重水堆废干燥剂解控脱氚方法探究

The Research on Tritium Removing of the Exhausted Molecular Sieve Used in Heavy Water Reactor Nuclear Plant

在重水堆机组中,氚是其产生的主要放射性物质之一,以氚化水的形状存在于重水系统中。在机组运行或设备检修中,免不了重水会由系统向外渗漏、泄漏或检修设备疏水时从系统中排出,泄漏的重水会有部分以水蒸汽的形式扩散到空气中,形成氚内照射剂量。重水价格昂贵,为了减少重水损失和净化空气降低辐射剂量的目的,在重水系统厂房设置了以分子筛干燥剂为吸附介质的重水蒸汽回收系统,当干燥剂使用一定的时间失效后,更换下来成为放射性废物而储存。废干燥剂中存在的放射性源项氚,如有效降低氚后废干燥剂即可解控为非放废物,可大量降低核电厂放射性废物储量,本试验拟通过直接加热及水分置换后加热的简单实用方法对放射性废干燥剂进行脱氚试验,探索放射性废物解控成非放射性废物可行方法,为核电厂放射性废物处理方法的一次有益尝试。

Tritium（H-3） is the by-product of PHWR（pressurized heavy water reactor）,it is widely existed in the heavy water systems in nuclear power plant.Minor heavy water will escape from the system or valves into the air as water vapors during normal operation or maintenance work.The H-3 contained air will contribute to inner-exposure to the staff and also because the heavy water is very expenslve,there are heavy water recollecting systems using molecular sieve as desiccants.When the desiccants exhausted it will be stored as radioactive waste in the plant mostly because of the high active H-3 contained in it.The chemistry lab has done some research of removing the high level H-3 contained in the exhausted molecular sieve through heating and exchanging with light water.If this can be applied to reduce the high level H-3 in the exhausted desiccants successfully the radioactive waste in the plant will decrease a lot.