In various monitoring and detection tools that use pulsed neutron generators as radiation sources,the gamma rays induced by the interaction with various nuclei at different stages of neutron transport can reflect info...In various monitoring and detection tools that use pulsed neutron generators as radiation sources,the gamma rays induced by the interaction with various nuclei at different stages of neutron transport can reflect information about the medium.These gamma rays are generated in two major interactions:inelastic scattering of fast neutrons and radiative capture of thermal neutrons,corresponding to the inelastic and capture gamma rays,respectively.However,the two types of gamma rays that reflect different properties of the medium are difficult to collect by normal detectors independently.The proportion of the two gamma rays needs to be solved for the separation of inelastic and capture gamma.Therefore,this study proposes an optimized spectra decomposition method to calculate the inelastic-to-capture ratio in the measured total gamma spectra based on the net inelastic and capture spectra obtained using the Geant4 simulation.Because the simulated data cannot reflect the energy resolution of the measured spectra,we introduce the Gaussian broadening function of the gamma detector while calculating the proportion of the spectra components,and achieve optimization of the proportion values and resolution parameters simultaneously.Based on the results,the total simulated spectra obtained by superimposing the broadened net inelastic and capture gamma spectra according to the calculated inelastic-to-capture ratio are in good agreement with their measured counterpart.展开更多
The Chinese Academy of Science has launched a thorium-based molten-salt reactor(TMSR)research project with a mission to research and develop a fission energy system of the fourth generation.The TMSR project intends to...The Chinese Academy of Science has launched a thorium-based molten-salt reactor(TMSR)research project with a mission to research and develop a fission energy system of the fourth generation.The TMSR project intends to construct a liquid fuel molten-salt reactor(TMSR-LF),which uses fluoride salt as both the fuel and coolant,and a solid fuel molten-salt reactor(TMSR-SF),which uses fluoride salt as coolant and TRISO fuel.An optimized 2 MWth TMSR-LF has been designed to solve major technological challenges in the Th-U fuel cycle.Preliminary conceptual shielding design has also been performed to develop bulk shielding.In this study,the radiation dose and temperature distribution of the shielding bulk due to the core were simulated and analyzed by performing Monte Carlo simulations and computational fluid dynamics(CFD)analysis.The MCNP calculated dose rate and neutron and gamma spectra indicate that the total dose rate due to the core at the external surface of the concrete wall was 1.91μSv/h in the radial direction,1.16μSv/h above and 1.33μSv/h below the bulk shielding.All the radiation dose rates due to the core were below the design criteria.Thermal analysis results show that the temperature at the outermost surface of the bulk shielding was 333.86 K,which was below the required limit value.The results indicate that the designed bulk shielding satisfies the radiation shielding requirements for the 2 MWth TMSR-LF.展开更多
在工业、环境和科学研究领域,元素分析的需求越来越大,而元素标准谱的准确性直接影响元素分析的准确性。本文研究了瞬发伽马中子活化分析(prompt gamma-ray neutron activation analysis,PGNAA)技术元素标准谱的构建,通过开发标准谱生成...在工业、环境和科学研究领域,元素分析的需求越来越大,而元素标准谱的准确性直接影响元素分析的准确性。本文研究了瞬发伽马中子活化分析(prompt gamma-ray neutron activation analysis,PGNAA)技术元素标准谱的构建,通过开发标准谱生成器(East China University of Technology Prompt Gamma-ray,ECUTPG),用于生成中子活化分析应用的标准谱。本文验证了LaBr3探测器与中子发生器一体机在元素分析载荷应用中,元素标准谱库的建立和实际效果,并通过解谱方法显示该元素标准谱库的可行性与准确性。展开更多
基金supported by the China Natural Science Fund(No.52171253)the Natural Science Foundation of Sichuan(No.2022NSFSC0949).
文摘In various monitoring and detection tools that use pulsed neutron generators as radiation sources,the gamma rays induced by the interaction with various nuclei at different stages of neutron transport can reflect information about the medium.These gamma rays are generated in two major interactions:inelastic scattering of fast neutrons and radiative capture of thermal neutrons,corresponding to the inelastic and capture gamma rays,respectively.However,the two types of gamma rays that reflect different properties of the medium are difficult to collect by normal detectors independently.The proportion of the two gamma rays needs to be solved for the separation of inelastic and capture gamma.Therefore,this study proposes an optimized spectra decomposition method to calculate the inelastic-to-capture ratio in the measured total gamma spectra based on the net inelastic and capture spectra obtained using the Geant4 simulation.Because the simulated data cannot reflect the energy resolution of the measured spectra,we introduce the Gaussian broadening function of the gamma detector while calculating the proportion of the spectra components,and achieve optimization of the proportion values and resolution parameters simultaneously.Based on the results,the total simulated spectra obtained by superimposing the broadened net inelastic and capture gamma spectra according to the calculated inelastic-to-capture ratio are in good agreement with their measured counterpart.
基金Supported by the"Strategic Priority Research Program"of the Chinese Academy of Sciences(No.XD02005002)
文摘The Chinese Academy of Science has launched a thorium-based molten-salt reactor(TMSR)research project with a mission to research and develop a fission energy system of the fourth generation.The TMSR project intends to construct a liquid fuel molten-salt reactor(TMSR-LF),which uses fluoride salt as both the fuel and coolant,and a solid fuel molten-salt reactor(TMSR-SF),which uses fluoride salt as coolant and TRISO fuel.An optimized 2 MWth TMSR-LF has been designed to solve major technological challenges in the Th-U fuel cycle.Preliminary conceptual shielding design has also been performed to develop bulk shielding.In this study,the radiation dose and temperature distribution of the shielding bulk due to the core were simulated and analyzed by performing Monte Carlo simulations and computational fluid dynamics(CFD)analysis.The MCNP calculated dose rate and neutron and gamma spectra indicate that the total dose rate due to the core at the external surface of the concrete wall was 1.91μSv/h in the radial direction,1.16μSv/h above and 1.33μSv/h below the bulk shielding.All the radiation dose rates due to the core were below the design criteria.Thermal analysis results show that the temperature at the outermost surface of the bulk shielding was 333.86 K,which was below the required limit value.The results indicate that the designed bulk shielding satisfies the radiation shielding requirements for the 2 MWth TMSR-LF.
文摘在工业、环境和科学研究领域,元素分析的需求越来越大,而元素标准谱的准确性直接影响元素分析的准确性。本文研究了瞬发伽马中子活化分析(prompt gamma-ray neutron activation analysis,PGNAA)技术元素标准谱的构建,通过开发标准谱生成器(East China University of Technology Prompt Gamma-ray,ECUTPG),用于生成中子活化分析应用的标准谱。本文验证了LaBr3探测器与中子发生器一体机在元素分析载荷应用中,元素标准谱库的建立和实际效果,并通过解谱方法显示该元素标准谱库的可行性与准确性。
