Accurate and reliable nuclear data libraries are essential for calculation and design of advanced nuclea systems. A 1200 fine group nuclear data library Hybrid Evaluated Nuclear Data Library/Fine Group(HENDL/FG with n...Accurate and reliable nuclear data libraries are essential for calculation and design of advanced nuclea systems. A 1200 fine group nuclear data library Hybrid Evaluated Nuclear Data Library/Fine Group(HENDL/FG with neutrons of up to 150 Me V has been developed to improve the accuracy of neutronics calculations and anal ysis. Corrections of Doppler, resonance self-shielding, and thermal upscatter effects were done for HENDL/FG Shielding and critical safety benchmarks were performed to test the accuracy and reliability of the library. The dis crepancy between calculated and measured nuclea parameters fell into a reasonable range.展开更多
In the nuclear reactor design, a code for automatically generated multi-temperature continuous-energy neutron cross section data library, which is called AMTND for short, was designed and developed to meet the need of...In the nuclear reactor design, a code for automatically generated multi-temperature continuous-energy neutron cross section data library, which is called AMTND for short, was designed and developed to meet the need of the reactor core design coupled with thermal-hydraulic design. The code can provide a point-wise crosssection at any temperature for a Monte Carlo neutron transport program, such as MCNP. In ensuring that the nuclear data produced by AMTND meets the testing of critical benchmark experiments, the time-consumed by the nuclear data generating of AMTND compared with NJOY's was carried out and the result shows the code's excellence. In order to test the accuracy of the code, the Doppler coefficient test benchmark was also carried out and the results verified the code preliminarily.展开更多
The stage efficiency of a single stage prototype ( d 70) centrifugal extractor and the cascade is tested by HNO 3 Nd 3+ and 30%TRPO kerosene system. The experimental results of the single stage centrifugal extractor s...The stage efficiency of a single stage prototype ( d 70) centrifugal extractor and the cascade is tested by HNO 3 Nd 3+ and 30%TRPO kerosene system. The experimental results of the single stage centrifugal extractor show that the carryover of the two phases decreases with increasing ratio of the two flow rate and rotation rate and the stage efficiency increases with not only decreasing total flow rate but also increasing rotor speed. However, the experimental results of the cascade show that the average stage efficiency of the cascade increases with not only decreasing total flow rate but also increasing rotor speed in both three stage mode and two stage mode.展开更多
In lead-cooled fast reactor(LFR)systems,the liquid lead-bismuth eutectic(LBE)coolant provides a cor-rosive environment that damages the steel components during high-temperature operation.This study investigated the mi...In lead-cooled fast reactor(LFR)systems,the liquid lead-bismuth eutectic(LBE)coolant provides a cor-rosive environment that damages the steel components during high-temperature operation.This study investigated the microstructural deterioration of 9Cr ferritic/martensitic(F/M)steel under thermal aging at 550℃for 2,000,10,000,or 20,000 h and its effect on oxidation corrosion in an LBE environment using multiscale characterization techniques.The results indicated that the thickness of the internal oxidation zone(IOZ)increased significantly with extended thermal aging,whereas that of the spinel layer remained relatively constant.The abundant subgrain boundaries that emerged during extensive thermal aging facil-itated Fe diffusion,and the enlarged Cr-rich M23C6 carbides contributed to the formation of preferential oxidation regions,accelerating IOZ layer growth.The spinel layer formed from the IOZ was influenced by microstructural defects within the IOZ.A theoretical model describing the accelerated oxide layer growth due to thermal aging was developed.These findings support the advancement of LFR technology.展开更多
Corrosion is an essential issue limiting the application of high-strength low-carbon steel in seawater environment. The impact of retained austenite on its corrosion behavior with immersion experiments and related cor...Corrosion is an essential issue limiting the application of high-strength low-carbon steel in seawater environment. The impact of retained austenite on its corrosion behavior with immersion experiments and related corrosion sensor technology was explored. A model that clarifies the micro-galvanic effect and the heat-induced changes to the shape and composition of retained austenite was used to discuss the findings. The results indicated that retained austenite was generated following an intercritical process and demonstrated approximately 48 mV higher Volta potential than the matrix. The retained austenite content first increased and then decreased with increasing intercritical temperatures, while reaching the maximum value of 8.5% at 660℃. With the increase in retained austenite content, the corrosion rate was increased by up to 32.8% compared to “quenching + tempering” (QT) specimen. The interfaces between the retained austenite and matrix were the priority nucleation sites for corrosion. Moreover, the retained austenite reduced the corrosion resistance of the steel by increasing the micro-galvanic effect and reducing rust layer compactness.展开更多
