Recent progress on nuclear liquid gas phase transition (LGPT) has been reviewed, especially for the signals of LGPT in heavy ion collisions. These signals include the power-law charge distribution, cluster emission ra...Recent progress on nuclear liquid gas phase transition (LGPT) has been reviewed, especially for the signals of LGPT in heavy ion collisions. These signals include the power-law charge distribution, cluster emission rate, nuclear Zipf law, bimodality, the largest fluctuation of the fragments, Δ-scaling, caloric curve, phase coexis- tence diagram, critical temperature, critical exponent analysis, negative specific heat capacity and spinodal instability etc. The systematic works of the authors on experimental and theoretical LGPT are also introduced.展开更多
On February 25, the Unit 1 of Ling’ao Nuclear Power Plant phase II underwent a 41-day-long hot functional test successfully with its major systems satisfying the requirements for
China and Canada have signed a project award agreement for the co-operation for the Qinshan Phase Ⅲ Candu nuclear power project, marking significant progress in commercial negotiations between both countries on the c...China and Canada have signed a project award agreement for the co-operation for the Qinshan Phase Ⅲ Candu nuclear power project, marking significant progress in commercial negotiations between both countries on the construction of two 700 megawatt class Candu units. The agreement, signed between the China National Nuclear Corp (CNNC) and the Atomic Energy of Canada Ltd (AECL) in Beijing on July 12, finalized the price and commercial terms for Qinshan Phase展开更多
China and Canada nailed down a deal to build the third phase of the Qinshan Nuclear Power Plant in Zhejiang Province in East China on Nov. 26, 1996. The contract was signed in Shanghai by China National Nuclear Corp (...China and Canada nailed down a deal to build the third phase of the Qinshan Nuclear Power Plant in Zhejiang Province in East China on Nov. 26, 1996. The contract was signed in Shanghai by China National Nuclear Corp (CNNC) and Atomic Energy of Canada Ltd(AECL). AECL will construct two 700 MW heavy water reactors for the Chinese nuclear power plant.展开更多
We investigated the correlations between the net baryon number and electric charge up to the sixth order related to the interactions of nuclear matter at low temperature and explored their relationship with the nuclea...We investigated the correlations between the net baryon number and electric charge up to the sixth order related to the interactions of nuclear matter at low temperature and explored their relationship with the nuclear liquid-gas phase transition(LGPT)within the framework of the nonlinear Walecka model.The calculations showed that strong correlations between the baryon number and electric charge existed near the LGPT,and higher-order correlations were more sensitive than the lower-order correlations near the phase transition.However,in the high-temperature region away from the LGPT,the rescaled lower-order correlations were relatively larger than most of the higher-order correlations.In addition,some of the fifth-and sixth-order correlations possibly changed sign from negative to positive along the chemical freeze-out line with decreasing temperature.In combination with future experimental projects at lower collision energies,the derived results can be used to study the phase structure of strongly interacting matter and analyze the related experimental signals.展开更多
The temperature of fragmenting source in central heavy-ion collisions at Fermi energy is investigated by the isospin-dependent quantum molecular dynamics model in combination with the statistical decay model GEMINI.Fi...The temperature of fragmenting source in central heavy-ion collisions at Fermi energy is investigated by the isospin-dependent quantum molecular dynamics model in combination with the statistical decay model GEMINI.Five different nuclear thermometers are used to extract nuclear temperature.We find that the He and Li isotope temperature reaches a plateau at about 70-100 MeV/nucleon of beam energy.The slope temperature and the quadrupole fluctuation temperature give high values.The quantum slope temperature and the quantum quadrupole fluctuation temperature are more close to the He and Li isotope temperatures.展开更多
The heavy-ion phase-space exploration (HIPSE) model is used to discuss the origin of the nuclear spin in intermediate energy heavy-ion collision (HIC).The spin of maximal projectile-like fragment is found to depend st...The heavy-ion phase-space exploration (HIPSE) model is used to discuss the origin of the nuclear spin in intermediate energy heavy-ion collision (HIC).The spin of maximal projectile-like fragment is found to depend strongly on impact parameter of a reaction system,while it relates weakly to the collision violence.Some interesting multi-fragmentation phenomena related to the spin are shown.We also found that the excitation energy in the de-excitation stage plays a robust role at the de-excitation stage in HIC.展开更多
