Professor Emeritus Satoru Tanaka, of the Department of Nuclear Engineering and Management, Graduate School of Engineering, the University of Tokyo, has been conferred The Order of the Sacred Treasure, Gold and Silver Star (Zuiho-jukosho), in the 2025 Autumn Conferment of Decorations.

Professor Tanaka served as a faculty member at the School of Engineering and the Graduate School of Engineering at the University of Tokyo for many years, beginning with his appointment as an Associate Professor in the School of Engineering in Showa 56 (1981) until his retirement in Heisei 26 (2014). During this time, he made significant contributions to the advancement of Fusion Reactor Fuel and Materials Engineering and Radioactive Waste Management Engineering, and worked toward the establishment of a new academic field: Comprehensive Nuclear Energy Studies.

In his academic pursuits, he achieved pioneering results in areas such as the chemical behavior of tritium on solid surfaces, which is currently a focus of attention due to the treated water from the Fukushima Daiichi Nuclear Power Plant. He also used computer simulations and spectroscopic measurements to elucidate the diffusion behavior of hydrogen isotopes and their desorption behavior from fusion reactor materials. Furthermore, in Radioactive Waste Management Engineering, he advanced research into the solution chemistry and adsorption reactions of radionuclides and actinide elements like uranium on mineral surfaces, contributing to the improved reliability of safety assessments for high-level radioactive waste disposal. Beyond this, he pursued a comprehensive evaluation of the nuclear fuel cycle, including non-proliferation, nuclear security, and waste disposal, and developed research from a broad perspective, incorporating the social acceptability of nuclear energy, which he termed Comprehensive Nuclear Energy Studies. For these outstanding achievements, he received numerous awards, including the Meritorious Service Award for Nuclear Safety (2010), Minister of Economy, Trade and Industry Award.

In terms of education and social contribution, Professor Tanaka not only contributed to the education of numerous young researchers, but also served as the President of the Atomic Energy Society of Japan (AESJ) in 2011. Following the Fukushima Daiichi Nuclear Power Plant accident in March 2011, he served as a Decontamination Advisor to Fukushima Prefecture and chaired the AESJ’s Investigation Committee on the Fukushima Daiichi Nuclear Power Plant Accident, as well as being the representative of the AESJ’s Fukushima Special Project, greatly contributing to the advancement of the nuclear engineering field and to society. Moreover, after his retirement from the University of Tokyo, he served as a Commissioner of the Nuclear Regulation Authority (NRA) from September 2014 to September 2024, and as the Deputy Chairman of the NRA from September 2017, where he devoted his efforts to the establishment and strengthening of Japan’s nuclear safety regulations.

The conferment of The Order of the Sacred Treasure, Gold and Silver Star, is a result of the extraordinarily high evaluation of Professor Tanaka’s long-standing and significant contributions in the academic, educational, and public sectors. The entire Department offers its heartfelt congratulations on this distinguished honor.

We sincerely wish Professor Tanaka continued good health and even greater success in his future endeavors.

Department of Nuclear Engineering and Management, Graduate School of Engineering, The University of Tokyo

Comment from Professor Emeritus Satoru Tanaka

I believe that receiving this decoration is due to the broad cooperation I received in nuclear-related education and research from faculty, staff, students, and many others associated with the University of Tokyo. The importance of nuclear energy and radiation utilization will only continue to grow. Correspondingly, the proper treatment and disposal of radioactive waste that is generated or has been generated from this utilization is a crucial matter that cannot be avoided. Furthermore, the development and strengthening of human resources related to this topic is currently a major challenge. As someone involved in the education and research of radioactive waste management, I am determined to contribute as much as possible to the resolution of these issues.