport calculation,depletion calculation,and sensitivity and uncertainty analysis.For the sensitivity analysis,the Contribution-Linked eigenvalue sensitivity/Uncertainty estimation via Track length importance Characterization(CLUTCH)method was applied to obtain sensitive information,and the "sandwich" method was used to quantify the k_(eff)uncertainty.We also compared the k_(eff)uncertainties to other typical reactors.Our results show that ^(235)U is the largest contributor to k_(eff)uncertainty for both the CZP and depletion conditions,while the contribution of ^(239)Pu is not very significant because of the design of low discharge burnup.It is worth noting that the radioactive capture reaction of ^(28)Si significantly contributes to the k_(eff)uncertainty owing to its specific fuel design.However,the k_(eff)uncertainty during the full lifetime depletion process was relatively stable,only increasing by 1.12%owing to the low discharge burnup design of small-sized HTGRs.These numerical results are beneficial for neutronics design and core parameters optimization in further uncertainty propagation and quantification study for small-sized HTGR.展开更多
The smuggling of special nuclear materials(SNMs)across national borders is becoming a serious threat to nuclear nonproliferation.This paper presents a feasibility study on the rapid interrogation of concealed SNMs by ...The smuggling of special nuclear materials(SNMs)across national borders is becoming a serious threat to nuclear nonproliferation.This paper presents a feasibility study on the rapid interrogation of concealed SNMs by combining scattering and transmission nuclear resonance fluorescence(s NRF and t NRF)spectroscopy.In s NRF spectroscopy,SNMs such as^(235,238)U are excited by a wide-band photon beam of appropriate energy and exhibit unique NRF signatures.Monte Carlo simulations show that one-dimensional scans can realize isotopic identification of concealed^(235,238)U when the detector array used for interrogation has sufficiently high energy resolution.The simulated isotopic ratio^(235U/238)U is in good agreement with the theoretical value when the SNMs are enclosed in relatively thin iron.This interrogation is followed by t NRF spectroscopy using a narrow-band photon beam with the goal of obtaining tomographic images of the concealed SNMs.The reconstructed image clearly reveals the position of the isotope^(235)U inside an iron rod.It is shown that the interrogation time of s NRF and t NRF spectroscopy is one order of magnitude lower than that when only t NRF spectroscopy is used and results in a missed-detection rate of 10^(-3).The proposed method can also be applied for isotopic imaging of other SNMs such as^(239,240)Pu and^(237)Np.展开更多
The results of an accident analysis for the loss of offsite power(LOOP)scenario in a reference Bushehr-1 VVER-1000/V446 nuclear power plant(NPP)are presented in this paper.This study attempted to provide a better anal...The results of an accident analysis for the loss of offsite power(LOOP)scenario in a reference Bushehr-1 VVER-1000/V446 nuclear power plant(NPP)are presented in this paper.This study attempted to provide a better analysis of LOOP accident management by integrating deterministic and probabilistic approaches.The RELAP5 code was used to investigate the occurrence of specific thermal–hydraulic phenomena.The probabilistic safety assessment of the LOOP accident is presented using the SAPHIRE software.LOOP accident data were extracted from the Bushehr NPP final safety analysis reports and probabilistic safety analysis reports.A deterministic approach was used to reduce the core damage frequency in the probabilistic analysis of LOOP accidents.The probabilistic approach was used to better observe the philosophy of defense in depth and safety margins in the deterministic analysis of the LOOP accident.The results show that the integration of the two approaches in LOOP accident investigations improved accident control.展开更多
Regarding the stage progress on the relativistic Hartree-Fock(RHF)model achieved recently,we review the extensive developments of the model itself,including the descriptions of axially deformed unstable nuclei and nuc...Regarding the stage progress on the relativistic Hartree-Fock(RHF)model achieved recently,we review the extensive developments of the model itself,including the descriptions of axially deformed unstable nuclei and nuclear spin-isospin excitations,which shows that a complete RHF framework is now available for exploring the tensor force effects in both ground state and excited states of unstable nuclei.Meanwhile,the recent RHF descriptions of the pseudo-spin symmetry restoration and the new magicity are also reviewed.It shows that the Fock terms,particularly theρ-tensor coupling and naturally introduced tensor force components,bring about significant improvements in maintaining the delicate in-medium balance of nuclear attractions and repulsions,and uniformly interpreting the emergence of new magicity inCa.The revealed microscopic mechanisms not only deepen our understanding on the properties of nuclear structure,but also help to guide the further development of the effective nuclear force.展开更多
Nuclear astrophysics is a rapidly developing interdisciplinary feld of research that has received extensive attention from the scientifc community since the midtwentieth century.Broadly,it uses the laws of extremely s...Nuclear astrophysics is a rapidly developing interdisciplinary feld of research that has received extensive attention from the scientifc community since the midtwentieth century.Broadly,it uses the laws of extremely small atomic nuclei to explain the evolution of the universe.Owing to the complexity of nucleosynthesis processes and our limited understanding of nuclear physics in astrophysical environments,several critical astrophysical problems remain unsolved.To achieve a better understanding of astrophysics,it is necessary to measure the cross sections of key nuclear reactions with the precision required by astrophysical models.Direct measurement of nuclear reaction cross sections is an important method of investigating how nuclear reactions infuence stellar evolution.Given the challenges involved in measuring the extremely low crosssections of nuclear reactions in the Gamow peak and preparing