Two recipes for modeling the dynamics of the nuclear fission process are known in literature. The underlying equations contain the driving, dissipative, and random forces. The two recipes are mostly different in the p...Two recipes for modeling the dynamics of the nuclear fission process are known in literature. The underlying equations contain the driving, dissipative, and random forces. The two recipes are mostly different in the prescriptions for the driving force. In this work we carefully compare these driving forces and the resulting fission rates. It turns out that the rates may be very close or strongly different depending on the value the shell correction to the nuclear deformation energy. We give arguments in favor of one of the recipes.展开更多
Project New Orion entails a pulsed nuclear space propulsion system that utilizes photofission through the implementation of an ultra-intense laser. The historical origins derive from the endeavors of Project Orion, wh...Project New Orion entails a pulsed nuclear space propulsion system that utilizes photofission through the implementation of an ultra-intense laser. The historical origins derive from the endeavors of Project Orion, which utilized thermonuclear devices to impart a considerable velocity increment on the respective spacecraft. The shear magnitude of Project Orion significantly detracts from the likelihood of progressive research development testing and evaluation. Project New Orion incorporates a more feasible pathway for the progressive research development testing and evaluation of the pulsed nuclear space propulsion system. Photofission through the application of an ultra-intense laser enables a much more controllable and scalable nuclear yield. The energy source for the ultra-intense laser is derived from a first stage liquid hydrogen and liquid oxygen chemical propulsion system. A portion of the thermal/kinetic energy of the rocket propulsive fluid is converted to electrical energy through a magneto-hydrodynamic generator with cryogenic propellant densification for facilitating the integral superconducting magnets. Fundamental analysis of Project New Orion demonstrates the capacity to impart a meaningful velocity increment through ultra-intense laser derived photofission on a small spacecraft.展开更多
In this study,the fission properties of^(180)Hg were investigated based on Skyrme density functional theory.The impact of the high-order hexadecapole moment(q_(40))was observed at large deformations.With the q_(40)con...In this study,the fission properties of^(180)Hg were investigated based on Skyrme density functional theory.The impact of the high-order hexadecapole moment(q_(40))was observed at large deformations.With the q_(40)constraint,smooth and continuous potential energy surfaces could be obtained.In particular,the hexadecapole moment constraint is essential for obtaining appropriate scission configurations.The static fission path based on the PES supports the asymmetric fission of^(180)Hg.The asymmetric distribution of the fission yields of^(180)Hg was reproduced by the time-dependent generator coordinate method and agreed well with the experimental data.展开更多
We studied the energy partition between two well-separated fission fragments associated with the partition of nucleons owing to quantum entanglement.This is different from most fission models that invoke an explicit s...We studied the energy partition between two well-separated fission fragments associated with the partition of nucleons owing to quantum entanglement.This is different from most fission models that invoke an explicit statistical partition of excitation energies.The dynamical fission evolution is described within the time-dependent Hartree-Fock+BCS framework.Excitation energies of isotopic fission fragments were obtained using the particle number projection method after the dynamical splitting of^(238)U.The resulting excitation energies of the light and heavy fragments are consistent with the appearance of sawtooth structures.We found that the pairing correlation strengths have a significant influence on the partition of the excitation energies.Furthermore,the excitation energies of isotopic fragments increase with increasing neutron number,implying the suppression of the production of neutron-rich beams in rare-isotope beam facilities.展开更多
A burnup calculation was performed to analyze the Apr`es ORIENT process, which aims to create highlyvaluable elements from fission products separated from spent nuclear fuels. The basic idea is to use nuclear transmut...A burnup calculation was performed to analyze the Apr`es ORIENT process, which aims to create highlyvaluable elements from fission products separated from spent nuclear fuels. The basic idea is to use nuclear transmutation induced by a neutron capture reaction followed by a β-decay, thus changing the atomic number Z of a target element in fission products by 1 unit. LWR(PWR) and FBR(MONJU) were considered as the transmutation devices. High rates of creation were obtained in some cases of platinum group metals(44Ru by FBR,46 Pd by LWR) and rare earth(64Gd