The progress of research going on in Group of Energy Materials (GEM), Material Research Center, in 2014 isin the following three aspects.1. Facility developmentIn order to push forward our study on fusion reactor mate...The progress of research going on in Group of Energy Materials (GEM), Material Research Center, in 2014 isin the following three aspects.1. Facility developmentIn order to push forward our study on fusion reactor materials, we upgraded the irradiation terminal (128#)of the sector focused cyclotron (SFC) at HIRFL, by developing a new specimen stage specific for irradiation withlow-fluence scattered ions. So far the terminal is capable of irradiation to both very low fluences (106 ions/cm2) andvery high fluences (typically 1016 ions/cm2) for various materials. Specimen temperature can be readily controlledusing the L-N2 cooling stage or the the high-T stage (up to 600 oC). Our recent investigation with transmissionelectron microscopy (TEM) of the defects produced by high-energy Ne ions in steel specimens provides a clearevidence that defects were produced uniformly along the depth in the specimen, indicating that the energy degraderof the terminal works effectively to disperse the ion energy in a wide range. A photo of the terminal together witha SRIM estimate of depth profiles of damage in an 8% Cr reduced activation ferritic/martensitic steel (RAFMS) isshown in Fig. 1.展开更多
In reactor physics tests, it is important to monitor sub-criticality continuously during criticality approach. Reactivity measurements by the inverse kinetics method are widely used during the operation of a nuclear r...In reactor physics tests, it is important to monitor sub-criticality continuously during criticality approach. Reactivity measurements by the inverse kinetics method are widely used during the operation of a nuclear reactor. This technique is successfully applied at sufficiently high power level or to a core without an external neutron source where the neutron source term in point reactor kinetics equations may be neglected. For operation at low power levels or in the sub-critical domain, the increase in the fluctuation of the neutron signal may cause difficulties in the evaluation of reactivity and the effect of direct emission from the external neutron source may not be neglected. Therefore, contribution of the neutron source must be taken into account and this implies knowledge of a quantity proportional to the source strength, which calls the source term and then it should be determined. The research work has been conducted to measure reactivity with source term using a dedicated reactivity measurement system by the Least Square Inverse Kinetics Method (LSIKM). Application to a simulator of HANARO research reactor, Korea Atomic Energy Research Institute (KAERI), with known source strength and reactivity worth has showed consistent and satisfactory agreement.展开更多
Assessment of the exposure dose for workers is crucial to protecting workers from the radiological risk.This preliminary study estimates the potential radiological exposure for a soil remediation worker at a nuclear d...Assessment of the exposure dose for workers is crucial to protecting workers from the radiological risk.This preliminary study estimates the potential radiological exposure for a soil remediation worker at a nuclear decommissioning site contaminated with Cs-137 in Korea,and then calculates the maximum workable soil concentration to comply with the occupational dose constraint of 20 mSv per year.The Korean characteristic data,detailed exposure scenarios for workers by the type of work,and relevant exposure pathways were used in the dose estimation.As a result,the most severe exposure-induced work type was identified as the excavator operation with an annual individual dose of 5.92×10^-5 mSv for a unit concentration of soil,from which the derived maximum workable soil concentration was 3.38×105 Bq/kg.Furthermore,dose contribution by each exposure pathway was found to be decreased in the following order:external radiation exposure,soil ingestion,dust inhalation,and skin contamination.The results of this study are expected to be used effectively to optimize radiation protection for workers and establish appropriate work procedures for future site remediation.展开更多
Atoms in the coherent superposition state prepared by a pulse pair are used as a novel optical memory material where a single interrogation pulse will produce a new pulse pair preserving the relative amplitudes and ph...Atoms in the coherent superposition state prepared by a pulse pair are used as a novel optical memory material where a single interrogation pulse will produce a new pulse pair preserving the relative amplitudes and phases of the preparing pulse pair. Such a coherent superposition state can also be specially tailored along the propagation path to generate Raman scattering in a relatively short distance with very high efficiency.展开更多
