Analysis of Options for Japan in the Peaceful Uses of Space Nuclear Power

This paper analyzes institutional, technological, and policy trends in Japan and the United States, focusing on Space Nuclear Propulsion and Power as a key technology for space exploration and sustained deep space activities at the Moon and beyond. The current status of research and development of radioisotope thermoelectric generators (RTG), lunar fission reactors (Fission Surface Power), and nuclear thermal and nuclear electric propulsion (NTP/NEP) are reviewed from a technical perspective. Their international institutional frameworks, relevant export control regulations, and the role of Japan-US cooperation are discussed. Research sources included policy documents and reports from NASA, the U.S. Department of Energy (DOE), and the UN Committee on the Peaceful Uses of Outer Space (UNCOPUOS), as well as company case studies, and interviews with over 30 experts, including government officials in Japan and the United States. The analysis confirmed that Japanese companies need to overcome multiple institutional barriers to participate in U.S. projects in the space nuclear energy field, including the need to establish a U.S. corporation, comply with the U.S. export regulations, and obtain a technical assistance agreement (TAA). It was also suggested that with the increasing security importance of space nuclear power, the current UNCOPUOS regime has limitations and a new framework with like-minded countries such as AUKUS is needed. This study introduces and provides practical suggestions on Japan's policy options and strategic positioning in the field of space and nuclear energy. It is intended to offer information that will contribute to Japanese policy formation in both international cooperation and domestic institutional development in the future.