Previous studies have investigated the boron isotopic composition of salt lake brines in the Qaidam Basin,western China.However,the research on boron isotopic composition of halite is very limited due to halite’s low
A 51.85 m firn core drilled in Princess Elizabeth Land, Antarctica, during the 1996-1997 Chinese First Antarctic Inland Expedition, has been measured for δ 18 O and major ions. Based on the high quality data ...A 51.85 m firn core drilled in Princess Elizabeth Land, Antarctica, during the 1996-1997 Chinese First Antarctic Inland Expedition, has been measured for δ 18 O and major ions. Based on the high quality data of the seasonal variations of major ions, the firn core was dated with errors within ±3 years. The 51.85 m firn core record extends for 251 years (A. D. 1745-1996). The results of the glaciochemistry data of the firn core show that the mean concentrations of Cl -, Na + and Mg 2+ are similar to those reported from other coastal areas in East Antarctica. However, mean concentrations of Ca 2+ are much higher than those reported from other regions, this anomaly phenomenon may be related to the strong local terrestrial sources. It is found that the variations of three kinds of sea salt ions (Cl -, Na + and Mg 2+ ) in the past 150 years show very similarly rising trends, which may be the results the Southern Hemisphere warming in the past century.展开更多
Fast reactors based on thorium fuel have enhanced inherent safety. Fluoride salt performs well as a coolant in high-temperature nuclear systems. In this paper,we present a reference core for a large fluoride-salt-cool...Fast reactors based on thorium fuel have enhanced inherent safety. Fluoride salt performs well as a coolant in high-temperature nuclear systems. In this paper,we present a reference core for a large fluoride-salt-cooled solid-fuel fast reactor(LSFR) using thorium–uranium fuel cycle. Neutronics physics of the LSFR reference core is investigated with 2D and 3D in-core fuel management strategy. The design parameters analyzed include the fuel volume fraction, power density level and continuous removal of fission products with 3D fuel shuffling that obtains better equilibrium core performance than 2D shuffling. A self-sustained core is achieved for all cases,and the core of 60% fuel volume fraction at 50 MW/m^3 power density is of the best breeding performance(average breeding ratio 1.134). The LSFR core based on thorium fuel is advantageous in its high discharge burn-up of 20–30% fissions per initial heavy metal atom, small reactivity swing over the whole lifetime(to simplify the reactivity control system), the negative reactivity temperature coefficient(intrinsically safe for all cases) and accepted cladding peak radiation damage. The LSFR reactor is a good alternative option for the deployment of a self-sustained thorium-based nuclear system.展开更多
When treated in pressure die casting processes the semi-solid aluminum alloys demand resilient cores which can bear the stress occurring during filling and the final pressure phase.The design of permanent cores is hig...When treated in pressure die casting processes the semi-solid aluminum alloys demand resilient cores which can bear the stress occurring during filling and the final pressure phase.The design of permanent cores is highly restricted in order to maintain removability.Lost cores provide the possibility of complex,undercut geometrical shapes which is mandatory for a variety of casting components.However,eligible materials which show appropriate resilience and proper decomposition properties at the same time,and in the upper echelon of cost-effectiveness,are seldom known.With the semi-solid process suited between HPDC and GDC regarding the core stress,several common and economically