TBP-TEVA萃取色层分离-α能谱法测定辐照镎靶溶解液中痕量236Pu的可行性

²³⁶Pu的含量控制是钚热源的一项重要参数，通过α能谱准确测量镎靶溶解液中痕量²³⁶Pu，建立镎靶辐照靶件溶解液中钚的分离方法。根据杂质组成特点采用TBP-TEVA萃取色层双柱分离，用氨基磺酸亚铁以及亚硝酸钠对钚进行调价，对靶件溶解液中的Al、Fe、U、Th和Np等进行分离，去污系数均大于10⁴，钚的回收率为90.7%。研究大量²³⁸Pu对α能谱测定²³⁶Pu的干扰，结果表明，大量²³⁸Pu会造成仪器本底升高，²³⁸Pu能谱峰分辨率降低；在7 500 Bq ²³⁸Pu干扰下，测量4.3 h 时，²³⁶Pu的最小可检测活度为1.20×10^-2 Bq（当量质量为6.11×10^-16 g）。计算结果表明，镎靶溶解液样品中钚的同位素比值n(²³⁶Pu)/n(²³⁸Pu) ≥4.63×10^-8时，取合适的样品量使得电沉积源中²³⁸Pu 活度在 450~7 500 Bq范围内，均可测量其中的痕量²³⁶Pu，同时可准确测定同位素比值n(²³⁶Pu)/n(²³⁸Pu)。

The Feasibility of Determining Trace 236Pu in the Solution of Neptunium Target by TBP-TEVA Column Extraction Separation-Alpha Spectrum

The content of²³⁶Pu in the²³⁸Pu product is limited in the range of 2 ppm to protect the workers during the manufacture of the heat source. Therefore, the content must be reduced as much as possible in the production process, and the²³⁶Pu content index must be strictly controlled. The control of plutonium content is an important parameter of plutonium heat source, studied the conditions for accurate measurement of trace²³⁶Pu in irradiated Np target. A separation method for Pu in the solution of irradiated Np target was established. According to the composition of solution, TBP-TEVA double extraction chromatographic column separation was adopted. The plutonium valence was adjusted by FS sulfonic acid and sodium nitrite, and the impurities of Al, Fe, U, Th and Np in the plutonium were decontaminated, the decontamination coefficient was greater than 10⁴, and the recovery of plutonium was 90.7%. In this paper, the interference of a large amount of²³⁸Pu on ²³⁶Pu was studied, and the results showed that a large amount of²³⁸Pu would cause increasing of the background, and coarsening of the resolution of²³⁸Pu peak and increase the MDA. The MDA of²³⁶Pu is 1.20×10^-2 Bq and the isotope ratios ofn(²³⁶Pu/²³⁸Pu) is 4.63×10^-8, when the²³⁸Pu is 7 500 Bq background interference and measure it for 4.3 h. When the isotope ratios ofn(²³⁶Pu/²³⁸Pu) is more than or equal 4.63×10^-8 in the sample of irradiation Np target, meanwhile sampling the suitable amount can make the²³⁸Pu activity in the electroplating source range from 450-7 500 Bq, then the trace²³⁶Pu can be detected, and the ratios ofn( ²³⁶Pu/²³⁸Pu) can be accurately measured. The determination of trace²³⁶Pu in ²³⁸Pu heat resource is an important technical indicator in neptunium target irradiation process and product of heat source. In this study, the combined TBP-TEVA resin was used to separate and purify the plutonium from the irradiated neptunium target solution, and the alpha energy spectrum method was used to analyze it.