Department of Science Education, Faculty of Education and Social Work, University of Valladolid, Spain.
J Environ Radioact. 2013 Oct;124:84-92. doi: 10.1016/j.jenvrad.2013.04.011. Epub 2013 May 13.
Coal-fired power-plants (CFPP) can be a source of contamination because the coal contains trace amounts of natural radionuclides, such as (40)K and (238)U, (232)Th and their decay products. These radionuclides can be released as fly ash from the CFPP and deposited from the atmosphere on the nearby top soils, therefore modifying the natural radioactivity background levels, and subsequently increasing the total radioactive dose received for the nearby population. In this paper, an area of 64 km(2) around the CFPP of Velilla del Río Carrión (Spain) has been studied by collecting 67 surface soil samples and measuring the activities of one artificial and six natural radionuclides by gamma spectrometry. The found results are similar to the background natural levels and ranged from 0 to 209 for (137)Cs, 11 to 50 for (238)U, 14 to 67 for (226)Ra, 29 to 380 for (210)Pb, 15 to 68 for (232)Th, 17 to 78 for (224)Ra, 97 to 790 for (40)K (all values in Bq kg(-1)). Besides the classical radiochemical tools, Analysis of Variance (ANOVA), Principal Component Analysis (PCA), Hierarchical Clustering Analysis (HCA), and kriging mapping have been used to the experimental dataset, allowing us to find the existence of two different models of spatial distribution around the CFPP. The first, followed by (238)U, (226)Ra, (232)Th, (224)Ra and (40)K can be assigned to 'natural background radioactivity', whereas the second model, followed by (210)Pb and (137)Cs, is based on 'atmospheric fallout radioactivity'. The main conclusion of this work is that CFPP has not influence on the radioactivity levels measured in the studied area, with has a mean annual outdoor effective dose E = 71 ± 22 μSv, very close to the average UNSCEAR value of 70 μSv, thus confirming the almost non-existent radioactive risk posed by the presence of the CFPP.
燃煤电厂（CFPP）可能是污染源，因为煤中含有痕量的天然放射性核素，如（40）K 和（238）U、（232）Th 及其衰变产物。这些放射性核素可以作为粉煤灰从 CFPP 中释放出来，并从大气中沉积在附近的表土上，从而改变自然放射性本底水平，并随后增加附近居民接受的总放射性剂量。在本文中，通过收集 67 个表层土壤样本并通过伽马谱法测量一种人工放射性核素和六种天然放射性核素的活度，对位于西班牙 Velilla del Río Carrión 的 CFPP 周围 64 平方公里的区域进行了研究。发现的结果与背景自然水平相似，（137）Cs 的范围为 0 至 209，（238）U 的范围为 11 至 50，（226）Ra 的范围为 14 至 67，（210）Pb 的范围为 29 至 380，（232）Th 的范围为 15 至 68，（224）Ra 的范围为 17 至 78，（40）K 的范围为 97 至 790（所有值均以 Bq·kg（-1）表示）。除了经典的放射化学工具外，方差分析（ANOVA）、主成分分析（PCA）、层次聚类分析（HCA）和克里金映射也被应用于实验数据集，使我们能够发现 CFPP 周围存在两种不同的空间分布模型。第一个模型，紧随其后的是（238）U、（226）Ra、（232）Th、（224）Ra 和（40）K，可以归因于“天然本底放射性”，而第二个模型，紧随其后的是（210）Pb 和（137）Cs，则基于“大气沉降放射性”。这项工作的主要结论是，CFPP 对研究区域测量的放射性水平没有影响，平均年户外有效剂量 E = 71 ± 22 μSv，非常接近 UNSCEAR 的平均 70 μSv 值，从而证实了 CFPP 存在带来的放射性风险几乎可以忽略不计。
