Armstrong Christopher R, Brant Heather A, Nuessle Patterson R, Hall Gregory, Cadieux James R
Nonproliferation Technology Section, Savannah River National Laboratory, Aiken, SC, 29808, USA.
Sci Rep. 2016 Feb 22;6:21512. doi: 10.1038/srep21512.
Owing to the rich history of heavy element production in the unique high flux reactors that operated at the Savannah River Site, USA (SRS) decades ago, trace quantities of plutonium with highly unique isotopic characteristics still persist today in the SRS terrestrial environment. Development of an effective sampling, processing, and analysis strategy enables detailed monitoring of the SRS environment, revealing plutonium isotopic compositions, e.g., (244)Pu, that reflect the unique legacy of plutonium production at SRS. This work describes the first long-term investigation of anthropogenic (244)Pu occurrence in the environment. Environmental samples, consisting of collected foot borne debris, were taken at SRS over an eleven year period, from 2003 to 2014. Separation and purification of trace plutonium was carried out followed by three stage thermal ionization mass spectrometry (3STIMS) measurements for plutonium isotopic content and isotopic ratios. Significant (244)Pu was measured in all of the years sampled with the highest amount observed in 2003. The (244)Pu content, in femtograms (fg = 10(-15) g) per gram, ranged from 0.31 fg/g to 44 fg/g in years 2006 and 2003 respectively. In all years, the (244)Pu/(239)Pu atom ratios were significantly higher than global fallout, ranging from 0.003 to 0.698 in years 2014 and 2003 respectively.
由于几十年前在美国萨凡纳河工厂（SRS）运行的独特高通量反应堆中重元素生产历史悠久，具有高度独特同位素特征的微量钚至今仍存在于SRS的陆地环境中。制定有效的采样、处理和分析策略能够对SRS环境进行详细监测，揭示钚的同位素组成，例如反映SRS钚生产独特遗留情况的（244）Pu。这项工作描述了对环境中人为（244）Pu存在情况的首次长期调查。在2003年至2014年的11年期间，在SRS采集了由收集的足部携带碎片组成的环境样本。对痕量钚进行了分离和纯化，随后通过三阶段热电离质谱（3STIMS）测量钚的同位素含量和同位素比率。在所有采样年份中均检测到显著的（244）Pu，2003年观测到的量最高。2006年和2003年每克的（244）Pu含量分别为0.31飞克/克至44飞克/克（飞克=10^(-15)克）。在所有年份中，（244）Pu/（239）Pu原子比均显著高于全球沉降物，2014年和2003年分别为0.003至0.698。
