The Fukushima meltdown is way too hot for humans

id=”article-body” section=”articleBody”> My nose itches. I instinctively reach up, but my fingers, wrapped in three gloves — one made of cloth, two of latex — hit the clear plastic shield of my full-face respirator mask.

My hand clumsily holds a reporter’s notebook and pen. I’m wearing white Tyvek coveralls over my trousers, shirt and head, which is capped off by a bright yellow hard hat.  I’m also wearing two layers of socks and heavy rubber boots. Walking around isn’t easy, and the gear feels like an awkward second — and third, and fourth — skin. The claustrophobic gear seems straight out of a thriller about a zombie apocalypse.

Fixing Fukushima is a CNET multi-part series that explores the role technology plays in cleaning up the worst nuclear disaster in history.

And then there’s that itch I just can’t scratch.

There’s a good reason for all that protection — I’m inside the cavernous top of the Unit 3 reactor in the Fukushima Daiichi Nuclear Power Plant. Yes, that Fukushima Daiichi, site of the world’s worst nuclear disaster.

Unit 3 was one of three reactors crippled on March 11, 2011, after a 9.0 earthquake struck 80 miles off the coast of Japan. (Units 4, 5 and 6 at Daiichi weren’t operating at the time.) The temblor shook so violently it shifted the Earth’s axis by nearly 4 inches and moved the coast of Japan by 8 feet. Eleven reactors at four nuclear power plants throughout the region were operating at the time. All shut down automatically. All reported no significant damage. 

An hour later, the tsunami reached shore.

Two 50-foot-high waves barreled straight at Fukushima Daiichi, washing over coastal seawalls and disabling the diesel generators powering the plant’s seawater cooling systems. Temperatures inside the reactors skyrocketed to as high as 5,000 degrees Fahrenheit.

Fuel rods became molten puddles of uranium that chewed through the floors below, leaving a radioactive cocktail of fuel rods, concrete, steel and melted debris. Molten fuel ultimately sank into the three reactors’ primary containment vessels, designed to catch and secure contaminated material.

Next Monday marks the eighth anniversary of the earthquake. After all this time, (he has a good point) Japanese energy giant Tokyo Electric Power Company, or Tepco, has barely scratched the surface of the problem. It’s cleared enough of the rubble on the top floor of the Unit 3 building to allow for my 10-minute visit.

I gaze up at the massive barrel vault ceiling, trying to get a handle on the sheer scale of everything. Radiation levels are too high for me to linger. My quickening pace and breath are betrayed by rapid flapping noises coming from the purple filters on both sides of my respirator mask.

At the far end of the room, there’s an enormous orange platform known as a fuel-handling machine. It has four giant metal legs that taper down, giving the structure a sort of animalistic look. Thin steel cables suspend a chrome robot in the center of the frame. The robot, largely obscured by a pink plastic wrapper, is equipped with so-called manipulators that can cut rubble and grab fuel rods. The robot will eventually pull radioactive wreckage out of a 39-foot-deep pool in the center of the room.

It’s just one of the many robots Tepco is using to clean up the power plant. It’s why I came to Japan this past November — to see how robots are working in one of the most extreme situations imaginable.

The Japanese government estimates it will cost $75.7 billion and take 40 years to fully decommission and tear down the facility. The Japan Atomic Energy Agency even built a research center nearby to mock up conditions inside the power plant, allowing experts from around the country to try out new robot designs for clearing away the wreckage.

The hope is that the research facility — along with a drone-testing field an hour away — can clean up Daiichi and revitalize Fukushima Prefecture, once known for everything from seafood to sake. The effort will take so long that Tepco and government organizations are grooming the next generation of robotics experts to finish the job.

Fukushima was a humbling moment. It showed the limits of robot technologies. Rian Whitton, ABI Research “It’s of the magnitude of putting a man on the moon,” says Lake Barrett, a senior adviser to Tepco who previously served as acting director of the Office of Civilian Radioactive Waste Management at the US Department of Energy. “Unless there’s an acceleration, I would not be surprised if it takes 60 years or so.”

Everything’s relative
There’s something quintessentially Japanese about hearing the jingle to the 1970s anime classic Space Battleship Yamato while taking an elevator to the top of a nuclear reactor.  

CNET photographer James Martin and I lock eyes when the tune plays, stirring memories from our childhoods. It’s a brief moment of whimsy in such deadly surroundings.