HANARO (High-Flux Advanced Neutron Application Reactor) is a 30MWth multi-purpose research reactor generating a very high neutron flux for scientific and technical applications. Since its initial criticality in Feb. 1...HANARO (High-Flux Advanced Neutron Application Reactor) is a 30MWth multi-purpose research reactor generating a very high neutron flux for scientific and technical applications. Since its initial criticality in Feb. 1995, it has worked as a national neutron source for neutron beam research, RI production and related research, material and fuel irradiation research, and neutron transmutation doping. The installation of a cold neutron source and related beam instrument makes HANARO serve as a regional source for beam research as well. As Korea is developing nuclear power systems and fuels, irradiation research is a main utilization subject in HANARO, and irradiation facilities have been actively utilized for various nuclear fuel and material irradiation tests requested by users from research institutes, universities, and industries. Most of the irradiation tests were related to the R & D relevant to the ageing management and safety evaluation of the present nuclear power reactors. Korea is conducting R & D programs relevant to new nuclear systems including a research reactor, System-integrated Modular Advanced Reactor (SMART), and future nuclear systems such as a very high temperature reactor system (VHTR) and sodium cooled fast reactor system (SFR). To effectively support the R&D for new nuclear systems, advanced irradiation technologies such as high-temperature irradiation, instrumentation, and long-term irradiation are being developed. In addition, research on the irradiation characteristics of super-conductor materials and new chemical materials is being conducted as a part of fundamental research.展开更多
Much in-class education and training for developing countries have focused on how a learner absorbs knowledge and skills efficiently or effectively in the class,but are less interested in how the learners should trans...Much in-class education and training for developing countries have focused on how a learner absorbs knowledge and skills efficiently or effectively in the class,but are less interested in how the learners should transfer the knowledge and skills into their jobs in their workplace.In principle,in-class education and training have a difficulty with applying the learned knowledge and skills to learners’jobs in the workplace in comparison with any other practical-basis training.To overcome this difficulty,many educational stakeholders in the nuclear field have concentrated on how learners can transfer the knowledge and skills absorbed in the class into their jobs in their workplace.The action learning activity for learners can be one of the solutions to apply the knowledge and skills to their job in the workplace.The purpose of this study is to clarify how the transfer of learning has been implemented in the nuclear-related continuing professional educations and training for developing countries in Korea.To accomplish this purpose,this study is implemented as follows.The first is to define the concept of the“transfer of learning”clearly.The second is to clarify the core elements of the transfer of learning.Along with the clarification,the third is to show how the transfer of learning has been implemented in the continuing professional nuclear-related education and training for developing countries in Korea.The fourth is to present core problems in such education and training.As the fifth,this study suggests alternatives to overcome the core problems in the nuclear-related continuing professional education and training.展开更多
Electrochemical water splitting to produce hydrogen fuel is a promising renewable energy-conversion technique.Large-scale electrolysis of freshwater may deplete water resources and cause water scarcity worldwide.Thus,...Electrochemical water splitting to produce hydrogen fuel is a promising renewable energy-conversion technique.Large-scale electrolysis of freshwater may deplete water resources and cause water scarcity worldwide.Thus,seawater electrolysis is a potential solution to the future energy and water crisis.In seawater electrolysis,it is critical to develop cost-effective electrocatalysts to split seawater without chloride corrosion.Herein,we present zinc-doped nickel iron(oxy)hydroxide nanocubes passivated by negatively charged polyanions(NFZ-PBA-S)that exhibits outstanding catalytic activity,stability,and selectivity for seawater oxidation.Zn dopants and polyanion-rich passivated surface layers in NFZ-PBA-S could effectively repel chlorine ions and enhance corrosion resistance,enabling its excellent catalytic activity and stability for seawater oxidation.展开更多
