背景:福岛第一核电站事故(2011年)将大量放射性物质释放到环境中,并产生了高放射性碎片。事故后对策目前正处于清除燃料碎片阶段,这需要分析环境和燃料中的放射性污染物。仅发射β的核素的光谱,如90Sr,重叠;因此,需要一种有效的核素分离方法。由于用于高剂量样品分析的常规方法存在很大的暴露风险并产生大量的二次放射性废物,允许减少辐射发射的更快的程序是非常理想的。
结果:在这项研究中,我们开发了一种基于液体闪烁计数(LSC)耦合毛细管瞬时等速电泳(ctITP)的90Sr2定量技术,随着两点检测和依靠快速浓缩,分离,并在一次运行中分馏1,4,7,10-四氮杂环十二烷-1,4,7,10-四乙酸(DOTA)络合的90Sr2。通过使用海水参考材料和从日本原子能机构的放射性废物处理设施中获得的放射性液体废物进行添加回收实验,验证了我们方法对实际样品分析的适用性。LSC测定的回收率为95-113%,表明定量分析成功。从福岛第一核电站获得的污染水样品中确定90Sr的回收率为90.1%,这是使用90Sr的标准添加进行分析的。所提出的方法在放射性基础上的灵敏度(检测限=0.016Bq)等于或高于使用离子交换LSC的常规方法(0.012-0.07Bq)。
■我们的方法允许以微升水平处理高剂量放射性样品,并且比常规离子交换方案快得多,而由于收集不准确和缺乏合适的化学系统,ctITP尚未用于实际应用。由于存在罕见的惰性Sr2复合物和精确的分馏,ctITP中的浓缩-分离-分馏方案是成功的。这项研究建立了一条更安全,更实用的放射性核素分析途径。
BACKGROUND: The Fukushima Daiichi Nuclear Power Plant accident (2011) released large amounts of radioactive substances into the environment and generated highly radioactive debris. Post-accident countermeasures are currently in the phase of fuel debris removal, which requires the analysis of radioactive contaminants in the environment and fuel. The spectra of solely β-emitting nuclides, such as 90Sr, overlap; thus, an effective method for nuclide separation is desired. Since conventional methods for high-dose sample analysis pose substantial exposure risks and generate large amounts of secondary radioactive waste, faster procedures allowing for decreased radiation emission are highly desirable.
RESULTS: In this study, we developed a 90Sr2+ quantitation technique based on liquid scintillation counting (LSC)-coupled capillary transient isotachophoresis (ctITP), along with two-point detection and relying on the rapid concentration, separation, and fractionation of 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA)-complexed 90Sr2+ in a single run. The applicability of our method for the analysis of real-world samples was verified by conducting addition-recovery experiments using a seawater reference material and radioactive liquid waste obtained from the radioactive waste treatment facility at the Japan Atomic Energy Agency. The recovery determined by LSC was 95-113%, indicating successful quantitative analysis. 90Sr recovery was determined to be 90.1% from a contaminated water sample obtained from the Fukushima Daiichi Nuclear Power Plant, which was analyzed using the standard addition of 90Sr. The sensitivity (detection limit = 0.016 Bq) of the proposed method on a radioactivity basis was equal to or higher than that of the conventional method using ion exchange-LSC (0.012-0.07 Bq).
UNASSIGNED: Our method allows for the handling of high-dose radioactive samples at the microliter level and is substantially faster than conventional ion exchange protocols, whereas ctITP has not been used for practical applications due to inaccurate collection and lack of a suitable chemical system. The concentration-separation-fractionation protocol in ctITP is successful due to the existence of a rare inert Sr2+ complex and precise fractionation. This study establishes a pathway toward safer and more practical analysis of radionuclides.