efficient lost core systems could be used.A selection of potentially suitable materials was identified and tested.The range of testing comprises widespread sand core-systems(amin-pur-coldbox and CO2-water-glass) as well as materials less commonly used,namely salt,plastic and zinc.Different types of conditioning are applied to enhance the surface properties.The mechanical properties of the sand cores are enhanced by different heat treatment methods during curing.The cores are tested producing a research component cast on a HPDC machine with semi-solid A356 slurry fabricated in the cooling channel process.The cast component was analyzed regarding shape stability,core removability and surface as well as the structure quality.The results show the importance of the surface conditioning for the sand-cores while salt and zinc produce good parts comparable to the reference steel core quality.展开更多
熔盐堆采用液态燃料,由于燃料的流动性,堆芯结构的变化会直接影响堆芯活性区的燃料盐装载量,从而影响堆芯物理特性参数。本文基于蒙特卡罗程序MCNP(Monte Carlo N Particle Transport Code),以2 MW液态燃料钍基熔盐堆(Thorium Molten Sa...熔盐堆采用液态燃料,由于燃料的流动性,堆芯结构的变化会直接影响堆芯活性区的燃料盐装载量,从而影响堆芯物理特性参数。本文基于蒙特卡罗程序MCNP(Monte Carlo N Particle Transport Code),以2 MW液态燃料钍基熔盐堆(Thorium Molten Salt Reactor-Liquid Fuel,TMSR-LF1)设计模型为参考,系统研究了套管破裂、石墨构件移动、石墨破损、燃料盐浸渗度等因素对堆芯反应性的影响。结果表明:对于堆芯套管破裂,堆芯引入正反应性,破裂位置离堆芯中心越近,引入的反应性越大;对于石墨构件移动,随着扇形石墨构件向外移动,堆芯反应性增加;对于堆芯石墨破损,破损发生后,原燃料盐流道被石墨堵住时,则堆芯反应性减小;对于堆芯石墨破损,破损发生后,新燃料盐流道形成时,当石墨破损半径较小时,堆芯反应性会增加,当石墨破损半径较大时,堆芯反应性会减小。对于堆芯石墨发生燃料盐浸渗,堆芯反应性增加,且燃料盐渗入量越大,反应性变化越大。本研究为2 MW TMSR-LF1安全分析提供参考依据。展开更多
熔盐堆(Molten Salt Reactor,MSR)采用熔融的氟化盐混合物作为燃料,由于核燃料的特殊性,MSR在中子物理学方面与传统固体燃料反应堆有着较大区别。本文基于蒙特卡罗程序MCNP(Monte Carlo N Particle Transport Code),以美国橡树岭国家实...熔盐堆(Molten Salt Reactor,MSR)采用熔融的氟化盐混合物作为燃料,由于核燃料的特殊性,MSR在中子物理学方面与传统固体燃料反应堆有着较大区别。本文基于蒙特卡罗程序MCNP(Monte Carlo N Particle Transport Code),以美国橡树岭国家实验室(Oak Ridge National Laboratory,ORNL)熔盐堆实验(Molten-Salt Reactor Experiment,MSRE)为参考反应堆,系统研究了堆芯尺寸、燃料盐体积比、燃料盐重金属摩尔比、燃料盐渗透等物理参数对堆芯物理特性参数的影响。结果表明:随着堆芯尺寸增加,堆芯临界装载量有最小值;随着燃料盐体积比增加,燃料盐回路系统中重金属临界装载量先减少后增加,燃料温度系数的绝对值同样先减小后增加;燃料盐浸渗对堆芯反应性的影响,与燃料盐体积比增加对堆芯反应性产生的影响一致。本研究为2 MW液态燃料钍基熔盐堆(Thorium Molten Salt Reactor-Liquid Fuel,TMSR-LF1)设计提供理论参考。展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos. 41002060, 41272274)the Foundation of Youth Innovation Promotion Association of Chinese Academy of Sciences (Grant to QS Fan)
文摘Previous studies have investigated the boron isotopic composition of salt lake brines in the Qaidam Basin,western China.However,the research on boron isotopic composition of halite is very limited due to halite’s low
基金the Key International Cooperation Project of Ministry of Science and Technology of China,No.2001CB711003the National Natural Science Foundation of China,No.40305007the Science and Technology Innovation Project of Northwest Normal University,No.NWNU-KJCXGC-02-20.
文摘A 51.85 m firn core drilled in Princess Elizabeth Land, Antarctica, during the 1996-1997 Chinese First Antarctic Inland Expedition, has been measured for δ 18 O and major ions. Based on the high quality data of the seasonal variations of major ions, the firn core was dated with errors within ±3 years. The 51.85 m firn core record extends for 251 years (A. D. 1745-1996). The results of the glaciochemistry data of the firn core show that the mean concentrations of Cl -, Na + and Mg 2+ are similar to those reported from other coastal areas in East Antarctica. However, mean concentrations of Ca 2+ are much higher than those reported from other regions, this anomaly phenomenon may be related to the strong local terrestrial sources. It is found that the variations of three kinds of sea salt ions (Cl -, Na + and Mg 2+ ) in the past 150 years show very similarly rising trends, which may be the results the Southern Hemisphere warming in the past century.
