12 Mars 2013
March 7, 2013
Cleanup work progresses in Fukushima, but residents still concerned
By SHUNSUKE KIMURA/ Staff Writer
FUKUSHIMA--For a problem caused by such advanced technology, the solution sounds decidedly low-tech.
Work to decontaminate areas awash with radioactive materials spewed from the stricken Fukushima No. 1 nuclear power plant two years ago generally centers on mowing grass, removing topsoil and wiping the roofs of homes with rags.
In the mountainous Onami district of Fukushima, some 56 kilometers from the crippled facility, radiation levels have come down sharply after cleanup crews had been through.
Some 470 homes in the district have been decontaminated to date, but that does not mean that residents' concerns have been allayed.
"Generally, people are reasonably satisfied, certainly to some extent," says Toshimichi Sato, 62, chief of a residents' association in the Onami district. "But they are not totally satisfied, either. The fact is, radiation is still a big problem that haunts us two years after the disaster."
The central government plans to complete the mammoth task of decontamination in highly contaminated areas in 11 municipalities in Fukushima Prefecture by March 2014, excluding forests. Local governments are responsible for other areas.
Full-scale decontamination work in Fukushima Prefecture first got under way in the Onami district in October 2011, seven months after the onset of the crisis.
On the first day that work started, then Prime Minister Yoshihiko Noda visited the district for an on-site inspection.
Given the lack of knowledge in how to remove radioactive materials efficiently, cleanup workers initially concentrated on washing tiles on roofs and collecting mud in gutters.
The work progressed fairly smoothly in Onami because a storage site for the contaminated soil was secured early on.
According to the Fukushima city government, the average radiation level measured at the entrances of 109 homes in the Onami district was 0.8 microsievert per hour in February 2012.
The figure is half of what it was before the decontamination work started, but many residents are keen for additional decontamination work to be carried out.
"Everyone is agonizing day after day," Sato says. "But if we give up, that will be the end of it. We will ask the government (to take further measures).
"We are not hoping they will create a brand new community. All we want is to return our Onami district to what it was before the disaster."
On a chilly day in late February, 62-year-old Yoshiharu Suda surveyed his snow-covered garden in Onami. The garden used to have more than 30 trees. Most were removed as part of decontamination work. Among the few exceptions is a persimmon tree that had been planted by Suda's mother as a housewarming present.
"My mother says the tree is bearing fruit," Suda says, examining the blackish persimmons that are left on the tree. The fruit is normally orange-red in color. "But I told her we cannot eat them."
Replacing topsoil with new dirt brought the radiation level at his house and garden down from 2.9 microsieverts per hour to 0.7 microsievert.
Suda says the radiation level is currently around 0.4 microsievert, but he is worried that it may rise.
"I'm scared that (the radiation level) may rise when the snow melts," he says. "But we probably have no choice but to keep on living here."
According to the Environment Ministry, the success of decontamination work varies depending on where the work is carried out and which procedures are employed.
A ministry survey found radiation levels of gutters, street runoffs and entrances to storm drains fell by 60 to 90 percent by first removing mud and wiping the surfaces or using high-pressure hoses.
Tests on various types of roof surfaces resulted in different levels of effectiveness.
Radiation levels on commonplace roofs were slashed by 20 to 60 percent, but decontamination work had only a limited effect on roofs made of cement tiles, mat clay tiles and painted steel sheets.
The ministry said the surface roughness, rust and other factors might compromise the effectiveness of decontamination work.
Removing topsoil at depths of between 3 and 5 centimeters reduced radiation levels by 40 to 80 percent. Radiation levels also dropped by 70 to 90 percent when surface grass was removed.
Decontamination work on asphalt or concrete-paved parking lots nearly halved radiation levels.
But spraying water on asphalt-paved roads with a pressurized hose only reduced radiation levels by 10 to 50 percent. Shaving the surface of such roads brought levels down by between 10 and 70 percent.
The drainage performance of the roads, along with surface roughness, might be responsible for the differences, ministry officials said.