标题： 从海水样品中分离$^{236}$U 和$^{239,240}$Pu 及其通过加速器质谱法的测定 显示英文标题

标题： Isolation of $^{236}$U and $^{239,240}$Pu from seawater samples and its determination by Accelerator Mass Spectrometry

摘要： 在本工作中，我们提出并评估了一种优化的放射化学程序，用于通过加速器质谱（AMS）分析海水样品中的$^{236}$U 和$^{239,240}$Pu。 该方法基于锕系元素与 Fe(OH)$_3$的共沉淀，并以简化的方式使用 TEVA 和 UTEVA 萃取色谱树脂进行最终的 U 和 Pu 纯化。 为了提高该方法的性能，使用 α 能谱（AS）和电感耦合等离子体质谱（ICP-MS）分析了 1 至 10 L 海水体积的放射化学回收率。 获得了稳健的 80% 钚回收率；然而，发现沉淀溶液中的 Fe(III) 浓度和样品体积是影响通过 Fe(OH)$_3$共沉淀进行初始铀提取的两个关键且相关的参数。 因此，我们提出一个表达式，根据样品中$^{236}$U 和$^{239,240}$Pu 的浓度以及 AMS 设施的性能参数来优化样品体积和 Fe(III) 的量。 该方法通过分析一组比对海水样品，并与瑞士苏黎世的离子束物理实验室（ETH）一起，对该方法进行了验证，当前 1 MV AMS 系统（CNA，西班牙塞维利亚）使用氦气作为剥离气体。 显示英文摘要

摘要： In this work we present and evaluate a radiochemical procedure optimised for the analysis of $^{236}$U and $^{239,240}$Pu in seawater samples by Accelerator Mass Spectrometry (AMS). The method is based on Fe(OH)$_3$ co-precipitation of actinides and uses TEVA and UTEVA extraction chromatography resins in a simplified way for the final U and Pu purification. In order to improve the performance of the method, the radiochemical yields are analysed in 1 to 10 L seawater volumes using alpha spectrometry (AS) and Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Robust 80% plutonium recoveries are obtained; however, it is found that Fe(III) concentration in the precipitation solution and sample volume are the two critical and correlated parameters influencing the initial uranium extraction through Fe(OH)$_3$ co-precipitation. Therefore, we propose an expression that optimises the sample volume and Fe(III) amounts according to both the $^{236}$U and $^{239,240}$Pu concentrations in the samples and the performance parameters of the AMS facility. The method is validated for the current setup of the 1 MV AMS system (CNA, Sevilla, Spain), where He gas is used as a stripper, by analysing a set of intercomparison seawater samples, together with the Laboratory of Ion Beam Physics (ETH, Z\"urich, Switzerland).