In Fukushima, Japan, one year after a nuclear meltdown sent a radioactive cloud into the sky and forced residents to flee their homes and businesses, workers are painstakingly carrying out a government mandate to clean up the contamination and prepare the land for thousands of evacuees to one day return.

Clad in rubber boots, heavy gloves and masks, the workers power-wash roofs and houses, chop branches from trees or scrub them clean, and bag up loose debris such as leaves collected from eavestroughs and gutters in an effort to remove the radiation resulting from the deadly trifecta of an earthquake, tsunami and nuclear meltdown that rocked the nation on March 11, 2011.

And in perhaps the most challenging element of the cleanup, workers are attempting to scrape off the top layer of soil and replace it with clean dirt, though no one is really sure if that will work, or where the contaminated soil will be stored once it is collected.

There are those who question the wisdom of trying to return at all, and wonder whether a cleanup is even possible.

"We're talking about an area the size of the state of Connecticut and it's an astronomical job to remove five centimetres of soil from the entire state of Connecticut," said Arnie Gundersen, a nuclear expert who arrived in Japan just days after the catastrophe to consult with the government.

The government has admitted that the most highly contaminated areas will likely never again be fit for human habitation, and much like Chernobyl in the Ukraine, will remain desolate, empty ghost towns for decades.

And even if they managed to accomplish the mammoth cleanup, there's no guarantee the land will ever be safe for the most vulnerable, Gundersen said in a phone interview from his home in Vermont.

The government's goal is to reduce the radiation level to 0.2 microsieverts per hour -- about the same amount of radiation from three CT scans.

"I guess I'm suggesting that for the people who have ancestral homes there and are 60 years old and beyond, I don't see a health risk. But for the 20-year-olds starting a family I would not go back and if it were my kids I would recommend (them) not to go back," Gundersen said.

When the 15-metre tsunami made landfall on March 11, 2011, triggered by a powerful magnitude 8.9 earthquake off the coast of Japan, it destroyed nearly everything that stood in its way.

Schools were demolished, vehicles were tossed about like toy cars, and factories, thousands of homes and the Fukushima Daiichi nuclear power plant were all virtually destroyed.

The massive wall of water hit the sea-level plant and wreaked havoc almost instantly, with water pouring into the generator stations that powered pumps which carried coolant water to the nuclear reactors.

The pumps stopped working, the cooling system failed, and the reactors soon began to heat up.

As a result, three of the nuclear reactors experienced full meltdown in the hours and days following the disaster, and it would be months before the plant was declared to be "stable" by the government.

As the world watched nervously, and while workers remained in the stricken plant bravely trying to minimize the damage, officials began evacuating residents while a radioactive fog spewed from the plant and creeped into the surrounding countryside.

Evacuations begin

First, 110,000 people within a 20-kilometre radius of the plant were told to leave. Within two weeks that was expanded to a voluntary evacuation for those between 20 and 30 kilometres. And finally in late April -- almost six weeks after the disaster -- the voluntary evacuation zone was extended to 50 kilometres.

To this day, except for certain known hotspots, the evacuation zone outside the initial 20-kilometre radius remains voluntary. And while some people have chosen to remain, most have abandoned their homes, farms and businesses and will likely never go back, Gundersen said.

Even if the government manages to scrape the soil and essentially scrub the entire area clean, there is little proof that the areas won't become re-contaminated since cesium 137 can travel with the wind, and can emerge from the most unlikely sources -- such as Japan's beautiful and iconic national tree.

"It turns out that cedar pollen is contaminated, and the cedar trees will be blossoming in the next few months," Gundersen said. "So we might have a burst of cesium again because of the cedar pollen releasing it."

"That will be an indication you will have recontamination of the soil, so even if you've cleaned it once it's not an indication it's going to stay clean."

This is particularly worrisome for schools, playgrounds and parks in the lesser-contaminated areas where the government is focusing much of its cleanup efforts. If an area gets a clean bill of health, but then becomes re-contaminated, the work will have been done essentially in vain.

Worse, if residents aren't aware of the recontamination, they could easily be exposed to unsafe levels of radiation.

There are also major questions around how the radiation is being measured.

"They're basing it on a gamma detector held about one metre from the ground and they're only measuring direct exposure, they're not measuring the hot particles, the cesium in the ground that gets into the kids' shoelaces and into their mouths," Gundersen said.

"We're not looking at the exposure that people are receiving internally because of all the contamination in the ground, and until the Japanese do that I don't think it's fair to suggest people should go back."

