压水堆核电站110mAg形态及脱除方法分析

Morphology and removal of 110mAg in PWR nuclear power station

压水堆核电站堆芯控制棒、一回路系统使用的含银(Ag)材料是导致一回路冷却剂中出现110mAg放射性核素的主要原因。本文针对压水堆核电站一回路系统及放射性废液中110mAg超标的工程实例研究了110mAg形态及其脱除方法。结果表明:在核电站堆芯冷却剂的水化学环境从"碱性-还原"到"酸性-氧化",再到"碱性-还原"的循环过程中,110mAg形态会从原子态Ag^0变成离子态Ag^+,再变成Ag^0纳米胶体;过滤+离子交换工艺对110mAg胶体态放射性核素的去污因子相对较低,而过滤+离子交换+吸附工艺对110mAg胶体态放射性核素脱除较为有效。

The Ag-containing material used in core control rods and primary loop system of pressurized water reactor(PWR) nuclear power plant is the main reason for introducing 110mAg radionuclides into the primary loop coolant.By taking the 110mAg overstandard in primary loop system and radioactive waste liquid in a PWR nuclear power plant as the example,this paper investigates the speciation and removal methods of 110mAg.The results show that,the water chemistry environment of the core coolant has undergone a cyclic process from "alkaline-reduction" to "acidic-oxidation" and then to "alkaline-reduction".In this process,the 110mAg morphology has correspondingly undergone a process from atomic Ag^0 to ionic Ag^+,and then to Ag^0 nano-colloid.The conventional "filtration + ion exchange" process has relatively low decontamination factor for 110mAg colloidal radionuclides,while the "filtration + ion exchange + adsorption" process may be an effective process for 110mAg colloidal radionuclide removal.