JAPAN IS STILL CLEANING UP ONE OF THE WORLD’S WORST NUCLEAR DISASTERS. HERE’S HOW FAR IT HAS COME—AND HOW FAR IT HAS YET TO GO.

A 50-foot wall of water spawned by the quake exploded over Daiichi’s seawall, swamping backup diesel generators. Four of six nuclear reactors on-site experienced a total blackout. In the days that followed, three of them melted down, spewing enormous amounts of radiation into the air and sea in what became the worst nuclear disaster since Chernobyl in 1986.

The Japanese government never considered abandoning Fukushima as the Soviet Union did with Chernobyl. It made the unprecedented decision to clean up the contaminated areas—in the process, generating a projected 22 million cubic meters of low-level radioactive waste—and return some 80,000 nuclear refugees to their homes. This past September, the first of 11 towns in Fukushima’s mandatory evacuation zone reopened after extensive decontamination, but fewer than 2 percent of evacuees returned that month. More will follow, but surveys indicate that the majority don’t want to go back. Some evacuees are afraid of radiation; many have simply moved on with their lives.

Another town scheduled to reopen, sometime in the next two years, is Tomioka, 6 miles south of the nuclear plant. One night this past fall I drove around Tomioka’s waterfront, which the tsunami had completely wiped out. It was eerily quiet, save for a loud, metallic clap echoing through the empty streets from the direction of an incineration facility. Wild boar scampered through fields where the old train station once stood. And a breeze carried the scent of mold and rot from shops and homes that had been cracked open by the earthquake and gutted by the tsunami. In one shop, a truck had been carried through a display window and deposited on the floor as if it had been deliberately parked there.

During the day, Tomioka, which once had 16,000 residents, is a vast construction site sprawling for miles across residential neighborhoods, commercial districts, and fallow rice fields. Thousands of decontamination workers equipped with little more than shovels strip 2 inches of contaminated topsoil in a 65-foot perimeter around every structure in town. They dump the soil into black decontamination bags, which they pile onto every street corner and empty lot. Some bags have been there so long, they’ve sprouted weeds. The workers also use dry hand towels to wipe down every single building, from the roof to the foundation, and pressure-wash any asphalt and concrete. It’s tedious, exhausting work.

“Tomioka exists only in name. It’ll never be a town again.”

The town allows residents to visit during the day, but special permission is required for overnight stays. When I met him, Kenichi Hiyashi, a broad-shouldered supervisor for a company cleaning up Tomioka, was about to move back to his house on the outskirts of town. Four and half years earlier, when he evacuated with his daughter and parents, radiation levels were 5 microsieverts per hour (µSv/h). Now they hovered at around 0.6 µSv/h—still more than twice the government’s long-term goal of 0.23 µSv/h, and about 15 times the normal background level in Tokyo. Hiyashi had returned to Tomioka, a mildly radioactive ghost town, for reasons millions of suburbanites could appreciate.

“The commute was killing me,” he lamented.

Hiyashi took me to see his house, which had been decontaminated just that week. In the driveway, an empty decontamination bag sagged in a steel frame. Bright pink tape marked areas of high radiation: downspouts, faucets, electrical conduit. We walked around the yard, avoiding piles of clean fill that hadn’t been raked out yet. The sun was going down over a dark stand of pine trees across the road. Crickets began to stir in the high grass growing beyond the decontamination buffer zone. Hiyashi put his hands on his hips and looked around at the neighborhood of darkened houses.

“Tomioka exists only in name,” he said. “It’ll never be a town again.” I got the sense that Hiyashi, like so many evacuees, would rather be compensated to relocate. Owning a house in a place few want to live isn’t much of an inheritance for his daughter.

II.

While the Japanese government rebuilds Fukushima prefecture, the Tokyo Electric Power Company (TEPCO) is slowly dismantling the Fukushima Daiichi nuclear power plant, a process that’s expected to cost at least $15 billion. Two weeks after I visited Hiyashi, I drove through Tomioka again, this time on a bus with a handful of other journalists headed to the site.

Inside the plant gates, guides wearing white TEPCO golf shirts herded us inside the Entrance Control Building, where some of the 7,000 employees who now work at Fukushima Daiichi strip out of their protective clothing in front of long rows of lockers. One of our guides said that things were beginning to return to normal, pointing out that workers no longer needed to wear full-face respirators at 90 percent of the site, and also that vending machines were recently installed outside the cafeteria. Given the popularity of vending machines in Japan, this wasn’t a stretch.

