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Studies of particle size distribution of Non-Exchangeable Organically Bound Tritium activities in the soil around Qinshan Nuclear Power Plant

Zhang, Qin, Du, Lin, Dai, Zhong-qin, Ma, Yu-hua, Qin, Lai-lai, Deng, Ke, Ma, Zhao-wei, Yang, Guo, Liu, Jia-yu, Liu, Wei
Journal of environmental radioactivity 2018 v.192 pp. 362-367
nuclear power, organic matter, particle size, particle size distribution, power plants, radioactivity, soil depth, tritium, China
The NE-OBT (Non-Exchangeable Organically Bound Tritium) in the soil plays a significant role in tritium migration and transformation. In order to further understand the NE-OBT activity in the soil, the particle size, vertical profile and spatial distribution of the NE-OBT activities in the soil were determined around the Qinshan Nuclear Power Plant (NPP) in China. The experimental results indicated that the NE-OBT preferred to concentrate in the soil particle sizes of 53–250 μm within the soil depth of 5 cm–25 cm. The NE-OBT activity showed significantly vertical variations, however, its largest activity did not appear at the surface soil (0–5 cm). Meanwhile, the NE-OBT had a significant spatial distribution, its activity decreased with the increasing distance from the NPP, especially from the HWRs. In this study, the NE-OBT activities have no significant relationship to the organic matter content in the soil. But the vertical profile distribution of the NE-OBT activity has a strong correlation with the NE-OBT/HTO ratio in the soil, which reflect the capability of living organisms converting HTO into NE-OBT. According to these analyses, we supposed that the NE-OBT in the soil may be derived from the microbial transformation of HTO.