基于伽马测量区分铀薄层和结块的方法研究

The Method of Differentiating Uranium Thin Layers from Agglomerates Based on Gamma Measurement

  • 摘要: 基于铀薄层与铀结块样品中235U特征γ射线(143、163、186 keV)净计数率比值在铀薄层与结块样品中的差异,建立一种快速甄别铀结块的方法。蒙特卡罗模拟结果表明,随着铀金属厚度增加,K143 keV/186 keVK163 keV/186 keV净计数率比值均呈现递减趋势,其中K143 keV/186 keV比值下降速率显著更快。当铀层厚度超过186 keV γ射线饱和吸收厚度(2 mm)时,定义为铀结块,此时比值趋于稳定(K143 keV/186 keV=0.115,K163 keV/186 keV=0.070);低于该厚度则为铀薄层。实验验证结果表明,铀结块样品的K143 keV/186 keVK163 keV/186 keV净计数率比值的实测值(0.113和0.067)与模拟结果(0.115和0.070)偏差小于5%。该比值差异可用于快速判定铀物料分布形态:若K143 keV/186 keVK163 keV/186 keV比值接近薄层理论值(0.213/0.094),表明分段伽马扫描(SGS)测量结果可靠;若接近结块阈值(0.115/0.070),则需修正自吸收误差或优化测量方案。

     

    Abstract: Based on the differences in the net count rate ratios of characteristic γ-rays (143, 163, 186 keV) of 235U between thin uranium layers and uranium agglomerate samples, a method for rapid discrimination of uranium agglomerates has been established.Monte Carlo simulations reveal that with increasing uranium metal thickness, both K143 keV/186 keV and K163 keV/186 keV net count rate ratios exhibit decreasing trends, with the K143 keV/186 keV ratio demonstrating a significantly faster decline rate. When uranium thickness exceeds the saturation absorption thickness (2 mm) for 186 keV γ-rays, it is defined as uranium agglomeration, where the ratios stabilize (K143 keV/186 keV=0.115, K163 keV/186 keV=0.070). Below this threshold, it is classified as uranium foil. Experimental validation shows that measured ratios in uranium lump samples (0.113 and 0.067) deviate by less than 5% from simulated values (0.115 and 0.070). The study demonstrates that these ratio differences can enable rapid determination of uranium material distribution patterns: if K143 keV/186 keV or K163 keV/186 KeV ratios approach theoretical foil values (0.213/0.094), segmented gamma scanning (SGS) measurements remain reliable;If approaching agglomeration thresholds (0.115/0.070), self-absorption correction or measurement protocol optimization becomes necessary.

     

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