The 2011 disaster at the Fukushima Daiichi nuclear power plant was the worst nuclear event since the Chernobyl merger in the former Soviet Union 25 years earlier.
It started with an earthquake. This resulted in 465,000 evacuations, $ 360 billion in economic losses and increased radiation levels in Tokyo, 140 kilometers away.
As with most disasters, several things must have gone wrong to produce such a catastrophic result. Below is a detailed account of how the devastation unfolded.
A broken photo frame lies in the mud in the exclusion zone, about 20 kilometers from the Fukushima nuclear power plant on April 7, 2011 in Minamisoma, Fukushima prefecture, Japan.
Athit Perawongmetha / Getty Images
March 11, 2011: An earthquake precipitates the crisis
2:46 p.m .: The westward moving Pacific Plate, an oceanic tectonic plate, slopes downward beneath the North American Plate, causing an earthquake 43 miles off the northeast coast of Honshu, the most populous island in Japan. The earthquake has a magnitude of 9.1, making it the largest earthquake in Japanese history – and one of the five strongest earthquakes on record in the world since the hold began. modern registers.
3:27 p.m .: The earthquake triggers a tsunami. The first wave arrives at the Fukushima Daiichi nuclear power plant as a 13-foot-high wave, which is deflected by a seawall built to withstand waves up to 33 feet high.
3.35 p.m .: A second wave, this one over 50 feet high, broke through the wall. He destroyed the seawater pumps, drowned the electrical panels that distribute energy to the water pumps and burst into the basements where emergency generators were housed. In five of the six reactors, the alternating current is lost; without electricity, water pumps cannot provide the constant flow of cold water to the extremely hot cores of reactors. Without the steady flow of cooling water, melting will inevitably follow.
READ MORE: Chernobyl timeline: How a nuclear accident turned into a historic disaster
3:37 p.m .: As the floods destroyed the generator back-up batteries, Unit 1 also lost direct current. The control room of units 1 and 2 becomes dark, depriving the operators of the power plants of any capacity to monitor the two reactors.
Just before 6 p.m.: A work team went to the 4th floor of the unit 1 reactor building without protective clothing. Their dosimeters read out-of-scale radiation levels, indicating that Unit 1’s core is exposed and its fuel rods are ruptured.
7:03 p.m .: Prime Minister Naoto Kan declares a nuclear emergency.
9:00 p.m .: The Japanese government is issuing evacuation orders for the several thousand residents living within a 3 km radius of the power plant.
Fukushima Daiichi Nucler Power Plant emerged after a strong 9.0 magnitude earthquake struck on March 11, 2011 off the coast of northeastern Japan.
The Asahi Shimbun / Getty Images
March 12: the evacuation zone expands, the roof blows
Shortly before 6 a.m.: Prime Minister Kan decides to go to Fukushima. He ordered the authorities to expand the evacuation zone to 10 kilometers. With the loss of coolant, the temperature and pressure increase inside the reactors.
10:09 am: The Tokyo Electric Power Company (TEPCO) announces that it has evacuated steam from Unit 1 in an attempt to lower the temperature and pressure. Ventilation means that radioactive material has been released into the air.
10:58 am: Unit 2, it is reported, has also been ventilated.
3:36 p.m .: A hydrogen explosion blows up the roof of Unit 1, causing the concrete walls to collapse and leaving only the steel frame. Four workers are injured in the explosion. In addition to damage to workers, the explosion damaged the electric cable that the workers had laid in order to restore power to units 1 and 2. The explosion also damaged the fire hoses that the workers had laid out, hindering the plant’s ability to supply coolant. the reactor core.
Just before 6.30 p.m .: The evacuation zone is extended to a radius of 20 kilometers.
8:20 p.m .: TEPCO begins to inject seawater into Unit 1, as a replacement coolant. The decision to use seawater is the death knell for Reactor 1: unlike fresh water, it irreparably corrodes pumps and pipes. At around the same time, the Japan Nuclear and Industrial Safety Agency (NISA) detects harmful radiation levels of cesium 137 and iodine 131 near the plant.
READ MORE: The Chernobyl cover-up: How authorities botched the evacuation of an irradiated city
March 13
6:23 a.m .: An NISA official announces that the emergency cooling system for the Unit 3 reactor has failed.
10:05 p.m .: TEPCO begins to inject seawater into unit 3.
10:09 p.m .: TEPCO announces a seawater injection plan in Unit 2, the first emergency reconnaissance in this reactor.
In this satellite view, the Fukushima Dai-ichi nuclear power plant after a massive earthquake and tsunami that followed on March 14, 2011. Japanese officials report that a fire at the distressed Fukushima nuclear power plant released material radioactive in the air in the latest development amid the chaos caused by the recent earthquake and tsunami that claimed at least 10,000 lives in northeastern Japan.
DigitalGlobe / Getty Images
March 14: The explosions continue
11:01 am: There is a hydrogen explosion in the unit 3 reactor. 11 workers are injured and the building structure is severely damaged.
March 15
6:14 am: A hydrogen explosion occurs in the unit 2 reactor.
During the day: Pumping of seawater continues at units 1, 2 and 3. Near the plant, radiation levels are measured at 400 millisieverts per hour. In comparison, the average person is exposed to around 2.4 millisieverts of radiation per year, which means that the radiation in Fukushima is 1.46 million times stronger than it would be in an average environment.
the 17th of March
The military begins using helicopters to dump seawater onto Unit 3, where radiation levels are 17 millisieverts per hour.
March 19
Replacement diesel generators are successfully implemented in Units 5 and 6, forcing water back into the cores of these reactors. Elsewhere, the extent of the damage becomes clearer: Milk and water in the large prefecture of Fukushima have excessively high levels of radioactive iodine.
READ MORE: Chernobyl: 7 people who played pivotal roles in world’s worst nuclear disaster
The radioactive soil has been decontaminated from the land around Fukushima and packed in black bags which are stacked on stacks while waiting to be transported to intermediate storage.
Jonas Gratzer / LightRocket / Getty Images
March 20: things start to stabilize
Temperatures stabilize at Units 5 and 6, providing the safe harbor of “cold shutdown” conditions. Power is restored to unit 2.
March 22
Eleven days after the initial disaster, power is restored to the control rooms of units 1 and 2. In the wastewater just south of the plant, radioactive iodine is measured to be 126.7 times higher than the legal limit.
March 25
Unit 1 reactor temperature is reduced to 204.5 degrees Celsius, safely within its design limits. The Japanese government is advising residents within 20 to 30 kilometers of the plant to voluntarily evacuate the area.
READ MORE: How the Three Mile Island crash was made worse by a chaotic response
March 26
The seawater tested near the plant has 1250 times the legal limit for iodine-131.
April 11
A new earthquake, magnitude 7.0, shakes eastern Japan. For 50 minutes, Fukushima loses energy, preventing the cooling water from reaching units 1, 2 and 3.
April 12: Declaration of atomic disaster
The International Atomic Energy Agency assigns the Fukushima crisis a disaster magnitude of 7, the highest of their magnitude.
May 11
Evacuees who have abandoned their homes within a 20-kilometer radius of Fukushima have two hours to return to pick up any important documents or belongings left in the initial haste of their evacuation.
February 2, 2012
Almost a year after the disaster, the village of Kawauchi – one of nine evacuated municipalities within 20 kilometers of the plant – announces its intention to reopen in the spring.
