Sr-90的加速器质谱高灵敏测量方法及其在环境中的应用研究

Sr-90 with high fission yields is an important nuclide in nuclear environmental research and nuclear accident assessment, Sr-90 is also an important nuclide in biomedical and agriculture research. Because of the pure β- decay nuclide with a long half-life of Sr-90, it requires time-consuming process of sample preparation and long time measurement, also because of the limitation of detection sensitivity, It is difficult to achieve rapid and high sensitivity determination for a large number of samples by radioactivity measurement method. Due to the limitation of measurement sensitivity, it is also difficult to meet the requirements of various actual samples measurement by using traditional mass spectrometry such as ICP-MS. The main aim of this project is to develop rapid and high sensitivity measurement technique for Sr-90 by AMS. Based on the characteristics of the high terminal voltage of HI-13 tandem accelerator and the high momentum resolution of Q3D magnetic spectrometer, the high sensitivity AMS measurement method of Sr-90 will be established with the distinctive dE-Q3D technique. The detection limit of 0.1mBq can be expected and reach the international advanced level. Combinating sample preparation the meashrement method of Sr-90 with the high sensitivity and rapid determination can be achieved. Based on these bases, samples from typical areas will be collected and measured. Through the determination of a large number of samples, it provides systematic data for environmental research and provides a good experimental basis for more extensive applications of Sr-90.

具有很高裂变产额的Sr-90是核环境研究、核事故评估的重要核素，Sr-90在生物医学、农业等研究方面也是重要核素。Sr-90为纯β-衰变且其半衰期长使得利用放射性测量时需冗长的样品前处理和很长的测量时间，也由于测量灵敏度的限制而难以实现大量样品快速及高灵敏测定；利用传统质谱技术（如ICP-MS）由于测量灵敏度的限制而难以满足各种实际样品测定。本项目则是发展可实现Sr-90高灵敏与快速测定的加速器质谱（ＡＭＳ）技术。基于中国原子能研究院HI-13串列加速器端电压高、Q3D磁谱仪动量分辨率高等特点，采用有特色的dE-Q3D技术建立Sr-90高灵敏AMS测量技术，预期探测限达到0.1mBq，达到国际先进水平，结合样品制备可实现Sr-90的高灵敏与快速测定。在此基础上开展典型地区环境样品的系统采集和测量，为环境研究提供完备数据，并为Sr-90的广泛应用提供良好实验基础。

具有很高裂变产额的Sr-90是核环境研究、核事故评估的重要核素，同时Sr-90在生物医学研究方面也是非常重要的核素。由于Sr-90的纯-放射性衰变且其28.8年的半衰期为使得在利用放射性测量时需要冗长的样品前处理过程和很长的测量时间，同时也由于测量灵敏度的限制难以实现大量样品快速与高灵敏测定；传统质谱方法由于灵敏度限制也难以满足更实际样品的测定。加速器质谱（AMS）具有灵敏度高和测量样品快的特点能满足Sr-90分析要求。基于中国原子能科学研究院HI-13串列加速器质谱装置具有的能量高和高分辨磁谱仪的特点, 本项目开展了Sr-90的AMS测量技术研究。通过样品制备流程的建立和选取SrF3-离子形式提高了Sr的负离子引出束流，同时将同量异位素本底压低约5个量级；基于串列加速器加速能量高和Q3D磁谱仪动量分辨高的特点，发展了独特的E-Q3D同量异位素分离技术，实现了Zr-90和 Sr-90的有效分离，将 Zr-90 的干扰本底压低约1个量级；最后，利用四阳极电离室探测器实现了Zr-90和Sr-90的鉴别，对90Zr的压低因子达到 6000。综合以上发展的技术方法实现了Sr-90的 AMS 高灵敏测量。90Sr的测量灵敏度达到90Sr/Sr=3E（-13），国内首次建立了Sr-90的AMS高灵敏分析技术。基于建立的AMS技术方法和环境样品的采集、制备和环境样品的测定，实现了环境样品的分析。本项目的开展为Sr-90在环境、生物等广泛领域的分析应用提供了良好基础。