A Scheme to efficiently select air-dose-rate measurement positions in estimating radiation source distribution

Machida, Masahiko  ; Yamada, Susumu  ; Yoshida, Toru*; Hasegawa, Yukihiro*; Yanagi, Hideaki*; Furutachi, Naoya*

The decommissioning of the Fukushima Daiichi Nuclear Power Station (1F) has been a long-standing wish of the residents and municipalities of Fukushima Prefecture, as well as a national crucial issue for the people of Japan. However, there have been numerous technical challenges associated with the actual decommissioning process. Then, resolving their problems and ensuring steady progress have been widely expected. Concurrently, the decommissioning of a nuclear power plant that experienced a severe accident has drawn global attention from nuclear professionals, scientists, and engineers, and international collaboration and knowledge integration have been strongly recommended. To respond such situations, Japan Atomic Energy Agency (JAEA), in collaboration with Tokyo Electric Power Company and other relevant organizations responsible for the decommissioning projects, has been conducting research and development with aiming at solving key technical issues associated with the decommissioning of 1F. This paper introduces a part of the research and development activities led by JAEA. The main topic of the present paper includes results from a government-commissioned R&D program. Now, one of the most critical challenges in the 1F decommissioning program is regarded as the safe retrieval of fuel debris that melted and relocated during the accident, and the subsequent treatment and disposal of this material as radioactive waste. To achieve this goal, improving the radiation environment in the working areas is now an essential R&D priority to ensure that retrieval operations can be carried out safely and efficiently.