Development of passive wireless communication systems operatable under inferior-wireless environment with obstacles (Contract research); FY2023 Nuclear Energy Science & Technology and Human Resource Development Project

Collaborative Laboratories for Advanced Decommissioning Science; Yokohama National University*

The Collaborative Laboratories for Advanced Decommissioning Science (CLADS), Japan Atomic Energy Agency (JAEA), had been conducting the Nuclear Energy Science & Technology and Human Resource Development Project (hereafter referred to "the Project") in FY2023. The Project aims to contribute to solving problems in the nuclear energy field represented by the decommissioning of the Fukushima Daiichi Nuclear Power Station, Tokyo Electric Power Company Holdings, Inc. (TEPCO). For this purpose, intelligence was collected from all over the world, and basic research and human resource development were promoted by closely integrating/collaborating knowledge and experiences in various fields beyond the barrier of conventional organizations and research fields. The sponsor of the Project was moved from the Ministry of Education, Culture, Sports, Science and Technology to JAEA since the newly adopted proposals in FY2018. On this occasion, JAEA constructed a new research system where JAEA-academia collaboration is reinforced and medium-to-long term research/development and human resource development contributing to the decommissioning are stably and consecutively implemented. Among the adopted proposals in FY2022, this report summarizes the research results of the "Development of passive wireless communication systems operatable under inferior-wireless environment with obstacles" conducted in FY2023. This study aims to develop a wireless communication system for obstacle-dense environments by designing base stations, sensor nodes (SN), positioning algorithms, and wireless area formation methods for electromagnetic wave-shielded regions. Key outcomes are as follows: For direction-finding with high-performance antennas, triangulation positioning accuracy was evaluated, and a sensor information demodulation system was built. SNs with frequency-scanning analog and frequency-fixed digital methods achieved communication distances of 6-8 meters and wireless charging of 1-2 V in 3-15 minutes at 6 meters. Diode characteristics remained unchanged after 1,000 Gy radiation. Positioning algorithms using multipath tomography were validated with a high-resolution measurement system in the lab. Simulations with reactor building CAD diagrams optimized node numbers and arrangements. Wireless coverage in electromagnetic wave-shielded regions was tested using a composite antenna (patch array and waveguide), achieving a range of approximately 1.5 meters.