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Gamma exposure from building materials – A dose model with expanded gamma lines from naturally occurring radionuclides applicable in non-standard rooms
Construction and Building Materials ( IF 7.4 ) Pub Date : 2017-11-12 , DOI: 10.1016/j.conbuildmat.2017.10.051
Tom Croymans , Federica Leonardi , Rosabianca Trevisi , Cristina Nuccetelli , Sonja Schreurs , Wouter Schroeyers

Building materials are a significant source of gamma rays exposure due to the presence of naturally occurring radionuclides. In order to protect the public from harmful radiation, the European Basic Safety Standards (Council directive 2013/59/Euratom) (European Council, 2014) introduced a one-size-fits-all building(s) (materials) activity concentration index (ACI) based on a limited set of gamma lines. The ACI is considered “as a conservative screening tool for identifying materials that may cause the reference level (i.e. 1 mSv/y) laid down in article 75(1) to be exceeded. Regarding calculation of dose, many factors such as density and thickness of the building material, as well as factors relating to the type of building, and the gamma emission data need to be taking into account to ensure accurate radiation protection. In this study the implementation of an expanded set of 1845 gamma lines, related to the decay series of 238U, 235U and 232Th as well as to 40K, into the calculation method of Markkanen (1995), is discussed. The expanded calculation method is called the Expanded Gamma Dose Assessment (EGDA) model. The total gamma emission intensity increased from 2.12 to 2.41 and from 2.41 to 3.04 for respectively the 238U and 232Th decay series. In case of 40K a decrease from 0.107 to 0.106 is observed. The 235U decay series is added, having a gamma emission intensity of 3.1. In a standard concrete room, the absorbed dose rates in air (DA) per unit of activity concentration of 0.849, 0.256, 1.08, 0.0767 nGy/h per Bq/kg are observed. The use of weighted average gamma lines increased the DA with 6.5% and 1% for respectively the 238U and 232Th decay series. A decrease of 4.5% is observed in the DA of 235U decay series when using the weighted average gamma lines in comparison to its non-averaged variant. The sensitivity of the EGDA model for density, wall thickness, presence of windows and doors and room size is investigated. Finally, a comparison of the index and dose calculations relevant for the dose assessment within the European legislative framework applicable towards building materials is performed. In cases where the ACI and density and thickness corrected dose calculation of Nuccetelli et al. (2015) cannot provide guidance, the EGDA allows performing more accurate dose assessment calculations leading to effective doses which can be several 100 µSv/y lower.



中文翻译:

建筑材料的伽玛射线暴露–适用于非标准房间的带有自然伽马射线扩展伽玛谱线的剂量模型

由于存在天然存在的放射性核素,建筑材料是伽玛射线暴露的重要来源。为了保护公众免受有害辐射的侵害,欧洲基本安全标准(理事会指令2013/59 / Euratom)(欧洲理事会,2014年)引入了一种“一刀切”的建筑物(材料)活动浓度指数( ACI)基于有限的伽玛线集。ACI被认为是“一种保守的筛选工具,用于识别可能导致超过第75(1)条规定的参考水平(即1 mSv / y)的材料关于剂量的计算,需要考虑许多因素,例如建筑材料的密度和厚度,以及与建筑物类型有关的因素,以及伽马发射数据,以确保准确的辐射防护。在这项研究中,讨论了将一组扩展的1845伽玛线(与238 U,235 U和232 Th以及40 K的衰减序列有关)的实现方法引入Markkanen(1995)的计算方法。扩展的计算方法称为扩展伽马剂量评估(EGDA)模型。238 U和232的总伽马发射强度分别从2.12增加到2.41和从2.41增加到3.04Th衰变系列。在40 K的情况下,观察到从0.107下降到0.106。在235 ü衰变系中添加,其具有3.1的伽马发射强度。在一个标准的混凝土房间中,每单位活动浓度每单位Bq / kg的空气中吸收的剂量率(D A)为0.849、0.256、1.08、0.0767 nGy / h。对于238 U和232 Th衰减序列,加权平均伽玛线的使用将D A分别提高了6.5%和1%。的4.5%的降低在d观察到235与非平均变量相比,使用加权平均伽玛线时的U衰减序列。研究了EGDA模型对密度,壁厚,门窗的存在和房间大小的敏感性。最后,在适用于建筑材料的欧洲立法框架内,对与剂量评估有关的指数和剂量计算进行了比较。在ACI和密度和厚度校正过的Nuccetelli等人的剂量计算中。(2015年)无法提供指导,EGDA可以执行更准确的剂量评估计算,从而产生的有效剂量可以低100 µSv / y。

更新日期:2017-11-12
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