主动中子多重性法估算铀材料质量的不确定性(英文)
Uncertainty of Uranium Mass Measurement by Active Neutron Multiplicity
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摘要: 近年来，国际社会对核材料保护、控制和衡算日益加强。对不明材料损失量(MUF) 的关注逐渐提升。铀材料质量不确定性测量在估算铀材料生产量中扮演重要角色。由于铀材料自发裂变相对较弱，主动中子多重性法被应用于估算铀材料质量。通过拟合对不同系列铀金属壳的数值模拟结果，获得了描述铀材料质量与主动中子多重性特征之间的算法和参数。得到的关系表明，可以通过分析不同重数中子多重性探测结果获得铀部件的质量。对不同探测条件下的模拟结果的定量分析，确定了探测系统设置对铀质量估算的影响，以及认知不确定性和随机不确定在估算过程中传播对质量估算的影响。对不确定度的分析获得了本文模拟采用的探测系统的最佳源强和探测时间窗设置，在此设置下，质量估算的不确定性最小。Recently, the international society pays more and more attention to nuclear material protection,control and accounting. The focus on the material unaccounted for (MUF) is enhanced. The uncertainty assessment of uranium mass measurement plays an essential role in estimating the production of uranium. Due to the relatively weak radioactivity of uranium, the active neutron multiplicity counting (ANMC) method is usually applied to assess the mass of uranium material. In this paper, the relations and parameters between the masses of the uranium objects and the features of the ANMCs are formulated by fitting the simulated results of different sets of uranium shells. The result indicates that,each mass of the objects could be obtained by analyzing the ANMCs of different orders. In order to study the effects of the detection system settings on the mass estimation, the propagation of the aleatoric and epistemic uncertainty of the method is quantitatively studied by the simulations with different detection onditions. The optimized settings of source intensity and detection coincidence gate width, which result in the minimal uncertainty of the mass estimation, are obtained for the simulated detection system.Abstract: Recently, the international society pays more and more attention to nuclear material protection,control and accounting. The focus on the material unaccounted for (MUF) is enhanced. The uncertainty assessment of uranium mass measurement plays an essential role in estimating the production of uranium. Due to the relatively weak radioactivity of uranium, the active neutron multiplicity counting (ANMC) method is usually applied to assess the mass of uranium material. In this paper, the relations and parameters between the masses of the uranium objects and the features of the ANMCs are formulated by fitting the simulated results of different sets of uranium shells. The result indicates that,each mass of the objects could be obtained by analyzing the ANMCs of different orders. In order to study the effects of the detection system settings on the mass estimation, the propagation of the aleatoric and epistemic uncertainty of the method is quantitatively studied by the simulations with different detection onditions. The optimized settings of source intensity and detection coincidence gate width, which result in the minimal uncertainty of the mass estimation, are obtained for the simulated detection system.
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