A triple disaster struck Japan’s main island on the afternoon of March 11, 2011. An earthquake measuring 9.0 on the Richter scale, never before recorded in the country, hit the east coast of the main island. Less than an hour after the strong tremors, giant waves washed over several areas of the Japanese coast, causing 16,000 deaths and the destruction of tens of thousands of homes, buildings and infrastructure. There were 241 municipalities affected in 10 provinces. Nearly half a million people had to be evacuated from the area.
The tsunami triggered a third tragic event: the Fukushima Daiichi Nuclear Power Plant was flooded by the waves, which caused the overheating of three nuclear reactors and the subsequent release of radioactive substances into the air. As a result of the accident, the worst since Chernobyl, the government established an evacuation zone within 30 kilometers of the plant, causing 160,000 residents of Fukushima prefecture to flee their homes.
There are no records of deaths caused by the nuclear accident that day. About 50 employees were injured in explosions that occurred in the buildings that housed the reactors. However, several people later died as a result of evacuation and physical stress, especially elderly people and patients who had to be transferred from risk areas. In 2018, the Japanese government acknowledged that one of the plant’s workers died of a cancer caused due to radiation exposure during the days after the accident.
According to the latest Japanese government report from February 2022, the death toll from the triple tragedy reached 19,747, including people who died due to physical exhaustion caused by evacuation, excessive work, among other indirect causes related to the earthquake. More than two thousand people are still considered missing.
Since that day, eleven years have passed and Japan still has to deal with the aftermath of the disaster. The challenges range from decontaminating areas and dismantling the Daiichi plant to rebuilding cities and caring for the mental health of affected residents.
The decontamination process
After the nuclear accident, 12% of Fukushima Prefecture was evacuated. The radiation level at the plant reached close to 12,000 μSv/h (microsievert per hour) on March 15, 2011, after an explosion in the chamber of one of the reactors, according to monitoring by the Tokyo Electric Power Company (Tepco), the company responsible for power plant. Sievert (Sv) is the unit used to measure the biological effects of radiation and the average dose to which a person is exposed is 2,400 μSv per year. Transcontinental flights and diagnostic tests increase exposure.
Radiation decreased considerably in the days following the explosions, reaching 53 μSv/h at the main entrance on April 25 of that year, but more than 100 Tepco workers received doses above 100,000 μSv by the end of 2011. In the city of Fukushima, capital of the prefecture that is about 60 kilometers from the plant, the radiation level rose to 20 μSv/h shortly after the accident.
Now, according to the local government, the restricted area is equivalent to approximately 2.4% of the territory and the number of residents who have not returned is 34,000, according to December 2021 data. Many have started their lives over in other cities and provinces, others they did not return because they still fear the effects of radiation or because the places where they lived were not released – an area of 337 square kilometers, close to the deactivated plant, is still considered “a zone of difficult return”.
In September last year, the radiation level in areas of the province outside the 20-kilometer radius of the plant was less than 0.12 μSv/h, equivalent to that recorded in cities such as London, Hong Kong and Seoul. In the exclusion zone, the measurement is higher: it varies from 0.09 to 4 μSv/h.
This reduction in radiation occurs mainly naturally. But the Japanese government also carried out decontamination of houses, buildings, forests near residential areas and crops, in order to remove radioactive materials from housing areas and lessen the impacts on human health and the environment.
Houses, for example, were decontaminated by washing and removing sediment in backyards – some buildings were demolished in the cities closest to the plant. Agricultural land that had not been sown had the topsoil removed. In the forests, organic sediments were removed from the soil and some plants were pruned.
According to Fukushima Prefecture, more than 20 kilometers of roads, 12,300 hectares of forest, 40,000 hectares of agricultural land, 12,376 public establishments and 441,000 homes were decontaminated. The rate of radiation from the air in residential and farm areas decreased by 60% after decontamination. In forests, the reduction was 30% and on roads, 44%. Decontamination work is still in progress, now in the areas defined as “hard-to-return zones”, closer to the plant.
