Np and Pu are two important actinides of concern for the safe long-term disposal of nuclear waste. Both actinides are, in addition, constituents of global nuclear fallout. Investigation of their environmental behavior requires ultra-sensitive analytical methods, but current methods for a concurrent determination in clay minerals are lacking. In the present study, a Pu isotope was investigated for use as a non-isotopic yield tracer for Np in extraction, purification, and mass spectrometric determination of Np and Pu isotopes in clay materials. Inductively coupled plasma mass spectrometry was used in this developmental study, but the method is intended for future ultra-trace analysis of global-fallout Np and Pu in clay-rich soil materials by the more sensitive accelerator mass spectrometry. Another field of application may be the investigation of diffusion patterns of actinides in compacted clay liners and potential host rocks for radioactive waste disposal. The analytical procedure includes the following steps: (1) extraction of Np and Pu from clay samples; (2) adjustment of Np and Pu to Np(IV) and Pu(III); (3) pre-concentration of Np and Pu by co-precipitation with iron hydroxide; (4) adjustment of Pu to Pu(IV); (5) extraction chromatographic separation of Pu and Np from iron and matrix elements; and (6) determination of Np and Pu by mass spectrometry. The analytical procedure was applied successfully to spiked montmorillonite and illite test portions of up to 1 g. High chemical yields near 90% were obtained for both Np and Pu. The suitability of Pu as a non-isotopic tracer for Np was indicated by Np/Pu chemical yield ratios close to unity. Accurate pH adjustment during the reductive co-precipitation and short processing times are vital to obtain high chemical yields and Np/Pu yield ratios close to unity.

中文翻译：

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同时测定粘土样品中 Np 和 Pu 的分析程序的改编

Np 和 Pu 是核废料安全长期处置所关注的两个重要的锕系元素。此外，这两种锕系元素都是全球核沉降的成分。对其环境行为的调查需要超灵敏的分析方法，但目前缺乏同时测定粘土矿物的方法。在本研究中，研究了一种 Pu 同位素作为 Np 的非同位素产率示踪剂，用于粘土材料中 Np 和 Pu 同位素的提取、纯化和质谱测定。在这项开发性研究中使用了电感耦合等离子体质谱法，但该方法旨在通过更灵敏的加速器质谱法在未来对富含粘土的土壤材料中的全球沉降 Np 和 Pu 进行超痕量分析。另一个应用领域可能是研究压实粘土衬里中锕系元素的扩散模式，以及用于放射性废物处置的潜在主岩。分析过程包括以下步骤：(1)从粘土样品中提取Np和Pu；(2)将Np和Pu调整为Np(IV)和Pu(III)；(3)与氢氧化铁共沉淀预浓缩Np和Pu；(4) Pu到Pu(IV)的调整；(5)萃取色谱分离铁和基体元素中的Pu和Np；(6)质谱法测定Np和Pu。该分析程序已成功应用于高达 1 g 的加标蒙脱石和伊利石测试部分。Np 和 Pu 都获得了接近 90% 的高化学产率。Pu 作为 Np 的非同位素示踪剂的适用性通过 Np/Pu 化学产率比接近 1 来表明。在还原共沉淀过程中准确调节 pH 值和较短的处理时间对于获得高化学产率和接近 1 的 Np/Pu 产率至关重要。