The accident at the Fukushima Daiichi Nuclear Power Plant (NPP), which occurred on March 11, 2011, has caused us to focus our attention on a large amount of spent nuclear fuels stored in NPPs. In addition, public anxiety regarding the treatment and disposal of high-level radioactive wastes that require long-term control is growing. The Japanese policy on the back-end of the nuclear fuel cycle is still unpredictable in the aftermath of the accident; moreover, these back-end issues are inevitable as long as nuclear energy is used. Therefore, research and development for enhancing the safety of various processes involved in nuclear energy production is being actively pursued worldwide. In particular, the nuclear transmutation technology— employed for reducing the toxicity of highly radioactive wastes—has been drawing significant attention.

In the KUR Research Program for Scientific Basis of Nuclear Safety, the Kyoto University Research Reactor Institute organized an international symposium “Nuclear back-end issues and the role of nuclear transmutation technology after the accident of TEPCO’s Fukushima Daiichi Nuclear Power Stations” in November 28th, 2013. Under such circumstances in which nuclear back-end issues and the role of nuclear transmutation technology after the accident at TEPCO’s Fukushima Daiichi NPP is gaining greater concern, this timely publication highlights the following topics: (1) Development of accelerator-driven systems (ADS), which is a brand-new reactor concept for transmutation of highly radioactive wastes; (2) Nuclear reactor systems from the point of view of the nuclear fuel cycle. How to reduce nuclear wastes or how to treat them including the debris from TEPCO’s Fukushima nuclear power stations is discussed; and (3) Environmental radioactiv­ity, radioactive waste treatment, and geological disposal policy.

State-of-the-art technologies for overall back-end issues of the nuclear fuel cycle as well as the technologies of transmutation are presented here. The chapter authors are actively involved in the development of ADSs and transmutation-related

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technologies. The future of the back-end issues is very uncertain after the accident in Fukushima Daiichi NPP, and this book provides an opportunity for readers to consider the future direction of those issues.

Sennan-gun, Osaka, Japan Ken Nakajima