Radioactive Waste Processing and Disposal
Overview of our laboratory and objectives of TG(2)-2 task group
The management and disposal systems for radioactive waste require that radioactive substances be isolated from living spaces, for example, by the use of underground spaces. “TG(2)-2: Radioactive Waste Disposal” is one of the most important topics for recovery from the Fukushima No. 1 nuclear power plant accidents, and this task group studied it as part of “TG2: Basic and fundamental study for processing of fuel debris and disposal of radioactive waste" with the aim of building stable management and disposal systems for radioactive waste. The study was based on transport phenomena in geosphere environment (transport of substances and heat), reaction engineering, radiochemistry, geotechnics, etc. and was conducted using multiple approaches. The radioactive waste generated by the accident at the Fukushima No. 1 nuclear power plant is different from that encountered at the normal decommissioning of nuclear power plants in terms of amounts and properties. Many ideas and insights are needed to solve these issues. In such a context, we aim to develop researchers and engineers who play a central role in this field by providing basic data on the interaction between nuclides and the cement based materials necessary for building radioactive waste management and disposal systems, and by studying how to utilize the data within a groundwater flow field in the geospherical environment, in coordination with other task groups and teachers at the National Institute of Technology, Fukushima College.
From the front line of research
We are engaged in research to build safe and reasonable processing and disposal methods for radioactive waste and to evaluate the super long-term performance of disposal systems. Among them is research into and development of stable barrier materials utilizing interaction between cement based materials and radioactive nuclides, etc., which we are approaching from a new standpoint by actively adopting peripheral technologies and insights. Studies on the management and disposal of radioactive waste have been progressing in collaboration with many and various experts both within and outside Japan. Among them, for radioactive waste generated by the accident of the Fukushima No. 1 nuclear power plant, in contrast to the conventional radioactive waste, it is necessary to collect more information about what nuclides exist in what chemical forms, where they are, and their quantity, and feedback the insights, which are obtained from investigation of their management and disposal systems, to the previous phases, namely, their processing processes. In this context, TG(2)-2 has a close relationship with TG(2)-1 ”Understanding Debris Properties and Waste Processing and Disposal of Debris” and advances our studies by exchanging information with TG(2)-1. In addition, with radioactive waste issues it is important to provide society with information about the current status of radioactive waste, to answer questions about it, and to manage and dispose of radioactive waste while performing technical reviews of these processes. In TG(2)-2, we will study and develop technologies, keeping TG(2)-3 “Social Acceptability” in mind constantly, and advance personnel development. This includes presentation of technical justifications such as retrievability of waste bodies and reversibility of management and disposal operation of radioactive waste, as well as reviews of such systems.
Currently, the Japanese government aims to summarize basic ideas about the processing and disposal of solid waste in FY 2017 and to verify the perspectives about the safety of processing and disposing of solid waste in in FY 2021 in the “Mid- and long-term roadmap for decommissioning, etc. of Fukushima No. 1-4 nuclear power plants.” The roadmap required the utilization of insights about conventional management and disposal systems for radioactive waste, identification of the differences among them, and the addressing of these differences. In addition, the Nuclear Damage Compensation and Decommissioning Facilitation Corporation (NDF) presented the “Technological Strategy Plan for Decommissioning 2015” in April, 2015, in order to provide specific technological justifications for the mid- and long-term roadmap mentioned above, and began investigations for the smooth implementation and revision of the roadmap. On the other hand, in this fiscal year, the special committee of the Atomic Energy Society of Japan on “Processing and disposal of radioactive waste generated by the accident at Fukushima No. 1 nuclear power plant” investigates the status of activities and waste management at Fukushima No. 1 nuclear power plant and the status of R&D for processing and disposal of the waste, reviews and develops the R&D plan for processing and disposal of the radioactive waste, and compiles reports summarizing the review results of each year. Furthermore, the International Research Institute for Nuclear Decommissioning (IRID) and the Japan Atomic Energy Agency (JAEA) are also taking leadership in this field and are engaged in day-to-day technological investigations. In TG(2)-2, we will continue to address the challenge of achieving the objectives mentioned above by engaging in these investigations and reviews by NDF, IRID, JAEA and AESJ and gathering feedback from teachers and graduate students involving this project, and members of expert panels.