为了使用简易的方法获取可靠的单元素伽马能谱,本文针对元素俘获能谱测井仪器单元素中子伽马能谱的获取进行了仿真模拟计算,包括中子源的选择、地层模型的设计以及探测器的布置。采用Monte Carlo方法中具有代表性的MCNP(Monte Carlo N-P...为了使用简易的方法获取可靠的单元素伽马能谱,本文针对元素俘获能谱测井仪器单元素中子伽马能谱的获取进行了仿真模拟计算,包括中子源的选择、地层模型的设计以及探测器的布置。采用Monte Carlo方法中具有代表性的MCNP(Monte Carlo N-Particle Transport Code System)程序模拟了Am-Be中子源产生的中子经过慢化后与地层元素发生热中子俘获反应的中子和光子的输运过程,记录了元素的特征γ射线和伽马能谱,获得的了十种元素的中子俘获伽马能谱。经过对比分析,模拟计算结果与斯伦贝谢公司公布的单元素标准γ能谱在特征峰位位置及谱形变化方面具有很好的一致性,且主要特征峰位所在的位置与国际原子能机构核数据中心数据一致,用实际测量谱验证表明了利用该方法获得的中子伽马能谱具有较强的实用性,对于元素俘获能谱测井数据处理的深化研究具有一定的实用价值,同时也为其他类型元素测井仪器数据处理提供了重要的借鉴意义。展开更多
It can be difficult to calculate some under-sampled regions in global Monte Carlo radiation transport calculations. The global variance reduction(GVR) method is a useful solution to the problem of variance reduction e...It can be difficult to calculate some under-sampled regions in global Monte Carlo radiation transport calculations. The global variance reduction(GVR) method is a useful solution to the problem of variance reduction everywhere in a phase space. In this research, a GVR procedure was developed and applied to the Chinese Fusion Engineering Testing Reactor(CFETR). A cylindrical CFETR model was utilized for comparing various implementations of the GVR method to find the optimum.It was found that the flux-based GVR method could ensure more reliable statistical results, achieving an efficiency being 7.43 times that of the analog case. A mesh tally of the scalar neutron flux was chosen for the GVR method to simulate global neutron transport in the CFETR model.Particles distributed uniformly in the system were sampled adequately through ten iterations of GVR weight window.All voxels were scored, and the average relative error was 2.4% in the ultimate step of the GVR iteration.展开更多
The distribution characteristics of the neutron field in cement was simulated using the MCNP code to comply with the requirements of an online Prompt Gamma Neutron Activation Analysis system.Simulation results showed ...The distribution characteristics of the neutron field in cement was simulated using the MCNP code to comply with the requirements of an online Prompt Gamma Neutron Activation Analysis system.Simulation results showed that the neutron relative flux proportion reduced with increasing cement thickness.When the cement thickness remains unchanged,the reduced proportion of thermal neutrons increases to a small extent,but the epithermal, intermediate,and fast neutrons will decrease according to the geometric progression.H element in the cement mainly affects the reduction of fast neutrons and other single-substance elements,e.g.,O,Ca,56Fe,Si,and Al.It also slows down the reduction of the fast neutrons via inelastic scattering.O contributes more than other elements in the reduction of fast neutrons.Changing the H content affects the thermal,epithermal,intermediate,and fast neutrons, while changing the Ca,Fe,and Si contents only influences the thermal,epithermal,and intermediate neutrons;hence, there is little effect on the reduction of fast neutrons.展开更多
A compensated neutron logger (CNL) is designed by using Monte-Carlo simulation for lead shield thickness, near-to-far detector spacing range, source-to-detector spacing range, and detector's effective length. The ...A compensated neutron logger (CNL) is designed by using Monte-Carlo simulation for lead shield thickness, near-to-far detector spacing range, source-to-detector spacing range, and detector's effective length. The calculated results indicate that the optimum conditions for CNL are 80-mm thick lead plus 1-cm thick LiOH shield in front of the near detector, 250 mm for the near-to-far detector distance (Δr), and the source-to-detector distance (r) of 90mm. Simultaneously, some conclusion also obtained here, near/far detector counting response ratio (R) increases with the effective length of detector, R increases with the porosity for oil and water sandstones, and the oil sandstone is a bit greater than water sandstone.展开更多
MCNP(Monte Carlo N-Particle Code)是基于Monte-Carlo方法的一个粒子输运计算程序。其输出数据信息量大,难以快速筛选处理有效数据。在分析MCNP输出数据主要内容的基础,设计了MCNP结果数据提取算法,采用VC++与MatlabCOM混合编程技术,...MCNP(Monte Carlo N-Particle Code)是基于Monte-Carlo方法的一个粒子输运计算程序。其输出数据信息量大,难以快速筛选处理有效数据。在分析MCNP输出数据主要内容的基础,设计了MCNP结果数据提取算法,采用VC++与MatlabCOM混合编程技术,实现了一个MCNP输出数据分析与可视化软件。应用结果表明,该软件满足了MCNP使用人员对MCNP输出数据快速分析与可视化的迫切需求。展开更多
