December 5, 2011
Scientists have proposed dumping soil contaminated by
radiation from the Fukushima nuclear disaster into the
deep sea, an idea certain to meet opposition both at home
A group led by Isao Tanihata, a professor at Osaka
University's Research Center for Nuclear Physics, and Kozi
Nakai, a former professor at the Tokyo University of
Science, said the best way to get rid of the radioactive
soil is to place it in noncorrosive, pressure-tight
vessels and dumping them at least 2,000 meters deep near
"The sea, away from all residents, would pose no problem,"
Tanihata told about 30 researchers at a study meeting at
Osaka University on Dec. 3.
The participants, including nuclear physicists and
researchers at the Japan Atomic Energy Agency, did not
object to the proposal from a scientific point of view.
But former education minister Akito Arima, who was also
present, said, "The sea is common property of all
humankind, and the key is whether fishermen and the
general public will support the proposal."
Tanihata and Nakai, who have been involved in compiling
the science ministry's soil contamination map, drafted the
proposal as the government faces difficulties finding a
final disposal site for soil contaminated with radioactive
materials from the crippled Fukushima No. 1 nuclear power
The group plans to submit a formal proposal to the
But it will be difficult to realize the project partly
because dumping contaminated soil into the sea could
constitute a violation of the London Convention, designed
to prevent marine pollution.
When Japan released more than one ton of low-density
radioactive water from the plant into the ocean in April,
criticism arose from governments overseas.
Tanihata estimates that a highly contaminated area of 150
square kilometers northwest of the Fukushima No. 1 plant
has about 750 trillion becquerels in the soil.
Tanihata said marine pollution will not worsen
substantially--even if the soil is dumped
directly--because its radiation levels are about 5 percent
of those already released into the sea in the Fukushima
He added that contaminated soil would not float even if
the vessel breaks and soil spills out.
The government plans to remove radioactive materials in
areas with annual radiation levels of 1 millisievert or
The removed soil could be stuck in temporary yards in
municipalities or a temporary storage facility to be set
up in Fukushima Prefecture if a final disposal site is not
The contaminated soil is expected to amount to 15 million
to 31 million cubic meters in Fukushima Prefecture alone.
By TAKUYA SUZUKI /Staff Writer