The off situ accurate reconstruction of the core neutron field is an important step in realizing real-time reactor monitoring.The existing off situ reconstruction method of the neutron field is only applicable to case...The off situ accurate reconstruction of the core neutron field is an important step in realizing real-time reactor monitoring.The existing off situ reconstruction method of the neutron field is only applicable to cases wherein a single region changes at a specified location of the core.However,when the neutron field changes are complex,the accurate identification of the individual changed regions becomes challenging,which seriously affects the accuracy and stability of the neutron field recon-struction.Therefore,this study proposed a dual-task hybrid network architecture(DTHNet)for off situ reconstruction of the core neutron field,which trained the outermost assembly reconstruction task and the core reconstruction task jointly such that the former could assist the latter in the reconstruction of the core neutron field under core complex changes.Furthermore,to exploit the characteristics of the ex-core detection signals,this study designed a global-local feature upsampling module that efficiently distributed the ex-core detection signals to each reconstruction unit to improve the accuracy and stability of reconstruction.Reconstruction experiments were performed on the simulation datasets of the CLEAR-I reactor to verify the accuracy and stability of the proposed method.The results showed that when the location uncertainty of a single region did not exceed nine and the number of multiple changed regions did not exceed five.Further,the reconstructed ARD was within 2%,RD_(max)was maintained within 17.5%,and the number of RD≥10%was maintained within 10.Furthermore,when the noise interference of the ex-core detection signals was within±2%,although the average number of RD≥10%increased to 16,the average ARD was still within in 2%,and the average RD_(max)was within 22%.Collectively,these results show that,theoretically,the DTHNet can accurately and stably reconstruct most of the neutron field under certain complex core changes.展开更多
Hydrogen-induced cracking (HIC) is one of the most complex material problems that hydrogen can diffuse into and interact with microstructure, degrading their mechanical properties. Microstructural modification is an e...Hydrogen-induced cracking (HIC) is one of the most complex material problems that hydrogen can diffuse into and interact with microstructure, degrading their mechanical properties. Microstructural modification is an effective way to enhance the resistance to HIC. The present study focused on the relationship between the retained austenite (RA) and HIC behavior in NiCrMoV/Nb multi-alloying ultra-strength steel. Results demonstrated that the maximum volume fraction of RA of 9.31% was obtained for QL30T specimen. After the deep cryogenic pretreatment, the volume fraction of RA reduced to 8.8%. RA could reduce the effective diffusion coefficient, while deep cryogenic pretreatment increased the susceptibility of the steel to HIC by a maxim of 14.8%. This was mainly due to the transformation of retained austenite into martensite, degrading the mechanical properties under hydrogen-charged condition. In addition, the deep cryogenic pretreatment had a significant effect on the crack initiation and propagation, with the intergranular (IG) fracture becoming the dominant fracture mode where an increase in the number of secondary cracks in the section. The interfaces of RA and matrix, as well as the grain boundaries, were the preferred sites for cracks initiation.展开更多
The precise determination of cross sections for key nuclear reactions within the Gamow window is crucial for advancing the study of stellar evolution and nucleosynthesis.However,extremely low reaction yields combined ...The precise determination of cross sections for key nuclear reactions within the Gamow window is crucial for advancing the study of stellar evolution and nucleosynthesis.However,extremely low reaction yields combined with the cosmic-ray-induced background make these measurements highly challenging,particularly for capture reactions.This work demonstrates the second configuration of the large-scale modular BGO detection array(LAMBDA-Ⅱ)designed to capture reaction measurements and introduces a method for suppressingγ-ray detection background in ground laboratories.By employing active and passive shielding,the background of LAMBDA-Ⅱwas significantly reduced by approximately two orders of magnitude,reaching 8.1×10^(-3)and 1.0×10^(-3)keV^(-1)h^(-1)in the 6-11 and 11-20 MeV energy ranges,respectively.When combined with a mA-scale intensity beam,this reduced background enables the investigation of several capture reactions of astrophysical interest in ground laboratories.展开更多
In 2011,the Chinese Academy of Sciences launched an engineering project to develop an acceleratordriven subcritical system(ADS)for nuclear waste transmutation.The China Lead-based Reactor(CLEAR),proposed by the Instit...In 2011,the Chinese Academy of Sciences launched an engineering project to develop an acceleratordriven subcritical system(ADS)for nuclear waste transmutation.The China Lead-based Reactor(CLEAR),proposed by the Institute of Nuclear Energy Safety Technology,was selected as the reference reactor for ADS development,as well as for the technology development of the Generation IV lead-cooled fast reactor.The conceptual design of CLEAR-I with 10 MW thermal power has been completed.KYLIN series lead-bismuth eutectic experimental loops have been constructed to investigate the technologies of the coolant,key components,structural materials,fuel assembly,operation,and control.In order to validate and test the key components and integrated operating technology of the lead-based reactor,the lead alloy-cooled non-nuclear reactor CLEAR-S,the lead-based zero-power nuclear reactor CLEAR-0,and the lead-based virtual reactor CLEAR-V are under realization.展开更多
A process for recovery of RE from Baotou rare earth concentrate was developed by fixing the fluorine and chlorinating RE with ammonium chloride in the ore. The optimum conditions were determined as follows: fixing the...A process for recovery of RE from Baotou rare earth concentrate was developed by fixing the fluorine and chlorinating RE with ammonium chloride in the ore. The optimum conditions were determined as follows: fixing the fluorine of the ore 80 min with the MgO dosage m (ore) / m (MgO) =3∶1 at 600 ℃; chlorinating the fixed fluorine calcine 80 min, with NH 4Cl dosage m (NH 4Cl) / m (ore) =2∶1 at 500 ℃. The RE recovery reaches 85% under optimum conditions. The products of fixing fluorine with MgO were determined by X ray diffraction, and the mechanism of fixing fluorine was also discussed.展开更多