by LWR,66 Dy by FBR). Therefore, systems based on LWR and FBR have their own advantages depending on target elements. Furthermore, it was found that creation rates of even Z(= Z + 1) elements from odd Z ones were higher than the opposite cases. This creation rate of an element was interpreted in terms of "average 1-group neutron capture cross section of the corresponding target element σc Z defined in this work. General trends of the creation rate of an even(odd) Z element from the corresponding odd(even) Z one were found to be proportional to the 0.78th(0.63th) power of σc Z, however with noticeable dispersion. The difference in the powers in the above analysis was explained by the difference in the number of stable isotopes caused by the even-odd effect of Z.展开更多
In this paper, a home-made code was designed to calculate the decay heat emitted by fission fragments as a result of successive radioactive emissions after a fission burst. The nuclear data necessary for the calculati...In this paper, a home-made code was designed to calculate the decay heat emitted by fission fragments as a result of successive radioactive emissions after a fission burst. The nuclear data necessary for the calculations was extracted from the latest version of the Evaluated Nuclear Data Library ENDF/B-VIII.0. The code can calculate the decay heat of thermal and fast neutron-induced fission reactions on the isotopes of Thorium, Protactinium, Uranium, Neptunium, Plutonium, Americium, Curium, California, Einsteinium, and Fermium. A numerical method was used in this work to calculate the decay heat of all fission fragments due to the individual thermal or fast fissions of the isotopes of the previous ten actinides. The most influential nuclei in the decay heat were also identified at different times after the fission event. Moreover, the code showed high capability in calculating the fission fragments inventories and decay heats due to the decay of fission fragments of 31 fissionable nuclei.展开更多
MIXED Oxide Nuclear fuel (MOX) contains both uranium and plutonium in oxidized form. It is important to calculate the nuclear decay heat due to the single thermal fission (fission due to 0.0235 eV neutron) for all fis...MIXED Oxide Nuclear fuel (MOX) contains both uranium and plutonium in oxidized form. It is important to calculate the nuclear decay heat due to the single thermal fission (fission due to 0.0235 eV neutron) for all fissile nuclei in the MOX fuels (U<sup>235</sup>, Pu<sup>239</sup>, and Pu<sup>241</sup>). These fissile nuclei are the main source of the decay heat in MOX fuel. Decay heat calculation of the weighted fissile material content in MOX fuel is also important. A numerical method was used in this work to calculate the concentrations of all fission products due to the individual thermal fission of the three fissile materials as a function of time N(t). The decay heat calculations for the three fissile materials are directly calculated using the summation method by knowing the different concentrations of fission products over time. The average decay heat of the MOX fuel in induced thermal fission is also concluded. The most influential nuclei in the decay heat were also identified. The method used has been validated by several comparisons before, but the new in this work is using the most recent Evaluated Nuclear Data Library ENDF/B-VIII.0. Calculations of decay heat show very common trends for a period of 10<sup>7</sup> sec after the fission burst of thermal fissions of individual fissile nuclei. Moreover, the code showed high capability in calculating the fission fragments inventories and decay heats due to the decay of fission fragments of 31 fissionable nuclei.展开更多
Using the Skyrme density functional theory,potential energy surfaces of^(240)Pu with constraints on the axial quadrupole and octupole deformations(q_(20)and q_(30))were calculated.The volume-like and surface-like pair...Using the Skyrme density functional theory,potential energy surfaces of^(240)Pu with constraints on the axial quadrupole and octupole deformations(q_(20)and q_(30))were calculated.The volume-like and surface-like pairing forces,as well as a combination of these two forces,were used for the Hartree–Fock–Bogoliubov approximation.Variations in the least-energy fission path,fission barrier,pairing energy,total kinetic energy,scission line,and mass distribution of the fission fragments based on the different forms of the pairing forces were analyzed and discussed.The fission dynamics were studied based on the timedependent generator coordinate method plus the Gaussian overlap approximation.The results demonstrated a sensitivity of the mass and charge distributions of the fission fragments on the form of the pairing force.Based on the investigation of the neutron-induced fission of^(239)Pu,among the volume,mixed,and surface pairing forces,the mixed pairing force presented a good reproduction of the experimental data.展开更多
