Uranium and thorium as natural radioactive elements are present everywhere in the environment. Their trace levels are also present in various materials, such as copper, used as a shielding material in gamma-ray spectrometry, usually located very close to the detector. Ultra-low levels of uranium and thorium in electrolytic copper were determined in this study using radiochemical neutron activation analysis (RNAA) via their induced nuclides U-239/Np-239 and Pa-233, respectively. After irradiation of copper together with uranium and thorium standards, various techniques were used for their separation from the matrix. To isolate of short-lived U-239, solvent extraction in a combination of tributyl phosphate (TBP) in toluene was used. To separate Np-239 and Pa-233, extraction chromatography using TEVA and TK-400 resins was applied. Special attention was paid to the estimation of radiochemical recovery, which was determined in each sample aliquot using U-235, Np-238 and Pa-231 tracers. For quantification of induced nuclides and tracers used in the experiment, gamma-ray spectrometry was used. Obtained results showed that electrolytic copper samples contained impurities of uranium and thorium in ultra-trace levels: up to 45 pg/g (550 nBq/g) for uranium and up to 80 pg/g (330 nBq/g) for thorium. The electrolytic copper also contained impurities of Ag, As, Au, Sb, Se and Zn as observed using the k₀-INAA technique.

铀和钍作为天然放射性元素在环境中无处不在。它们的痕量水平也存在于各种材料中，例如铜，在伽马射线光谱法中用作屏蔽材料，通常位于非常靠近探测器的位置。在本研究中，使用放射化学中子活化分析 (RNAA) 分别通过诱导核素 U-239/Np-239 和 Pa-233 测定了电解铜中超低浓度的铀和钍。铜与铀和钍标准一起辐照后，使用各种技术将它们从基质中分离出来。为了分离短寿命的 U-239，使用了在甲苯中的磷酸三丁酯 (TBP) 组合中的溶剂萃取。为了分离 Np-239 和 Pa-233，应用了使用 TEVA 和 TK-400 树脂的萃取色谱法。特别注意放射化学回收率的估计，这是使用 U-235、Np-238 和 Pa-231 示踪剂在每个样品等分试样中确定的。为了量化实验中使用的诱导核素和示踪剂，使用了伽马射线光谱法。获得的结果表明，电解铜样品含有超痕量水平的铀和钍杂质：铀高达 45 pg/g (550 nBq/g)，钍高达 80 pg/g (330 nBq/g)。电解铜还含有 Ag、As、Au、Sb、Se 和 Zn 杂质，如使用 获得的结果表明，电解铜样品中含有超痕量铀和钍杂质：铀高达 45 pg/g (550 nBq/g)，钍高达 80 pg/g (330 nBq/g)。电解铜还含有 Ag、As、Au、Sb、Se 和 Zn 杂质，如使用 获得的结果表明，电解铜样品含有超痕量水平的铀和钍杂质：铀高达 45 pg/g (550 nBq/g)，钍高达 80 pg/g (330 nBq/g)。电解铜还含有 Ag、As、Au、Sb、Se 和 Zn 杂质，如使用k ₀ -INAA 技术。