The Lessons Learned 10 Years After Japan's Fukushima Nuclear Disaster

The Fukushima Daiichi nuclear disaster began 10 years ago today, marking one of the most serious nuclear accidents in history.

The disaster was deemed to be a level 7 incident on the International Nuclear and Radiological Event Scale—the highest number possible.

It was the worst nuclear accident since Chernobyl in 1986, and it took place amid an earthquake and tsunami that, aside from the nuclear incident, caused nearly 20,000 deaths.

What happened?

Fukushima damage
Damage to the No. 3 reactor building at Fukushima Daiichi nuclear power plant. It took months to cool down the reactors after generators failed. Christopher Furlong/Getty

The nuclear disaster occurred when a 50-foot tsunami struck the power plant after a major earthquake occurred off Japan's coast on the afternoon of March 11, 2011. The plant's emergency systems automatically shut down the reactors after the earthquake, but diesel generators required to cool the reactor cores down were knocked offline by the water that followed.

Plant workers and emergency service personnel struggled for days afterward to restore power to the plant and siphon heat away from the nuclear reactor units, which ended up partially melting and releasing radiation into the air as well as Tokyo Bay and the Pacific Ocean. Meanwhile, Japan's Prime Minister Naoto Kan ordered everyone living within 12 miles to evacuate, affecting tens of thousands of people.

It wasn't until December that the plant reached a "cold shutdown" condition, following months of cooling efforts.

The number of fatalities linked to radiation exposure as a result of the disaster has been a matter of contention. In 2018, Japan announced a worker at the plant had died after being exposed to radiation during the disaster, following a lung cancer diagnosis in 2016.

However, a United Nations Scientific Committee on the Effects of Atomic Radiation 2020 report found "no deterministic health effects or deaths have been observed among workers engaged in emergency work that could be attributed to radiation exposure."

The Japanese government awarded compensation to six power station workers who all developed cancer following the disaster up to the end of 2018. The UN report claimed this "does not imply a scientifically proven cause-effect relationship between radiation exposure and any particular case of cancer."

Many people died as a result of the evacuation efforts. The UNSCEAR 2020 report stated: "More than 50 hospitalized patients were reported to have died either during or soon after the evacuation and upwards of 100 elderly people may have died in subsequent months because of a variety of conditions linked to the evacuation." World Nuclear said official figures showed there had been 2,313 disaster-related deaths among evacuees.

Scientists have come forward to state what lessons should have been learned from one of the worst nuclear accidents of all time.

Looking back

People wear face masks at Fukushima
Foreign journalists receive information about decommissioning works between reactor unit 2 and unit 3 (in background) at the Fukushima power plant on July 27, 2018. Reports into the incident have been made in the following years, including the UNSCEAR's 2020 report which looked at health implications and radionuclides. Kimimasa Mayama/AFP/Getty

Prof. Richard Wakeford, Centre for Occupational and Environmental Health at the U.K.'s University of Manchester, said in a statement: "Basically, the accident occurred because the station was inundated by a tsunami that damaged emergency equipment and flooded the back-up electricity generators, so the three hot reactor cores were left without adequate cooling leading to damage to, and melting of, nuclear fuel. This was a failure of 'defense in depth': if the first defensive line fails (in this case, the tsunami seawall), there must be reliable defenses in reserve.

"The significant challenge to the radiation safety community is to ensure that major nuclear accidents can be avoided, or the consequences limited. Robust independent regulation is essential, and regulatory systems have been strengthened around the world (especially in Japan) as a result of the Fukushima accident.

"Fortunately, the radiation doses received by workers and the public were nowhere near the high doses received after the Chornobyl accident in 1986. The first concern after an accident at an operating nuclear reactor is to ensure that doses received by thyroid glands, especially those of children, from intakes of radioactive iodine are limited by appropriate protective measures, such as banning local milk supplies. It would appear that restricting intakes of radioiodine was largely successful, although a handful of workers received high thyroid doses."

Prof. Laurence Williams, Centre for Nuclear Engineering, Imperial College London, said in a statement: "The accident at the Fukushima Daiichi nuclear power plant was an accident made in Japan. The fact that the nuclear safety regulator at the time (NISA) was not independent was a major contributor to the accident.

"Had there been a strong, effective and independent nuclear safety regulator, the nuclear reactors at the site would have survived the earthquake and the subsequent tsunami. Ten years on it is important to remember that independence is the cornerstone of effective nuclear safety regulation and we forget this at our peril."

Prof. Jim Smith, professor of Environmental Science at the U.K.'s Portsmouth University, said in a statement: "Ten years after the Fukushima accident, the science so far has confirmed both the initial expectations of low health risks from radiation and the often devastating psychological and social impacts of the accident.

"The initial rapid evacuation and ban on contaminated foodstuffs have kept radiation doses to the population well within the range people get from natural background radiation in many countries, including the U.K. But the evacuation—in many cases permanent—of more than 150,000 people damaged lives and destroyed livelihoods."

Fukushima nuclear plant
Radiation contaminated water tanks and the damaged reactors at Fukushima Daiichi nuclear power plant, February 25, 2016. Tens of thousands of people were evacuated following the incident in 2011. Christopher Furlong/Getty