Phase field simulations of phase separation in Fe-Cr binary alloys were performed by using the Cahn-Hilliard diffusion function. A new mobility model in relation to aging temperature and Cr content was used in the sim...Phase field simulations of phase separation in Fe-Cr binary alloys were performed by using the Cahn-Hilliard diffusion function. A new mobility model in relation to aging temperature and Cr content was used in the simulations. Two alloys of Fe-30at%Cr and Fe-35at%Cr were investigated at two different aging temperatures of 573 and 673 K. The phase separation kinetics was found to consist of three stages： wavelength modulation, amplitude increase, and coarsening of Cr-enriched regions. A higher thermal aging temperature accelerated the phase separation and increased the wavelength of concentration fluctuation. While the effect of Cr content on the phase separation kinetics was slight, Fe-Cr alloys with a higher Cr content were found to generate a larger number and a finer size of Cr-enriched regions. The simulation results provide consultation for design and safe operation of duplex stainless steel pipes in nuclear power plants.展开更多
Vapor-water two phase flow separation in pressure vessel of nuclear power plants is accomplished with swirl motion using vanes. In order to reduce separation pressure loss and to make it economic, a new type of low co...Vapor-water two phase flow separation in pressure vessel of nuclear power plants is accomplished with swirl motion using vanes. In order to reduce separation pressure loss and to make it economic, a new type of low cost simplified innovative separator using lattice core configuration is proposed where swirling is caused by the orthogonal driving flow. The performance of the separator has been assessed numerically with the commercial CFD code FLUENT 14.0. The numerical analysis is compared with the experiment. The geometry and flow conditions are chosen according to the experiment. In the analysis, standard k – e and realizable k – e turbulence models are implemented. The prediction of maximum air void fraction with realizable k – e model was almost the same as input air void fraction but the void fraction computed by standard k – e model was compared better with the experimental results than the realizable k – e model. Some discrepancies in flow pattern between the experimental and simulation results are observed which might be due to the difference of nozzle shape. However, a more detailed model is necessary to arrive at the final conclusion.展开更多
We report 7SAs NMR studies on single crystals of rare-earth doped iron pnictide superconductor Ca1-xPrxFe2As2. In both cases of x = 0.075, 0.15, a large increase of Vq upon cooling is consistent with the tetragonal-co...We report 7SAs NMR studies on single crystals of rare-earth doped iron pnictide superconductor Ca1-xPrxFe2As2. In both cases of x = 0.075, 0.15, a large increase of Vq upon cooling is consistent with the tetragonal-collapsed tetragonal structure transition. A sharp drop of the Knight shift is also seen just below the structure transition, which suggests the quenching of Fe local magnetism, and therefore offers important understanding of the collapsed tetragonal phase. At even low temperatures, the 1/75 T1 is enhanced and forms a peak at T ≈ 25 K, which may be caused by the magnetic ordering of the Pr3＋ moments or soin dynamics of mobile domain walls.展开更多
The interplay between superconductivity and structural phase transition has attracted enormous interest in recent years. For example, in Fe-pnictide high temperature superconductors, quantum fluctuations in associatio...The interplay between superconductivity and structural phase transition has attracted enormous interest in recent years. For example, in Fe-pnictide high temperature superconductors, quantum fluctuations in association with structural phase transition have been proposed to lead to many novel physical properties and even the superconductivity itself. Here we report a finding that the quasi-skutterudite superconductors （Sr1-xCax）3Ir4Sn13 （x = 0, 0.5, 1） and Ca3Rh4Snl3 show some unusual properties similar to the Fe-pnictides, through 119Sn nuclear magnetic resonance （NMR） measurements. In （Sr1-xCax）3Ir4Sn13, the NMR linewidth increases below a temperature T＊ that is higher than the structural phase transition temperature Ts. The spin-lattice relaxation rate （1/T1 ） divided by temperature （T）, 1/TI T and the Knight shift K increase with decreasing T down to T＊, but start to decrease below T＊, and followed by more distinct changes at Ts. In contrast, none of the anomalies is observed in Ca3Rh4Sn13 that does not undergo a structural phase transition. The precursory phenomenon above the structural phase transition resembles that occurring in Fe-pnictides. In the superconducting state of Ca3Ir4Sn13, 1/T1 decays as exp（-△/kBT） with a large gap △ = 2.21kBTc, yet without a Hebel-Slichter coherence peak, which indicates strong-coupling superconductivity. Our results provide new insight into the relationship between superconductivity and the electronic-structure change associated with structural phase transition.展开更多