The saturation of the compacted bentonite buffer in the deep geological repository can cause bentonite swelling,intrusion into rock fractures,and erosion.Inevitably,erosion and subsequent bentonite mass loss due to gr...The saturation of the compacted bentonite buffer in the deep geological repository can cause bentonite swelling,intrusion into rock fractures,and erosion.Inevitably,erosion and subsequent bentonite mass loss due to groundwater inflow can aggravate the overall integrity of the engineered barrier system.Therefore,the coupled hydro-mechanical interaction between the buffer and rock during groundwater inflow and bentonite intrusion should be evaluated to guarantee the long-term safety of deep geological disposal.This study investigated the effect of bentonite erosion and intrusion on the elastic wave propagation characteristics in jointed rocks using a quasi-static resonant column test.Jointed rock specimens with different joint conditions(i.e.joint surface saturation and bentonite filling)were prepared using granite rock discs sampled from the Korea Underground Research Tunnel(KURT)and Gyeongju bentonite.The long-wavelength longitudinal and shear wave velocities were measured under different normal stress levels.A Hertzian-type power model was used to fit the wave velocities,and the relationship between the two fitted parameters provided the trend of joint conditions.Numerical simulations using three-dimensional distinct element code(3DEC)were conducted to better understand how the long-wavelength wave propagates through wet bentonite-filled rock joints.展开更多
We investigate the effect of ion irradiation on MgB_(2) thin films with small grains of approximately 122 nm and 140 nm.The flux pinning by grain boundaries is insignificant in the pristine MgB_(2) films due to good i...We investigate the effect of ion irradiation on MgB_(2) thin films with small grains of approximately 122 nm and 140 nm.The flux pinning by grain boundaries is insignificant in the pristine MgB_(2) films due to good inter-grain connectivity,but is significantly improved after 120-keV Mn-ion irradiation.The scaling behavior of the flux pinning force density for the ion-irradiated MgB_(2) thin films with nanoscale grains demonstrates the predominance of pinning by grain boundaries,in contrast to the single-crystalline MgB_(2) films where normal point pinning was dominant after low-energy ion irradiation.These results suggest that irradiation-induced defects can accumulate near the grain boundaries in metallic MgB_(2) superconductors.展开更多
The carbon steels dispersed with ultrafine TiC particles were fabricated by conventional casting method. The casting process is more economical than other available routes for metal matrix composite production, and th...The carbon steels dispersed with ultrafine TiC particles were fabricated by conventional casting method. The casting process is more economical than other available routes for metal matrix composite production, and the large sized components to be fabricated in short processing time. However, it is extremely difficult to obtain uniform dispersion of ultrafine ceramic particles in liquid metals due to the poor wettability and the specific gravity difference between the ceramic particle and metal matrix. In order to solve these problems, the mechanical milling (MM) and surface-active processes were introduced. As a result, Cu coated ultrafine TiC powders made by MM process using high energy ball milling machine were mixed with Sn powders as a surfactant to get better wettability by lowering the surface tension of carbon steel melt. The microstructural investigations by OM show that ultrafine TiC particles are distributed uniformly in carbon steel matrix. The grain sizes of the cast matrix with ultrafine TiC particles are much smaller than those without ultrafine TiC particles. This is probably due to the fact that TiC particles act as nucleation sites during solidification. The wear resistance of cast carbon steel composites added with MMed TiC/Cu-Sn powders is improved due to grain size refinement.展开更多
The amounts of nuclear materials in the Li Cl-KCl salt in pyroprocessing have to be analyzed to prevent the diversion of the nuclear material.An alternative method to the chemical analysis has been pursued,and laser-i...The amounts of nuclear materials in the Li Cl-KCl salt in pyroprocessing have to be analyzed to prevent the diversion of the nuclear material.An alternative method to the chemical analysis has been pursued,and laser-induced breakdown spectroscopy(LIBS)is one candidate.In the present work,an in situ and quantitative analysis method of electro-recovery(ER)salt was proposed and demonstrated by using LIBS combined with dipstick sampling.Two types of simulated salt samples were prepared:ER salt sample and salt obtained from the dipstick sampling,and pulsed neodymium-doped yttrium aluminum garnet(Nd:YAG)laser with a wavelength of 532 nm was focused on the salt to generate plasma.The plasma emission was measured by using an Echelle spectrometer with a resolution of 0.01 nm in conjunction with an Intensified Charge-Coupled Detector camera.The U and other rare earth peaks in the spectra were identified.The best Limit of Detection and Root Mean Square Error of Calibration of U were 38 ppm and 0.0203 wt%,respectively.Our work shows that the U in the pyroprocessing ER salt can be monitored with LIBS.展开更多