radioactive targets,indirect methods,such as the transfer reaction,coulomb dissociation,and surrogate ratio methods,have been developed over the past several decades.These are powerful tools in the investigation of,for example,neutron-capture(n,r)reactions with short-lived radioactive isotopes.However,direct measurement is still preferable,such as in the case of reactions involving light and stable nuclei.As an essential part of stellar evolution,these low-energy stable nuclear reactions have been of particular interest in recent years.To overcome the diffculties in measurements near or deeply within the Gamow window,the combination of an underground laboratory and high-exposure accelerator/detector complex is currently the optimal solution.Therefore,underground experiments have emerged as a new and promising direction of research.In addition,to better simulate the stellar environment in the laboratory,research on nuclear physics under laser-driven plasma conditions has gradually become a frontier hotspot.In recent years,the CIAE team conducted a series of distinctive nuclear astrophysics studies,relying on the Jinping Underground Nuclear Astrophysics platform and accelerators in Earth’s surface laboratories,including the Beijing Radioactive Ion beam Facility,as well as other scientifc platforms at home and abroad.This research covered nuclear theories,numerical models,direct measurements,indirect measurements,and other novel approaches,achieving great interdisciplinary research results,with high-level academic publications and signifcant international impacts.This article reviews the above research and predicts future developments.展开更多
In this study, the rapidity distribution, collective flows, and nuclear stopping power in ^(197)Au+^(197)Au collisions at intermediate energies were investigated using the ultrarelativistic quantum molecular dynamics(...In this study, the rapidity distribution, collective flows, and nuclear stopping power in ^(197)Au+^(197)Au collisions at intermediate energies were investigated using the ultrarelativistic quantum molecular dynamics(UrQMD) model with GEMINI++ code. The UrQMD model was adopted to simulate the dynamic evolution of heavy-ion collisions, whereas the GEMINI++ code was used to simulate the decay of primary fragments produced by UrQMD. The calculated results were compared with the INDRA and FOPI experimental data. It was found that the rapidity distribution, collective flows, and nuclear stopping power were affected to a certain extent by the decay of primary fragments, especially at lower beam energies. Furthermore, the experimental data of the collective flows and nuclear stopping power at the investigated beam energies were better reproduced when the sequential decay effect was included.展开更多
The present paper describes the development and applications of nuclear track detection technique in Pakistan. Pakistan entered in the field of nuclear tracks in early 1970s when it was still quite new. Highlights of ...The present paper describes the development and applications of nuclear track detection technique in Pakistan. Pakistan entered in the field of nuclear tracks in early 1970s when it was still quite new. Highlights of successes of different Pakistani laboratories, working on nuclear tracks, achieved on their own or in collaboration with similar centers in the world are described briefly. The robust features of this investigation are the comprehensive investigation of the addressed research, analysis and review of results, and discussions with the perspectives of applications and new research directions. Further analysis of the published results by the present author and some new results are also presented. This paper portrays a comprehensive picture of the nuclear track detection research and technology in Pakistan and can be useful for a similar development in any country around the globe.展开更多
The intricate balance between reactor economics and safety necessitates the emergence of new and advanced nuclear systems and,very importantly,advanced materials,which can overcome current shortcomings and bring about...The intricate balance between reactor economics and safety necessitates the emergence of new and advanced nuclear systems and,very importantly,advanced materials,which can overcome current shortcomings and bring about more economic nuclear systems with designed-in inherent safety features.These advances will achieve greater safety and better nuclear reactor economics by reaching longer reactor lives with higher levels neutron irradiation,and by providing higher operation temperatures and resistance to more aggressive corrosive environments.This paper provides a review of the current state of research and development on innovative nuclear fuel materials design and development which have the potential of benefiting simultaneously reactor economics and safety.Our discussion focuses on three areas of research:Accident-tolerant Fuels(ATFs),Oxidation Dispersion Strengthened(ODS)steels and High Entropy Alloys(HEAs).The paper also gives a prospective description of future research activities on these materials.展开更多
文摘One of the main issues in designing optimum tapered cascades for uranium enrichment for annual fuel production in a power reactor is whether to employ large(fat)or small(thin)cascades.What will be the permissible and optimal ranges of the number of machines that can be used in a cascade?For the first time,the permissible and optimal ranges of the number of gas centrifuges that can be utilized in a cascade were investigated using two types of centrifuges,and the performance of small and large tapered cascades was discussed.The particle swarm optimization algorithm(PSO)has been used to optimize tapered cascades.The results show:(1)For the first centrifuge,41 cascades(91≤n≤4897)and for the second centrifuge,49 cascades(18≤n≤3839)with small and large sizes can be used in enrichment facilities,and the best cascade for them has 530(with 23 stages)and 39(with 7 stages)centrifuges,respectively.(2)For both centrifuges,when 600≤n(number of centrifuges=n),the large cascade performance changes are relatively insignificant.(3)For both types of gas centrifuges,the annual los s of separation power in enrichment facilities is approximately 1.25%-4.82%of the total separation work required.
