It‘s the moment when the alarms on the Geiger counters all start going off at once that it sinks in.

The bus is going inside the 12 mile ring around the Fukushima Daiichi nuclear power plant that just about everyone has been evacuated from. Up the coast, the earthquake and tsunami of March 11, 2011 destroyed entire towns and left mountains of wreckage. But here, in the fallout zone of the tsunami-caused triple nuclear meltdown, the devastation is invisible.

Outside the windows of our bus, we pass abandoned fields and towns that used to be crowded with people but are now empty except for left-behind animals. Inside, the passengers are completely covered in Tyvek suits, nothing exposed.

The plume of radioactive fallout from the three crippled reactors contaminated an area the size of New Jersey.

It’s still early in the clean-up process. The first phase of the cleanup only began in January, nine months after the tsunami, when the government finally declared the plant stable. But one thing is already certain — the cleanup is venturing into almost completely uncharted territory. No one has any idea whether it will succeed.

Less than a mile from the plant, government contractors at one of 19 model cleanup sites shovel dirt into thick plastic bags after tearing up the driveway on an abandoned house. Across the road, tractors scrape soil from a contaminated rice field. But the most dangerous radiation levels at this site are in a tall stand of cedars. Standing amid the trees, looking at the forest and rivers beyond, you get a sense how difficult it is to clean up this kind of landscape.

Cleanup workers have no experience with radiation

And that’s the crux of the challenge. The Japanese government says it wants to make the entire contaminated area safe to live in again, all 8,000 square miles of it. But no one’s ever really tried something like this before. Even the contractors hired by the government have no experience with radiation cleanup. So the contractors and scientists are using sites like this one to try to see what works and what doesn’t.

They’re digging up soil, spraying chemical fixation agents, even blasting iron shot over paved surfaces. But the results so far have been uneven at best. In this stand of cedars, for instance, workers have removed branches, leaf debris, even some of the topsoil, exposing the tree’s roots, but now they may also have to remove the trees themselves, because radiation levels are still more than 600 times the government’s ultimate goal.

Shinichi Nakayama, a nuclear engineer with the Japan Atomic Energy Agency who’s overseeing this initial phase of the cleanup, said they’re finding that forests are the most challenging areas. That’s a problem, because about 70 percent of the contaminated land consists of forested hills and mountains. And he said he doesn’t know if it’s even possible to clean up this kind of terrain.

But “no” is not an answer local officials are willing to accept.

The regional government in Fukushima City has set a cleanup target of one millisievert of radiation exposure per year, the low end of an internationally accepted range of safety. And Katsumasa Suzuk, who heads the government’s decontamination division, said he hoped the model cleanup projects will meet that target. That would pave the way for the larger decontamination effort to begin and ultimately make it safe for the 80,000 evacuees to go home.

What to do with all the waste?

But even if the effort succeeds, it raises another problem: what to do with all the waste?

For now, bags of contaminated soil are being temporarily stored in makeshift facilities like the lined pit that now occupies a former sports field at an abandoned school. Overall, the cleanup is expected to generate at least three and a half billion cubic feet of radioactive waste — enough to fill the Dallas Cowboys stadium, the world’s largest, 34 times. The government still doesn’t know where that waste will go.

And then there’s this question: once the cleanup is finally complete, what kind of place will the evacuees be going back to?

Nakayama, the official overseeing the initial decontamination, said there are limits to how much cleaning the natural environment can take. That’s one of the biggest dilemmas here. The more radioactive material you remove to make the area safe for humans, the more damage you’re doing to the land, creating a whole new set of environmental problems like erosion, decreased soil fertility and potentially throwing off the entire balance of the local ecosystem.

Kiyomi Yokota, an environmentalist from Fukushima, said it’s an impossible undertaking.

Yokota said if all the trees are removed, the still-radioactive soils would erode into the rivers or the fields, where the farmers grow their food, recontaminating areas even after they’ve been cleaned.

He said the government should do what the Soviet Union did after the Chernobyl disaster — create a permanent “no go” zone for the most contaminated areas, and then use some of the cleanup funds to help people relocate.

These days, Yokota is doing independent radiation testing for a Japanese television company, and he said he’s finding hotspots in places the government has declared safe, some with readings close to those found inside the evacuation zone.

Yokota said he no longer lets his daughter, 3, play outside. And he’s careful about the food they eat. He’d like to leave, but he doesn’t have the means.

Even if the government did help people like Yokota relocate, Japan, unlike the Soviet Union, is already a very crowded country. One year after the disaster, most of the evacuees live in compact, temporary housing. And there are very few places they could go to recreate the coastal farms many of them left behind.

Even if government gives the OK to return, farmers worry about public trust

A group of evacuated dairy farmers meet at a community center in Minamisoma, just north of the evacuation zone. They showed off pictures they took the first time they were allowed to go back to their farms. Nearly every one of their cows had died. One photograph shows a thick wooden beam that was chewed through by a starving animal.

Unlike Yokota, 62 year-old Ise Hangui says he wants to return to his hometown for good. He wonders, though — even if the government declares his farm safe, will consumers ever trust his milk again?

And, he asks, why should they? He and the other farmers said they don’t trust the government anymore either.

Shinji Watanabe, 53, said he still can’t decide whether he’ll return to his farm, even if he’s allowed to, because he can’t get enough information from the government to know whether it’s safe. He said it would be one thing for him and his wife to return, since they’ve already lived much of their lives. But his dreams of working with his son, and eventually his grandchildren, are gone. And he can’t imagine growing old without them.

And that raises yet another dilemma in the legacy of Fukushima. Even if the government spends tens, even hundreds of billions of dollars cleaning up the contaminated zone, no one knows if residents like Watanabe even want to go home.