Fixing Fukushima

Fukushima’s nuclear disaster defense? A massive underground ice wall

Inside a Fukushima reactor: How VR gave me a scary-real experience

Fukushima’s ice wall keeps radiation from spreading around the world

A rare look at the meltdown inside Fukushima Daiichi Nuclear Power Plant

The Fukushima nuclear disaster’s legacy: An inescapable stigma
Two years ago, Tepco erected a dome over the Unit 3 reactor and fuel pool so that engineers could bring in heavy equipment and now, us.

Roughly 60 feet below me, radiation is being emitted at 1 sievert per hour. A single dose at that level is enough to cause radiation sickness such as nausea, vomiting and hemorrhaging. One dose of 5 sieverts an hour would kill about half of those exposed to it within a month, while exposure to 10 sieverts in an hour would be fatal within weeks.

Unit 3 is the least contaminated of the three destroyed reactors.  

Radiation in Unit 1 has been measured at 4.1 to 9.7 sieverts per hour. And two years ago, a reading taken at the deepest level of Unit 2 was an “unimaginable” 530 sieverts, according to The Guardian. Readings elsewhere in Unit 2 are typically closer to 70 sieverts an hour, still making it the hottest of Daiichi’s hotspots.  

Bundled up for a 10-minute visit to Unit 3. 

James Martin/CNET The reactors’ hostile environments brought most of the early robots to their figurative knees: High gamma radiation levels scrambled the electrons within the semiconductors serving as the robots’ brains — ruling out machines that are too sophisticated. Autonomous robots would either shut down or get snared by misshapen obstacles in unexpected places.

The robots also had to be nimble enough to avoid disturbing the volatile melted fuel rods, essentially playing the world’s deadliest game of “Operation.” At least initially, they weren’t. 

“Fukushima was a humbling moment,” says Rian Whitton, an analyst at ABI Research. “It showed the limits of robot technologies.”

Robot love
Consider the Scorpion, a 24-inch-long robot that could curl up its camera-mounted tail for better viewing angles. In December 2016, workers cut out a hole in the PCV of Unit 2 for the Scorpion to enter. Tepco hoped the robot, with its two cameras and sensors to gauge radiation levels and temperatures, would finally provide a glimpse inside the reactor.  

The Scorpion became stuck after just two hours in what was supposed to have been a 10-hour mission, blocked by lumps of melted metal. It had taken Toshiba over two and a half years, and an undisclosed sum, to develop the robot.

Touring the Fukushima power plant requires a near-constant change of rubber boots. 

James Martin/CNET “Even if the [Scorpion] failed in its mission, the data that we received from the robot has been beneficial,” Hideki Yagi, general manager of Tepco’s Nuclear Power Communications Unit, tells me through an interpreter, noting that engineers have since added guide pipes and other design elements to help new machines get around.

Still, the failure underscores the inherent weakness of flashy robots with multiple parts versus simpler, purpose-built alternatives. “They’re trying to develop sophisticated technology without understanding the full solution,” says an industry expert who isn’t authorized to talk publicly about the decontamination process.

Barrett lays part of the blame on Tepco’s sole reliance on established Japanese manufacturers like Toshiba and Hitachi, saying the utility needs to embrace more of an experimental, Silicon Valley mentality.

“Where’s the long-haired kid with the body piercings?” he says. “You got to have one or two of them.”

(For the record, I never saw anyone with long hair or body piercings on my trip.)

Success after failure
Seven months after the Scorpion setback, in July 2017, Toshiba sent a small (12 inches long and 5 inches around) submersible robot, nicknamed Sunfish, into the flooded PCV of Unit 3. On its second day of reconnaissance, Sunfish Sunfish recorded the first signs of melted fuel inside a reactor.

Toshiba returned to the heavily contaminated Unit 2 in January 2018 with a new machine carrying one camera that could pan and tilt and another attached to the tip of a telescopic guide pipe, offering a bird’s-eye view. Once that machine reached the heart of the PCV, workers remotely lowered the pan-and-tilt camera an additional seven and a half feet to take photos.

Some of the robots being used for reconnaissance missions inside Daiichi’s reactors. 

James Martin/CNET “This has to all be created to address specific challenges,” says Takayuki Nakahara, a specialist for Toshiba who helped create the structure to lower the robot.

The robot not only survived Unit 2’s mega-radioactivity, it showed Tepco that the floor of the PCV held mud and pebbles thought to be melted fuel debris, adding new wrinkles to the cleanup task.

In February, Tepco sent a modified version of the same robot back down, where it was able to touch some of the pebbles for the first time. The company said the robot was able to grip smaller pebbles with its hand-like attachment, as well as take more photos and get radiation and temperature readings without disturbing the surrounding environment. But it also noted that the robot couldn’t grab the larger rock structures, and are re-evaluating the robot.