Nov 25, 2019

Highly Radioactive Particles From Fukushima Mapped

A recent study published in the scientific journal "Chemosphere,"
involving scientists from Japan, Finland, France, and the United
States, addresses these issues.

The team, led by Dr. Satoshi Utsunomiya, Ryohei Ikehara, and Kazuya
Morooka of Kyushu University, a prestigious research school in
Fukuoka, Japan, developed a method in 2018 that allows scientists to
quantify the amount of cesium-rich microparticles in soil and sediment

They have now applied their method to a wide range of soil samples
taken from within, and outside, the Fukushima Daiichi nuclear
exclusion zone, and this has allowed them to publish the first
quantitative map of cesium-rich microparticle distribution in parts of
Fukushima region.

The map shows three regions of interest within 60 kilometers from the
Fukushima Daiichi site

Dr. Utsunomiya said, "Using our method, we have determined the number
and amount of cesium-rich microparticles in surface soils from a wide
range of locations up to 60 km from the Fukushima Daiichi site. Our
work reveals three regions of particular interest."

"In two regions to the northwest of the damaged nuclear reactors, the
number of cesium-rich microparticles per gram of soil ranged between
22 and 101, and the amount of total soil cesium radioactivity
associated with the microparticles ranged from 15–37 percent," said
Dr. Utsunomiya.

"In another region to the southwest of the nuclear reactors, 1–8
cesium-rich microparticles were found per gram of soil, and these
microparticles accounted for 27–80 percent of the total soil cesium
radioactivity," he said.

Professor Gareth Law from the University of Helsinki, a co-author of
the study, said that the paper "reports regions where the cesium-rich
microparticles are surprisingly abundant and account for a large
amount of soil radioactivity."

"This data, and application of our technique to a wider range of
samples could help inform clean-up efforts," Law said.

Abundance and distribution of radioactive cesium-rich microparticles
released from the Fukushima Daiichi Nuclear Power Plant into the
environment, Ryohei Ikehara, Kazuya Morooka, Mizuki Suetake, Tatsuki
Komiya, Eitaro Kurihara, Masato Takehara, Ryu Takami, Chiaki Kino,
Kenji Horie, Mami Takehara, Shinya Yamasaki, Toshihiko Ohnuki, Gareth
Law, William Bower, Bernd Grambow, Rodney Ewing, Satoshi Utsunomiya.
2019. Chemosphere, Volume 241, February 2020, 125019