电子探针显微分析(Electron Probe Micro-Analyze,EPMA)作为一种高空间分辨率的微区分析技术,旨在实现对辐照后核燃料中裂变气体Xe的浓度分布、局部富集及迁移行为的准确分析,并揭示辐照损伤对燃料性能的影响。EPMA通过测量X射线的特征...电子探针显微分析(Electron Probe Micro-Analyze,EPMA)作为一种高空间分辨率的微区分析技术,旨在实现对辐照后核燃料中裂变气体Xe的浓度分布、局部富集及迁移行为的准确分析,并揭示辐照损伤对燃料性能的影响。EPMA通过测量X射线的特征谱线,对Xe进行定性和定量分析,并结合透射电镜(Transmission Electron Microscope,TEM)和二次离子质谱仪(Secondary Ion Mass Spectrometry,SIMS)等其他分析技术,以获取更全面的裂变气体行为信息。本文系统总结近年来EPMA在辐照后核燃料Xe浓度分析中的应用,探讨影响分析准确性的关键因素(如样品制备、仪器参数及数据处理方法等),并评述了提高分析精度的优化方法。通过优化实验条件、改进数据处理算法及结合互补分析技术,可显著提升EPMA的定量准确性。未来,EPMA与其他技术的联用将进一步深化对裂变气体行为的理解,为核燃料性能评估提供更可靠的数据支持。展开更多
We propose an efficient approach to describe the fission-fragment charge yields for actinides based on the driving potential of the fissioning system.Considering the properties of primary fission fragments at their gr...We propose an efficient approach to describe the fission-fragment charge yields for actinides based on the driving potential of the fissioning system.Considering the properties of primary fission fragments at their ground states,the driving potential,which represents the potential energies of the system around scission configuration and closely relates to the yields of fragments,can be unambiguously and quickly obtained from the Skyrme energy-density functional together with the Weizs?cker-Skyrme mass model.The fission-fragment charge distributions for thermal-neutron-induced fission and spontaneous fission of a series of actinides,especially the odd-even staggering in the charge distributions,can be well reproduced.Nuclear dynamical deformations and pairing corrections of fragments play an important role in the charge distributions.展开更多
An attempt is made to locate nuclear technology within a logical context considering history, risks, societal catastrophes and perspectives: the need is identified for a new direction in the exploitation in order to r...An attempt is made to locate nuclear technology within a logical context considering history, risks, societal catastrophes and perspectives: the need is identified for a new direction in the exploitation in order to restore the role in energy production. We depict the situation coming from a marvelous history of discoveries started at the beginning of the XX century;heroes are recalled who made possible something that is inconceivable today: design, construction and production of electricity in a few years;that history was tainted by intentional nuclear explosions, </span><i><span style="font-size:12px;font-family:Verdana;">i.e.</span></i><span style="font-size:12px;font-family:Verdana;"> the original sin that we are now paying. Then, we attempt to show that the societal risk is an inherent part of the civilization. Restoring the public trust (towards nuclear fission technology) by matching nuclear safety with the current technological status and advancers in risk assessment is the key objective. The </span></span><span style="font-family:Verdana;font-size:12px;">“</span><span style="font-family:Verdana;font-size:12px;">independent assessment</span><span style="font-family:Verdana;font-size:12px;">”</span><span style="font-family:Verdana;font-size:12px;">, or a principle for the exploitation of nuclear energy already stated in the 50’s of the previous century, shall then re-appear. This is used to erect the signpost for a </span><span style="font-family:Verdana;font-size:12px;">“</span><span style="font-family:Verdana;font-size:12px;">dynamic barricade</span><span style="font-family:Verdana;font-size:12px;">”</span><span style="font-family:Verdana;font-size:12px;"> to further reduce the risk of operation of nuclear reactors and to match the design with current technological capabilities and with the frontiers of the research.展开更多
Photofission enables a unique capability for the domain of non-chemical space propulsion. An ultra-intense laser enables the capacity to induce nuclear fission through the development of bre- msstrahlung photons. A fu...Photofission enables a unique capability for the domain of non-chemical space propulsion. An ultra-intense laser enables the capacity to induce nuclear fission through the development of bre- msstrahlung photons. A fundamental architecture and performance analysis of a photofission pulsed space propulsion system through the operation of an ultra-intense laser is presented. A historical perspective of previous conceptual nuclear fission propulsion systems is addressed. These applications use neutron derived nuclear fission;however, there is inherent complexity that has precluded further development. The background of photofission is detailed. The conceptual architecture of photofission pulsed space propulsion and fundamental performance parameters are established. The implications are the energy source and ultra-intense laser can be situated far remote from the propulsion system. Advances in supporting laser technologies are anticipated to increase the potential for photofission pulsed space propulsion. The fundamental performance analysis of the photofission pulsed space propulsion system indicates the architecture is feasible for further evaluation.展开更多
