I will first discuss briefly why an “antimatter physicist” started to work actively in Fukushima. I will then focus on the present situation in Fukushima from the radiological protection view point, and discuss what are the lessons we have learned in these six years.
The Fukushima Daiichi accident contaminated the soil of densely-populated regions of Fukushima Prefecture with radioactive cesium, which poses risks of internal and external exposures to the residents.
Our extensive surveys however showed that the internal exposure levels of Fukushima residents are negligibly low. Nevertheless, families with small children are still much concerned about internal exposures. We therefore developed a whole body counter for small children, called the ‘BABYSCAN’, with which we have scanned more than 10,000 babies, and have shown that Fukushima babies are free of radiocesium.
As for the external exposure, we launched a project to compare personal doses of high-school students living in Fukushima, outside of Fukushima, France, Poland and Belarus. This study, participated by more than 200 students and teachers, has clearly shown that the external doses in Fukushima are well within the range of natural background.
These are good news, but the fact remains that nearly 50,000 people are still unable to return even though the radiation level in most areas have become low enough. The problems in Fukushima, after six years, are mostly psychosocial, rather than radiation risks.
Ryugo Hayano is Emeritus Professor at the University of Tokyo. He has been the spokesperson of an “antimatter” research team called “ASACUSA”, at CERN’s antiproton decelerator facility, since 1997. In 2008 he received the Nishina Memorial Prize, the most prestigious physics prize in Japan, for his study.
Since March 2011, his tweets related to the Fukushima Dai-ichi accident attracted some 150,000 followers; his activities in Fukushima include systematic measurement of school lunch for radiocaesium, study of internal exposures using whole body counters, development of a whole-body counter for small children (BABYSCAN), and comparison of external radiation doses of high school students living in Fukushima, outside of Fukushima, France, Poland and Belarus. He is also known as the author of a successful book “We want to know - a conversation about radiation and its effects in the aftermath of the accident”.