文摘Amidst the growing global emphasis on nuclear safety,the integrity of nuclear reactor systems has garnered attention in the aftermath of consequential events.Moreover,the rapid development of artificial intelligence technology has provided immense opportunities to enhance the safety and economy of nuclear energy.However,data-driven deep learning techniques often lack interpretability,which hinders their applicability in the nuclear energy sector.To address this problem,this study proposes a hybrid data-driven and knowledge-driven artificial intelligence model based on physics-informed neural networks to accurately compute the neutron flux distribution inside a nuclear reactor core.Innovative techniques,such as regional decomposition,intelligent k_(eff)(effective multiplication factor)search,and k_(eff)inversion,have been introduced for the calculation.Furthermore,hyperparameters of the model are automatically optimized using a whale optimization algorithm.A series of computational examples are used to validate the proposed model,demonstrating its applicability,generality,and high accuracy in calculating the neutron flux within the nuclear reactor.The model offers a dependable strategy for computing the neutron flux distribution in nuclear reactors for advanced simulation techniques in the future,including reactor digital twinning.This approach is data-light,requires little to no training data,and still delivers remarkably precise output data.
基金supported by the National Natural Science Foundation of China(Nos.12475174 and U2267207)YueLuShan Center Industrial Innovation(No.2024YCII0108)+2 种基金Natural Science Foundation of Hunan Province(No.2022JJ40345)Science and Technology Innovation Project of Hengyang(No.202250045336)the Project of State Key Laboratory of Radiation Medicine and Protection,Soochow University(No.GZK12023031)。
文摘The Monte Carlo(MC)method offers significant advantages in handling complex geometries and physical processes in particle transport problems and has become a widely used approach in reactor physics analysis,radiation shielding design,and medical physics.However,with the rapid advancement of new nuclear energy systems,the Monte Carlo method faces challenges in efficiency,accuracy,and adaptability,limiting its effectiveness in meeting modern design requirements.Overcoming technical obstacles related to high-fidelity coupling,high-resolution computation,and intelligent design is essential for using the Monte Carlo method as a reliable tool in numerical analysis for these new nuclear energy systems.To address these challenges,the Nuclear Energy and Application Laboratory(NEAL)team at the University of South China developed a multifunctional and generalized intelligent code platform called MagicMC,based on the Monte Carlo particle transport method.MagicMC is a developing tool dedicated to nuclear applications,incorporating intelligent methodologies.It consists of two primary components:a basic unit and a functional unit.The basic unit,which functions similarly to a standard Monte Carlo particle transport code,includes seven modules:geometry,source,transport,database,tally,output,and auxiliary.The functional unit builds on the basic unit by adding functional modules to address complex and diverse applications in nuclear analysis.MagicMC introduces a dynamic Monte Carlo particle transport algorithm to address time-space particle transport problems within emerging nuclear energy systems and incorporates a CPU-GPU heterogeneous parallel framework to enable high-efficiency,high-resolution simulations for large-scale computational problems.Anticipating future trends in intelligent design,MagicMC integrates several advanced features,including CAD-based geometry modeling,global variance reduction methods,multi-objective shielding optimization,high-resolution activation analysis,multi-physics coupling,and radiation therapy.In this paper,various numerical benchmarks-spanning reactor transient simulations,material activation analysis,radiation shielding optimization,and medical dosimetry analysis-are presented to validate MagicMC.The numerical results demonstrate MagicMC's efficiency,accuracy,and reliability in these preliminary applications,underscoring its potential to support technological advancements in developing high-fidelity,high-resolution,and high-intelligence MC-based tools for advanced nuclear applications.