A model of a fissioning nucleus that splits symmetrically both axially and equatorially is used to show how one can predict the presence of a fission barrier of several tens of MeV for nuclides of mass number A ~ 90 a...A model of a fissioning nucleus that splits symmetrically both axially and equatorially is used to show how one can predict the presence of a fission barrier of several tens of MeV for nuclides of mass number A ~ 90 and of ~ 10 MeV for elements such as uranium. While the present model sacrifices some physical realism for the sake of analytic and programming simplicity, it does reproduce the general behavior of the run of fission barrier energy as a function of mass number as revealed by much more sophisticated models. Its intuitive appeal and tractability make it appropriate for presentation in a student-level “Modern Physics” class.展开更多
Concerning the increasing global energy demand, the current paper considers nuclear energy as a solution. Within this context, the 2011 disaster in Fukushima Nuclear Power Plant and, particularly, the technical disord...Concerning the increasing global energy demand, the current paper considers nuclear energy as a solution. Within this context, the 2011 disaster in Fukushima Nuclear Power Plant and, particularly, the technical disorders in boiling water reactors are explained. The deficiency of safety technique in boiling water reactors is explained. The deficiencies in safety procedure of this type of reactors manifested during 2011 earthquake and subsequent tsunami are explained. To complete the discussion, the newer technologies of reactors enabling them to act more safely during natural disasters are introduced. These investigations indicate that despite improvement in the fission reactor technologies, the danger embedded in them still remains. Therefore, the nuclear fusion using Deuterium-Tritium reaction is the best way forward for energy production in the future, and the best candidate of this type of reactors is Tokamak.展开更多
A new composite of silicone rubber and boric acid was developed to be used as a personal wearing for protection from nuclear radiation. The capability of this material for absorbing thermal neutrons of different inten...A new composite of silicone rubber and boric acid was developed to be used as a personal wearing for protection from nuclear radiation. The capability of this material for absorbing thermal neutrons of different intensities followed by a detonation of nuclear weapon has been investigated. This investigation was performed by using californium-252 neutron source of like fission spectrum. The thermal neutron flux was measured behind different thicknesses of the developed material using a BF3 detector. Two positions of measurements were performed;at position near the detonation where the intensity of thermal neutron flux is low and at position far from the detonation where the intensity of thermal neutron is high. For both cases, the contribution of total thermal, initial incident and new produced thermal neutron fluxes are measured. The obtained results indicated that, addition of boron with concentration of about 17% to the silicon rubber tends to decrease the flux by more than 70%.展开更多
This paper describes a freely-available spread-sheet that has been developed to simulate the conditions of reaction rate, core acceleration and velocity, energy generation, and pressure within a detonating fission-bom...This paper describes a freely-available spread-sheet that has been developed to simulate the conditions of reaction rate, core acceleration and velocity, energy generation, and pressure within a detonating fission-bomb core. When applied to a model of the Hiroshima Little Boy bomb, the spreadsheet predicts a yield of 12.7 kilotons, a figure in reasonable agreement with published values.展开更多
A new method for three-dimensional simulation of the interaction between the gas and the solid around is developed.The effects of the gas on the thermal-mechanical behaviors within the surrounded solid are performed b...A new method for three-dimensional simulation of the interaction between the gas and the solid around is developed.The effects of the gas on the thermal-mechanical behaviors within the surrounded solid are performed by replacing the internal gas with an equivalent solid in the modeling,which can make it convenient to simulate the thermal-mechanical coupling effects in the solid research objects with gases in them.The applied thermal expansion coefficient,Young's modulus and Poisson's ratio of the equivalent solid material are derived.A series of tests have been conducted;and the proposed equivalent solid method to simulate the gas effects is validated.展开更多