基金supported by the ‘‘Strategic Priority Research Program’’ of the Chinese Academy of Sciences(No.XDA02010200)the Frontier Science Key Program of Chinese Academy of Sciences(No.QYZDY-SSW-JSC016)
文摘Fast reactors based on thorium fuel have enhanced inherent safety. Fluoride salt performs well as a coolant in high-temperature nuclear systems. In this paper,we present a reference core for a large fluoride-salt-cooled solid-fuel fast reactor(LSFR) using thorium–uranium fuel cycle. Neutronics physics of the LSFR reference core is investigated with 2D and 3D in-core fuel management strategy. The design parameters analyzed include the fuel volume fraction, power density level and continuous removal of fission products with 3D fuel shuffling that obtains better equilibrium core performance than 2D shuffling. A self-sustained core is achieved for all cases,and the core of 60% fuel volume fraction at 50 MW/m^3 power density is of the best breeding performance(average breeding ratio 1.134). The LSFR core based on thorium fuel is advantageous in its high discharge burn-up of 20–30% fissions per initial heavy metal atom, small reactivity swing over the whole lifetime(to simplify the reactivity control system), the negative reactivity temperature coefficient(intrinsically safe for all cases) and accepted cladding peak radiation damage. The LSFR reactor is a good alternative option for the deployment of a self-sustained thorium-based nuclear system.
文摘When treated in pressure die casting processes the semi-solid aluminum alloys demand resilient cores which can bear the stress occurring during filling and the final pressure phase.The design of permanent cores is highly restricted in order to maintain removability.Lost cores provide the possibility of complex,undercut geometrical shapes which is mandatory for a variety of casting components.However,eligible materials which show appropriate resilience and proper decomposition properties at the same time,and in the upper echelon of cost-effectiveness,are seldom known.With the semi-solid process suited between HPDC and GDC regarding the core stress,several common and economically efficient lost core systems could be used.A selection of potentially suitable materials was identified and tested.The range of testing comprises widespread sand core-systems(amin-pur-coldbox and CO2-water-glass) as well as materials less commonly used,namely salt,plastic and zinc.Different types of conditioning are applied to enhance the surface properties.The mechanical properties of the sand cores are enhanced by different heat treatment methods during curing.The cores are tested producing a research component cast on a HPDC machine with semi-solid A356 slurry fabricated in the cooling channel process.The cast component was analyzed regarding shape stability,core removability and surface as well as the structure quality.The results show the importance of the surface conditioning for the sand-cores while salt and zinc produce good parts comparable to the reference steel core quality.
文摘熔盐堆采用液态燃料,由于燃料的流动性,堆芯结构的变化会直接影响堆芯活性区的燃料盐装载量,从而影响堆芯物理特性参数。本文基于蒙特卡罗程序MCNP(Monte Carlo N Particle Transport Code),以2 MW液态燃料钍基熔盐堆(Thorium Molten Salt Reactor-Liquid Fuel,TMSR-LF1)设计模型为参考,系统研究了套管破裂、石墨构件移动、石墨破损、燃料盐浸渗度等因素对堆芯反应性的影响。结果表明:对于堆芯套管破裂,堆芯引入正反应性,破裂位置离堆芯中心越近,引入的反应性越大;对于石墨构件移动,随着扇形石墨构件向外移动,堆芯反应性增加;对于堆芯石墨破损,破损发生后,原燃料盐流道被石墨堵住时,则堆芯反应性减小;对于堆芯石墨破损,破损发生后,新燃料盐流道形成时,当石墨破损半径较小时,堆芯反应性会增加,当石墨破损半径较大时,堆芯反应性会减小。对于堆芯石墨发生燃料盐浸渗,堆芯反应性增加,且燃料盐渗入量越大,反应性变化越大。本研究为2 MW TMSR-LF1安全分析提供参考依据。
文摘熔盐堆(Molten Salt Reactor,MSR)采用熔融的氟化盐混合物作为燃料,由于核燃料的特殊性,MSR在中子物理学方面与传统固体燃料反应堆有着较大区别。本文基于蒙特卡罗程序MCNP(Monte Carlo N Particle Transport Code),以美国橡树岭国家实验室(Oak Ridge National Laboratory,ORNL)熔盐堆实验(Molten-Salt Reactor Experiment,MSRE)为参考反应堆,系统研究了堆芯尺寸、燃料盐体积比、燃料盐重金属摩尔比、燃料盐渗透等物理参数对堆芯物理特性参数的影响。结果表明:随着堆芯尺寸增加,堆芯临界装载量有最小值;随着燃料盐体积比增加,燃料盐回路系统中重金属临界装载量先减少后增加,燃料温度系数的绝对值同样先减小后增加;燃料盐浸渗对堆芯反应性的影响,与燃料盐体积比增加对堆芯反应性产生的影响一致。本研究为2 MW液态燃料钍基熔盐堆(Thorium Molten Salt Reactor-Liquid Fuel,TMSR-LF1)设计提供理论参考。
