For most earthquakes, few scars in the environment and society are felt 10 years on. Not, however, for the Fukushima nuclear disaster.
On March 11, 2011, a 9.1 magnitude earthquake occurred off the coast of eastern Japan. It was the fourth largest in recorded history, producing a tsunami that engulfed Japan’s northeastern coastline, particularly damaging Miyagi, Iwate and Fukushima prefectures. More than 15,000 people were killed, 6,000 were injured, and more than 2,000 people were missing.
Meltdown
Upon detecting the earthquake, all the active reactors in the plant shut down. They withstood the earthquake without serious damage. Though the frisson reactions ceased, the fuel rods were still hot. Normally, pumps in the reactors would circulate water through the cores to remove the heat.
But at the Fukushima power plant, the external power supply was damaged from the earthquake, and flooding from the tsunami destroyed the emergency cooling system. With the pumps unable to push seawater through the coolant systems, the temperature and pressure in three reactors kept increasing. Venting of the steam pressure building up led to hydrogen explosions, releasing radiation into the atmosphere. In an investigation, the remains of the melted fuel rods have been found at the bottom of the pressure vessel; some have breached the vessel and dropped into the containment building.
Under normal circumstances, spent fuel rods will continue generating decay heat. They need to be moved to pools of circulating water for years to have the heat reduced to a certain degree, before being stored in dry casks.
And the used rods at the Fukushima power plant have been cooling down for 10 years, and authorities plan to pick them up from the water this year.
Water Contamination
Over the past decade, the water used to cool down the spent fuel rods has become contaminated. While the earthquake has damaged the facilities and caused leaks, a large amount of groundwater has been flowing into the reactor buildings and contaminated. According to a 2015 report by the International Atomic Energy Agency, about 800 square meters of radioactive water are produced at the Fukushima power plant. Many water tanks have been built to store the water. It is expected that around 1.37 million square meters of radioactive water could be stored here.
According to government data, around 1.24 million square meters of radioactive water has been stored at the Fukushima power plant as of February 18, 2021.
Currently, the water is filtered by a process designed to remove radioactive contaminants, including cesium, strontium, cobalt, antimony, ruthenium, iodine, tectonium, and rhodium. Tritium, the isotope of hydrogen, isn’t removable.
The water, which contains tritium, has taken up 91% of the storage space. A long-term solution is a matter of urgency.
The Japanese government once considered diluting the tritium-tainted water to meet international standards before discharging it into the sea. But the plan faced severe opposition by the public. According to NHK, 51% of the people oppose discharging the polluted water into the sea.
Soil Contamination
Radiation from the hydrogen explosions contaminated the surrounding soil. Japanese authorities have carried out decontamination work in areas surrounding the power plant, including Iwate, Miyagi, Fukushima, Ibaraki, Tochigi, Gunma, Saitama, and Chiba. Fukushima Prefecture contained the most area that required decontamination.
In the decontaminating soil, the first step is digging up a thick layer of topsoil and plants, and pile them in a waterproof manner in what’s called a Temporary Storage Site (TSS). The equipment used to deal with contaminated soil are marked as waste material.
All contaminated soil and waste are then transported to an Interim Storage Facility. There that which is combustible will be incinerated, and the ash stored. Soil will be separated out and buried in a storage soil facility, while the ash is stored separately.
All areas in Fukushima Prefecture declared cleared in 2018. Around 14 million cubic meters of soil and related waste were removed.
According to official sources, as of February 25, 2021, 74.9% of the contaminated soil and related waste in Fukushima Prefecture have been transported to the interim storage facilities located around the Fukushima nuclear power plant. Other prefectures and cities cleared about 470,000 cubic meters of contaminated soil and waste, which are temporarily held locally.
However, these are still temporary or intermediate storage facilities. According to the plan, all polluted waste will be moved to an undetermined final disposal site outside Fukushima Prefecture after 30 years.
Most countries have lifted bans on importing food products from the five Japanese prefectures most affected by the disaster.
In 2011, after the disaster occured, many countries restricted or outright banned Japanese food imports. But now, the majority of these countries have scrapped the restrictions. The graph below shows the change in the number of countries banning, limiting, and allowing Japanese food imports.
Regulations for Japanese food imports vary among countries that still have restrictions in place. Some prohibit specific products from certain areas, while others demand a certificate of origin or proof of radiation detection. The countries that have not fully removed restrictions on Japanese food imports are China, Russia, Singapore, the United States, Philippines, United Arab Emirates, Hong Kong, Macau, European Union (excluding Iceland, Norway, Switzerland, and Liechtenstein), and Taiwan.
Since March 26, 2011, Taiwan has banned the import of food products produced in five Japanese prefectures: Fukushima, Ibaraki, Tochigi, Gunma, and Chiba. Importers of food products from other prefectures need to provide a certificate of origin. Taiwanese authorities will examine eight categories of the food imports (fresh/refrigerated vegetables and fruit, frozen vegetables and fruit, fresh/refrigerated seafood, frozen seafood, dairy, baby food, mineral/drinking water, or seaweed) in batches to confirm the level of radiation.
Decommissioning
At the end of February 2021, the Tokyo Electric Power Company (Tepco) announced that it had taken out all the nuclear fuel used in the “Used Nuclear Fuel Pool” of Unit 3. They hope to be able to do the same on Units 1 and 2 by the end of 2031.
However, Greenpeace issued a report in early March, saying their test indicated “radiation well above the Japanese government’s decontamination target levels” across the Special Decontamination Area.
It is estimated that the waste furnace will cost at least 2 trillion yen. If compensation and decontamination costs are added, it will cost at least 12.7 trillion yen, or about US$24.8 billion.
Tepco estimates that it will take another 30 to 40 years to complete the incineration.
