加速器屏蔽体中氚的提取和比活度测量

使用红外炉发展了一种从活化混凝土中提取氚的方法。通过研究氚的提取效率与加热温度、加热时间的关系，获得了氚的提取优化条件为在800℃下加热30min，Ar气流量设置为200mL/min。氚由两个冷凝管收集，然后装到1个小玻璃瓶中，与液体闪烁体混合，使用液体闪烁计数器计数。使用这种方法提取氚只需55min。相对于使用电子炉提取氚的方法，氚的提取效率可达到100%。收集了两个加速器屏蔽体中的混凝土样品，测量了样品中的γ射线核素和氚的放射性比活度。结果显示，氚的比活度与¹⁵²Eu和⁶⁰Co的比活度有很强的相关性。可得出结论：氚主要产生于热中子俘获反应⁶Li(n,α)³H。因而，可使用⁶⁰Co的放射性比活度简单估计活化的混凝土样品中氚的放射性比活度。

Extraction and Specific Activity Measurement of Tritium Induced in Accelerator Shielding

An infrared furnace (ULVAC RHL-410P) was newly applied to the extraction of tritium from concrete samples. After studying the tritium recovery yield regarding temperature and time, the best extraction conditions were set to 800 ℃ for 30 min under Ar-gas flow of 200 mL/min. Tritium was collected in two cold traps and transferred to a vial for liquid scintillation counting. It only took 55 min for the extraction of tritium. Reproducibility and recovery yield of tritium were about 100% compared to the values obtained by the ordinary heating method using an electric furnace. γ- ray emitters and tritium of concrete samples collected from several accelerator facilities were determined. The activity of tritium strongly correlated with that of ¹⁵²Eu and ⁶⁰Co, so it was found that tritium was produced by thermal neutron reaction of the 、⁶Li(n, α)³H. The results indicate that the tritium activity in concrete can be estimated from the ⁶⁰Co activity obtained easily by γ-ray measurement.