After a briefing, we were taken to an adjoining building where TEPCO had a special viewing room outfitted with thick, radiation-proof portholes. Carved from a 115-foot coastal bluff in the late 1960s, the Fukushima Daiichi complex has two main terraces separated by a steep slope. From my vantage point seven stories above the upper terrace, I could see the entire 860-acre site, a bustling city of workers garbed in white Tyvek suits. Construction vehicles rumbled down roads between blocks of drab industrial buildings. Before the disaster, much of the plant’s grounds were covered in pine trees that served as a bird sanctuary.

“Every time I come here, I’m so surprised,” said one TEPCO guide as he stared in awe at row upon row of water tanks below. “Two years ago, it was all flat land.” Half a mile to the east, where the site meets the Pacific Ocean, four of the reactors rise up from the lower terrace: Unit 4 with its trellislike support structure; the stub of Unit 3; the deceivingly intact Unit 2, which is the only damaged reactor to still sport its outer shell; and Unit 1, clad in beige panels. The different appearance of each reactor reflected the complexity of decommissioning the site.

“At Fukushima Daiichi, there’s no textbook,” said chief decommissioning officer, Naohiro Masuda, when I spoke to him at TEPCO’s headquarters in Tokyo a week earlier. “There are three reactors [that melted down], and each has a different manner in which the fuel melted. The buildings are damaged in different ways. So we need to think of three different methods to solve this problem.” In other words, Fukushima Daiichi has three separate decommissioning projects, not just one.

A reactor like those at Fukushima Daiichi is essentially a sophisticated machine for boiling water. Fission heat from nuclear fuel rods makes steam that spins a turbine, producing electricity. The steam is condensed, cooled, and pumped back into the reactor core to keep the fuel from overheating, and to make more steam. If water circulation stops, the rods can get so hot that they begin to lose integrity. In a worst-case scenario, they melt like wax candles, and the molten fuel pools up inside the reactor, releasing massive amounts of radiation.

The technologies required to scoop melted fuel out of the damaged reactors don’t even exist yet.

Masuda estimates that decommissioning the Fukushima Daiichi site—removing all nuclear and radiological hazards—will take three to four decades, although he acknowledged that the technologies required to scoop melted fuel out of the damaged reactors don’t even exist yet.

“Engineers are studying the problem,” he says, “but we don’t think that there’sno way to remove the fuel. There’s huge risk involved. If you make one small mistake, it might cause a huge problem for the local people, or even worldwide. We have to be aware of that possibility.”

To get a closer look at the reactors, we donned anti-contamination gear: safety helmet, dust mask, goggles, two pairs of latex gloves, one pair of cotton gloves, long-sleeved undershirt with breast pockets to hold a dosimeter (a device the size of a flip phone that measures the amount of radiation a person absorbs), disposable pants, two pairs of socks, Tyvek suit, rubber boots, disposable boot covers, and masking tape to seal the shirt cuffs. All of these precautions were supposed to keep radioactive contaminants from getting inside our lungs and on our skin. It provided no protection whatsoever against gamma radiation. A TEPCO handout informed us that our dosimeters were set to beep in 20 µSv intervals. Properly clothed, we clambered aboard a bus upholstered in thick plastic and duct tape.

III.

Once landscaped with greenery, the long, steep slope separating the upper and lower terraces of Fukushima Daiichi is now a moonscape of smooth concrete, designed to keep rainwater from soaking into the contaminated ground. As the bus descended toward the ocean, we passed an area piled high with the sun-bleached trunks of dead pine trees. Only a few cherry trees had been spared the chainsaw.

Our first stop was an unremarkable windowless building situated on a hillside. Standing on top of it, I was eye-level with the roofs of the four damaged reactors. They were 19 stories tall, except for Unit 3, shortened by a hydrogen explosion that blew its top off. Crane booms used to erect new reactor coverings dangled high above them. The coverings prevent the spread of radioactive dust. Ultimately, they will provide a frame from which to suspend equipment, when TEPCO finally gets around to extracting the melted fuel.

Even under ordinary conditions, retrieving fuel rods from a nuclear reactor’s core is a delicate procedure requiring the use of specialized machinery. The fuel rods are sealed inside a reactor pressure vessel (RPV), a 750-ton steel capsule filled with water lodged in the heart of the reactor. Surrounding the RPV is the primary containment vessel (PCV), a massive, pear-shaped structure made of concrete up to 5 feet thick and lined with 5 inches of steel. The PCV, in turn, is embedded in a concrete honeycomb of utility rooms filled with a labyrinth of pipes, pumps, and other equipment. The only part of the reactor visible to the eye is a thin outer layer of sheet metal and concrete.

Fatal radiation levels make it impossible to send inspection crews inside the reactor. Instead, TEPCO sent two robots.

