秦山核电基地外围植被中^(14)C水平分布研究

Terrestrial Distribution of ^(14)C in Vicinity of Qinshan Nuclear Power Plant

为了解秦山核电基地外围14 C的水平分布与规律,本文采用加速器质谱法(AMS)对秦山核电基地外围6.5km以内的植物样品(苔藓、松针)与食物样品中的14 C比活度进行测量。测量结果显示:苔藓样品的14 C比活度范围为223.0～265.6Bq/kg C(本底为223.8Bq/kg C),14 C比活度随距排放点距离的增加呈降低的趋势,在距排放源6.5km处达到了本底水平。与松针相比,苔藓更适合做核设施14 C排放的指示植物。苔藓样品的14 C比活度分布规律表明,14 C气态污染物在大气中的扩散受地形和风向因素的影响。食物样品的14 C比活度比参照样品高8.5～13.0Bq/kg C(大米样品除外),给当地公众带来的附加剂量为0.5μSv/a。

To study the 14C levels in the food samples and botanic samples（moss and pine needle） which were distributed in the radius of 6.5 kilometer,14C specific activity was measured using accelerator mass spectrometry（AMS）.The 14C specific activity in moss samples,which ranges from 223.0 to 265.6 Bq/kg C,decreases with increasing of the distance from the stacks of Plant Ⅲ（heavy water reactor） and reaches to the background（223.8 Bq/kg C） at a distance of 6.5 km.Compared to pine needle sample,moss sample is a better indicator to investigate the 14C distribution close to Qinshan Nuclear Power Plant.The 14C specific activity distribution in moss samples shows that the diffusion of the 14C pollutant discharged from the Qinshan Nuclear Power Plant is affected by the geographical and meteorological conditions.The excess 14C specific activities in the food samples range from 8.5 to 13.0 Bq/kg C（except for rice samples）,resulting a radiation dose of 0.5 μSv/a to the public.