This article proposes to associate a Deuterium-Deuterium (D-D) fusion reactor with a PWR (fission Pressurized Water Reactor) in a hybrid reactor. Even if the mechanical gain (Q factor) of the D-D fusion reactor is bel...This article proposes to associate a Deuterium-Deuterium (D-D) fusion reactor with a PWR (fission Pressurized Water Reactor) in a hybrid reactor. Even if the mechanical gain (Q factor) of the D-D fusion reactor is below the unity and consequently consumes more energy than it supplies, due to the high energy amplification factor of the PWR fission reactor, the global yield is widely superior to 1. As the energy supplied by the fusion reactor is relatively low and as the neutrons supplied are mainly issued from D-D fusions (at 2.45 MeV), the problems of heat flux and neutrons damage connected with materials, as with D-T fusion reactors are reduced. Of course, there is no need to produce Tritium with this D-D fusion reactor. This type of reactor is able to incinerate any mixture of natural Uranium, natural Thorium and depleted Uranium (waste issued from enrichment plants), with natural Thorium being the best choice. No enriched fuel is needed. So, this type of reactor could constitute a source of energy for several thousands of years because it is about 90 more efficient than a standard fission reactor, such as a PWR or a Candu one, by extracting almost completely the energy from the fertile materials U238 and Th232. For the fission part, PWR technology is mature. For the fusion part, it is based on a reasonable hypothesis done on present Stellarators projects. The working of this reactor is continuous, 24 hours a day. In this paper, it will be targeted a reactor able to provide net electric power of about 1400 MWe, as a big fission power plant.展开更多
文摘Two recipes for modeling the dynamics of the nuclear fission process are known in literature. The underlying equations contain the driving, dissipative, and random forces. The two recipes are mostly different in the prescriptions for the driving force. In this work we carefully compare these driving forces and the resulting fission rates. It turns out that the rates may be very close or strongly different depending on the value the shell correction to the nuclear deformation energy. We give arguments in favor of one of the recipes.
文摘Project New Orion entails a pulsed nuclear space propulsion system that utilizes photofission through the implementation of an ultra-intense laser. The historical origins derive from the endeavors of Project Orion, which utilized thermonuclear devices to impart a considerable velocity increment on the respective spacecraft. The shear magnitude of Project Orion significantly detracts from the likelihood of progressive research development testing and evaluation. Project New Orion incorporates a more feasible pathway for the progressive research development testing and evaluation of the pulsed nuclear space propulsion system. Photofission through the application of an ultra-intense laser enables a much more controllable and scalable nuclear yield. The energy source for the ultra-intense laser is derived from a first stage liquid hydrogen and liquid oxygen chemical propulsion system. A portion of the thermal/kinetic energy of the rocket propulsive fluid is converted to electrical energy through a magneto-hydrodynamic generator with cryogenic propellant densification for facilitating the integral superconducting magnets. Fundamental analysis of Project New Orion demonstrates the capacity to impart a meaningful velocity increment through ultra-intense laser derived photofission on a small spacecraft.
基金supported by the National Key R and D Program of China(No.2022YFA1602000)National Natural Science Foundation of China(Nos.12275081 and U1732138)Continuous-support Basic Scientific Research Project.
文摘In this study,the fission properties of^(180)Hg were investigated based on Skyrme density functional theory.The impact of the high-order hexadecapole moment(q_(40))was observed at large deformations.With the q_(40)constraint,smooth and continuous potential energy surfaces could be obtained.In particular,the hexadecapole moment constraint is essential for obtaining appropriate scission configurations.The static fission path based on the PES supports the asymmetric fission of^(180)Hg.The asymmetric distribution of the fission yields of^(180)Hg was reproduced by the time-dependent generator coordinate method and agreed well with the experimental data.
基金supported by the National Key R&D Program of China(Nos.2023YFE0101500,2023YFA1606403)the National Natural Science Foundation of China(Nos.12475118,12335007)the State Key Laboratory of Nuclear Physics and Technology,Peking University(No.NPT2023ZX01)。
文摘We studied the energy partition between two well-separated fission fragments associated with the partition of nucleons owing to quantum entanglement.This is different from most fission models that invoke an explicit statistical partition of excitation energies.The dynamical fission evolution is described within the time-dependent Hartree-Fock+BCS framework.Excitation energies of isotopic fission fragments were obtained using the particle number projection method after the dynamical splitting of^(238)U.The resulting excitation energies of the light and heavy fragments are consistent with the appearance of sawtooth structures.We found that the pairing correlation strengths have a significant influence on the partition of the excitation energies.Furthermore,the excitation energies of isotopic fragments increase with increasing neutron number,implying the suppression of the production of neutron-rich beams in rare-isotope beam facilities.