The microstructures of the brazed joints for commercially pure Ti and stainless steel were investigated by the applications of various filler alloys including Ag-, Ti-, Zr- and Ni-based alloys. Generally, the dissimil...The microstructures of the brazed joints for commercially pure Ti and stainless steel were investigated by the applications of various filler alloys including Ag-, Ti-, Zr- and Ni-based alloys. Generally, the dissimilar joints between Ti and stainless steel were dominated by the Ti-based intermetallic compounds (IMCs), e.g. (Ti, Zr)2(Fe, Ni), TiFe, TiCu, and Ti2(Fe, Ni), due to a significant dissolution of Ti from the base metal. The (Fe-Cr) σ phase was also observed near the stainless steel due to a segregation of Cr into the interface region. This research demonstrates empirically that the brittleness of the Ti and stainless steel joint can not be avoided only by applying single braze alloy or single insert metal, and thus an introduction of additional suitable interlayer between the filler alloy and the base metal is necessary to prevent the brittleness of the joint.展开更多
This study investigates the risks of non-conservative piping design according to ASME B31.1 for hightemperature piping subjected to long-term operation at high temperature in a creep regime based on a sensitivity anal...This study investigates the risks of non-conservative piping design according to ASME B31.1 for hightemperature piping subjected to long-term operation at high temperature in a creep regime based on a sensitivity analysis of the hold time. Design evaluations of hightemperature piping were conducted over a range of hold times in the creep regime according to ASME B31.1,which implicitly considers the creep effects, and the French high-temperature design code of the RCC-MRx, which explicitly considers the creep effects. Conservatisms were quantified among the codes in terms of the hold times. In the case of B31.1, the design evaluation results do not change depending on the hold time at high temperature,whereas in the case of RCC-MRx, they do. It was shown that the design limits of RCC-MRx were exceeded when the hold time exceeded certain values, whereas those of B31.1 were satisfied regardless of the hold times. Thus, the design evaluations according to B31.1 did not consistently yield conservative results and might lead to non-conservative results in the case of long-term operations in the creep range.展开更多
文摘The progress of research going on in Group of Energy Materials (GEM), Material Research Center, in 2014 isin the following three aspects.1. Facility developmentIn order to push forward our study on fusion reactor materials, we upgraded the irradiation terminal (128#)of the sector focused cyclotron (SFC) at HIRFL, by developing a new specimen stage specific for irradiation withlow-fluence scattered ions. So far the terminal is capable of irradiation to both very low fluences (106 ions/cm2) andvery high fluences (typically 1016 ions/cm2) for various materials. Specimen temperature can be readily controlledusing the L-N2 cooling stage or the the high-T stage (up to 600 oC). Our recent investigation with transmissionelectron microscopy (TEM) of the defects produced by high-energy Ne ions in steel specimens provides a clearevidence that defects were produced uniformly along the depth in the specimen, indicating that the energy degraderof the terminal works effectively to disperse the ion energy in a wide range. A photo of the terminal together witha SRIM estimate of depth profiles of damage in an 8% Cr reduced activation ferritic/martensitic steel (RAFMS) isshown in Fig. 1.
文摘In reactor physics tests, it is important to monitor sub-criticality continuously during criticality approach. Reactivity measurements by the inverse kinetics method are widely used during the operation of a nuclear reactor. This technique is successfully applied at sufficiently high power level or to a core without an external neutron source where the neutron source term in point reactor kinetics equations may be neglected. For operation at low power levels or in the sub-critical domain, the increase in the fluctuation of the neutron signal may cause difficulties in the evaluation of reactivity and the effect of direct emission from the external neutron source may not be neglected. Therefore, contribution of the neutron source must be taken into account and this implies knowledge of a quantity proportional to the source strength, which calls the source term and then it should be determined. The research work has been conducted to measure reactivity with source term using a dedicated reactivity measurement system by the Least Square Inverse Kinetics Method (LSIKM). Application to a simulator of HANARO research reactor, Korea Atomic Energy Research Institute (KAERI), with known source strength and reactivity worth has showed consistent and satisfactory agreement.
基金This study was supported by the National Research Foundation of Korea(NRF)grant funded by the Korean government(No.NRF-2017-M2A8A4015252)it has been conducted as a part of the project of emergency preparedness for nuclear research facilities in Korea Atomic Energy Research Institute(KAERI).
