Development of Simultaneous Removal System for Radioactively Gaseous and Particulate Matters generated by Dismantlement of Nuclear Power Plants

核电站拆除产生的放射性气体和颗粒物同步去除系统的开发

基本信息

批准号：
11450289
负责人：
EMI Hitoshi
金额：
$ 7.36万
依托单位：
Kanazawa University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B).
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-11450289/
关键词：
Cobalt Calbonyl Decomposition Particle Formation Simultaneous Removal Radioactive Matter Dismantlement Thermal Cutting

项目摘要

The present work is aimed at developing a simultaneous removal system for gaseous and particulate matters generated by thermal cutting of activated steel constructions during the dismantlement of aged nuclear power plants. In the present work, we focused on octacarbonyl di-cobalt(OCDC), which belongs to cobalt-compounds with high radioactivity during the thermal cutting of steel constructions, and investigated its behaviors in gas phase. OCDC vapor was generated by atomization of OCDC-solution prepared with hexane followed by filtration of the formed mists. Then, we measured its decomposition rates at various residence times, its vapor concentrations and temperatures based on the assumption that this reaction is consecutive first-order reactions via an intermediate. As a result, it was found that the former process of decomposition into the intermediate dominates these reactions. Also, we estimated the size of generated particles, considering the decomposition tube to adjust the residence time for reaction as a diffusion tube, and obtained that the size was estimated to be at least larger than 1 nm. These findings suggested that we need the residence time of formed OCDC vapor more than 20s and the surrounding temperature somewhat higher than room one in order to convert it into particles and subsequently remove them with HEPA filters.

目前的工作旨在开发一种同时去除系统，用于在拆除老化核电站期间通过热切割活化钢构造产生的气态和颗粒物。在目前的工作中，我们专注于八八核二铜（OCDC），该工作属于钢构建体热切割期间具有较高放射性的钴化合物，并研究了其在气相中的行为。 OCDC蒸气是通过用己烷制成的OCDC-soluste制成的，然后过滤成型的雾化物的雾化产生的。然后，我们基于以下假设，即该反应是通过中间体连续的一阶反应，我们测量了其蒸气浓度和温度的分解速率。结果，发现以前的分解过程中的中间体占主导地位。同样，我们估计了生成的颗粒的大小，考虑到分解管以调整反应的停留时间为扩散管，并获得了估计的大小至少大于1 nm。这些发现表明，我们需要形成的OCDC蒸气的停留时间超过20 s，周围温度略高于一个房间，以将其转换为颗粒，然后用HEPA过滤器将其删除。