IAEA experts at the Fukushima Daiichi nuclear power plant

Fukushima plant clean-up postponed by robot development delays

The removal of highly radioactive melted fuel from Fukushima's damaged reactors has been postponed due to delays in the development of a remote-controlled robotic arm.

Tokyo Electric Power Company Holdings (Tepco) had originally planned to begin removing melted fuel from the Unit 2 reactor at the Fukushima Daiichi plant last year, 10 years after the disaster triggered by a massive earthquake and tsunami on 11 March 2011.

That plan was postponed until later this year, and now will be delayed further until about autumn next year because of additional work needed to improve the performance of the robotic arm needed for the fuel removal process, the company said.

The giant arm, jointly developed by Veolia Nuclear Solutions of Britain and Japan’s Mitsubishi Heavy Industries, has been transported to Japan and is being adjusted at a testing facility south of the Fukushima plant.

The delay will not affect the overall decommissioning at the plant, which is expected to take 30-40 years, Tepco said. However, experts have said the completion target is too optimistic.

In March 2011, a large undersea quake off the coast of Japan triggered a massive tsunami. At the time, three of the six nuclear reactors at the Fukushima Daiichi nuclear plant were in operation. When the huge waves flooded the backup generators, the cooling systems failed, causing the reactors to go into meltdown.  

The meltdown was considered the worst nuclear disaster since that of Chernobyl, Ukraine, in April 1986.

During the accident, an estimated 880 tons of highly radioactive nuclear fuel in the three damaged reactors melted and fell to the bottom of their primary containment vessels, where it hardened, most likely mixed with broken parts of the reactor and the concrete foundation. Its removal is by far the toughest challenge of the decommissioning process.

Although there were no reported deaths or cases of radiation sickness directly caused by the nuclear accident, over 100,000 people were evacuated from their homes as a preventative measure and many have not returned. 

To date, Tepco has made progress in assessing the condition of the fuel in the reactors in recent years by sending remote-controlled robots inside the primary containment vessels. But data and images provided by the probes are still partial, and experts say it is too early to imagine when or how the clean-up will end.

Earlier this year, Tepco executives were ordered by a court to pay a $94.8bn (£80bn) fine for failing to exercise due care and carry out preventative measures such as placing an emergency power source on higher ground, which could have avoided the worst of the disaster. 

The continuing need to cool the fuel remaining in the reactors has resulted in massive amounts of treated but still radioactive used cooling water that is being stored in about 1,000 tanks on the grounds of the plant. Seven years after the disaster, a Greenpeace report found that radiation levels in the area continued to be up to 100 times higher than normal.

The government has announced a plan to start releasing the stored water into the sea after further treatment and dilution in the spring of 2023, a plan that has been fiercely opposed by local residents, the fishing community and neighbouring countries.

Despite the Japanese public position against nuclear energy, during an energy policy meeting this week, Prime Minister Fumio Kishida revealed he had directed a government panel to look into how “next-generation nuclear reactors equipped with new safety mechanisms” could be used to help Japan achieve its goal of carbon neutrality by 2050. 

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