Radiation "hotspots" hinder Japan response to nuclear crisis

A radiation monitor indicates 0.82 microsieverts per hour at a checkpoint to the restricted zone of a 20km radius around the crippled Fukushima Daiichi Nuclear Power Plant, in Kawauchi village, about 20 km (12 miles) from the plant in Fukushima prefecture, May 10, 2011.

KANAGAWA, Japan (Reuters) - Hisao Nakamura still can't accept that his crisply cut field of deep green tea bushes south of Tokyo has been turned into a radioactive hazard by a crisis far beyond the horizon.

"I was more than shocked," said Nakamura, 74, who, like other tea farmers in Kanagawa has been forced to throw away an early harvest because of radiation being released by the Fukushima Daiichi plant 300 kilometers (180 miles) away.

"Throwing way what you've grown with great care is like killing your own children."

More than three months after the Fukushima nuclear plant was hit by a quake and tsunami that triggered the world's worst nuclear disaster since Chernobyl, Japanese officials are still struggling to understand where and how radiation released in the accident created far-flung "hotspots" of contamination.

The uncertainty itself is proving a strain.

"Stress has serious health effects. The Japanese people no longer trust the nuclear industry and the government. People do not know whether their food and their land is safe," said Kim Kearfott, an expert on radiation health risks at the University of Michigan, who toured Japan in May.

Fukushima is estimated to have released just 15 percent of the radiation at Chernobyl, but a complicated software modeling system created by the government to predict where the radiation would drift proved useless.

Under pressure to provide a more accurate picture of the contamination, the Ministry of Education has promised to complete a detailed survey of the evacuated area by October.

Since last week, local governments have been enlisted to provide daily reports of radiation.

More than 1,000 public schools in Fukushima were equipped with dosimeters in late May and teachers were asked to record hourly radiation readings to help create a contamination map.

But some experts say even these added steps are far from enough. "We need a new and more comprehensive system for monitoring radiation," said Takumi Gotoh, a Nagoya-based cancer specialist. "The system that exists now is not sufficient."

Data so far shows the most heavily contaminated area is to the northwest of Fukushima, where experts believe radioactive debris was carried by winds in March and then deposited as snow and rain.

In the city of Date, for example, some 50 km (30 miles) to the northwest of Fukushima, ground radiation was near 24 millisieverts per year as of early June. That is above the international standard for annual exposure by nuclear workers.

There is little data on how badly contaminated the now-abandoned area of forced evacuation is in the 20-kilometer (12-mile) zone around the Fukushima plant. Critics also say the monitoring of ground and seawater also needs to be stepped up.

'I WANT TO DIG A HOLE'

The incomplete data has complicated Japan's response to the disaster and planning for an environmental clean-up expected to take years and cost tens of billions of dollars.

It has also created a mood of quiet despair in already devastated communities. "I never believe anything I hear any more on radiation," said Shukuko Kuzumi, 63, who lives in Iwaki, about 50 km to the south of Fukushima.

"I want to dig a hole in the ground and scream."

More than 24,000 people were killed by the quake and tsunami. Tens of thousands more remain evacuated because of the radiation threat.

One of the high-profile casualties from the hotspot phenomenon has been the tea crop in Kanagawa and neighboring Shizuoka, where cesium was found at a level that exceeded the government's legal limit by as much as 35 percent.

"We never thought that that the nuclear accident would affect our products," said Susumu Yamaguchi, 58, who heads a farmers' cooperative in the village of Kiyokawa.

Yamaguchi has lost a crop worth over $20,000. Another farmer he knows has simply given up his field.

Others want answers: How did radioactive cesium from the reactors at Fukushima end up here?

Tetsuo Iguchi, a specialist on radiation monitoring at Nagoya University, says experts don't know.

Iguchi is working as a consultant with a government group that is urging thousands of tonnes of contaminated soil to be cleared off and then sent to storage, possibly inside the Fukushima complex. That project will last into 2012 at least.

"Even that is optimistic," he said. "Nothing like this has ever been done before."

More radiation could spill from Fukushima into the sea if efforts to start a French-built water treatment facility hit a snag. The equipment is needed to decontaminate the water that has accumulated in underground structures on the site after being pumped in to cool the melted cores on three reactors.

"Unfortunately, there is still a real possibility of further significant releases of radioactivity," experts from the Carnegie Endowment for International Peace said in a statement.

(Editing by Linda Sieg and Nick Macfie)