Cope S Joseph, Hayes Robert B
J Radiol Prot. 2019 Sep;39(3):749-765. doi: 10.1088/1361-6498/ab1bfd. Epub 2019 Apr 24.
In air filter assay for radiological emergency response, radon (Rn) and thoron (Rn) progeny are known interferents to transuranic activity estimation. Previous work detailed a conservative, graded approach for TRU alpha activity estimation from air samples void of transuranic activity yet containing varying amounts of radon and thoron progeny. Validation of this method to produce rapid, conservative and defensible transuranic alpha activity estimates was accomplished through introduction of surrogate transuranic activity, Pu and Th check sources, along with the naturally occurring radioactive progeny from an environmental air filter. Following air collection, the filter was centre hole-punched with the transuranic check source placed underneath the filter during counting. With the surrogate transuranic activity introduced into the measurement, verification of the previously studied methodology for rapid transuranic activity estimation was determined with quantifiable conservative bias. 70 environmental filters with various levels of radon progeny and air sampling duration were collected; 35 examined with the Pu check source and 35 studied with the Th check source. To characterise the expected transuranic activity introduced to the counting experiment without the environmental interferents of radon and thoron progeny, 30 blank filters were counted using the described experimental setup with each of the respective surrogate sources. Following characterisation of the sources with blank filters, transuranic activity estimation comparison against the 70 environmental filters with natural background radioactive progeny interferents was accomplished. This work contributes to the comprehensive analysis of operational air samples by detailing validation results for a rapid and conservative transuranic alpha activity estimation methodology.
在用于放射应急响应的空气过滤器检测中，氡（Rn）和钍射气（Tn）子体是超铀元素活度估算的已知干扰物。先前的工作详细介绍了一种保守的分级方法，用于从不含超铀元素活度但含有不同量氡和钍射气子体的空气样本中估算超铀α活度。通过引入替代超铀元素活度、钚和钍检查源以及环境空气过滤器中的天然放射性子体，完成了对该方法产生快速、保守且可靠的超铀α活度估算的验证。空气采集后，在计数期间，将过滤器中心打孔，并将超铀元素检查源置于过滤器下方。随着替代超铀元素活度引入测量，通过可量化的保守偏差确定了先前研究的快速超铀元素活度估算方法的验证情况。收集了70个具有不同水平氡子体和空气采样持续时间的环境过滤器；其中35个用钚检查源进行检测，35个用钍检查源进行研究。为了表征在没有氡和钍射气子体的环境干扰情况下引入计数实验的预期超铀元素活度，使用所述实验装置对30个空白过滤器与各自的替代源进行计数。在用空白过滤器对源进行表征之后，完成了与70个具有天然本底放射性子体干扰的环境过滤器的超铀元素活度估算比较。这项工作通过详细说明快速且保守的超铀α活度估算方法的验证结果，有助于对运行空气样本进行全面分析。