Lithium heat pipes have broad applications in heat pipe cooling reactors and hypersonic vehicles owing to their ultra-high working temperature.In particular,when the length of the lithium heat pipe is ultra-long,the f...Lithium heat pipes have broad applications in heat pipe cooling reactors and hypersonic vehicles owing to their ultra-high working temperature.In particular,when the length of the lithium heat pipe is ultra-long,the flow and heat transfer characteristics are more complex.In this study,an improved lumped parameter model that considers the Marangoni effect,bending effect,and different vapor flow patterns and Mach numbers was developed.Thereafter,the proposed model was verified using the University of New Mexico’s Heat Pipe and HTPIPE models.Finally,the verified model was applied to simulate the steady-state operation of an ultra-long lithium heat pipe in a Heat PipeSegmented Thermoelectric Module Converters space reactor.Based on the results:(1)Vapor thermal resistance was dominant at low heating power and decreased with increasing heating power.The vapor flow inside the heat pipe developed from the laminar to the turbulent phase,whereas the liquid phase in the heat pipe was always laminar.(2)The vapor pressure drop caused by bending was approximately 22–23%of the total,and the bending effect on the liquid pressure drop could be ignored.(3)The Marangoni effect reduced the capillary limit by hindering the liquid reflux,especially at low vapor temperatures.Without considering the Marangoni effect,the capillary limit of the lithium heat pipe was overestimated by 9%when the vapor temperature was 1400 K.(4)The total thermal resistance of the heat pipe significantly increased with increasing adiabatic length when the vapor temperature was low.Further,the wick dryness increased with increasing adiabatic length at any vapor temperature.Such findings improve on current knowledge for the optimal design and safety analysis of a heat pipe reactor,which adopts ultra-long lithium heat pipes.展开更多
Alpha radiolysis of nitric acid aqueous solution by a ^(238)Pu source is investigated experimentally and theoretically.The time dependence of the nitrous acid yield on dose rate,nitric acid concentration,and nitrate i...Alpha radiolysis of nitric acid aqueous solution by a ^(238)Pu source is investigated experimentally and theoretically.The time dependence of the nitrous acid yield on dose rate,nitric acid concentration,and nitrate ion concentration is studied.A novel kinetic model for the α-radiolysis of nitric acid aqueous solution is established,by considering the direct and indirect effects.The simulation results agree well with the experimental data,indicating the validity of our model to treat the reaction paths for generation and consumption of nitrous acid.It is shown that the redox reactions involving Pu cannot be neglected in theα-radiolysis of the solution.The results provide a better understanding of the α-ray radiolysis of aqueous nitric acid.展开更多
Lead and lead-alloys are proposed in future advanced nuclear system as coolant and spallation target.To test the natural circulation and gas-lift and obtain thermal-hydraulics data for computational fluid dynamics(CFD...Lead and lead-alloys are proposed in future advanced nuclear system as coolant and spallation target.To test the natural circulation and gas-lift and obtain thermal-hydraulics data for computational fluid dynamics(CFD) and system code validation, a lead–bismuth eutectic rectangular loop, the KYLIN-Ⅱ Thermal Hydraulic natural circulation test loop, has been designed and constructed by the FDS team. In this paper, theoretical analysis on natural circulation thermal-hydraulic performance is described and the steady-state natural circulation experiment is performed. The results indicated that the natural circulation capability depends on the loop resistance and the temperature and center height differences between the hot and cold legs. The theoretical analysis results agree well with,while the CFD deviate from, the experimental results.展开更多
Based on the design of CLEAR(China LEAd-based Reactor), it is important to study the molten LBE(LeadBismuth Eutectic)/water interaction following an incidental steam generator tube rupture(SGTR) accident.Experiments w...Based on the design of CLEAR(China LEAd-based Reactor), it is important to study the molten LBE(LeadBismuth Eutectic)/water interaction following an incidental steam generator tube rupture(SGTR) accident.Experiments were carried out to investigate the fragmentation behavior of the molten LBE/water contacting interface, with a high-speed video camera to record the fragmentation behavior of 300–600?C LBE at 20?C and 80?C of water temperature. Violent explosion phenomenon occurred at water temperature of 20?C, while no explosion occurred at 80?C. Shapes of the LBE debris became round at 80?C of water temperature, whereas the debris was of the needle-like shape at 20?C. For all the molten LBE and water temperatures in the present study,the debris sized at 2.8–5.0 mm had the largest mass fraction. The results indicate that the dominant physical mechanism of the molten LBE fragmentation was the Kelvin-Helmholtz instability between LBE/water direct contact interface.展开更多
Zirconia nano-particles have been produced by the hydrolysis of ZrOCl2 solution in the reverse micelles of a liquid-liquid two-phase system, in which sodium bis（2-ethylhexyl） sulfosuccinite （AOT） and toluene were ...Zirconia nano-particles have been produced by the hydrolysis of ZrOCl2 solution in the reverse micelles of a liquid-liquid two-phase system, in which sodium bis（2-ethylhexyl） sulfosuccinite （AOT） and toluene were chosen as the surfactant and organic phase, respectively. The reverse micelles prevented the aggregation of primary particles and reduced the diameters of zirconia nanoparticles. Superfine zirconia powders soft-aggregated by the zirconia nano-particles were obtained. The diameters of zirconia nanoparticles were influenced by the quantity of the surfactant.展开更多
Adsorption and desorption of hydrogen on/from single-vacancy and double-vacancy graphenes were studied by means of first-principles calculations. The structure and stability of continuous hydrogenation in single vacan...Adsorption and desorption of hydrogen on/from single-vacancy and double-vacancy graphenes were studied by means of first-principles calculations. The structure and stability of continuous hydrogenation in single vacancy were investigated. Several new stable structures were found, along with their corresponding energy barriers. In double-vacancy graphene, the preferred sites of H atoms were identified, and H2 molecule desorption and adsorption of from/on were calculated from the energy barriers. This work provides a systematic and comprehensive understanding of hydrogen behavior on defected graphene.展开更多