Shucking our contaminated shoe covers, we boarded the bus and motored down a road at the base of the reactors. Units 1, 3, and 4 had suffered hydrogen explosions that looked dramatic in news footage. In reality the explosions blew apart only the reactors’ thin outer layers, leaving the massive PCVs mostly intact. At least that’s the hope. Nobody can say for certain if the earthquake, hydrogen explosions, or some unknown event—a mysterious explosion was heard coming from deep inside Unit 2, for instance—had cracked the PCVs. Fatal radiation levels make it impossible to send inspection crews inside the reactors.

Instead, TEPCO sent two robots into the PCV of Unit 1 this past April to locate the melted fuel. One robot stopped working within three hours; the other persevered for four days. The best information TEPCO has received so far about the location of fuel debris came from a recent muon scan of Unit 1. The scan revealed a void inside the reactor pressure vessel, confirming the worst-case scenario: Molten fuel had burned clean through it and slumped to the bottom of the primary containment vessel. Fuel had probably melted through the RPVs in Units 2 and 3 as well. The likelihood of TEPCO meeting its 2021 deadline for the start of fuel-debris removal is, at best, remote. In the meantime, there’s plenty of other decommissioning work to keep the company busy.

IV.

My dosimeter beeped its first 20 µSv alert as the bus passed the Common Pool Building, where thousands of spent nuclear fuel assemblies sit submerged underwater. Nuclear reactors have to be refueled about every three years. At Fukushima Daiichi, hot spent fuel initially cools off in a pool on the top floor of the reactors before being transferred to the Common Pool Building. Unit 4 was offline at the time of the disaster, and therefore didn’t melt down. In December 2014, TEPCO reached a major milestone when cranes hoisted the last fuel assembly from Unit 4’s spent fuel pool. It plans to pluck the remaining spent fuel from the other reactors beginning in 2019.

The bus turned sharply onto a steel-plated road that ran between the ocean and the four turbine buildings. Together, the buildings formed a featureless white wall longer than a Nimitz-class aircraft carrier. Tsunami-tossed wreckage was strewn against their foot: twisted ductwork, chunks of broken concrete pronged with rusty rebar, and large pieces of smashed equipment. We were perhaps 12 feet above sea level, the lowest point at the site, and an ideal vantage point from which to appreciate the immensity of both the reactor facilities and the tsunami that inundated them. Looking out to sea, it was terrifying to imagine a 50-foot tide of water rolling over the breakwaters and plowing into the bus.

Five years after the meltdowns, contaminated water continues to flow from the site into the ocean. Although TEPCO’s most recent analysis of seawater shows a “nondetectable” level of cesium, that level merely reflects a regulatory threshold. “Non­detectable doesn’t mean the plant isn’t leaking into the sea,” says Ken Buesseler, a marine chemist with Woods Hole Oceanographic Institution. “In fact, TEPCO’s data, like our own, shows continued elevated levels of cesium in ocean waters closest to the plant.”

The bus braked in front of Unit 4. We got out to look at what TEPCO called the “seaside impermeable wall”: 594 concrete-and-steel piles that run almost half a mile along the waterfront. It is the last line of defense between Fukushima Daiichi and the sea, though it is designed to protect the sea from the nuclear plant, not vice versa.

To understand the full scale of the water problem at Fukushima Daiichi, you have to go back to the disaster’s early days. Under normal conditions, water circulates through the reactor facilities in a closed loop to cool the nuclear fuel and generate steam. That loop broke during the disaster, and TEPCO resorted to pouring seawater into the overheating reactors. The reactors and turbine buildings quickly began filling up with thousands of tons of highly contaminated seawater.

“A few more days and water would have overflowed the plant, which would’ve taken whatever they had and squared it in terms of a catastrophe,” recalls John Raymont, founder of Kurion, a nuclear waste management company based in Irvine, California. “We heard that some of the men at the site would step in a puddle and get radiation burns immediately from it.”

There are no longer skin-searing puddles of radioactive water on the ground at Fukushima Daiichi. But TEPCO is still circulating 320 metric tons of water per day into the reactors to keep the melted fuel cool. An ad-hoc circulation loop now pumps contaminated water from the reactors to a purification system custom-built by Kurion that removes two of the worst radionuclides: cesium and strontium. Most of the water then goes back into the reactors, while some gets piped to the tank farm.

In two hours on-site, most of it riding on a bus, I’d received a radiation dose equivalent of at least four chest x-rays.