基金supported by the National Natural Science Foundation of China(Nos.11775311 and U2067205)the Stable Support Basic Research Program Grant(BJ010261223282)the Research and Development Project of China National Nuclear Corporation。
文摘Lead(Pb)plays a significant role in the nuclear industry and is extensively used in radiation shielding,radiation protection,neutron moderation,radiation measurements,and various other critical functions.Consequently,the measurement and evaluation of Pb nuclear data are highly regarded in nuclear scientific research,emphasizing its crucial role in the field.Using the time-of-flight(ToF)method,the neutron leakage spectra from three^(nat)Pb samples were measured at 60°and 120°based on the neutronics integral experimental facility at the China Institute of Atomic Energy(CIAE).The^(nat)Pb sample sizes were30 cm×30 cm×5 cm,30 cm×30 cm×10 cm,and 30 cm×30 cm×15 cm.Neutron sources were generated by the Cockcroft-Walton accelerator,producing approximately 14.5 MeV and 3.5 MeV neutrons through the T(d,n)^(4)He and D(d,n)^(3)He reactions,respectively.Leakage neutron spectra were also calculated by employing the Monte Carlo code of MCNP-4C,and the nuclear data of Pb isotopes from four libraries:CENDL-3.2,JEFF-3.3,JENDL-5,and ENDF/B-Ⅷ.0 were used individually.By comparing the simulation and experimental results,improvements and deficiencies in the evaluated nuclear data of the Pb isotopes were analyzed.Most of the calculated results were consistent with the experimental results;however,a few areas did not fit well.In the(n,el)energy range,the simulated results from CENDL-3.2 were significantly overestimated;in the(n,inl)D and the(n,inl)C energy regions,the results from CENDL-3.2 and ENDF/B-Ⅷ.0 were significantly overestimated at 120°,and the results from JENDL-5 and JEFF-3.3 are underestimated at 60°in the(n,inl)D energy region.The calculated spectra were analyzed by comparing them with the experimental spectra in terms of the neutron spectrum shape and C/E values.The results indicate that the theoretical simulations,using different data libraries,overestimated or underestimated the measured values in certain energy ranges.Secondary neutron energies and angular distributions in the data files have been presented to explain these discrepancies.
基金supported by the‘Young Scientist Scheme’of the National Key R&D Program of China(No.2021YFA1601500)National Natural Science Foundation of China(Nos.12075104,12375109,11875070,and 11935001)+1 种基金Anhui Project(Z010118169)Key Research Foundation of the Education Ministry of Anhui Province(No.2023AH050095)。
文摘Nuclearβ-decay,a typical decay process for unstable nuclei,is a key mechanism for producing heavy elements in the Universe.In this study,neural networks were employed to predictβ-decay half-lives and,for the first time,to identify abnormal trends in nuclearβ-decay half-lives based on deviations between experimental values and the predictions of neural networks.Nuclei exhibiting anomalous increases,abrupt peaks,sharp decreases,abnormal odd-even oscillations,and excessively large experimental errors in theirβ-decay half-lives,which deviate from systematic patterns,were identified through deviations.These anomalous phenomena may be associated with shell effects,shape coexistence,or discrepancies in the experimental data.The discovery and analysis of these abnormal nuclei provide a valuable reference for further investigations using sophisticated microscopic theories,potentially offering insights into new physics through studies of nuclearβ-decay half-lives.
基金Supported by Shanghai Nuclear Engineering Research&Design Institute Co.,Ltd.
文摘Current sway test platforms for marine nuclear equipment face challenges in meeting the GJB 150.23A requirements.This is primarily because of the performance limitations of conventional actuators under extreme marine conditions.This study aimed to overcome these constraints using an innovative parallel mechanism design.We developed a novel 6-PUS parallel platform featuring six kinematic chains with hybrid series-parallel actuators.Each chain combines(1)force-speed adaptive transmission,(2)redundant motor-driven dual-screw actuation,and(3)passive load-balancing mechanisms.Comprehensive kinematic/dynamic modeling and experimental validation were conducted.Tests demonstrated the capability of the platform to achieve cyclic speeds of±45°/7 s and±30°/3 s while supporting 10-ton loads.Successful sway tests on nuclear components(reactor pressurizer and control rod drive mechanism)confirmed the operational reliability.This work presented three key innovations:(1)a new parallel-platform architecture that overcomes the limitations of conventional actuators;(2)integrated hybrid actuation with adaptive transmission;and(3)high-speed,heavy-load performance that meets stringent marine testing standards.This solution significantly advances nuclear equipment qualification testing technology.
基金supported by the National Natural Science Foundation of China(No.12175102)Hunan Provincial Natural Science Foundation(No.2022JJ40346)the 2022 Hunan Provincial University Student Innovation and Entrepreneurship Training Program(No.S202210555144).