A direct incident fluence measurement method based on amorphous silicon electronic portal imaging device(a-Si EPID) has been developed for pretreatment verification of intensity-modulated radiation therapy(IMRT).The E...A direct incident fluence measurement method based on amorphous silicon electronic portal imaging device(a-Si EPID) has been developed for pretreatment verification of intensity-modulated radiation therapy(IMRT).The EPID-based incident fluence conversion method deconvolves EPID images to the primary response distribution based on measured lateral scatter kernels in the EPID detector using Conjugate Gradient algorithm.The primary response is converted to the incident fluence based on measured fluence conversion matrix which corrects for off-axis position dependence of the a-Si EPID response and the "horn" beam profile caused by flatting filter. To verify feasibility and accuracy of this method, square fields of various sizes and two IMRT plans were delivered. The dose distributions computed based on EPID-derived incident fluence were compared with the measurement data. For all square field sizes except the smallest field(2 cm), the mean dose differences in cross-line dose profiles were within 1% excluding the penumbra region, and gamma passing percentages with a 2%/2 mm criterion were about 99%. For two IMRT plans, the least gamma passing percentage for all eight IMRT fields was 98.14% with 2%/3 mm criteria. It can be concluded that our direct EPID-based incident fluence conversion method is accurate and capable of being applied to pretreatment dose verification in clinical routines.展开更多
Current-conductive mold was recently developed to extend electroslag remelting(ESR)functions to overcome some solidification defects by changing the current path.The macrostructures,microstructures,macrosegregation,an...Current-conductive mold was recently developed to extend electroslag remelting(ESR)functions to overcome some solidification defects by changing the current path.The macrostructures,microstructures,macrosegregation,and microsegregation of the Inconel 718 ingots produced by the custom laboratory-scale ESR furnace under different current paths(the classical ESR and the single power,and two circuits ESR process with current-conductive mold(ESR-STCCM))with the same power input were compared and investigated.The results indicate that when the ingot was produced during ESR and ESR-STCCM processes,at the same power input,the pool depth was 104 and 90 mm,respectively.A flatter and shallower molten pool was obtained during ESR-STCCM process.Moreover,compared with a classical ESR ingot,the cooling rate of the centerline of ESR-STCCM ingot was increased from 12.7 to 16.7 K min^(−1).The increased cooling rates caused by decreased melting rate and thinner slag skin reduced the growth angle of columnar crystal to the vertical axis and the secondary dendrite arm spacing.Furthermore,the macrosegregation and microsegregation of segregation elements for ESR-STCCM process were dramatically reduced compared with ESR process.The average volume fraction of Laves phase was reduced from 7.39%to 6.14%,and the segregation of Nb in Laves phase was significantly reduced.展开更多
Oxygen control technology is a critical issue for compatibility of candidate structural materials with liquid lead-bismuth eutectic(LBE) in accelerator driven systems. Performances of a self-developed Pt/air sensor an...Oxygen control technology is a critical issue for compatibility of candidate structural materials with liquid lead-bismuth eutectic(LBE) in accelerator driven systems. Performances of a self-developed Pt/air sensor and another one from Karlsruher Institute of Technology(KIT) were tested in stagnant oxygen-saturated liquid LBE.Calibrations showed that the trend and values of corrected electromotive force(EMF) of the self-developed sensor, with a bias voltage of 20 mV, were consistent with theoretical results above 425℃, and similar results were obtained in cross-calibration test with EMF value of KIT sensor as reference. In stability test at 450℃ for 100 hours, the KIT sensor performed better than the self-developed one, which showed signal fluctuations.Both sensors exhibited quick response to temperature variations in the responsiveness test.展开更多
Using ammonium chloride （NH4Cl） as a chlorinating agent, the effects of chlorinating temperature, chlorinating time and NH4Cl dosage on chlorination of La2O3 and CeO2, and the thermal decomposition of LaCl3·7H2...Using ammonium chloride （NH4Cl） as a chlorinating agent, the effects of chlorinating temperature, chlorinating time and NH4Cl dosage on chlorination of La2O3 and CeO2, and the thermal decomposition of LaCl3·7H2O and CeCl3·7H2O were investigated. The results show that 80% of both La2O3 and CeO2 can be chlorinated at 300 ℃ for 90 min, and have no advantage to chlorination of lanthanum and cerium oxides at higher temperature. The thermal decomposition of LaCl3 and CeCl3 is carried out to explore the mechanism of chlorinating lanthanum and cerium oxides. At the same time, the chlorination of lanthanum and cerium oxides is not devoted to the HCl decomposed from NH4Cl, but to NH4Cl directly taking part in the chlorination of La2O3 and CeO2. The lanthanum and cerium oxides in chlorination firstly form intermediate LaOCl and CeOCl, and then transfer to LaCl3 and CeCl3, finally to La2O3 and CeO2, respectively. The thermal decomposition analyses of LaCl3·7H2O and CeCl3·7H2O further prove the existence of the intermediates LaOCl and CeOCl. Therefore the chlorinating temperature and time should strictly be controlled when the lanthanum oxide and cerium oxide are chlorinated with NH4Cl. And over-dosage of NH4Cl should be also applied in the process of chlorination.展开更多
基金supported by the Natural Science Foundation of China(Nos.11405204 11305205 and 10675123)Special Program for Informatization of Chinese Academy of Sciences(No.XXH12504-1-09)the National Special Program for ITER(No.2014GB1120001)
文摘Accurate and reliable nuclear data libraries are essential for calculation and design of advanced nuclea systems. A 1200 fine group nuclear data library Hybrid Evaluated Nuclear Data Library/Fine Group(HENDL/FG with neutrons of up to 150 Me V has been developed to improve the accuracy of neutronics calculations and anal ysis. Corrections of Doppler, resonance self-shielding, and thermal upscatter effects were done for HENDL/FG Shielding and critical safety benchmarks were performed to test the accuracy and reliability of the library. The dis crepancy between calculated and measured nuclea parameters fell into a reasonable range.