There are 1,000 tanks at Fukushima Daiichi, containing more than 700,000 metric tons of contaminated water, equivalent to nearly 300 Olympic-size swimming pools. TEPCO can’t go on building tanks forever, nor can it discharge the water into the ocean. The water is contaminated with high levels of tritium, a radioisotope that can’t be removed using conventional filtration technology. Even if TEPCO could eliminate the tritium overnight, it’s doubtful the government would allow the company to dump potentially 1 million tons of “purified” Fukushima water into the ocean before the 2020 Tokyo Olympics; it would be a public relations nightmare. In the meantime, water tanks are sprouting up all over the site like colonies of toadstools after a rainstorm.

We boarded the bus and headed toward reactor Units 5 and 6. On the way, we stopped briefly at various well heads and filtration facilities designed to trap and treat hundreds of tons of groundwater that flows downhill toward the ocean every day—right beneath the crippled reactors. Some of the groundwater mixes with the highly contaminated water in the reactors and must be treated and pumped to the tank farm; some ends up leaking into the ocean, untreated. TEPCO has been testing an underground “ice wall” to divert the flow of groundwater around the reactor facilities, but there’s no word on when the company will switch it on.

Located on high ground, Units 5 and 6 were untouched by the tsunami. But they lie directly in the path of the radioactive plume that ended up contaminating 3,500 square miles of land northwest of the plant. We passed dead pine trees scattered like orange toothpicks along the edge of a wooded area. Pine trees are particularly radiosensitive, and these had probably suffered the same fate as trees in Chernobyl’s infamous Red Forest, a tract of pines killed by fallout. For the second and last time, my dosimeter beeped a 20 µSv alert. In two hours on-site, most of it riding on a bus, I’d received a radiation dose equivalent of at least four chest X-rays.

V.

The Fukushima disaster had a chilling effect on the nuclear-power industry worldwide. Germany, for example, is phasing out of nuclear energy altogether. China suspended its rapidly expanding nuclear-energy program. And in Japan, where nuclear power supplied 30 percent of the country’s energy, the entire reactor fleet was taken offline. But the nuclear chill has begun to warm up lately. Ten new reactors went online last year, the most since 1990. China now has 24 reactors under construction, with more on the books. Last August, Japan quietly restarted its first reactor since the disaster.

Ikuro Anzai, an owlish 75-year-old nuclear scientist from Kyoto, is skeptical of this development. He’s spent his career criticizing the incestuous relationship between government regulators and the nuclear industry that allowed companies like TEPCO to ignore safety warnings. In his view, Japan should follow Germany’s example. Until that happens, the least the government could do is educate a skittish public about the health effects of radiation exposure. Anzai can’t do much about the former, but few are better equipped, or motivated, to address the latter. He travels to Fukushima prefecture every month to measure radiation levels to reassure those who no longer trust the government—to say nothing about the nuclear industry—to protect their safety.

“The accident destroyed people’s trust in the industry, in the government, and experts,” Anzai said. “As a scientist, I want to make a sincere effort to stand beside victims and help minimize their exposure to radiation, and to restore trust in scientists.”

On a drizzly afternoon, I met Anzai at the Torikawa Nursery School in Fukushima City, about 40 miles from Fukushima Daiichi. Although residents were never evacuated, radioactive hot spots in some parts of town still exceed the government’s long-term decontamination goal of 0.23 µSv/h. A gamma spectrometer hung on a strap over Anzai’s shoulder as I followed him down winding lanes to an old Buddhist temple in the center of a residential neighborhood. Anzai knelt next to a swing set and held the spectrometer’s sensor over a hole he’d made in the coarse sand. “Zero point zero seven microsieverts per hour,” he announced. “It’s the same as my office in Kyoto.”

That was less than half the radiation levels Anzai found when he surveyed the same walking route two years ago, good news for the children who attended Torikawa Nursery School. Ever since the disaster they’ve been cooped up out of fear of being exposed to radiation. Now they could take their daily walk again.

“It’s important for children to be able to touch the snow and step on the ice,” the director of the nursery school, Miyoko Sato, told me. “But we still worry about the food the children eat.” Food grown in Fukushima prefecture—famous for its produce in Japan—is closely monitored for radioactive contamination, but the school still sources its food from outside it. Understandably, many parents no longer trust authorities on any matter concerning radiation, which is ironic, because the food restrictions that the government put in place after the disaster were, in Anzai’s view, one of the few things it did right.

As the cleanup of Fukushima prefecture and the decommissioning of the nuclear plant move forward, Anzai has one simple piece of advice for Japan’s government and its nuclear industry, one that he’s been repeating for more than four decades: “Don’t hide, don’t lie, and don’t underestimate.”

In many ways, rebuilding Fukushima is the easy part. Japan has recovered from far worse. Restoring public faith will be much more difficult because trust has no half-life.