Radionuclide Capture Techniques for Nuclear Operations and Decommissioning

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Several nuclear power plants in Canada are either starting the decommissioning process or are in preparation for decommissioning (Nuclear Power Demonstration Plant, Gentilly1, Gentilly2, Pickering 1-8) which covers the decontamination and dismantling of structures, systems and components, the disposal of active waste in long term disposal facilities and remediation of the site. The scope of work is on the order of several billion dollars. Other countries, such as the United States and Japan, are farther along in the decommissioning process and most of the technologies currently available will come from outside Canada. While the technology does exist, much of that technology is based upon clearance limits that are 25 times higher than Canada permits. As such, the application of those technologies may not be cost effective for Canada and/or may introduce a higher burden on the environment due to the generation of secondary contamination/waste (through aerosol, dust generation, effluents, etc.). Decontamination effectiveness is determined by the Decontamination Factor (DF) which equals initial Activity/final Activity. Due to Canada's low clearance levels, the DF may need to be in the range of 100 or higher whereas most available techniques provide DF in the range of 4-20. This means that decontamination may not be useful for most of the facility and the majority of the material will need to go to a nuclear waste disposal site (which is currently not available) as opposed to being recycled. This research has two main themes: identification of radiation sources and capture of those radiation sources. In the first theme, the research will consider current dismantling techniques that may generate secondary wastes (aerosols containing radionuclide particles). The nature of the secondary waste is important to identify as the potential exists to clean the secondary waste and achieve greater environmental protection at potentially lower costs. In the second theme, gels and the use of the electrohydrodynamic and plasma processes to clean material and capture the radiation will be a key method to explore for the different applications. The work needs to be extended to determine the effectiveness of these techniques for other potentially radioactive species such as Cesium, Iron, Tritium, and Chlorine. The research will consider how various factors such as surface conditions, environment conditions, dust loads, species concentration, and chemical reactions may affect the capture efficiency of a given species. The intent is to develop techniques with high decontamination factors or techniques that can be combined with existing techniques to improve the net efficiency of radionuclide capture. This research will identify improvements that will meet Canada's needs for protecting the environment. The research will assist Canadian Companies with developing their own capabilities in decommissioning and reduce reliance on foreign companies.