基金Supported by the National Natural Science Foundation of China(No.91326101)
文摘In the nuclear reactor design, a code for automatically generated multi-temperature continuous-energy neutron cross section data library, which is called AMTND for short, was designed and developed to meet the need of the reactor core design coupled with thermal-hydraulic design. The code can provide a point-wise crosssection at any temperature for a Monte Carlo neutron transport program, such as MCNP. In ensuring that the nuclear data produced by AMTND meets the testing of critical benchmark experiments, the time-consumed by the nuclear data generating of AMTND compared with NJOY's was carried out and the result shows the code's excellence. In order to test the accuracy of the code, the Doppler coefficient test benchmark was also carried out and the results verified the code preliminarily.
文摘The stage efficiency of a single stage prototype ( d 70) centrifugal extractor and the cascade is tested by HNO 3 Nd 3+ and 30%TRPO kerosene system. The experimental results of the single stage centrifugal extractor show that the carryover of the two phases decreases with increasing ratio of the two flow rate and rotation rate and the stage efficiency increases with not only decreasing total flow rate but also increasing rotor speed. However, the experimental results of the cascade show that the average stage efficiency of the cascade increases with not only decreasing total flow rate but also increasing rotor speed in both three stage mode and two stage mode.
基金supported by the Natural Science Foundation of Shandong Province with grant No.ZR2023ME196the Science and Technology Support Plan for Young Innovation of Colleges and Universities of Shandong Province with grant No.2022KJ273+1 种基金the Youth Innovation Promotion Association of the Chinese Academy of Sciences with grant No.2017486the Patent Navigation Project of Shandong Province with grant No.D202327.
文摘In lead-cooled fast reactor(LFR)systems,the liquid lead-bismuth eutectic(LBE)coolant provides a cor-rosive environment that damages the steel components during high-temperature operation.This study investigated the microstructural deterioration of 9Cr ferritic/martensitic(F/M)steel under thermal aging at 550℃for 2,000,10,000,or 20,000 h and its effect on oxidation corrosion in an LBE environment using multiscale characterization techniques.The results indicated that the thickness of the internal oxidation zone(IOZ)increased significantly with extended thermal aging,whereas that of the spinel layer remained relatively constant.The abundant subgrain boundaries that emerged during extensive thermal aging facil-itated Fe diffusion,and the enlarged Cr-rich M23C6 carbides contributed to the formation of preferential oxidation regions,accelerating IOZ layer growth.The spinel layer formed from the IOZ was influenced by microstructural defects within the IOZ.A theoretical model describing the accelerated oxide layer growth due to thermal aging was developed.These findings support the advancement of LFR technology.
文摘Corrosion is an essential issue limiting the application of high-strength low-carbon steel in seawater environment. The impact of retained austenite on its corrosion behavior with immersion experiments and related corrosion sensor technology was explored. A model that clarifies the micro-galvanic effect and the heat-induced changes to the shape and composition of retained austenite was used to discuss the findings. The results indicated that retained austenite was generated following an intercritical process and demonstrated approximately 48 mV higher Volta potential than the matrix. The retained austenite content first increased and then decreased with increasing intercritical temperatures, while reaching the maximum value of 8.5% at 660℃. With the increase in retained austenite content, the corrosion rate was increased by up to 32.8% compared to “quenching + tempering” (QT) specimen. The interfaces between the retained austenite and matrix were the priority nucleation sites for corrosion. Moreover, the retained austenite reduced the corrosion resistance of the steel by increasing the micro-galvanic effect and reducing rust layer compactness.
基金supported by the National Natural Science Foundation of China(No.12305344)the 2023 Anhui university research project of China(No.2023AH052179).