文摘Assessment of the exposure dose for workers is crucial to protecting workers from the radiological risk.This preliminary study estimates the potential radiological exposure for a soil remediation worker at a nuclear decommissioning site contaminated with Cs-137 in Korea,and then calculates the maximum workable soil concentration to comply with the occupational dose constraint of 20 mSv per year.The Korean characteristic data,detailed exposure scenarios for workers by the type of work,and relevant exposure pathways were used in the dose estimation.As a result,the most severe exposure-induced work type was identified as the excavator operation with an annual individual dose of 5.92×10^-5 mSv for a unit concentration of soil,from which the derived maximum workable soil concentration was 3.38×105 Bq/kg.Furthermore,dose contribution by each exposure pathway was found to be decreased in the following order:external radiation exposure,soil ingestion,dust inhalation,and skin contamination.The results of this study are expected to be used effectively to optimize radiation protection for workers and establish appropriate work procedures for future site remediation.
文摘Atoms in the coherent superposition state prepared by a pulse pair are used as a novel optical memory material where a single interrogation pulse will produce a new pulse pair preserving the relative amplitudes and phases of the preparing pulse pair. Such a coherent superposition state can also be specially tailored along the propagation path to generate Raman scattering in a relatively short distance with very high efficiency.
文摘HANARO (High-Flux Advanced Neutron Application Reactor) is a 30MWth multi-purpose research reactor generating a very high neutron flux for scientific and technical applications. Since its initial criticality in Feb. 1995, it has worked as a national neutron source for neutron beam research, RI production and related research, material and fuel irradiation research, and neutron transmutation doping. The installation of a cold neutron source and related beam instrument makes HANARO serve as a regional source for beam research as well. As Korea is developing nuclear power systems and fuels, irradiation research is a main utilization subject in HANARO, and irradiation facilities have been actively utilized for various nuclear fuel and material irradiation tests requested by users from research institutes, universities, and industries. Most of the irradiation tests were related to the R & D relevant to the ageing management and safety evaluation of the present nuclear power reactors. Korea is conducting R & D programs relevant to new nuclear systems including a research reactor, System-integrated Modular Advanced Reactor (SMART), and future nuclear systems such as a very high temperature reactor system (VHTR) and sodium cooled fast reactor system (SFR). To effectively support the R&D for new nuclear systems, advanced irradiation technologies such as high-temperature irradiation, instrumentation, and long-term irradiation are being developed. In addition, research on the irradiation characteristics of super-conductor materials and new chemical materials is being conducted as a part of fundamental research.
文摘Much in-class education and training for developing countries have focused on how a learner absorbs knowledge and skills efficiently or effectively in the class,but are less interested in how the learners should transfer the knowledge and skills into their jobs in their workplace.In principle,in-class education and training have a difficulty with applying the learned knowledge and skills to learners’jobs in the workplace in comparison with any other practical-basis training.To overcome this difficulty,many educational stakeholders in the nuclear field have concentrated on how learners can transfer the knowledge and skills absorbed in the class into their jobs in their workplace.The action learning activity for learners can be one of the solutions to apply the knowledge and skills to their job in the workplace.The purpose of this study is to clarify how the transfer of learning has been implemented in the nuclear-related continuing professional educations and training for developing countries in Korea.To accomplish this purpose,this study is implemented as follows.The first is to define the concept of the“transfer of learning”clearly.The second is to clarify the core elements of the transfer of learning.Along with the clarification,the third is to show how the transfer of learning has been implemented in the continuing professional nuclear-related education and training for developing countries in Korea.The fourth is to present core problems in such education and training.As the fifth,this study suggests alternatives to overcome the core problems in the nuclear-related continuing professional education and training.
