Anniversary: Reflecting on the impacts of Fukushima Daiichi

09 March 2021

The slow-down in the development of nuclear energy globally, as a result of the Fukushima Daiichi accident, poses dire consequences for our fight against climate change, global human health and the resilience of global electricity systems, writes Sama Bilbao y León, director general of World Nuclear Association.

Staff working on ALPS clean-up treatment of contaminated water (Image: Tepco)

On 11 March 2011 at 2:46pm the Great East Japan Earthquake, the most powerful ever recorded in the country, shook Japan for six minutes. In response to the earthquake 11 reactors at four nuclear power plants at Fukushima Daiichi, Fukushima Daini, Onagawa and Tokai shut down generation automatically as they were designed to do. As the reactors stopped generating electricity, external power was used to run control systems and to circulate water cooling the still-hot nuclear fuel in the reactors.

Ten minutes after the earthquake, the first of two huge tsunami waves hit the Japanese coast. The waves, travelling at up to 700 km/h and with a height of up to 40m, caused unimaginable devastation up to 10km inland. Nearly 20,000 people died in the disaster, the majority from drowning, and more than 2500 people are still missing. More than one million buildings were damaged, and more than four million people lost their electricity supply. Many industrial facilities were affected, resulting in significant damage and irreversible environmental impacts.

At Fukushima Daiichi, the tsunami arrived 50 minutes after the earthquake. It flooded and destroyed all but one of the diesel generators which provided the site with power. In the midst of impossibly challenging circumstances, and despite courageous efforts by the workers to power the systems, it was not possible to maintain the cooling of the reactors. The fuel in reactors 1, 2 and 3 melted, and the accumulation of hydrogen, produced by the reaction of the hot zirconium fuel cladding with water, resulted in explosions at reactors 1, 2 and 4 over the days that followed. These explosions, along with venting of the reactors to reduce pressure, released radioactive material. Much of this was blown by prevailing winds to sea, but a change in wind direction later on resulted in contamination to the north-west of the plant.

Cooling was restored over the three days following the accident, at first using seawater, and then with fresh water. Fresh water cooling and off-site electricity supply were restored within 15 days, but still much remained to be done.

Over the last 10 years a huge effort has been under way at Fukushima Daiichi to restore the site. Enormous progress has been made thanks to the cooperation and support of the global nuclear community, and the openness and transparency of Japan throughout. As a result, most of the site can now be accessed using regular protective clothing and the removal of the fuel assemblies in the fuel pools at units 3 and 4 has been completed.

The full decommissioning of the site will not be complete for several decades, the complexities of removing fuel that had melted from the damaged reactors presents a challenging project. Just as important are the efforts already under way to rebuild the social and economic fabric of the region, not only in the areas affected by the accident, but also the much broader area impacted by the earthquake and resulting tsunami.

We have also seen a decade of action from the global nuclear industry. In response to the accident, governments, regulators and nuclear operators around the world carried out ‘stress tests’ on their plants to explore how they could minimise the risk of similar accidents happening. Existing units have been hardened against extreme external events. New reactor designs have incorporated these systems, and emergency response regulations have applied the lessons learned from the event.

In addition, there have been global efforts to move to a more systematic and holistic approach to safety, with more effective coordination between regulatory authorities, government and industry. There has also been more emphasis on the importance of cultural aspects in organisational and safety culture.

When the events at Fukushima Daiichi were unfolding, authorities implemented progressively larger evacuation zones, requiring those within 20km of the site to evacuate immediately. These evacuation zones were a blanket measure, rather than reflecting any increase in radiation detected. In all evacuated areas permission to return has been slow, with tens of thousands of people living in temporary accommodation for long periods of time.

The rapidly implemented and protracted evacuation has resulted in well-documented significant negative social and health impacts. In total, it is thought to have been responsible for more than 2000 premature deaths among the 160,000 who were evacuated. The rapid evacuation of the frail elderly, as well at those requiring hospital care had a near-immediate toll. The prolonged evacuation and widespread stigmatisation have resulted in evacuees reporting stress, anxiety and other mental health issues, and higher incidence of smoking and alcohol abuse.

When facing future scenarios concerning public health and safety, whatever the event, it is important that authorities take an all-hazards approach. There are risks involved in all human activities, not just nuclear power generation. Actions taken to mitigate a situation should not result in worse impacts than the original events. This is particularly important when managing the response to incidents at nuclear facilities where fear of radiation may lead to an overly conservative assessment and a lack of perspective for relative risks.

The same all-hazards perspective is needed when looking at energy policy in a broader context. Within days of the events, Germany decided on the premature closure of its nuclear power plants, with around half closing immediately, and the rest to be shut by 2022. This is despite its own nuclear safety authority determining the reactors were safe to continue operating. The closure of nuclear plants in Germany has meant that the expansion in renewable generation there has largely resulted in the replacement of one low-carbon form of generation - nuclear energy - with another, instead of replacing fossil fuels. Although the last nuclear plants in Germany will close next year, coal won’t be phased out until 2038 and then will be replaced by fossil gas.

According to one study, in 2013 alone the pollution from Germany’s coal-fired power plants was responsible for the deaths of more than 1800 people, and imports into Germany of electricity generated by coal plants in other countries resulted in a similar number of fatalities.

While most countries did not react as extremely as Germany did, there was a slow-down in the expected development of new nuclear projects. This has already impacted the global level of generation from nuclear power and, with it, progress towards achieving the decarbonisation of the global electricity mix. While the effects of this delay will take longer to be felt, it potentially will have an even greater impact on people and the environment, unless urgent action is taken to accelerate the rate of nuclear construction and maintain the operation of existing plants wherever possible.

The global nuclear industry has come together to support Japan and has risen to the challenge of responding quickly and effectively to address the event and its consequences, and has put in place measures to minimise the likelihood of a similar event happening again. Yet, despite the serious consequences of the event to the global nuclear sector, the graver and broader consequences are still to manifest themselves. It is the slow-down in the development of nuclear energy globally that will have the biggest impact, with dire consequences for our fight against climate change, global human health and the resilience of global electricity systems.

Researched and written by World Nuclear News