核电厂主冷却剂泵内插件清洗技术探讨与优化

为了去除长期运行后附着在主泵内插件表面的高放射性活化腐蚀产物,为主泵解体提供较低辐射的维修环境,采用稀释化学去污工艺对秦山一期核电厂两台主泵进行去污工作,经预氧化和还原两个过程,分别通过氧化三价铬氧化物及还原三价铁氧化物等,有效地溶解和去除内插件表面致密金属氧化物薄膜。实验结果表明,该方法对铁、铬、镍等主要金属氧化物洗脱效果明显;分析实验结果得到相关金属在表面氧化膜中占比情况;去污后内插件表面剂量率大幅度降低,其中主要中子活化产物Co-58和Cr-51活度洗脱效果明显。主泵A表面剂量率从最高111 mSv/h降至0.060 mSv/h,主泵B表面剂量率从最高114 mSv/h降至0.068 mSv/h,已经能够满足解体检修的工作条件。该方法适用于溶解和去除一回路运行中形成的活化腐蚀产物,现有清洗条件也利于该工艺的实施。

In order to remove highly radioactive ACPs(activated corrosion products)on the surface of the attached to the plug-in surface of the main coolant pump after long operation of the nuclear power plant,provide a low radiation maintenance environment for the main coolant pump disintegration.Decontamination of two Pumps in Qinshan Unit I by using diluted chemistry to decontamination,Through the two processes of pre-oxidation and reduction,by oxidizing Cr3+and reducing Fe3+,deliquescence and clean surface metal oxide thin film.The results showed that elution effect on the iron,chrome,Nie and other main metal oxides are obviously;Obtain the proportion of metals in the surface oxide film;After decontamination,the surface dose rate of the insert is greatly reduced;the dose rates of major ACPs such as Co-58 and Cr-51 get great reduction.the dose rate of the Pump A was reduced from 111mSv/h to 0.060mSv/h,and the dose rate of the Pump B was reduced from 114mSv/h to 0.068mSv/h,the working conditions of disassembly maintenance have been met.This method is suitable for dissolving and removing oxide film formed in primary operation.Existing decontamination conditions are also conducive to the implementation of the process.