核设施氚气态释放后植物中有机氚的研究进展

从核设施释放到大气中的氚主要以氚化水（HTO）和氚化氢（HT）两种形式存在，最终以HTO的形式进入植物体。植物体中的氚有两种化学形态：自由水氚（TFWT）和有机氚（OBT），其中OBT又被细分为交换性OBT和非交换性OBT。与TFWT相比，OBT在植物体内有较长的滞留时间和较大的剂量转换因子，在氚的食入剂量中OBT占主要份额，因此有必要对植物中的OBT展开全面研究。本文就植物中OBT的定义、交换性OBT和非交换性OBT的确定、OBT的形成过程及其影响因子、OBT预测模型的研究进行综述，同时对今后植物中OBT应重点研究的内容进行了简单分析，以期为植物中OBT的研究提供一定的参考。为准确评价OBT造成的辐射剂量，今后对OBT的研究中应着重从测量、夜间形成机理和环境中的行为等方面进行。

Overview of Organically Bound Tritium in Plant for Atmospheric Release of Tritium From Nuclear Installation

The two major forms of tritium (tritiated water vapor (HTO) and tritiated hydrogen gas (HT)) which are released into the atmosphere from nuclear installations easily pass through the stomata and root of growing crop plants to enter into their water pools by the way of HTO. The two chemical forms of tritium presented in the plant are tissue free water tritium (TFWT) and organically bound tritium (OBT) as exchangeable organically bound tritium (E-OBT) and non-exchangeable organically bound tritium (NE-OBT). OBT remains in the plant for a long time and its dose coefficients are higher than that of HTO, so the OBT may be the dominant contributor to the dose by ingestion and it is important to comprehensive studies on OBT. The study presents an overview of the definition of OBT, the determination of E-OBT and NE OBT, the formation of OBT, factors of controlling OBT production in plants and OBT concentration predictive models in plant. At the same time, the key questions in the future study on OBT in plant were described. The present study should provide some references to study OBT in the plant. In order to evaluate the radiation dose from OBT accurately, further study will be required to understand OBT measurements, mechanisms of OBT production in night and the fate in the environment.