文摘The off situ accurate reconstruction of the core neutron field is an important step in realizing real-time reactor monitoring.The existing off situ reconstruction method of the neutron field is only applicable to cases wherein a single region changes at a specified location of the core.However,when the neutron field changes are complex,the accurate identification of the individual changed regions becomes challenging,which seriously affects the accuracy and stability of the neutron field recon-struction.Therefore,this study proposed a dual-task hybrid network architecture(DTHNet)for off situ reconstruction of the core neutron field,which trained the outermost assembly reconstruction task and the core reconstruction task jointly such that the former could assist the latter in the reconstruction of the core neutron field under core complex changes.Furthermore,to exploit the characteristics of the ex-core detection signals,this study designed a global-local feature upsampling module that efficiently distributed the ex-core detection signals to each reconstruction unit to improve the accuracy and stability of reconstruction.Reconstruction experiments were performed on the simulation datasets of the CLEAR-I reactor to verify the accuracy and stability of the proposed method.The results showed that when the location uncertainty of a single region did not exceed nine and the number of multiple changed regions did not exceed five.Further,the reconstructed ARD was within 2%,RD_(max)was maintained within 17.5%,and the number of RD≥10%was maintained within 10.Furthermore,when the noise interference of the ex-core detection signals was within±2%,although the average number of RD≥10%increased to 16,the average ARD was still within in 2%,and the average RD_(max)was within 22%.Collectively,these results show that,theoretically,the DTHNet can accurately and stably reconstruct most of the neutron field under certain complex core changes.
文摘Hydrogen-induced cracking (HIC) is one of the most complex material problems that hydrogen can diffuse into and interact with microstructure, degrading their mechanical properties. Microstructural modification is an effective way to enhance the resistance to HIC. The present study focused on the relationship between the retained austenite (RA) and HIC behavior in NiCrMoV/Nb multi-alloying ultra-strength steel. Results demonstrated that the maximum volume fraction of RA of 9.31% was obtained for QL30T specimen. After the deep cryogenic pretreatment, the volume fraction of RA reduced to 8.8%. RA could reduce the effective diffusion coefficient, while deep cryogenic pretreatment increased the susceptibility of the steel to HIC by a maxim of 14.8%. This was mainly due to the transformation of retained austenite into martensite, degrading the mechanical properties under hydrogen-charged condition. In addition, the deep cryogenic pretreatment had a significant effect on the crack initiation and propagation, with the intergranular (IG) fracture becoming the dominant fracture mode where an increase in the number of secondary cracks in the section. The interfaces of RA and matrix, as well as the grain boundaries, were the preferred sites for cracks initiation.
基金Supported by the National Key R&D Program of China(Nos.2022YFA1602301,2022YFA1603300,and 2023YFA1606701)National Natural Science Foundation of China(Nos.U1867211,12275026,and 12222514)the CAS Light of West China Program grant No.2020-82。
文摘The precise determination of cross sections for key nuclear reactions within the Gamow window is crucial for advancing the study of stellar evolution and nucleosynthesis.However,extremely low reaction yields combined with the cosmic-ray-induced background make these measurements highly challenging,particularly for capture reactions.This work demonstrates the second configuration of the large-scale modular BGO detection array(LAMBDA-Ⅱ)designed to capture reaction measurements and introduces a method for suppressingγ-ray detection background in ground laboratories.By employing active and passive shielding,the background of LAMBDA-Ⅱwas significantly reduced by approximately two orders of magnitude,reaching 8.1×10^(-3)and 1.0×10^(-3)keV^(-1)h^(-1)in the 6-11 and 11-20 MeV energy ranges,respectively.When combined with a mA-scale intensity beam,this reduced background enables the investigation of several capture reactions of astrophysical interest in ground laboratories.
文摘In 2011,the Chinese Academy of Sciences launched an engineering project to develop an acceleratordriven subcritical system(ADS)for nuclear waste transmutation.The China Lead-based Reactor(CLEAR),proposed by the Institute of Nuclear Energy Safety Technology,was selected as the reference reactor for ADS development,as well as for the technology development of the Generation IV lead-cooled fast reactor.The conceptual design of CLEAR-I with 10 MW thermal power has been completed.KYLIN series lead-bismuth eutectic experimental loops have been constructed to investigate the technologies of the coolant,key components,structural materials,fuel assembly,operation,and control.In order to validate and test the key components and integrated operating technology of the lead-based reactor,the lead alloy-cooled non-nuclear reactor CLEAR-S,the lead-based zero-power nuclear reactor CLEAR-0,and the lead-based virtual reactor CLEAR-V are under realization.
文摘A process for recovery of RE from Baotou rare earth concentrate was developed by fixing the fluorine and chlorinating RE with ammonium chloride in the ore. The optimum conditions were determined as follows: fixing the fluorine of the ore 80 min with the MgO dosage m (ore) / m (MgO) =3∶1 at 600 ℃; chlorinating the fixed fluorine calcine 80 min, with NH 4Cl dosage m (NH 4Cl) / m (ore) =2∶1 at 500 ℃. The RE recovery reaches 85% under optimum conditions. The products of fixing fluorine with MgO were determined by X ray diffraction, and the mechanism of fixing fluorine was also discussed.
基金the CASHIPS Director’s Fund(No.YZJJ2021QN36)the Key Research Program of the Chinese Academy of Sciences(No.ZDRW-KT-2019-1-0202).
