Climbing without a map: After 10 years, Japan’s nuclear clean-up has no end in sight
Then they went back to work, demolishing the reactors that had melted down in the days after a tsunami on March 11, 2011.
The job is considered to be the most expensive and dangerous nuclear remediation ever attempted. A decade later, an army of engineers, scientists, and 5,000 workers are still planning a project that many expect will not be completed in their lifetime.
Naoaki Okuzumi, head of research at the leading Japanese research institute for decommissioning, compares the work ahead to climbing a mountain range – without a map.
“We feel like you think the peak is right there, but then you reach it and you can see another peak further behind,” Okuzumi told Reuters.
Okuzumi and others must find a way to remove and safely store 880 tons of highly radioactive uranium fuel along with a larger mass of concrete and metal that the fuel melted into during the accident a decade ago.
The robot tools for this task are not yet available. There is no plan where the radioactive material will be placed when it is removed.
Japan’s government says the job could last 40 years. Outside experts say it could take twice as long, which will drive completion towards the end of the century.
Tepco’s Fukushima Daiichi nuclear power plant, which once had six reactors, was plunged into crisis by the tsunami following a 9.0-magnitude quake off the coast of northern Japan on March 11, 2011.
The quake and tsunami flooded the emergency generators in Fukushima and switched off the cooling systems. The reactors quickly overheated and exploded as uranium nuclei melted. The radioactive feathers that formed forced the evacuation of around 160,000 people.
It wasn’t until 2017 that engineers realized how complicated cleaning was going to get. At that point, five specially designed robots had been sent through the dark, contaminated water that had been pumped in to cool the uranium. But radiation zapped their electronics.
A robot the size of a loaf of bread, developed by Toshiba Corp, nicknamed the “little sunfish”, gave an early glimpse into the chaotic damage around the kernels.
Kenji Matsuzaki, a robotic technician at Toshiba who led the development of the Sunfish, had assumed that they would find molten fuel at the bottom of the reactors.
However, the first video images of the sunfish showed a tumult of destruction with overturned structures in the reactor, clumps of undetectable brown debris, and dangerous radioactive metal.
“I expected it to break but I didn’t expect it to be that bad,” said Matsuzaki.
The delivery of a robotic fuel removal arm, developed under a $ 16 million program with the UK’s Nuclear Decommissioning Authority, has been delayed until 2022. Tepco plans to use it to remove some debris from Reactor 2 to test and help plan main operations.
The project had some success. About 2,000 spent fuel rods in reactors # 3 and # 4, which if overheated, could have caused another massive radiological release, were removed after huge frames and cranes were erected over the buildings.
Radiation has been reduced at most workplaces in Fukushima, about the size of New York’s Central Park. In most areas of the plant, the 5,000 workers no longer require the special protective gear that slowed down work in Japan’s hot, humid summers.
However, cleaning has been delayed by the accumulation of contaminated water in tanks that populate the site. The molten cores are kept cool by pumping water into damaged reactor vessels.
The water is pumped out and treated. Storage tanks now contain enough radioactive water to fill more than 500 Olympic swimming pools. Tepco assumes that the storage space will be maximum in the next year.
Most analysts expect the government to dump the water into the ocean after further treatment. The fishing communities have opposed it, and South Korea and China have objected to such a move.
It is not yet planned where the radioactive waste from the reactors will be deposited.
“It is not good to just move high-level radioactive waste from the nuclear reactor to another location on the facility,” said Hiroshi Miyano, head of the decommissioning committee of the Atomic Energy Society of Japan. “Where will the garbage go? Is it pulverized? These are the questions that need to be asked.”