Abstract：
In August 2023, the long-planned discharging of radioactive wastewater from the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) started after the confirmation of its feasibility and safety. As this water contains elevated amounts of tritium even after being diluted, a lot of resources have been invested in the monitoring of the Fukushima coastal region where the discharge outlet is located. We compare the first 3H surface activity concentrations from these measurements (up to the end of November 2023) with the available background values to evaluate a possible impact of the long-term discharging on humans and environmental levels of the radionuclide of interest in the same or nearby area. From our results, we can conclude that the joint effect of horizontal and vertical mixing has been significant enough to reduce tritium concentrations at the monitored locations in the region close to the FDNPP port two days after the end of the respective phase of the discharging beyond the detection limit of the applied analytical methods (∼0.3 Bq L-1) which is by five orders of magnitude lower than safety limit for drinking water set by the World Health Organization (WHO). Moreover, the distant correlation analysis showed that tritium concentrations at stations located further than 1.4 km were very close to pre-discharge levels (∼0.4 Bq L-1). We also estimated that the 3H activity concentration in the offshore Fukushima region would be elevated by 0.01 Bq L-1 at maximum over a year of continuous discharging, which is in concordance with the already published modeling papers and much less than the impact of the FDNPP accident in 2011.
摘要：
2023年8月，福岛第一核电站（FDNPP）的放射性废水排放计划在其可行性和安全性得到确认后开始。由于这种水即使在稀释后也含有大量的氚，已在对排放口所在的福岛沿海地区的监测中投入了大量资源。我们将这些测量结果的第一个3H表面活性浓度（截至2023年11月底）与可用背景值进行比较，以评估长期排放对人类的可能影响以及同一或附近区域感兴趣的放射性核素的环境水平。从我们的结果来看,我们可以得出的结论是，水平和垂直混合的联合作用足以在排放的各个阶段结束后两天降低FDNPP港口附近区域监测位置的tri浓度，超出了所应用的分析方法的检测极限（〜0.3BqL-1），比世界卫生组织（WHO）设定的饮用水安全极限低五个数量级。此外，远距相关分析表明，位于1.4km以外的站点的tri浓度非常接近排放前水平（〜0.4BqL-1）。我们还估计，在连续排放的一年中，福岛近海地区的3H活性浓度将最高升高0.01BqL-1，这与已经发表的建模论文一致，远低于2011年FDNPP事故的影响。
