This was supported by the Great Britain Sasakawa Foundation.
The summary of Professor Yamaguchi’s talk:
When the earthquake and the tsunami hit northern Japan on 11 March 2011, Professor Katsuhiko Yamaguchi, a physicist at Fukushima University, was in Paris on his way back from Cambridge to Japan. French government asked French nationals residing in Japan to leave the country immediately, but he flew in the opposite direction. Upon his arrival, he found the travel from airport to home problematic, but, more importantly, he found few information about the accident at Fukushima Daiichi nuclear power plant. He wanted to have primary, not secondary, data about the fallout. This led him to ask his colleagues within the Faculty of Symbiotic Systems Engineering to form a radiation assessment team. As the Faculty was not teaching nuclear-related subjects, there were neither nuclear specialists nor survey meters. Their first task was to borrow survey meters from other universities and research institutions.
The absence of nuclear specialists seemed a problem at first, but it turned out that the multi-disciplinary nature of the Faculty, with diverse expertise to pursue the symbiotic relationship among human, industries and the environment, was an asset in creating, based on scientific methodology, a comprehensive radiation assessment map covering the whole Fukushima Prefecture. At the time of carrying out an assessment for the map in late March 2011, there were two similar maps: a simulation map by the Japanese governmental organisation; and an aerial map by the US Army. The Fukushima University team wanted to make a map on foot, dividing the prefecture equally into 2X2 km units and measuring radiation level at a point on a road in each unit at the same height from the ground. The resultant map showed that the fallout was not uniformly distributed. Rather it was higher in the areas in the northwest of the nuclear plant, compared with other areas. The map was presented, firstly, to the national government, and the government later changed the evacuation zone from a concentric one to the one based on actual, measured radiation level. It was then provided to local municipalities in Fukushima Prefecture, which used it in delivering necessary measures for local residents. Finally, in April, it was made public through mass media and the team’s homepage.
Their method of conducting a necessary research and presenting the obtained data to relevant people has been applied to various radiation-related issues in Fukushima, such as decontamination. The team measured the radiation level of the soil to find that the contamination was concentrated in the top soil, and experimented removing the top soil, lowering the soil’s radiation level significantly. Based on this finding, decontamination has been carried out in Fukushima. There was rumor circulated outside Fukushima that cars were carrying radioactive materials, and some Fukushima-numbered cars (in Japan, a car number includes some numbers and the name of an area it is registered) were seen suspiciously. The team measured the radiation level of a tunnel. It was much higher at the entrance/exit than inside, indicating that cars were not carrying radioactive materials. Professor Yamaguchi ended his talk by saying: ‘Why do we investigate? For money? No. We would like to reconstruct Fukushima with citizens. We would like to recover beautiful nature. I would like to say this: We believe in Fukushima.’