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，用于清除老化核电站拆除过程中活化钢结构的热切割产生的气体和颗粒物质。在本工作中，我们重点研究了八羰基二钴（OCDC），它属于在钢结构热切割过程中具有高放射性的钴化合物，并研究了其在气相中的行为。通过雾化用己烷制备的OCDC溶液，然后过滤形成的雾，产生OCDC蒸气。然后，我们基于该反应是通过中间体的连续一级反应的假设，测量了其在不同停留时间下的分解速率、其蒸气浓度和温度。结果发现，前者分解成中间体的过程主导了这些反应。此外，我们将调节反应停留时间的分解管视为扩散管，估计了生成颗粒的尺寸，并得出估计尺寸至少大于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 秒，并且周围温度略高于房间的温度，才能将其转化为颗粒，然后用 HEPA 过滤器将其去除。