文摘Lithium heat pipes have broad applications in heat pipe cooling reactors and hypersonic vehicles owing to their ultra-high working temperature.In particular,when the length of the lithium heat pipe is ultra-long,the flow and heat transfer characteristics are more complex.In this study,an improved lumped parameter model that considers the Marangoni effect,bending effect,and different vapor flow patterns and Mach numbers was developed.Thereafter,the proposed model was verified using the University of New Mexico’s Heat Pipe and HTPIPE models.Finally,the verified model was applied to simulate the steady-state operation of an ultra-long lithium heat pipe in a Heat PipeSegmented Thermoelectric Module Converters space reactor.Based on the results:(1)Vapor thermal resistance was dominant at low heating power and decreased with increasing heating power.The vapor flow inside the heat pipe developed from the laminar to the turbulent phase,whereas the liquid phase in the heat pipe was always laminar.(2)The vapor pressure drop caused by bending was approximately 22–23%of the total,and the bending effect on the liquid pressure drop could be ignored.(3)The Marangoni effect reduced the capillary limit by hindering the liquid reflux,especially at low vapor temperatures.Without considering the Marangoni effect,the capillary limit of the lithium heat pipe was overestimated by 9%when the vapor temperature was 1400 K.(4)The total thermal resistance of the heat pipe significantly increased with increasing adiabatic length when the vapor temperature was low.Further,the wick dryness increased with increasing adiabatic length at any vapor temperature.Such findings improve on current knowledge for the optimal design and safety analysis of a heat pipe reactor,which adopts ultra-long lithium heat pipes.
基金partly supported by the National Natural Science Foundation of China(No.21377122)
文摘Alpha radiolysis of nitric acid aqueous solution by a ^(238)Pu source is investigated experimentally and theoretically.The time dependence of the nitrous acid yield on dose rate,nitric acid concentration,and nitrate ion concentration is studied.A novel kinetic model for the α-radiolysis of nitric acid aqueous solution is established,by considering the direct and indirect effects.The simulation results agree well with the experimental data,indicating the validity of our model to treat the reaction paths for generation and consumption of nitrous acid.It is shown that the redox reactions involving Pu cannot be neglected in theα-radiolysis of the solution.The results provide a better understanding of the α-ray radiolysis of aqueous nitric acid.
基金supported by the National Natural Science Foundations of China(Nos.51401205 and 51301163)the Strategic Priority Research Program of Chinese Academy of Sciences(No.XDA03040000)
文摘Lead and lead-alloys are proposed in future advanced nuclear system as coolant and spallation target.To test the natural circulation and gas-lift and obtain thermal-hydraulics data for computational fluid dynamics(CFD) and system code validation, a lead–bismuth eutectic rectangular loop, the KYLIN-Ⅱ Thermal Hydraulic natural circulation test loop, has been designed and constructed by the FDS team. In this paper, theoretical analysis on natural circulation thermal-hydraulic performance is described and the steady-state natural circulation experiment is performed. The results indicated that the natural circulation capability depends on the loop resistance and the temperature and center height differences between the hot and cold legs. The theoretical analysis results agree well with,while the CFD deviate from, the experimental results.
基金Supported by National Natural Science Foundation of China(No.11302224)Strategic Priority Science & Technology Program of the Chinese Academy of Sciences(No.XDA03040000)
文摘Based on the design of CLEAR(China LEAd-based Reactor), it is important to study the molten LBE(LeadBismuth Eutectic)/water interaction following an incidental steam generator tube rupture(SGTR) accident.Experiments were carried out to investigate the fragmentation behavior of the molten LBE/water contacting interface, with a high-speed video camera to record the fragmentation behavior of 300–600?C LBE at 20?C and 80?C of water temperature. Violent explosion phenomenon occurred at water temperature of 20?C, while no explosion occurred at 80?C. Shapes of the LBE debris became round at 80?C of water temperature, whereas the debris was of the needle-like shape at 20?C. For all the molten LBE and water temperatures in the present study,the debris sized at 2.8–5.0 mm had the largest mass fraction. The results indicate that the dominant physical mechanism of the molten LBE fragmentation was the Kelvin-Helmholtz instability between LBE/water direct contact interface.
文摘Zirconia nano-particles have been produced by the hydrolysis of ZrOCl2 solution in the reverse micelles of a liquid-liquid two-phase system, in which sodium bis（2-ethylhexyl） sulfosuccinite （AOT） and toluene were chosen as the surfactant and organic phase, respectively. The reverse micelles prevented the aggregation of primary particles and reduced the diameters of zirconia nanoparticles. Superfine zirconia powders soft-aggregated by the zirconia nano-particles were obtained. The diameters of zirconia nanoparticles were influenced by the quantity of the surfactant.
基金supported by the National Natural Science Foundation of China(Grant No.5160121211475082)‘‘Strategic Priority Research Program of Chinese Academy of Sciences’’ Thorium Molten Salts Reactor Fund
文摘Adsorption and desorption of hydrogen on/from single-vacancy and double-vacancy graphenes were studied by means of first-principles calculations. The structure and stability of continuous hydrogenation in single vacancy were investigated. Several new stable structures were found, along with their corresponding energy barriers. In double-vacancy graphene, the preferred sites of H atoms were identified, and H2 molecule desorption and adsorption of from/on were calculated from the energy barriers. This work provides a systematic and comprehensive understanding of hydrogen behavior on defected graphene.
