Scientists from MEPhI, Tokyo Tech and AIST Jointly Develop Safety Technologies For Fukushima-Daiichi NPS Decommissioning

Scientists of the Institute of Nuclear Physics and Technology (INPhE) MEPhI together with Japanese colleagues from the Tokyo Institute of Technology (Tokyo Tech) and the National Institute of Advanced Industrial Science and Technology (AIST) are developing the criticality safety technologies for Fukushima Daiichi NPS decommissioning. The research is based on the development of the computational and experimental technology concept for determining fuel debris characteristics and fuel debris criticality analysis using non-destructive experimental methods and their calculated support, including the development of a new comprehensive methods and codes.

The results of experimental studies using the unique MEPhI facility for active neutron analysis, the AWCC neutron coincidence counter, HPGe and He-3 detectors to study the fuel debris properties and characteristics will be presented. The results of the joint development of criticality impact analysis method for fuel debris weakly coupled systems will be shown. The Japanese side will demonstrate the criticality characteristics measurement system for fuel debris. The experimental results in combination with mathematical modeling will allow to determine the optimal scientific and technical solutions to create a new measuring technology with high performance characteristics.

To optimize the process of work on handling the fuel debris, as well as to carry out mathematical modeling of possible development scenarios during the nuclear power plant decommissioning a virtual analogue of the computational and experimental system will be developed. An important component of the need to use virtual reality technologies and mathematical modeling is the complexity, and in this case, the inability of a real experiment repeatability.

The project relevance is confirmed by the strategic plan for decommissioning the Fukushima-Daiichi NPS, which notes the need to study and improve technologies for determining the properties and characteristics of fuel debris, including research on the assessment of radioactive sources in fuel debris. At the same time, according to the medium- and long-term decommissioning plan published by TEPCO, there is currently no full assessment of the possibility of criticality in the extraction of fuel debris, which requires scientific research in this direction and the immediate development of a method for its extraction, and also design and manufacture of equipment for the Fukushima-Daiichi NPS decommissioning.

The results obtained during the joint project will contribute to the improvement of decommissioning technologies for nuclear power plants, ensure the safety of operations to extract fuel debris at the Fukushima-Daiichi NPЫ and in the elimination of the consequences of severe accidents at nuclear power plants with core melt in the event of their occurrence.

The modern concept of international cooperation implies the formation of international scientific and technological teams, the purposes of which are the development and improvement of technologies, the development of new products, the exchange of knowledge and experience both in the global interests of the world level and in the interests of one country.

National Research Nuclear University MEPhI has been cooperating with the Tokyo Institute of Technology since 1993. Universities conduct joint research and student exchange programs. As part of the student exchange programs, a Japan-Russian forum is held annually. The team of performers is a member of a five-year project "Training of leading scientists and engineers in the field of healthcare, medicine, nuclear energy and the energy industry between Japan and Russia".

This work is carried out with the financially supported by the Ministry of Science and Higher Education of the Russian Federation. Agreement No. 075-15-2021-1393 dated October 28, 2021

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