西安加速器质谱中心129I加速器质谱分析方法建立及其在我国核环境示踪中的应用

摘要

Nuclear safety and environmental protection is a fundamental concern for the growing nuclear power industry in China.129I can be used as an efifciency tool to trace nuclear environmental safety. The newly established 3MV Accelerator Mass Spectrometry (AMS) facility in Xi'an, with an instrument background and analytical precision of 2×10-14 and 1.75% respectively for129I/127I ratio, provides analytical capabilities to carry out129I tracer studies. Methods for different type samples preparation have been established in Xi'an AMS Center, including soil, water, plant etc. We develop a carrier free method for AMS measurement of low level129I in samples with low total iodine concentration. Samples collected adjacent to a nuclear power plant give129I/127I ratios from (0.8~1.1)×10-10, which is in same order of magnitude with the reported environmental background data, relfecting a safe nuclear environment in terms of129I.%随着中国核电的快速发展，核环境安全问题成为备受关注的基础性问题。129I的加速器质谱（AMS）分析能够为我国核环境安全监测提供新的手段。新建立的西安加速器质谱中心对129I测定的灵敏度达2×10-14，精度1.75%，为开展129I的应用研究提供了良好的基础。西安加速器质谱中心已经建立了129I-AMS分析的日常测量方法，建立了水样、土壤、植物等多种类型样品的制样方法，创新性地开发了无载体样品制备方法，解决了低碘含量样品中超低水平129I的分离和制备技术难题。利用新建立的方法分析了我国一个核电站周边环境的129I水平，结果表明129I/127I比值范围为（0.8~1.1）×10-10，与报道的大范围环境大气沉降本底水平一致，这说明没有明显可测量的129I从核电厂排放到海水中，其周边环境安全可靠。