文摘Owing to the inherent limitation of the internal pulse ionization chamber within the AlphaGUARD PQ2000 radon monitor,that is,its inability to discriminate the energy levels of α particles,the ingress of^(220)Rn from the surrounding environment,along with its decay progeny,poses a substantive challenge in accurately determining the^(222)Rn concentration in the measurement outcomes.Among these,the protracted influence primarily stems from the two enduring decay progenies,namely^(212)Pb with a half-life of 10.64 h and^(212)Bi with a half-life of 60.54 min.This study explored the influence of^(220)Rn progeny on the measurement results of an AlphaGUARD PQ2000 radon monitor by developing a theoretical calculation model.The response coefficient related to the residual^(220)Rn progeny within the AlphaGUARD PQ2000 radon monitor was experimentally validated.In addition,this study investigated the effects of temperature and wind speed on the sensitivity of the instrument to^(220)Rn gas.The research findings revealed commendable agreement between the experimentally measured response coefficients of the residual^(220)Rn progeny and the corresponding values derived from the theoretical model.Notably,both the response coefficients of the AlphaGUARD PQ2000 radon monitor to^(220)Rn gas and its internal residual^(220)Rn progeny increased with elevated temperatures and increased wind speeds,providing a reference for correcting the impact of^(220)Rn and its progeny on the measurement results of^(222)Rn concentration obtained using the AlphaGUARD PQ2000 radon monitor.
文摘Subcritical reactors(SCRs)or subcritical assemblies(SCAs)are the main infrastructure for designing power reactors.These reactors are widely used for training and research because of their high level of inherent safety.The objective of this study is to design a subcritical reactor using a pressurized water reactor(PWR)conventional fuel following two safety points.In the first approach,deeply placed SCR cores with an infinite multiplication factor(k_(∞))of less than unity were identified using the DRAGON lattice code.In the second approach,subcritical reactor cores with an effective multiplication factor(k_(eff))of less than unity were determined by coupling the cell calculations of the DRAGON lattice code and core calculations of the DONJON code.For the deeply subcritical reactor design,it was found that the reactor would remain inherently subcritical while using fuel rods with ^(235)U enrichment of up to 0.9%,regardless of the pitch of the fuel rods.In the second approach,the optimal pitches(1.3 to 2.3 cm)were determined for different fuel enrichment values from 1 to 5%.Subsequently,the k_(eff) was obtained for a fuel rod arrangement of 8×8 to 80×80,and the states in which the reactor would be subcritical were determined for different fuel enrichments at the corresponding optimal pitch.To validate the models used in the DRAGON and DONJON codes,the k_(eff) of the Isfahan Light Water Subcritical Reactor(LWSCR)was experimentally measured and compared with the results of the calculations.Finally,the effects of fuel and moderator temperature changes were investigated to ensure that the designed assemblies remained in the subcritical state at all operational temperatures.
文摘As the primary functional component of a fusion reactor,the fusion blanket pebble bed,composed of numerous particles,is crucial for tritium breeding,neutron multiplication,and radiation shielding.Particles within tritium-breeding pebble beds are subjected to prolonged neutron irradiation,high thermal loads,and strong magnetic fields in fusion environments.Such conditions render them susceptible to pulverization and fragmentation.The resulting fragments and powders migrate and are deposited into the gas channel,driven by the purge gas.The reduction in the effective flow area of the gas increases the flow resistance,resulting in tritium retention,degraded heat transfer,and other adverse effects.These conditions impair the thermodynamic properties of the pebble beds and hinder the self-maintenance of tritium.Limited information exists on powder migration and clogging mechanisms in fusion blanket pebble beds,particularly under diverse physical conditions.The aim of this study was to use a computational fluid dynamics model coupled with the discrete element method(CFD-DEM)to numerically explore powder migration and clogging in pebble beds.The model considers factors such as breeder orientation,purge velocity,powder size distribution,and friction coefficient.We propose two migration and clogging mechanisms.One involves powder with a large particle size,and the other does not.The results indicate that the powder migration velocity progresses through three stages:rapid decay,linear decay,and stability.Pebble-bed clogging manifests in two forms:extensive superficial clogging and uniform internal clogging.Two fitted curves were used to depict the migration and clogging tendencies.The powder size distribution significantly influenced the powder migration.The breeder orientation,powder size,and friction coefficient affected the distribution of the clogging powders.However,the impact of the purge velocity on powder migration and clogging in pebble beds was limited,and this effect varied significantly with different particle size ratios.Based on the analysis,a formula is proposed to characterize the behavior of the powder in the pebble beds.The results of this study can aid in analyzing and predicting powder dynamics in pebble beds.