In nuclear reactors cooled by liquid metals, ultrasound is the only type of field that allows obtaining images of the reactor cores and diagnostics of the integrity of the fuel assemblies. The article discusses the fe...In nuclear reactors cooled by liquid metals, ultrasound is the only type of field that allows obtaining images of the reactor cores and diagnostics of the integrity of the fuel assemblies. The article discusses the features of the practical realization of ultrasonic imaging systems based on phased arrays and offers an alternative solution of imaging on the basis of the acoustic lenses of refractive and diffraction types. Using lenses eliminates many of the technical and technological problems associated with the development of multi-element phased arrays. It is shown that lens systems allow using traditional methods of transformation of acoustic fields into the visible images by 2D piezo matrix and a more promising way of acoustooptical transformation based on coherent optical interferometry.展开更多
Nuclear binding energies, charge radii and the charge distributions of even-even tin （Sn） isotopes are calculated using relativistic mean field theory, and the theoretical results are found to be in accordance with ...Nuclear binding energies, charge radii and the charge distributions of even-even tin （Sn） isotopes are calculated using relativistic mean field theory, and the theoretical results are found to be in accordance with the experimental data. The nuclear charge form factors for Sn isotopes are calculated using the phase-shift analysis method. It is shown that the minima of the charge form factors shift upward and inward with an increase in the neutron number of the Sn isotopes.展开更多
The paper reports some technical solutions, which suggested or used for increasing of environmental protection during accidents at NPPs. For NNPs with two protective shells and pressure release system such as WWER-100...The paper reports some technical solutions, which suggested or used for increasing of environmental protection during accidents at NPPs. For NNPs with two protective shells and pressure release system such as WWER-1000 a comprehensive, passive-mode environmental protection system of decontamination of the radioactive steam-air mixture from the containment and the intercontainment area was suggested. This system includes the “wet” stage (scrubbers, etc.), the “dry” stage (sorption module), and also an ejector, which in a passive mode is capable of solving the multi-purpose task of decontamination of the air-steam mixture. For WWER-440/230 NPPs three protection levels: 1) a jet-vortex condenser;2) the spray system;3) a sorption module were suggested and installed. For modern designs of new generation NPPs, which do not provide for pressure release systems, a new passive filtering system together with the passive heat-removal system, which can be used during severe accidents in case all power supply units become unavailable, was proposed and after modernization was installed at the KudanKulam NPP (India).展开更多
基金the National Natural Science Foundation of China for the Distinguished Young Scholar (No. 19725521) the National Natural Science Foundation of China (No. 19705012)+1 种基金 the Science and Technology Development Foundation of Shanghai (No.97QA14038)the Major State Basic Research Development Program of China (No. G200077400)
文摘Recent progress on nuclear liquid gas phase transition (LGPT) has been reviewed, especially for the signals of LGPT in heavy ion collisions. These signals include the power-law charge distribution, cluster emission rate, nuclear Zipf law, bimodality, the largest fluctuation of the fragments, Δ-scaling, caloric curve, phase coexis- tence diagram, critical temperature, critical exponent analysis, negative specific heat capacity and spinodal instability etc. The systematic works of the authors on experimental and theoretical LGPT are also introduced.
文摘On February 25, the Unit 1 of Ling’ao Nuclear Power Plant phase II underwent a 41-day-long hot functional test successfully with its major systems satisfying the requirements for
文摘China and Canada have signed a project award agreement for the co-operation for the Qinshan Phase Ⅲ Candu nuclear power project, marking significant progress in commercial negotiations between both countries on the construction of two 700 megawatt class Candu units. The agreement, signed between the China National Nuclear Corp (CNNC) and the Atomic Energy of Canada Ltd (AECL) in Beijing on July 12, finalized the price and commercial terms for Qinshan Phase
文摘China and Canada nailed down a deal to build the third phase of the Qinshan Nuclear Power Plant in Zhejiang Province in East China on Nov. 26, 1996. The contract was signed in Shanghai by China National Nuclear Corp (CNNC) and Atomic Energy of Canada Ltd(AECL). AECL will construct two 700 MW heavy water reactors for the Chinese nuclear power plant.
基金supported by the National Natural Science Foundation of China(Nos.12475145,11875213)the Natural Science Basic Research Plan in Shaanxi Province of China(No.2024JC-YBMS-018).