文摘A burnup calculation was performed to analyze the Apr`es ORIENT process, which aims to create highlyvaluable elements from fission products separated from spent nuclear fuels. The basic idea is to use nuclear transmutation induced by a neutron capture reaction followed by a β-decay, thus changing the atomic number Z of a target element in fission products by 1 unit. LWR(PWR) and FBR(MONJU) were considered as the transmutation devices. High rates of creation were obtained in some cases of platinum group metals(44Ru by FBR,46 Pd by LWR) and rare earth(64Gd by LWR,66 Dy by FBR). Therefore, systems based on LWR and FBR have their own advantages depending on target elements. Furthermore, it was found that creation rates of even Z(= Z + 1) elements from odd Z ones were higher than the opposite cases. This creation rate of an element was interpreted in terms of "average 1-group neutron capture cross section of the corresponding target element σc Z defined in this work. General trends of the creation rate of an even(odd) Z element from the corresponding odd(even) Z one were found to be proportional to the 0.78th(0.63th) power of σc Z, however with noticeable dispersion. The difference in the powers in the above analysis was explained by the difference in the number of stable isotopes caused by the even-odd effect of Z.
文摘In this paper, a home-made code was designed to calculate the decay heat emitted by fission fragments as a result of successive radioactive emissions after a fission burst. The nuclear data necessary for the calculations was extracted from the latest version of the Evaluated Nuclear Data Library ENDF/B-VIII.0. The code can calculate the decay heat of thermal and fast neutron-induced fission reactions on the isotopes of Thorium, Protactinium, Uranium, Neptunium, Plutonium, Americium, Curium, California, Einsteinium, and Fermium. A numerical method was used in this work to calculate the decay heat of all fission fragments due to the individual thermal or fast fissions of the isotopes of the previous ten actinides. The most influential nuclei in the decay heat were also identified at different times after the fission event. Moreover, the code showed high capability in calculating the fission fragments inventories and decay heats due to the decay of fission fragments of 31 fissionable nuclei.
文摘MIXED Oxide Nuclear fuel (MOX) contains both uranium and plutonium in oxidized form. It is important to calculate the nuclear decay heat due to the single thermal fission (fission due to 0.0235 eV neutron) for all fissile nuclei in the MOX fuels (U<sup>235</sup>, Pu<sup>239</sup>, and Pu<sup>241</sup>). These fissile nuclei are the main source of the decay heat in MOX fuel. Decay heat calculation of the weighted fissile material content in MOX fuel is also important. A numerical method was used in this work to calculate the concentrations of all fission products due to the individual thermal fission of the three fissile materials as a function of time N(t). The decay heat calculations for the three fissile materials are directly calculated using the summation method by knowing the different concentrations of fission products over time. The average decay heat of the MOX fuel in induced thermal fission is also concluded. The most influential nuclei in the decay heat were also identified. The method used has been validated by several comparisons before, but the new in this work is using the most recent Evaluated Nuclear Data Library ENDF/B-VIII.0. Calculations of decay heat show very common trends for a period of 10<sup>7</sup> sec after the fission burst of thermal fissions of individual fissile nuclei. Moreover, the code showed high capability in calculating the fission fragments inventories and decay heats due to the decay of fission fragments of 31 fissionable nuclei.
基金supported by the National Key R&D Program of China(No.2022YFA1602000)National Natural Science Foundation of China(Nos.12275081,U2067205,11790325,and U1732138)the Continuous-support Basic Scientific Research Project。
文摘Using the Skyrme density functional theory,potential energy surfaces of^(240)Pu with constraints on the axial quadrupole and octupole deformations(q_(20)and q_(30))were calculated.The volume-like and surface-like pairing forces,as well as a combination of these two forces,were used for the Hartree–Fock–Bogoliubov approximation.Variations in the least-energy fission path,fission barrier,pairing energy,total kinetic energy,scission line,and mass distribution of the fission fragments based on the different forms of the pairing forces were analyzed and discussed.The fission dynamics were studied based on the timedependent generator coordinate method plus the Gaussian overlap approximation.The results demonstrated a sensitivity of the mass and charge distributions of the fission fragments on the form of the pairing force.Based on the investigation of the neutron-induced fission of^(239)Pu,among the volume,mixed,and surface pairing forces,the mixed pairing force presented a good reproduction of the experimental data.