基金supported by National Key R&D Program of China(No.2022YFC2404604)Chongqing Research Institution Performance Incentive Guidance Special Project(No.CSTB2023JXJL-YFX0080)Chongqing Medical Scientific Research Project(Joint project of Chongqing Health Commission and Science and Technology Bureau)(No.2022DBXM005)。
文摘This study aimed to integrate Monte Carlo(MC)simulation with deep learning(DL)-based denoising techniques to achieve fast and accurate prediction of high-quality electronic portal imaging device(EPID)transmission dose(TD)for patientspecific quality assurance(PSQA).A total of 100 lung cases were used to obtain the noisy EPID TD by the ARCHER MC code under four kinds of particle numbers(1×10^(6),1×10^(7),1×10^(8)and 1×10^(9)),and the original EPID TD was denoised by the SUNet neural network.The denoised EPID TD was assessed both qualitatively and quantitatively using the structural similarity(SSIM),peak signal-to-noise ratio(PSNR),and gamma passing rate(GPR)with respect to 1×10^(9)as a reference.The computation times for both the MC simulation and DL-based denoising were recorded.As the number of particles increased,both the quality of the noisy EPID TD and computation time increased significantly(1×10^(6):1.12 s,1×10^(7):1.72 s,1×10^(8):8.62 s,and 1×10^(9):73.89 s).In contrast,the DL-based denoising time remained at 0.13-0.16 s.The denoised EPID TD shows a smoother visual appearance and profile curves,but differences between 1×10^(6)and 1×10^(9)still remain.SSIM improves from 0.61 to 0.95 for 1×10^(6),0.70 to 0.96 for 1×10^(7),and 0.90 to 0.97 for 1×10^(8).PSNR increases by>20%for 1×10^(6)and 1×10^(7),and>10%for 1×10^(8).GPR improves from 48.47%to 89.10%for 1×10^(6),61.04%to 94.35%for 1×10^(7),and 91.88%to 99.55%for 1×10^(8).The method that combines MC simulation with DL-based denoising for EPID TD generation can accelerate TD prediction and maintain high accuracy,offering a promising solution for efficient PSQA.
基金supported by the National Natural Science Foundation of China(Nos.11875125,11747312,11675066,and 11505057)the Zhejiang Provincial Natural Science Foundation of China(No.LY18A050002)
文摘The effects of the in-medium nucleon-nucleon(NN) elastic cross section on the observables in heavy ion collisions in the Fermi energy domain are investigated within the framework of the ultrarelativistic quantum molecular dynamics model. The results simulated using medium correction factors of F=σ_(NN)^(in-medium)/σ_(NN)^(free)=0.2,0.3,0.5,and the density-and momentum-dependent factor obtained from the FU3 FP1 parametrization are compared with the FOPI and INDRA experimental data. It is found that the calculations using the correction factors F=0.2 and 0.5 reproduce the experimental data(i.e.,collective flow and nuclear stopping) at 40 and 150 MeV/nucleon, respectively. Calculations with the FU3 FP1 parametrization can best fit these experimental data. These conclusions can be confirmed in both^(197)Au+^(197)Au and^(129)Xe+^(120)Sn.
基金supported by the National Natural Science Foundation of China(No.12222512,U2032209,12075045,12335011,1875097,11975257,62074146,11975115,12205374,12305210,11975292,12005276,12005278,12375193,12227805,12235012,12375191,12005279)the National Key Research and Development Program of China(2021YFA1601300)+13 种基金the Strategic Priority Research Program of Chinese Academy of Sciences(XDB34000000)the CAS Pioneer Hundred Talent Programthe CAS“Light of West China”Programthe Natural Science Foundation of Liaoning Province(No.101300261)the Dalian Science and Technology Innovation Fund(2023JJ12GX013)the Special Projects of the Central Government in Guidance of Local Science and Technology Development(Research and development of three-dimensional prospecting technology based on Cosmic-ray muons)(YDZX20216200001297)the Science and Technology Planning Project of Gansu(20JR10RA645)the Lanzhou University Talent Cooperation Research Funds sponsored by both Lanzhou City(561121203)the Gansu provincial science and technology plan projects for talents(054000029)the Beijing Natural Science Foundation(No.1232033)the Beijing Hope Run Special Fund of Cancer Foundation of China(No.LC2021B23)the Guangdong Major Project of Basic and Applied Basic Research(No.2020B0301030008)the Scientific Instrument Developing Project of the Chinese Academy of Sciences(No.GJJSTD20210009)the Youth Innovation Promotion Association CAS(2021450)。
文摘“A Craftsman Must Sharpen His Tools to Do His Job,”said Confucius.Nuclear detection and readout techniques are the foundation of particle physics,nuclear physics,and particle astrophysics to reveal the nature of the universe.Also,they are being increasingly used in other disciplines like nuclear power generation,life sciences,environmental sciences,medical sciences,etc.The article reviews the short history,recent development,and trend of nuclear detection and readout techniques,covering Semiconductor Detector,Gaseous Detector,Scintillation Detector,Cherenkov Detector,Transition Radiation Detector,and Readout Techniques.By explaining the principle and using examples,we hope to help the interested reader underst and this research field and bring exciting information to the community.