文摘We investigated the correlations between the net baryon number and electric charge up to the sixth order related to the interactions of nuclear matter at low temperature and explored their relationship with the nuclear liquid-gas phase transition(LGPT)within the framework of the nonlinear Walecka model.The calculations showed that strong correlations between the baryon number and electric charge existed near the LGPT,and higher-order correlations were more sensitive than the lower-order correlations near the phase transition.However,in the high-temperature region away from the LGPT,the rescaled lower-order correlations were relatively larger than most of the higher-order correlations.In addition,some of the fifth-and sixth-order correlations possibly changed sign from negative to positive along the chemical freeze-out line with decreasing temperature.In combination with future experimental projects at lower collision energies,the derived results can be used to study the phase structure of strongly interacting matter and analyze the related experimental signals.
基金Supported by National Natural Science Foundation of China(Grant Nos.11025524 and 11161130520)National Basic Research Program of China(Grant No.2010CB832903)
文摘The temperature of fragmenting source in central heavy-ion collisions at Fermi energy is investigated by the isospin-dependent quantum molecular dynamics model in combination with the statistical decay model GEMINI.Five different nuclear thermometers are used to extract nuclear temperature.We find that the He and Li isotope temperature reaches a plateau at about 70-100 MeV/nucleon of beam energy.The slope temperature and the quadrupole fluctuation temperature give high values.The quantum slope temperature and the quantum quadrupole fluctuation temperature are more close to the He and Li isotope temperatures.
基金Partially supported by NSFC of China under contract No.11035009,No.10979074,No.10875160,No.10805067 and No.10975174the 973-Program under contract No.2007CB815004+1 种基金the Shanghai Development Foundation for Science and Technology under contract No.09JC1416800the Knowledge Innovation Project of CAS under Grant No.KJCX2-EW-N01
文摘The heavy-ion phase-space exploration (HIPSE) model is used to discuss the origin of the nuclear spin in intermediate energy heavy-ion collision (HIC).The spin of maximal projectile-like fragment is found to depend strongly on impact parameter of a reaction system,while it relates weakly to the collision violence.Some interesting multi-fragmentation phenomena related to the spin are shown.We also found that the excitation energy in the de-excitation stage plays a robust role at the de-excitation stage in HIC.
基金the National High-Tech Research and Development Program of China(Nos.2012AA03A507 and 2012AA050901)the Na-tional Science and Technology Major Project of China(No.2011ZX06004)
文摘Phase field simulations of phase separation in Fe-Cr binary alloys were performed by using the Cahn-Hilliard diffusion function. A new mobility model in relation to aging temperature and Cr content was used in the simulations. Two alloys of Fe-30at%Cr and Fe-35at%Cr were investigated at two different aging temperatures of 573 and 673 K. The phase separation kinetics was found to consist of three stages： wavelength modulation, amplitude increase, and coarsening of Cr-enriched regions. A higher thermal aging temperature accelerated the phase separation and increased the wavelength of concentration fluctuation. While the effect of Cr content on the phase separation kinetics was slight, Fe-Cr alloys with a higher Cr content were found to generate a larger number and a finer size of Cr-enriched regions. The simulation results provide consultation for design and safe operation of duplex stainless steel pipes in nuclear power plants.
