低本底实验室γ谱仪探测限研究
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摘要
使用一台高纯锗γ谱仪在一般实验室和低本底实验室铁室中对高纯锗γ谱仪铅室本底计数率水平和3种不同介质样品γ核素进行测量分析,研究低本底实验室铁室中高纯锗γ谱仪铅室本底计数率水平的优化程度,分析测量气溶胶、生物灰、河水样品中 ~(137)Cs、~(134)Cs两种核素的探测限值,研究探测限值与测量时间的变化趋势,以及对于测量时间的优化程度。结果表明,低本底实验室铁室测量高纯锗铅室本底计数率水平比一般实验室降低了25. 6%。按不同时间测量的探测限值拟合曲线表明 ~(137)Cs、~(134)Cs两种核素的探测限值均随时间的增加而下降。不同介质样品测量中,核素 ~(137)Cs探测限值优化百分比范围为28. 81%～29. 63%,核素~(134)Cs探测限值优化百分比范围为21. 44%～25. 12%。核素 ~(137)Cs的探测限优化百分比均大于核素~(134)Cs,核素 ~(137)Cs的探测限优化程度比~(134)Cs的探测限优化程度大。在应急情况下,可结合低本底实验室铁室的测量分析结果,选择与可探测到的最低活度相对应的最优测量活时间,提高应急监测能力。
A high-purity Ge gamma spectrometer was used to measure the background level of its lead chambers and the gamma nuclides of three different media samples in general laboratory and low-background laboratory iron chambers,to study the optimization of the background level of the high-purity Ge lead chamber in low-background laboratory iron chambers. To measure the minimum detectable concentration( MDC) of ~(137)Cs and ~(134)Cs in the samples of the aerosol,bio-ash and river water,and study the change trend of the MDC and the measurement time,and the degree of optimization of the measurement time. The results showed that the background level of the high-purity Ge lead chamber in the low-background laboratory iron chamber reduced 25. 6% compared with the general laboratory. The fitting curve of the MDC at different times indicated that the MDC of the two nuclides of ~(137)Cs and ~(134)Cs decrease with time. In the measurement of different medium samples,the optimum percentages of the MDC of nuclide ~(137)Cs ranged from 28. 81% to 29. 63%,and the optimum percentages of the MDC of nuclide ~(134)Cs ranged from 21. 44% to 25. 12%. The MDC and the optimization percentage of the radionuclide ~(137)Cs were both greater than that of the radionuclide ~(134)Cs. In the case of emergency,we can combine with the measurement and analysis results of the low-background laboratory iron chamber,to select the optimal measurement live time corresponding to the detectable minimum activity and to improve the emergency monitoring capability.
A high-purity Ge gamma spectrometer was used to measure the background level of its lead chambers and the gamma nuclides of three different media samples in general laboratory and low-background laboratory iron chambers,to study the optimization of the background level of the high-purity Ge lead chamber in low-background laboratory iron chambers. To measure the minimum detectable concentration( MDC) of ~(137)Cs and ~(134)Cs in the samples of the aerosol,bio-ash and river water,and study the change trend of the MDC and the measurement time,and the degree of optimization of the measurement time. The results showed that the background level of the high-purity Ge lead chamber in the low-background laboratory iron chamber reduced 25. 6% compared with the general laboratory. The fitting curve of the MDC at different times indicated that the MDC of the two nuclides of ~(137)Cs and ~(134)Cs decrease with time. In the measurement of different medium samples,the optimum percentages of the MDC of nuclide ~(137)Cs ranged from 28. 81% to 29. 63%,and the optimum percentages of the MDC of nuclide ~(134)Cs ranged from 21. 44% to 25. 12%. The MDC and the optimization percentage of the radionuclide ~(137)Cs were both greater than that of the radionuclide ~(134)Cs. In the case of emergency,we can combine with the measurement and analysis results of the low-background laboratory iron chamber,to select the optimal measurement live time corresponding to the detectable minimum activity and to improve the emergency monitoring capability.
引文
[1]黄乃明,莫光华. HPGeγ能谱仪测量中探测限的计算.全国放射性流出物和环境监测与评价研讨会论文汇编[C].
[2] HJ/T 61-2001,辐射环境监测技术规范[S].
[3] GB/T 11713-2015,高纯锗γ能谱分析通用方法[S].
[4] GB/T 184-1999,气溶胶中放射性核素的γ能谱分析方法[S].
[5] GB/T 16145-1995,生物样品中放射性核素的γ能谱分析方法[S].
[6] GB/T 16140-1995,水中放射性核素的γ能谱分析方法[S].
[7]姚帅墨,张庆,周强,等.食品和饮用水放射性监测时测量时间探测限关系初步研究[J].中国辐射卫生,2016,25(2):150-153.
[8]拓飞,张京,李文红,等.食品放射性测量中马林杯干样与圆柱盒灰样探测限比较研究[J].中国医学装备,2014,11(11):1-3.
[2] HJ/T 61-2001,辐射环境监测技术规范[S].
[3] GB/T 11713-2015,高纯锗γ能谱分析通用方法[S].
[4] GB/T 184-1999,气溶胶中放射性核素的γ能谱分析方法[S].
[5] GB/T 16145-1995,生物样品中放射性核素的γ能谱分析方法[S].
[6] GB/T 16140-1995,水中放射性核素的γ能谱分析方法[S].
[7]姚帅墨,张庆,周强,等.食品和饮用水放射性监测时测量时间探测限关系初步研究[J].中国辐射卫生,2016,25(2):150-153.
[8]拓飞,张京,李文红,等.食品放射性测量中马林杯干样与圆柱盒灰样探测限比较研究[J].中国医学装备,2014,11(11):1-3.