As a result of this work, about 14 million cubic meters of contaminated soil needed to be stored. First, the material had been placed in hundreds of locations close to where it was removed, in special plastic bags surrounded by sandbags to block contamination from the air. In 2017, this material began to be shipped to the Interim Storage Facility, an area of 1,600 hectares close to the plant, where soil and radioactive waste will be stored until 2045. This work is expected to be completed by 2022. Sites that served of temporary storage are being restored.
After this period, the Japanese government will have to transport the contaminated soil to a location outside Fukushima Prefecture, which has not yet been chosen, so that this material is permanently stored. Other types of waste generated from the disaster, as well as the remains of buildings that were demolished in the decontamination process, are also being treated. By mid-2020, 480,000 tonnes had been incinerated and 1.6 million tonnes had been recycled in Fukushima Prefecture.
The Ministry of the Environment of Japan wants to promote “as much as possible” the recycling of soil in order to reduce the volume of material that will be permanently stored. Recycled soil could be used, for example, in government construction across Japan, such as road repairs. But convincing the population that this is a good idea will be another challenge for the authorities.
The first pilot projects, announced for Fukushima Prefecture, did not please the residents, especially the farmers in the region, who are still suffering the consequences of the nuclear disaster, such as the prices of products grown there, which are still below the national average and suffer import restrictions from some countries.
The challenge of dismantling the plant
The decommissioning of the Fukushima-Daiichi nuclear power plant is also a long-term job, estimated at 40 years. The process, carried out by Tepco and monitored by the Japanese government and international agencies, involves three phases: the extraction of nuclear fuel, the extraction of the melted fuel in the nuclear reactors and the dismantling of the plant.
According to the latest report published on the Japanese Ministry of Economy website, from January 2022, the removal of fuel (rods containing uranium capsules) from the Used Fuel Pools (PCU) has been completed in two of the plant’s four reactors. affected by the tsunami. The forecast for the other two is that the extraction of radioactive material will begin between 2024 and 2027, and that this phase will be completed by 2031.
Tepco is also studying how to remove radioactive debris with robots. In Units 1 through 3, where there were explosions, the fuel and the metal casing tube covering the copper melted and then solidified into fuel debris. Preparations are underway to retrieve these remains remotely. The dismantling of the reactor facilities is the last step towards the decommissioning of the plant.
The company and the Japanese government also had to take steps to treat contaminated water from the plant’s system, used to cool fuel waste, and store it. In the treatment process, 62 types of radioactive substances have their concentration reduced to internationally recommended levels for the disposal of waste water from nuclear plants, with the exception of tritium, a radioactive isotope of hydrogen that is present in the environment and is harmful to humans. only in very high doses.
By 2020, approximately 140,000 liters of contaminated water were being generated per day. Tepco has built more than 1,000 tanks to store around 1.25 million tons of processed water at the site, but it is estimated that this year these reservoirs will reach full capacity. That’s why the operator and the government of Japan announced last year that they are planning to release this water into the ocean over the next few decades.
The process, as the director of the International Atomic Energy Agency (IAEA) explained at the time of the announcement, has already been done before and the water will be diluted to reduce tritium contamination to lower levels than recommended by the Organization. World Health Organization for drinking water.
However, the plan did not please neighboring countries such as China and South Korea, environmental groups such as Greenpeace, which ask that the water be released only after the filtration process is improved, and the region’s fishermen, who are wary. that this damages the image of the Fukushima fishing industry after years of efforts to improve it with customers and dealers.
Despite the protests, preparations for the release are underway. In February of this year, six IAEA officials and eight experts from different countries visited Japan to verify the contaminated water treatment process, observing technical aspects related to the radiological characterization of the water to be discarded, aspects related to the safety of the process and the Japan government assessment of radiological environmental impact. A report is due in April.
This report is part of a three-part series on the revitalization of Fukushima and the challenges facing the Japanese government after the great earthquake and nuclear accident of 2011.
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