某氯化稀土γ能谱测量结果分析

Analysis of measurement results of γ energy spectrum of a rare earth chloride

目的分析某氯化稀土测量结果,进一步认识放射性不平衡样品的测量分析。方法依据《土壤中放射性核素的γ能谱分析方法》(GB/T 11743—2013)对某氯化稀土样品进行测量。结果2019.4.26、2019.5.31和2021.1.13某氯化稀土样品中^(228)Ac活度浓度测量结果分别为3.5×10^(4)、3.5×10^(4)和2.9×10^(4) Bq·kg^(-1),^(208)Tl活度浓度分别为2.05×10^(3)、2.43×10^(3)和6.5×10^(3) Bq·kg^(-1);^(227)Th活度浓度分别为7.2×10^(2)、7.7×10^(2)和7.1×10^(2) Bq·kg^(-1);^(234m)Pa活度浓度分别为8.5×10^(2)、7.3×10^(2)和4.4×10^(2) Bq·kg^(-1),^(214)Pb活度浓度分别为5.5×10^(3)、5.4×10^(3)和5.6×10^(3) Bq·kg^(-1),^(214)Bi活度浓度分别为6.1×10^(3)、6.0×10^(3)和6.2×10^(3) Bq·kg^(-1);^(138)La(788.742keV)活度浓度分别为3.3×10^(1)、2.7×10^(1)和2.2×10^(1) Bq·kg^(-1),^(138)La(1435.795keV)活度浓度分别为5.2×10^(1)、5.2×10^(1)和5.6×10^(1) Bq·kg^(-1)。结论氯化稀土样品钍系、铀系放射性平衡已破坏;锕-铀系^(227)Ac活度在产品制备完成140 d后测量;达到部分放射性平衡时,选择^(234m)Pa的1001.441keV特征γ射线全能峰分析母体^(238)U活度更为合理;^(138)La活度测量应选择1435.795 keV特征γ射线全能峰。

Objective The measurement results of a rare earth chloride were analyzed to further understand the measurement and analysis of radioactive non-equilibrium samples.Methods The rare earth chloride samples were measured according to China recommendatory national standard of determination of radionuclides in soil by gamma spectrometry(GB/T11743—2013).Results The rare earth samples were measured three times on April 26,2019,May 31,2019,and January13,2021,respectively.The activity concentrations of ^(228)Ac in the sample were 3.5×10^(4),3.5×10^(4) and2.9×10^(4) Bq·kg^(-1),respectively.The activity concentrations of ^(208)Tl in the sample were 2.05×10^(3),2.43×10^(3) and6.5×10^(3) Bq·kg^(-1),respectively.The activity concentrations of ^(227)Th in the sample were 7.2×10^(2),7.7×10^(2) and7.1×10^(2) Bq·kg^(-1),respectively.The activity concentrations of ^(234m)Pa in the sample were 8.5×10^(2),7.3×10^(2) and4.4×10^(2) Bq·kg^(-1),respectively.The activity concentrations of ^(214)Pb in the sample were 5.5×10^(3),5.4×10^(3) and5.6×10^(3) Bq·kg^(-1),respectively.The activity concentrations of ^(214)Bi in the sample were 6.1×10^(3),6.0×10^(3) and 6.2×10^(3) Bq·kg^(-1),respectively.The activity concentrations of ^(138)La at 788.742 keV in the sample were 3.3×10^(1),2.7×10^(1) and 2.2×10^(1) Bq·kg^(-1),respectively.The activity concentrations of ^(138)La at 1435.795 keV in the sample were 5.2×10^(1),5.2×10^(1) and 5.6×10^(1) Bq·kg^(-1),respectively.Conclusion The radioactive equilibrium of thorium family and uranium family in the rare earth chloride samples was destroyed.The activity of ^(227)Ac in actinuium-uranium family should be measured 140 days after the completion of the product preparation.When partial radioactivity equilibrium is reached,it is more reliable to choose theγ-ray characteristics peak(1001.441 keV)of ^(234m)Pa to determine the activity of the parent ^(238)U.For the activity measurement of ^(138)La,theγ-ray characteristics peak at 1435.795 keV should be selected.