基金supported by the National Natural Science Foundation of China(No.12075067)the National Key R&D Program of China(No.2018YFE0180900)。
文摘To benefit from recent advances in modeling and computational algorithms,as well as the availability of new covariance data,sensitivity and uncertainty analyses are needed to quantify the impact of uncertain sources on the design parameters of small prismatic high-temperature gascooled reactors(HTGRs).In particular,the contribution of nuclear data to the k_(eff)uncertainty is an important part of the uncertainty analysis of small-sized HTGR physical calculations.In this study,a small-sized HTGR designed by China Nuclear Power Engineering Co.,Ltd.was selected for k_(eff)uncertainty analysis during full lifetime burnup calculations.Models of the cold zero power(CZP)condition and full lifetime burnup process were constructed using the Reactor Monte Carlo Code RMC for neutron transport calculation,depletion calculation,and sensitivity and uncertainty analysis.For the sensitivity analysis,the Contribution-Linked eigenvalue sensitivity/Uncertainty estimation via Track length importance Characterization(CLUTCH)method was applied to obtain sensitive information,and the "sandwich" method was used to quantify the k_(eff)uncertainty.We also compared the k_(eff)uncertainties to other typical reactors.Our results show that ^(235)U is the largest contributor to k_(eff)uncertainty for both the CZP and depletion conditions,while the contribution of ^(239)Pu is not very significant because of the design of low discharge burnup.It is worth noting that the radioactive capture reaction of ^(28)Si significantly contributes to the k_(eff)uncertainty owing to its specific fuel design.However,the k_(eff)uncertainty during the full lifetime depletion process was relatively stable,only increasing by 1.12%owing to the low discharge burnup design of small-sized HTGRs.These numerical results are beneficial for neutronics design and core parameters optimization in further uncertainty propagation and quantification study for small-sized HTGR.
基金supported by the National Natural Science Foundation of China(No.11675075)Youth Talent Project of Hunan Province,China(No.2018RS3096)+1 种基金Independent Research Project of Key Laboratory of Plasma Physics,CAEP(No.JCKYS2020212006)Innovation and Entrepreneurship Training Program for College Students of University of South China(No.X2019083)。
文摘The smuggling of special nuclear materials(SNMs)across national borders is becoming a serious threat to nuclear nonproliferation.This paper presents a feasibility study on the rapid interrogation of concealed SNMs by combining scattering and transmission nuclear resonance fluorescence(s NRF and t NRF)spectroscopy.In s NRF spectroscopy,SNMs such as^(235,238)U are excited by a wide-band photon beam of appropriate energy and exhibit unique NRF signatures.Monte Carlo simulations show that one-dimensional scans can realize isotopic identification of concealed^(235,238)U when the detector array used for interrogation has sufficiently high energy resolution.The simulated isotopic ratio^(235U/238)U is in good agreement with the theoretical value when the SNMs are enclosed in relatively thin iron.This interrogation is followed by t NRF spectroscopy using a narrow-band photon beam with the goal of obtaining tomographic images of the concealed SNMs.The reconstructed image clearly reveals the position of the isotope^(235)U inside an iron rod.It is shown that the interrogation time of s NRF and t NRF spectroscopy is one order of magnitude lower than that when only t NRF spectroscopy is used and results in a missed-detection rate of 10^(-3).The proposed method can also be applied for isotopic imaging of other SNMs such as^(239,240)Pu and^(237)Np.
文摘The results of an accident analysis for the loss of offsite power(LOOP)scenario in a reference Bushehr-1 VVER-1000/V446 nuclear power plant(NPP)are presented in this paper.This study attempted to provide a better analysis of LOOP accident management by integrating deterministic and probabilistic approaches.The RELAP5 code was used to investigate the occurrence of specific thermal–hydraulic phenomena.The probabilistic safety assessment of the LOOP accident is presented using the SAPHIRE software.LOOP accident data were extracted from the Bushehr NPP final safety analysis reports and probabilistic safety analysis reports.A deterministic approach was used to reduce the core damage frequency in the probabilistic analysis of LOOP accidents.The probabilistic approach was used to better observe the philosophy of defense in depth and safety margins in the deterministic analysis of the LOOP accident.The results show that the integration of the two approaches in LOOP accident investigations improved accident control.
基金Supported by the Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDB34000000)the Fundamental Research Funds for the Central Universities(lzujbky-2021-sp41 and lzujbky-2021-sp36)
文摘Regarding the stage progress on the relativistic Hartree-Fock(RHF)model achieved recently,we review the extensive developments of the model itself,including the descriptions of axially deformed unstable nuclei and nuclear spin-isospin excitations,which shows that a complete RHF framework is now available for exploring the tensor force effects in both ground state and excited states of unstable nuclei.Meanwhile,the recent RHF descriptions of the pseudo-spin symmetry restoration and the new magicity are also reviewed.It shows that the Fock terms,particularly theρ-tensor coupling and naturally introduced tensor force components,bring about significant improvements in maintaining the delicate in-medium balance of nuclear attractions and repulsions,and uniformly interpreting the emergence of new magicity inCa.The revealed microscopic mechanisms not only deepen our understanding on the properties of nuclear structure,but also help to guide the further development of the effective nuclear force.