基金Supported by National Natural Science Foundation of China(No.11305203)Natural Science Foundation of Anhui Province(No.1508085QH180)
文摘A direct incident fluence measurement method based on amorphous silicon electronic portal imaging device(a-Si EPID) has been developed for pretreatment verification of intensity-modulated radiation therapy(IMRT).The EPID-based incident fluence conversion method deconvolves EPID images to the primary response distribution based on measured lateral scatter kernels in the EPID detector using Conjugate Gradient algorithm.The primary response is converted to the incident fluence based on measured fluence conversion matrix which corrects for off-axis position dependence of the a-Si EPID response and the "horn" beam profile caused by flatting filter. To verify feasibility and accuracy of this method, square fields of various sizes and two IMRT plans were delivered. The dose distributions computed based on EPID-derived incident fluence were compared with the measurement data. For all square field sizes except the smallest field(2 cm), the mean dose differences in cross-line dose profiles were within 1% excluding the penumbra region, and gamma passing percentages with a 2%/2 mm criterion were about 99%. For two IMRT plans, the least gamma passing percentage for all eight IMRT fields was 98.14% with 2%/3 mm criteria. It can be concluded that our direct EPID-based incident fluence conversion method is accurate and capable of being applied to pretreatment dose verification in clinical routines.
基金supported by the National Natural Science Foundation of China(Grant Nos.51674070,51874085,and U1435205)Also,this project was supported by the Transformation Project of Major Scientific and Technological Achievements in Shenyang(Grant No.Z17-5-003)and the"Innovation&Entrepreneurship Talents"Introduction Plan of Jiangsu Province in 2018.
文摘Current-conductive mold was recently developed to extend electroslag remelting(ESR)functions to overcome some solidification defects by changing the current path.The macrostructures,microstructures,macrosegregation,and microsegregation of the Inconel 718 ingots produced by the custom laboratory-scale ESR furnace under different current paths(the classical ESR and the single power,and two circuits ESR process with current-conductive mold(ESR-STCCM))with the same power input were compared and investigated.The results indicate that when the ingot was produced during ESR and ESR-STCCM processes,at the same power input,the pool depth was 104 and 90 mm,respectively.A flatter and shallower molten pool was obtained during ESR-STCCM process.Moreover,compared with a classical ESR ingot,the cooling rate of the centerline of ESR-STCCM ingot was increased from 12.7 to 16.7 K min^(−1).The increased cooling rates caused by decreased melting rate and thinner slag skin reduced the growth angle of columnar crystal to the vertical axis and the secondary dendrite arm spacing.Furthermore,the macrosegregation and microsegregation of segregation elements for ESR-STCCM process were dramatically reduced compared with ESR process.The average volume fraction of Laves phase was reduced from 7.39%to 6.14%,and the segregation of Nb in Laves phase was significantly reduced.
基金Supported by the National Nature Science Foundation of China(No.51301163)the Important Direction Program of Chinese Academy of Sciences(No.XDA03040200)
文摘Oxygen control technology is a critical issue for compatibility of candidate structural materials with liquid lead-bismuth eutectic(LBE) in accelerator driven systems. Performances of a self-developed Pt/air sensor and another one from Karlsruher Institute of Technology(KIT) were tested in stagnant oxygen-saturated liquid LBE.Calibrations showed that the trend and values of corrected electromotive force(EMF) of the self-developed sensor, with a bias voltage of 20 mV, were consistent with theoretical results above 425℃, and similar results were obtained in cross-calibration test with EMF value of KIT sensor as reference. In stability test at 450℃ for 100 hours, the KIT sensor performed better than the self-developed one, which showed signal fluctuations.Both sensors exhibited quick response to temperature variations in the responsiveness test.
文摘Using ammonium chloride （NH4Cl） as a chlorinating agent, the effects of chlorinating temperature, chlorinating time and NH4Cl dosage on chlorination of La2O3 and CeO2, and the thermal decomposition of LaCl3·7H2O and CeCl3·7H2O were investigated. The results show that 80% of both La2O3 and CeO2 can be chlorinated at 300 ℃ for 90 min, and have no advantage to chlorination of lanthanum and cerium oxides at higher temperature. The thermal decomposition of LaCl3 and CeCl3 is carried out to explore the mechanism of chlorinating lanthanum and cerium oxides. At the same time, the chlorination of lanthanum and cerium oxides is not devoted to the HCl decomposed from NH4Cl, but to NH4Cl directly taking part in the chlorination of La2O3 and CeO2. The lanthanum and cerium oxides in chlorination firstly form intermediate LaOCl and CeOCl, and then transfer to LaCl3 and CeCl3, finally to La2O3 and CeO2, respectively. The thermal decomposition analyses of LaCl3·7H2O and CeCl3·7H2O further prove the existence of the intermediates LaOCl and CeOCl. Therefore the chlorinating temperature and time should strictly be controlled when the lanthanum oxide and cerium oxide are chlorinated with NH4Cl. And over-dosage of NH4Cl should be also applied in the process of chlorination.