基金supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF)funded by the Ministry of Science,ICT and Future Planning (2021R1A2C2091497 and 2022R1A2C2010162)supported by“Regional Innovation Strategy (RIS)”through the National Research Foundation of Korea (NRF)funded by the Ministry of Education (MOE) (2022RIS-005)+1 种基金supported by the Ministry of Trade,Industry,and Energy (20018145)supported by KIST Institutional Program (Project Nos.2V09781)。
文摘Electrochemical water splitting to produce hydrogen fuel is a promising renewable energy-conversion technique.Large-scale electrolysis of freshwater may deplete water resources and cause water scarcity worldwide.Thus,seawater electrolysis is a potential solution to the future energy and water crisis.In seawater electrolysis,it is critical to develop cost-effective electrocatalysts to split seawater without chloride corrosion.Herein,we present zinc-doped nickel iron(oxy)hydroxide nanocubes passivated by negatively charged polyanions(NFZ-PBA-S)that exhibits outstanding catalytic activity,stability,and selectivity for seawater oxidation.Zn dopants and polyanion-rich passivated surface layers in NFZ-PBA-S could effectively repel chlorine ions and enhance corrosion resistance,enabling its excellent catalytic activity and stability for seawater oxidation.
基金funding support from the Nuclear Research and Development Program of the National Research Foundation of Korea(Grant Nos.2021M2E1A1085193 and 2020M2C9A1062949).
文摘The saturation of the compacted bentonite buffer in the deep geological repository can cause bentonite swelling,intrusion into rock fractures,and erosion.Inevitably,erosion and subsequent bentonite mass loss due to groundwater inflow can aggravate the overall integrity of the engineered barrier system.Therefore,the coupled hydro-mechanical interaction between the buffer and rock during groundwater inflow and bentonite intrusion should be evaluated to guarantee the long-term safety of deep geological disposal.This study investigated the effect of bentonite erosion and intrusion on the elastic wave propagation characteristics in jointed rocks using a quasi-static resonant column test.Jointed rock specimens with different joint conditions(i.e.joint surface saturation and bentonite filling)were prepared using granite rock discs sampled from the Korea Underground Research Tunnel(KURT)and Gyeongju bentonite.The long-wavelength longitudinal and shear wave velocities were measured under different normal stress levels.A Hertzian-type power model was used to fit the wave velocities,and the relationship between the two fitted parameters provided the trend of joint conditions.Numerical simulations using three-dimensional distinct element code(3DEC)were conducted to better understand how the long-wavelength wave propagates through wet bentonite-filled rock joints.
基金the support of the accelerator group and operators of KOMAC (KAERI (C.K.,J.S.))Project supported by the National Research Foundation (NRF)of Korea through a grant funded by the Korean Ministry of Science and ICT (Grant No.2021R1A2C2010925 (T.P.,Y.H.,J.S.))+2 种基金the Basic Science Research Program through the NRF of Korea funded by the Ministry of Education (Grant Nos.NRF-2019R1F1A1055284 (J.M.L.,W.N.K.)and NRF2021R1I1A1A01043885 (S.G.J.,Y.H.))the National Natural Science Foundation of China (Grant Nos.12035019 (J.L.))the Chinese Scholarship Council (CSC)for fellowship support。
文摘We investigate the effect of ion irradiation on MgB_(2) thin films with small grains of approximately 122 nm and 140 nm.The flux pinning by grain boundaries is insignificant in the pristine MgB_(2) films due to good inter-grain connectivity,but is significantly improved after 120-keV Mn-ion irradiation.The scaling behavior of the flux pinning force density for the ion-irradiated MgB_(2) thin films with nanoscale grains demonstrates the predominance of pinning by grain boundaries,in contrast to the single-crystalline MgB_(2) films where normal point pinning was dominant after low-energy ion irradiation.These results suggest that irradiation-induced defects can accumulate near the grain boundaries in metallic MgB_(2) superconductors.
基金supported by the Korea Atomic Energy Research Institute (KAERI) R&D Program
文摘The carbon steels dispersed with ultrafine TiC particles were fabricated by conventional casting method. The casting process is more economical than other available routes for metal matrix composite production, and the large sized components to be fabricated in short processing time. However, it is extremely difficult to obtain uniform dispersion of ultrafine ceramic particles in liquid metals due to the poor wettability and the specific gravity difference between the ceramic particle and metal matrix. In order to solve these problems, the mechanical milling (MM) and surface-active processes were introduced. As a result, Cu coated ultrafine TiC powders made by MM process using high energy ball milling machine were mixed with Sn powders as a surfactant to get better wettability by lowering the surface tension of carbon steel melt. The microstructural investigations by OM show that ultrafine TiC particles are distributed uniformly in carbon steel matrix. The grain sizes of the cast matrix with ultrafine TiC particles are much smaller than those without ultrafine TiC particles. This is probably due to the fact that TiC particles act as nucleation sites during solidification. The wear resistance of cast carbon steel composites added with MMed TiC/Cu-Sn powders is improved due to grain size refinement.
