Abstract Pursuant to European Directive 2013/59, materials additioned with NORM waste must be characterised radiologically to determine their acceptability for use in construction. The radionuclides studied to judge that acceptability, 232Th, 226Ra and 40K, are normally measured with gamma spectrometry. Gamma detectors are calibrated by using standards as similar as possible in dimensions and chemical composition as the matrix in the samples to be measured. In light of the broad spectrum of chemical and physical characteristics of NORM samples, experimental calibration is often beyond the means of gamma spectrometry laboratories. As a result, Monte Carlo-based methods are deployed to simulate the experimental setup consisting in detector and sample, both geometrically and chemically. Canberra Industries’ LabSOCS (Laboratory Sourceless Calibration Software) is one of the tools available for such calculations. This study verified the accuracy and precision of the counting efficiency delivered by LabSOCS, both with the standard powder geometry and a new geometry consisting in a 5 cm cubic specimen of Portland cement paste. The findings showed that in both geometries the accuracy and precision of LabSOCS-calculated efficiency (by specimen height and activity), across an energy range from 45.64 keV (210Pb) to 1460.82 keV (40K) met the acceptability criteria routinely applied in environmental radioactivity laboratories. The geometry proposed yielded activity values for the end construction material closer to the true indices than the conventional method consisting in summing the partial activities of the unreacted components.

中文翻译：

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伽马光谱法和 LabSOCS 计算的硬化硅酸盐水泥浆四边形和立方体试样的放射学表征效率

摘要 根据欧洲指令 2013/59，添加 NORM 废物的材料必须进行放射学表征，以确定其在建筑中使用的可接受性。为判断可接受性而研究的放射性核素 232Th、226Ra 和 40K，通常用伽马能谱法测量。伽马探测器通过使用尺寸和化学成分与待测样品中的基质尽可能相似的标准进行校准。鉴于 NORM 样品具有广泛的化学和物理特性，实验校准通常超出了伽马光谱实验室的手段。因此，部署了基于蒙特卡罗的方法来模拟由检测器和样品组成的实验装置，无论是几何上还是化学上。Canberra Industries 的 LabSOCS（实验室无源校准软件）是可用于此类计算的工具之一。这项研究验证了 LabSOCS 提供的计数效率的准确性和精确性，包括标准粉末几何形状和由 5 厘米立方波特兰水泥浆样品组成的新几何形状。研究结果表明，在两种几何形状中，LabSOCS 计算的效率（按样品高度和活性）的准确性和精度在 45.64 keV (210Pb) 到 1460.82 keV (40K) 的能量范围内满足环境放射性实验室常规应用的可接受标准. 所提出的几何形状产生的最终建筑材料的活性值比传统方法更接近真实指数，传统方法包括对未反应组分的部分活性求和。