Ferenc Dalnoki-Veress, a physicist and scientist-in-residence at the James Martin Center for Nonproliferation Studies, has closely studied the Fukushima disaster with a focus on how the Japanese government has measured radiation and determined so-called safe zones.

Evacuations should have taken place much sooner than they did, modelling should have been used to warn the public about the approaching radioactive plume, and a sophisticated evacuation model should have been used, he said.

"The 'should haves' go on and on," Dalnoki-Veress said in an interview conducted over email.

"The government should have been especially concerned about hot spots which may occur where the contamination is particularly high, rather than circular 'emergency planning zones.'"

Both Gundersen and Dalnoki-Veress agree the government took too long to order evacuations. And the long-term consequences will only be known down the road.

Danger was downplayed

Gundersen said the Japanese simply refused to acknowledge the seriousness of the situation. While he was appearing on CNN calling Fukushima a Chernobyl-like Level 7 disaster, Japanese officials were still insisting it was only a Level 5.

"The net effect is that by ignoring the fact that this was as severe as Chernobyl they put a lot of lives at risk and only time will tell what the exact number is. But it would have been a lot lower if they had moved faster," he said.

Japan has committed $14 billion through March 2014 for the cleanup, but it's likely to take years, even decades to complete.

And no one is even sure what to do with the contaminant once it is collected. According to estimates from Japan's Environment Ministry there will be 130 million cubic yards of soil when all is said and done -- enough to fill 80 domed Major League baseball stadiums.

Gundersen said he thinks the government will eventually decide to clean up some areas, but in other places the contamination will be left to break down on its own over time or to slowly leach into creeks, rivers and the ocean, where it will eventually be diluted and carried away.

"It will contaminate the rivers and the river sediment and the ocean but it will gradually leave the land," he said.

Measuring the risks

Dennis Riches, a Canadian expat who lives in Tokyo with his Japanese wife and their three children, is worried about radiation exposure even though he lives more than 200 kilometres away from the plant.

Riches purchased a handheld dosimeter, which he uses to measure cesium 137 levels in food products such as fruit and meat purchased locally. For the most part he has found levels well within safe limits.

But when he tested an area on a pedestrian path near his home where rain washes sand down from higher ground to collect along the sidewalk, he found levels were much higher.

At this so-called hotspot he recorded gamma dose levels of 0.50 to 0.60 microsieverts per hour, or two to three times the target level in cleanup areas within the evacuation zone.

Other areas around his neighbourhood averaged about 0.14 microsieverts per hour.

Riches cleaned up the area on his own and called the city to remove the bags. He said workers did it reluctantly, admitting they had no plan in place to deal with such material.

Six months later, he found the same spot was re-contaminated.

While he said he is worried about hotspots near his home and around Tokyo, and the slow rate at which they're being cleaned up -- if at all -- Riches said he recognizes that the danger is low compared to within the evacuation zone.

"No one is going to grow food in these gutters and ditches where the hotspots are found, and no one is going to stand on them around the clock. So it's a danger that can be avoided in the short term, but needs to be dealt with in the long term," he told in an email interview.

As for the likelihood of evacuees ever being able to return to their homes, Riches doesn't rule it out, but said he would rather see the money spent relocating those who were affected, and helping them re-establish their lives elsewhere in the country.

"After all, we are talking about less than 1 per cent of the Japanese population," he said.

Gundersen agrees the fallout from Fukushima has spread much farther than the evacuation zone. Many of the hotspots Riches referred to in Tokyo, he said, would be considered radioactive waste by Canadian standards, but are paid little attention to in Japan, which is clearly focused on other problems.

"The country is contaminated," he said. "Over the next 20 years we're likely to see a million cancers, but they have a latency period so we haven't been able to see those yet."

For Gundersen, the situation in Japan has finally tipped the scales once and for all against nuclear power. He said he started his career 40 years ago very much in favour of nuclear power, viewing it as an option that could wean the world off of oil and coal. Later, he saw it as an environmentally friendly option that could help reduce global warming, but required stronger regulation.

Post-Fukushima, he doesn't see it that way.

"Fukushima has changed my view entirely. I'm at a point now where we're not smart enough to figure out what Mother Nature or a terrorist can throw at us. With this technology the risks are just too high."

For Riches, the stakes are indeed high. But with deep roots established over roughly 20 years living in the country, an established career and close extended family, all of which would be drastically disrupted with a move, he's weighed the risks and decided to stay.

"We realized there are chemical and radiological risks everywhere," Riches said.

"When all was considered, it made more sense to stand our ground, be hopeful and try to contribute here in some way toward a solution," he said.

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