基于蒙特卡罗光线踪迹法研究了半透明多壳层球形粒子的辐射性质,并通过BHCOAT程序验证其精度。对比光线踪迹法,分析了有效介质理论(effective medium theory,EMT)的应用范围,并用光线踪迹法计算了多层球形粒子内光谱吸收分布。研究结果...基于蒙特卡罗光线踪迹法研究了半透明多壳层球形粒子的辐射性质,并通过BHCOAT程序验证其精度。对比光线踪迹法,分析了有效介质理论(effective medium theory,EMT)的应用范围,并用光线踪迹法计算了多层球形粒子内光谱吸收分布。研究结果表明,蒙特卡罗光线踪迹法适合于计算粒子尺度参数x>30的多层球形粒子辐射吸收。层间折射率和消光系数偏差较小时,有效介质理论结合Mie理论可用来近似估算多层粒子的辐射特性。当层间光学常数偏差较大时,特别是对于精度要求较高的情况,EMT-Mie理论不再适用。层间光学常数不同导致光谱辐射吸收分布显著不均匀。展开更多
The pipe holdup measurement is very important for decommissioning nuclear facilities and nu- clear-material control and accounting. The absolute detection efficiencies (εsp) of full-energy γ rays peak under dif- fer...The pipe holdup measurement is very important for decommissioning nuclear facilities and nu- clear-material control and accounting. The absolute detection efficiencies (εsp) of full-energy γ rays peak under dif- ferent source density distribution function have been simulated using the Monte Carlo (MC) software, and the counting rates (n0) of the characteristic γ rays have been measured using the γ spectrometer followed by the calculation of the holdup. The holdup is affected by the energy of γ rays, distance at which they are detected, pipe material, thickness, and source distribution of pipe, especially source distribution at a short distance. The comparative test of 235U refer- ence materials on the inner wall of Fe and Al pipes (the total mass of 235U is 44.6 mg and 222.8 mg, respectively) have been accomplished using this method. The determined result of 235U is 43.2 mg (U0.95rel = 5.4%) and 216.2 mg (U0.95rel = 3.2%), respectively, which are in accordance with the reference values.展开更多
文摘基于蒙特卡罗光线踪迹法研究了半透明多壳层球形粒子的辐射性质,并通过BHCOAT程序验证其精度。对比光线踪迹法,分析了有效介质理论(effective medium theory,EMT)的应用范围,并用光线踪迹法计算了多层球形粒子内光谱吸收分布。研究结果表明,蒙特卡罗光线踪迹法适合于计算粒子尺度参数x>30的多层球形粒子辐射吸收。层间折射率和消光系数偏差较小时,有效介质理论结合Mie理论可用来近似估算多层粒子的辐射特性。当层间光学常数偏差较大时,特别是对于精度要求较高的情况,EMT-Mie理论不再适用。层间光学常数不同导致光谱辐射吸收分布显著不均匀。
文摘The pipe holdup measurement is very important for decommissioning nuclear facilities and nu- clear-material control and accounting. The absolute detection efficiencies (εsp) of full-energy γ rays peak under dif- ferent source density distribution function have been simulated using the Monte Carlo (MC) software, and the counting rates (n0) of the characteristic γ rays have been measured using the γ spectrometer followed by the calculation of the holdup. The holdup is affected by the energy of γ rays, distance at which they are detected, pipe material, thickness, and source distribution of pipe, especially source distribution at a short distance. The comparative test of 235U refer- ence materials on the inner wall of Fe and Al pipes (the total mass of 235U is 44.6 mg and 222.8 mg, respectively) have been accomplished using this method. The determined result of 235U is 43.2 mg (U0.95rel = 5.4%) and 216.2 mg (U0.95rel = 3.2%), respectively, which are in accordance with the reference values.