基金supported by The National S&T Major Special Project(No.2011ZX05020-008)
文摘为了使用简易的方法获取可靠的单元素伽马能谱,本文针对元素俘获能谱测井仪器单元素中子伽马能谱的获取进行了仿真模拟计算,包括中子源的选择、地层模型的设计以及探测器的布置。采用Monte Carlo方法中具有代表性的MCNP(Monte Carlo N-Particle Transport Code System)程序模拟了Am-Be中子源产生的中子经过慢化后与地层元素发生热中子俘获反应的中子和光子的输运过程,记录了元素的特征γ射线和伽马能谱,获得的了十种元素的中子俘获伽马能谱。经过对比分析,模拟计算结果与斯伦贝谢公司公布的单元素标准γ能谱在特征峰位位置及谱形变化方面具有很好的一致性,且主要特征峰位所在的位置与国际原子能机构核数据中心数据一致,用实际测量谱验证表明了利用该方法获得的中子伽马能谱具有较强的实用性,对于元素俘获能谱测井数据处理的深化研究具有一定的实用价值,同时也为其他类型元素测井仪器数据处理提供了重要的借鉴意义。
基金supported by the National Special Project for Magnetic Confined Nuclear Fusion Energy(Nos.2013GB108004 and2015GB108002)the Chinese National Natural Science Foundation(No.11175207)
文摘It can be difficult to calculate some under-sampled regions in global Monte Carlo radiation transport calculations. The global variance reduction(GVR) method is a useful solution to the problem of variance reduction everywhere in a phase space. In this research, a GVR procedure was developed and applied to the Chinese Fusion Engineering Testing Reactor(CFETR). A cylindrical CFETR model was utilized for comparing various implementations of the GVR method to find the optimum.It was found that the flux-based GVR method could ensure more reliable statistical results, achieving an efficiency being 7.43 times that of the analog case. A mesh tally of the scalar neutron flux was chosen for the GVR method to simulate global neutron transport in the CFETR model.Particles distributed uniformly in the system were sampled adequately through ten iterations of GVR weight window.All voxels were scored, and the average relative error was 2.4% in the ultimate step of the GVR iteration.
基金Supported by National Natural Science Foundation for Distinguished Young Scholar(41025015)NSFC(40974065,11105132)+3 种基金Province Key Technology R&D Program(2011FZ0055)National High Technology Research and Development Program of China(2012AA063501)the Basic Research for Application of Sichuan Province(2012JY0109)China Postdoctoral Science Foundation(2012M520245)
文摘The distribution characteristics of the neutron field in cement was simulated using the MCNP code to comply with the requirements of an online Prompt Gamma Neutron Activation Analysis system.Simulation results showed that the neutron relative flux proportion reduced with increasing cement thickness.When the cement thickness remains unchanged,the reduced proportion of thermal neutrons increases to a small extent,but the epithermal, intermediate,and fast neutrons will decrease according to the geometric progression.H element in the cement mainly affects the reduction of fast neutrons and other single-substance elements,e.g.,O,Ca,56Fe,Si,and Al.It also slows down the reduction of the fast neutrons via inelastic scattering.O contributes more than other elements in the reduction of fast neutrons.Changing the H content affects the thermal,epithermal,intermediate,and fast neutrons, while changing the Ca,Fe,and Si contents only influences the thermal,epithermal,and intermediate neutrons;hence, there is little effect on the reduction of fast neutrons.
基金Partially supported by National Key Technology R&D Program of China(2008BAK47B04)Innovation Method Work(2008IM040500)+1 种基金National Natural Science Foundation of China(40673058)Sichuan province Key Technology R&D Program(2008GZ0040, 2008GZ0197)
文摘A compensated neutron logger (CNL) is designed by using Monte-Carlo simulation for lead shield thickness, near-to-far detector spacing range, source-to-detector spacing range, and detector's effective length. The calculated results indicate that the optimum conditions for CNL are 80-mm thick lead plus 1-cm thick LiOH shield in front of the near detector, 250 mm for the near-to-far detector distance (Δr), and the source-to-detector distance (r) of 90mm. Simultaneously, some conclusion also obtained here, near/far detector counting response ratio (R) increases with the effective length of detector, R increases with the porosity for oil and water sandstones, and the oil sandstone is a bit greater than water sandstone.
文摘MCNP(Monte Carlo N-Particle Code)是基于Monte-Carlo方法的一个粒子输运计算程序。其输出数据信息量大,难以快速筛选处理有效数据。在分析MCNP输出数据主要内容的基础,设计了MCNP结果数据提取算法,采用VC++与MatlabCOM混合编程技术,实现了一个MCNP输出数据分析与可视化软件。应用结果表明,该软件满足了MCNP使用人员对MCNP输出数据快速分析与可视化的迫切需求。