基金Supported by the National Natural Science Foundation of China under Grant No 10535030. The authors gratefully acknowledge Professor Zhongli Liu and Mr Zhiming Hu for their technical assistance. We also wish to thank Dr Liming Chen and Dr Leifeng Cao for fruitful discussion.
文摘产生在的一块 wake 地里的高精力电子加速强烈超短波(30 fs ) 激光脉搏簇气体喷气相互作用试验性地被表明。有 60 兆电子伏的精力的相对论的电子被观察。这些高精力电子分成了二根横梁由于相对论激光自我集中。
基金supported by a National Research Foundation of Korea(NRF)grant funded by the Korean Government’s Ministry of Science and ICT(MSIT)(No.NRF2017M2A8A5015084)partly supported by the Nuclear Safety Research Program through the Korea Foundation of Nuclear Safety(Ko FONS)using the financial resource granted by the Nuclear Safety and Security Commission(NSSC)of the Republic of Korea(No.1903014)。
文摘The amounts of nuclear materials in the Li Cl-KCl salt in pyroprocessing have to be analyzed to prevent the diversion of the nuclear material.An alternative method to the chemical analysis has been pursued,and laser-induced breakdown spectroscopy(LIBS)is one candidate.In the present work,an in situ and quantitative analysis method of electro-recovery(ER)salt was proposed and demonstrated by using LIBS combined with dipstick sampling.Two types of simulated salt samples were prepared:ER salt sample and salt obtained from the dipstick sampling,and pulsed neodymium-doped yttrium aluminum garnet(Nd:YAG)laser with a wavelength of 532 nm was focused on the salt to generate plasma.The plasma emission was measured by using an Echelle spectrometer with a resolution of 0.01 nm in conjunction with an Intensified Charge-Coupled Detector camera.The U and other rare earth peaks in the spectra were identified.The best Limit of Detection and Root Mean Square Error of Calibration of U were 38 ppm and 0.0203 wt%,respectively.Our work shows that the U in the pyroprocessing ER salt can be monitored with LIBS.
基金supported by the Korea Atomic Energy Research Institute (KAERI) R&D Program
文摘The microstructures of the brazed joints for commercially pure Ti and stainless steel were investigated by the applications of various filler alloys including Ag-, Ti-, Zr- and Ni-based alloys. Generally, the dissimilar joints between Ti and stainless steel were dominated by the Ti-based intermetallic compounds (IMCs), e.g. (Ti, Zr)2(Fe, Ni), TiFe, TiCu, and Ti2(Fe, Ni), due to a significant dissolution of Ti from the base metal. The (Fe-Cr) σ phase was also observed near the stainless steel due to a segregation of Cr into the interface region. This research demonstrates empirically that the brittleness of the Ti and stainless steel joint can not be avoided only by applying single braze alloy or single insert metal, and thus an introduction of additional suitable interlayer between the filler alloy and the base metal is necessary to prevent the brittleness of the joint.
基金supported by National Research Foundation Grants(NRF-2012M2A8A2025635 and NRF-2017K1A3A7A03086464)funded by the Korean Government(Ministry of Science,ICT and Future Planning)
文摘This study investigates the risks of non-conservative piping design according to ASME B31.1 for hightemperature piping subjected to long-term operation at high temperature in a creep regime based on a sensitivity analysis of the hold time. Design evaluations of hightemperature piping were conducted over a range of hold times in the creep regime according to ASME B31.1,which implicitly considers the creep effects, and the French high-temperature design code of the RCC-MRx, which explicitly considers the creep effects. Conservatisms were quantified among the codes in terms of the hold times. In the case of B31.1, the design evaluation results do not change depending on the hold time at high temperature,whereas in the case of RCC-MRx, they do. It was shown that the design limits of RCC-MRx were exceeded when the hold time exceeded certain values, whereas those of B31.1 were satisfied regardless of the hold times. Thus, the design evaluations according to B31.1 did not consistently yield conservative results and might lead to non-conservative results in the case of long-term operations in the creep range.