文摘电子探针显微分析(Electron Probe Micro-Analyze,EPMA)作为一种高空间分辨率的微区分析技术,旨在实现对辐照后核燃料中裂变气体Xe的浓度分布、局部富集及迁移行为的准确分析,并揭示辐照损伤对燃料性能的影响。EPMA通过测量X射线的特征谱线,对Xe进行定性和定量分析,并结合透射电镜(Transmission Electron Microscope,TEM)和二次离子质谱仪(Secondary Ion Mass Spectrometry,SIMS)等其他分析技术,以获取更全面的裂变气体行为信息。本文系统总结近年来EPMA在辐照后核燃料Xe浓度分析中的应用,探讨影响分析准确性的关键因素(如样品制备、仪器参数及数据处理方法等),并评述了提高分析精度的优化方法。通过优化实验条件、改进数据处理算法及结合互补分析技术,可显著提升EPMA的定量准确性。未来,EPMA与其他技术的联用将进一步深化对裂变气体行为的理解,为核燃料性能评估提供更可靠的数据支持。
基金supported by the National Natural Science Foundation of China(Nos U1867212,11875323,12147211)Guangxi Natural Science Foundation(No.2017GXNSFGA198001)
文摘We propose an efficient approach to describe the fission-fragment charge yields for actinides based on the driving potential of the fissioning system.Considering the properties of primary fission fragments at their ground states,the driving potential,which represents the potential energies of the system around scission configuration and closely relates to the yields of fragments,can be unambiguously and quickly obtained from the Skyrme energy-density functional together with the Weizs?cker-Skyrme mass model.The fission-fragment charge distributions for thermal-neutron-induced fission and spontaneous fission of a series of actinides,especially the odd-even staggering in the charge distributions,can be well reproduced.Nuclear dynamical deformations and pairing corrections of fragments play an important role in the charge distributions.
文摘An attempt is made to locate nuclear technology within a logical context considering history, risks, societal catastrophes and perspectives: the need is identified for a new direction in the exploitation in order to restore the role in energy production. We depict the situation coming from a marvelous history of discoveries started at the beginning of the XX century;heroes are recalled who made possible something that is inconceivable today: design, construction and production of electricity in a few years;that history was tainted by intentional nuclear explosions, </span><i><span style="font-size:12px;font-family:Verdana;">i.e.</span></i><span style="font-size:12px;font-family:Verdana;"> the original sin that we are now paying. Then, we attempt to show that the societal risk is an inherent part of the civilization. Restoring the public trust (towards nuclear fission technology) by matching nuclear safety with the current technological status and advancers in risk assessment is the key objective. The </span></span><span style="font-family:Verdana;font-size:12px;">“</span><span style="font-family:Verdana;font-size:12px;">independent assessment</span><span style="font-family:Verdana;font-size:12px;">”</span><span style="font-family:Verdana;font-size:12px;">, or a principle for the exploitation of nuclear energy already stated in the 50’s of the previous century, shall then re-appear. This is used to erect the signpost for a </span><span style="font-family:Verdana;font-size:12px;">“</span><span style="font-family:Verdana;font-size:12px;">dynamic barricade</span><span style="font-family:Verdana;font-size:12px;">”</span><span style="font-family:Verdana;font-size:12px;"> to further reduce the risk of operation of nuclear reactors and to match the design with current technological capabilities and with the frontiers of the research.
文摘Photofission enables a unique capability for the domain of non-chemical space propulsion. An ultra-intense laser enables the capacity to induce nuclear fission through the development of bre- msstrahlung photons. A fundamental architecture and performance analysis of a photofission pulsed space propulsion system through the operation of an ultra-intense laser is presented. A historical perspective of previous conceptual nuclear fission propulsion systems is addressed. These applications use neutron derived nuclear fission;however, there is inherent complexity that has precluded further development. The background of photofission is detailed. The conceptual architecture of photofission pulsed space propulsion and fundamental performance parameters are established. The implications are the energy source and ultra-intense laser can be situated far remote from the propulsion system. Advances in supporting laser technologies are anticipated to increase the potential for photofission pulsed space propulsion. The fundamental performance analysis of the photofission pulsed space propulsion system indicates the architecture is feasible for further evaluation.
