Eight years ago, a magnitude 9 earthquake shook Japan, leading to a terrifying tsunami that killed 15,896 people. It was the strongest ever recorded in the Asian country and was the cause of the Fukushima Daiichi Nuclear Disaster, the second-most serious nuclear disaster since the 1986 Chernobyl event.
The facility had six nuclear reactors. In March 2011, reactor 4 was defueled, and reactor 5 and 6 were in cold shutdown for maintenance. The moment the earthquake struck, reactor 1, 2, and 3 shut down automatically and emergency generators came on to continue to provide coolant and keep the reactors from melting. Then, the tsunami hit.
The incredible wave topped the power plant's 5.7-meter (19-foot) seawall, flooding the facility and shutting down the emergency generators. Switching stations that provided power to three backup generators also flooded, despite being located uphill. The reactor cooling system was switched to batteries. More emergency generators were dispatched, but it took many hours to get there due to poor road conditions after the tsunami. The disaster was a perfect storm of underestimating nature’s power, possible design problems, and unfortunate equipment failure.
Over the following days, reactions between the water and fuel rod cladding led to the formation of hydrogen gas, which ignited in an explosive manner. The roof of reactor 1, 3, and 4 blew up, injuring 16 people in total. Without coolant, the core melted and nuclear material was either released to avoid greater risk or leaked out into the ocean. Research estimates that, at most, the contamination was 42 percent of Chernobyl's emissions.
Despite the radiation leak, there was no death due to acute radiation syndrome. In total, 37 workers received physical injuries during the aftermath and two had radiation burns. A former station workman has since died of cancer related to the disaster and his family was awarded compensation. The evacuation, however, caused more deaths, with over 2,000 disaster-related deaths of hospital inpatients and elderly people who died from hypothermia, deterioration of their pre-existing condition, dehydration in the evacuation, or from long-term displacement sparked by the disaster.
Estimations from the World Health Organization don't see any major radiation risk in the evacuated population. The report shows that they were exposed to so little radiation that it does not significantly affect their overall cancer risk. Given the extensive use of remote technology, the clean-up crew is also not expected to be affected by the radiation.
However, nuclear contamination persists in the region. While certain isotopes have a short half-life, others like cesium-137 will remain in the environment for decades. In the summer of 2011, these long-lasting radioactive elements were measured at contamination levels in the soil between 1.6 and 4.6 times the legal limit. The soil is also affecting wildlife, from plants to mushrooms to wild animals. Researchers have been collecting data on these wild populations from the beginning, with research on-going. There is a lot we don’t know about organisms' tolerance to ionizing radiation. In Chernobyl, we saw the decay of some species, while certain wild populations began to thrive due to the sudden disappearance of humans.
Researchers also witnessed declines in both the abundance and diversity of birds in the first three years after the nuclear accident. This wasn't across the board though, with some species being more sensitive than others. There were also declines in certain insects, as well as harmful mutations, although it is uncertain whether or not these were related to Fukushima. The picture is unfortunately far from complete. Teams are also decontaminating nearby waters, but they have so far failed to safely remove the most dangerous radioactive isotopes. Research has found that sand along the coastline has also been contaminated.
The decontamination of the facility, the water, and the nearby area is ongoing. It is a challenging endeavor and needs to be done correctly. The team is planning to decontaminate soil that releases more than 1 millisievert of radiation per year, which is the EPA limit for a yearly dose. Around 4 sieverts of radiation is enough to kill a person. The highest recorded level inside the melted reactors was 530 sieverts per hour, but thankfully radiation is not leaking out of them.
The decommissioning of the nuclear power station is expected to last for decades. The removal of the fuel in the three reactors that suffered the core meltdown is expected to start in 2021. It is also been suggested that a sarcophagus like the one being built in Chernobyl could help. There are currently no plans for this course of action, but if taken, it might not be as simple as putting a lid on the reactors. The entire facility will have to be strengthened to be more resilient in case of another extreme natural disaster.