文摘Vapor-water two phase flow separation in pressure vessel of nuclear power plants is accomplished with swirl motion using vanes. In order to reduce separation pressure loss and to make it economic, a new type of low cost simplified innovative separator using lattice core configuration is proposed where swirling is caused by the orthogonal driving flow. The performance of the separator has been assessed numerically with the commercial CFD code FLUENT 14.0. The numerical analysis is compared with the experiment. The geometry and flow conditions are chosen according to the experiment. In the analysis, standard k – e and realizable k – e turbulence models are implemented. The prediction of maximum air void fraction with realizable k – e model was almost the same as input air void fraction but the void fraction computed by standard k – e model was compared better with the experimental results than the realizable k – e model. Some discrepancies in flow pattern between the experimental and simulation results are observed which might be due to the difference of nozzle shape. However, a more detailed model is necessary to arrive at the final conclusion.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 11074304 and 11222433)the National Basic Research Program of China (Grant Nos. 2010CB923004 and 2011CBA00112)supported by AFOSR-Multidisciplinary University, ResearchInitiative (Grant No. FA9550-09-1-0603)
文摘We report 7SAs NMR studies on single crystals of rare-earth doped iron pnictide superconductor Ca1-xPrxFe2As2. In both cases of x = 0.075, 0.15, a large increase of Vq upon cooling is consistent with the tetragonal-collapsed tetragonal structure transition. A sharp drop of the Knight shift is also seen just below the structure transition, which suggests the quenching of Fe local magnetism, and therefore offers important understanding of the collapsed tetragonal phase. At even low temperatures, the 1/75 T1 is enhanced and forms a peak at T ≈ 25 K, which may be caused by the magnetic ordering of the Pr3＋ moments or soin dynamics of mobile domain walls.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11674377 and 11634015)the National Key R&D Program of China(Grant Nos.2017YFA0302904 and 2016YFA0300502)+1 种基金the Strategic Priority Research Program(B)of the Chinese Academy of Sciences(Grant No.XDB07020200)supported by the Youth Innovation Promotion Association of CAS
文摘The interplay between superconductivity and structural phase transition has attracted enormous interest in recent years. For example, in Fe-pnictide high temperature superconductors, quantum fluctuations in association with structural phase transition have been proposed to lead to many novel physical properties and even the superconductivity itself. Here we report a finding that the quasi-skutterudite superconductors （Sr1-xCax）3Ir4Sn13 （x = 0, 0.5, 1） and Ca3Rh4Snl3 show some unusual properties similar to the Fe-pnictides, through 119Sn nuclear magnetic resonance （NMR） measurements. In （Sr1-xCax）3Ir4Sn13, the NMR linewidth increases below a temperature T＊ that is higher than the structural phase transition temperature Ts. The spin-lattice relaxation rate （1/T1 ） divided by temperature （T）, 1/TI T and the Knight shift K increase with decreasing T down to T＊, but start to decrease below T＊, and followed by more distinct changes at Ts. In contrast, none of the anomalies is observed in Ca3Rh4Sn13 that does not undergo a structural phase transition. The precursory phenomenon above the structural phase transition resembles that occurring in Fe-pnictides. In the superconducting state of Ca3Ir4Sn13, 1/T1 decays as exp（-△/kBT） with a large gap △ = 2.21kBTc, yet without a Hebel-Slichter coherence peak, which indicates strong-coupling superconductivity. Our results provide new insight into the relationship between superconductivity and the electronic-structure change associated with structural phase transition.
文摘In nuclear reactors cooled by liquid metals, ultrasound is the only type of field that allows obtaining images of the reactor cores and diagnostics of the integrity of the fuel assemblies. The article discusses the features of the practical realization of ultrasonic imaging systems based on phased arrays and offers an alternative solution of imaging on the basis of the acoustic lenses of refractive and diffraction types. Using lenses eliminates many of the technical and technological problems associated with the development of multi-element phased arrays. It is shown that lens systems allow using traditional methods of transformation of acoustic fields into the visible images by 2D piezo matrix and a more promising way of acoustooptical transformation based on coherent optical interferometry.
基金supported by National Natural Science Foundation of China(Nos.10535010,10675090,10775068,10735010,10975072and11035001)the 973 National Major State Basic Research and Development of China(2007CB815004)+1 种基金CAS Knowledge Innovation Project(KJCX2-SW-N02)the Research Fund of Doctoral Point(RFDP)(Nos.20070284016,20100091110028)
文摘Nuclear binding energies, charge radii and the charge distributions of even-even tin （Sn） isotopes are calculated using relativistic mean field theory, and the theoretical results are found to be in accordance with the experimental data. The nuclear charge form factors for Sn isotopes are calculated using the phase-shift analysis method. It is shown that the minima of the charge form factors shift upward and inward with an increase in the neutron number of the Sn isotopes.
文摘The paper reports some technical solutions, which suggested or used for increasing of environmental protection during accidents at NPPs. For NNPs with two protective shells and pressure release system such as WWER-1000 a comprehensive, passive-mode environmental protection system of decontamination of the radioactive steam-air mixture from the containment and the intercontainment area was suggested. This system includes the “wet” stage (scrubbers, etc.), the “dry” stage (sorption module), and also an ejector, which in a passive mode is capable of solving the multi-purpose task of decontamination of the air-steam mixture. For WWER-440/230 NPPs three protection levels: 1) a jet-vortex condenser;2) the spray system;3) a sorption module were suggested and installed. For modern designs of new generation NPPs, which do not provide for pressure release systems, a new passive filtering system together with the passive heat-removal system, which can be used during severe accidents in case all power supply units become unavailable, was proposed and after modernization was installed at the KudanKulam NPP (India).