文摘A model of a fissioning nucleus that splits symmetrically both axially and equatorially is used to show how one can predict the presence of a fission barrier of several tens of MeV for nuclides of mass number A ~ 90 and of ~ 10 MeV for elements such as uranium. While the present model sacrifices some physical realism for the sake of analytic and programming simplicity, it does reproduce the general behavior of the run of fission barrier energy as a function of mass number as revealed by much more sophisticated models. Its intuitive appeal and tractability make it appropriate for presentation in a student-level “Modern Physics” class.
文摘Concerning the increasing global energy demand, the current paper considers nuclear energy as a solution. Within this context, the 2011 disaster in Fukushima Nuclear Power Plant and, particularly, the technical disorders in boiling water reactors are explained. The deficiency of safety technique in boiling water reactors is explained. The deficiencies in safety procedure of this type of reactors manifested during 2011 earthquake and subsequent tsunami are explained. To complete the discussion, the newer technologies of reactors enabling them to act more safely during natural disasters are introduced. These investigations indicate that despite improvement in the fission reactor technologies, the danger embedded in them still remains. Therefore, the nuclear fusion using Deuterium-Tritium reaction is the best way forward for energy production in the future, and the best candidate of this type of reactors is Tokamak.
文摘A new composite of silicone rubber and boric acid was developed to be used as a personal wearing for protection from nuclear radiation. The capability of this material for absorbing thermal neutrons of different intensities followed by a detonation of nuclear weapon has been investigated. This investigation was performed by using californium-252 neutron source of like fission spectrum. The thermal neutron flux was measured behind different thicknesses of the developed material using a BF3 detector. Two positions of measurements were performed;at position near the detonation where the intensity of thermal neutron flux is low and at position far from the detonation where the intensity of thermal neutron is high. For both cases, the contribution of total thermal, initial incident and new produced thermal neutron fluxes are measured. The obtained results indicated that, addition of boron with concentration of about 17% to the silicon rubber tends to decrease the flux by more than 70%.
文摘This paper describes a freely-available spread-sheet that has been developed to simulate the conditions of reaction rate, core acceleration and velocity, energy generation, and pressure within a detonating fission-bomb core. When applied to a model of the Hiroshima Little Boy bomb, the spreadsheet predicts a yield of 12.7 kilotons, a figure in reasonable agreement with published values.
基金Supported by Natural Science Foundation of China(Nos.10772049 and 11072062)Research and Development Program of China(863 Program, No.2009AA04Z408)+1 种基金Natural Science Foundation of Shanghai(No.06ZR14009)Pujiang Scholar Program and the Wangdao Scholar Program(No.08076) of Fudan University
文摘A new method for three-dimensional simulation of the interaction between the gas and the solid around is developed.The effects of the gas on the thermal-mechanical behaviors within the surrounded solid are performed by replacing the internal gas with an equivalent solid in the modeling,which can make it convenient to simulate the thermal-mechanical coupling effects in the solid research objects with gases in them.The applied thermal expansion coefficient,Young's modulus and Poisson's ratio of the equivalent solid material are derived.A series of tests have been conducted;and the proposed equivalent solid method to simulate the gas effects is validated.
文摘This article proposes to associate a Deuterium-Deuterium (D-D) fusion reactor with a PWR (fission Pressurized Water Reactor) in a hybrid reactor. Even if the mechanical gain (Q factor) of the D-D fusion reactor is below the unity and consequently consumes more energy than it supplies, due to the high energy amplification factor of the PWR fission reactor, the global yield is widely superior to 1. As the energy supplied by the fusion reactor is relatively low and as the neutrons supplied are mainly issued from D-D fusions (at 2.45 MeV), the problems of heat flux and neutrons damage connected with materials, as with D-T fusion reactors are reduced. Of course, there is no need to produce Tritium with this D-D fusion reactor. This type of reactor is able to incinerate any mixture of natural Uranium, natural Thorium and depleted Uranium (waste issued from enrichment plants), with natural Thorium being the best choice. No enriched fuel is needed. So, this type of reactor could constitute a source of energy for several thousands of years because it is about 90 more efficient than a standard fission reactor, such as a PWR or a Candu one, by extracting almost completely the energy from the fertile materials U238 and Th232. For the fission part, PWR technology is mature. For the fusion part, it is based on a reasonable hypothesis done on present Stellarators projects. The working of this reactor is continuous, 24 hours a day. In this paper, it will be targeted a reactor able to provide net electric power of about 1400 MWe, as a big fission power plant.