基金National Natural Science Foundation of China(Nos.12435010)National Key R&D Program of China(No.2022YFA1602301)。
文摘Nuclear astrophysics is a rapidly developing interdisciplinary feld of research that has received extensive attention from the scientifc community since the midtwentieth century.Broadly,it uses the laws of extremely small atomic nuclei to explain the evolution of the universe.Owing to the complexity of nucleosynthesis processes and our limited understanding of nuclear physics in astrophysical environments,several critical astrophysical problems remain unsolved.To achieve a better understanding of astrophysics,it is necessary to measure the cross sections of key nuclear reactions with the precision required by astrophysical models.Direct measurement of nuclear reaction cross sections is an important method of investigating how nuclear reactions infuence stellar evolution.Given the challenges involved in measuring the extremely low crosssections of nuclear reactions in the Gamow peak and preparing radioactive targets,indirect methods,such as the transfer reaction,coulomb dissociation,and surrogate ratio methods,have been developed over the past several decades.These are powerful tools in the investigation of,for example,neutron-capture(n,r)reactions with short-lived radioactive isotopes.However,direct measurement is still preferable,such as in the case of reactions involving light and stable nuclei.As an essential part of stellar evolution,these low-energy stable nuclear reactions have been of particular interest in recent years.To overcome the diffculties in measurements near or deeply within the Gamow window,the combination of an underground laboratory and high-exposure accelerator/detector complex is currently the optimal solution.Therefore,underground experiments have emerged as a new and promising direction of research.In addition,to better simulate the stellar environment in the laboratory,research on nuclear physics under laser-driven plasma conditions has gradually become a frontier hotspot.In recent years,the CIAE team conducted a series of distinctive nuclear astrophysics studies,relying on the Jinping Underground Nuclear Astrophysics platform and accelerators in Earth’s surface laboratories,including the Beijing Radioactive Ion beam Facility,as well as other scientifc platforms at home and abroad.This research covered nuclear theories,numerical models,direct measurements,indirect measurements,and other novel approaches,achieving great interdisciplinary research results,with high-level academic publications and signifcant international impacts.This article reviews the above research and predicts future developments.
基金partly supported by the National Natural Science Foundation of China (Nos. U2032145 and 11875125)the National Key Research and Development Program of China (No. 2020YFE0202002)。
文摘In this study, the rapidity distribution, collective flows, and nuclear stopping power in ^(197)Au+^(197)Au collisions at intermediate energies were investigated using the ultrarelativistic quantum molecular dynamics(UrQMD) model with GEMINI++ code. The UrQMD model was adopted to simulate the dynamic evolution of heavy-ion collisions, whereas the GEMINI++ code was used to simulate the decay of primary fragments produced by UrQMD. The calculated results were compared with the INDRA and FOPI experimental data. It was found that the rapidity distribution, collective flows, and nuclear stopping power were affected to a certain extent by the decay of primary fragments, especially at lower beam energies. Furthermore, the experimental data of the collective flows and nuclear stopping power at the investigated beam energies were better reproduced when the sequential decay effect was included.
文摘The present paper describes the development and applications of nuclear track detection technique in Pakistan. Pakistan entered in the field of nuclear tracks in early 1970s when it was still quite new. Highlights of successes of different Pakistani laboratories, working on nuclear tracks, achieved on their own or in collaboration with similar centers in the world are described briefly. The robust features of this investigation are the comprehensive investigation of the addressed research, analysis and review of results, and discussions with the perspectives of applications and new research directions. Further analysis of the published results by the present author and some new results are also presented. This paper portrays a comprehensive picture of the nuclear track detection research and technology in Pakistan and can be useful for a similar development in any country around the globe.
文摘The intricate balance between reactor economics and safety necessitates the emergence of new and advanced nuclear systems and,very importantly,advanced materials,which can overcome current shortcomings and bring about more economic nuclear systems with designed-in inherent safety features.These advances will achieve greater safety and better nuclear reactor economics by reaching longer reactor lives with higher levels neutron irradiation,and by providing higher operation temperatures and resistance to more aggressive corrosive environments.This paper provides a review of the current state of research and development on innovative nuclear fuel materials design and development which have the potential of benefiting simultaneously reactor economics and safety.Our discussion focuses on three areas of research:Accident-tolerant Fuels(ATFs),Oxidation Dispersion Strengthened(ODS)steels and High Entropy Alloys(HEAs).The paper also gives a prospective description of future research activities on these materials.
