In one of the world's most technologically advanced nations, a triple catastrophe -- earthquake, tsunami and nuclear meltdown -- struck with awesome ferocity. In the aftermath, millions wondered how much of Japan's Fukushima disaster could have been avoided. According to international experts, the nuclear accident was, tragically, entirely preventable. Here's the story of the worst nuclear accident of the 21st century -- so far.
The Fukushima Daiichi Nuclear Plant
There are two nuclear power plants in the Fukushima prefecture in east-central Japan: the Daiichi plant and the Daini plant, located roughly 7 miles apart. The Fukushima Daiichi plant is sited about 130 miles north of Tokyo on the island of Honshu, the largest of the thousands of islands that make up the nation of Japan.
(Because only the Daiichi plant was involved in what's commonly known as the "Fukushima disaster," this article will focus on that nuclear power plant, not the nearby Daini plant.)
Six nuclear reactors were built at the Fukushima Daiichi facility; construction of these reactors began in the 1960s and was completed in the 1970s. The reactors, designed by the American company General Electric, are boiling water reactors that create electricity through steam-powered electrical generators. Capable of producing 4.7 gigawatts of electricity, when constructed it was one of the most powerful nuclear plants in the world.
The Daiichi plant was located near the seaside and was originally designed to withstand a tsunami wave about 10 feet high -- despite the fact that the Fukushima shore had experienced eight tsunamis higher than that in the past century alone. Two recent Japanese tsunamis, in 1983 and 1993, measured 47 feet and 102 feet high, respectively. Though plant operator Tokyo Electric Power Company (TEPCO) knew of these safety vulnerabilities, it shrugged off repeated warnings of Fukushima's safety shortcomings, doing little to implement recommended changes in the plant's design or emergency response plans.
In other words, it was only a matter of time before disaster struck. And in March of 2011, it struck with terrifying fury.
The Fukushima Earthquake and Tsunami
At 2:46 in the afternoon of Friday, March 11, 2011, a mammoth earthquake of magnitude 9.0 hammered the east coast of Japan; the epicenter was about 81 miles offshore. The quake was so powerful it moved Japan several feet to the east, and the coastline sunk about 17 inches in some areas. Hundreds of aftershocks, some as strong as 7.1, rocked the area for several days afterwards.
The Fukushima Daiichi plant was reportedly able to withstand the earthquakes without any significant damage, and the facility went into automatic shutdown, as it was designed to do. Backup generators supplied electricity to the plant to maintain critical cooling operations inside the six reactors.
However, within an hour, a tsunami wave measuring up to 49 feet high hit the Fukushima coast. In the aftermath of the natural disaster, over 19,000 people were killed, mostly due to the sudden flooding that destroyed millions of buildings in an area of over 200 square miles.
When the tsunami crashed into TEPCO's Fukushima plant, 12 of the 13 backup generators were flooded beneath the tsunami, completely disabling them. Without any source of electrical energy, and despite desperate efforts from emergency crews, there was no way to keep the nuclear reactors cooled down to safe levels. And when nuclear reactors can't be kept cool and nuclear fuel rods overheat, nuclear meltdown begins, releasing radiation into the environment.
Meltdown conditions caused tremendous heat and pressure to build up inside Fukushima's reactors, triggering the first of several explosions on March 12. Soon, large sections of the facility were completely destroyed and radioactive iodine-131 and caesium-137 were released into the atmosphere. Within days of the disaster, three of the six reactors were in full meltdown.
Though large swaths of the Fukushima area had already been evacuated (or destroyed), the government instituted a larger, 20-kilometer (12.4 mile) evacuation zone around the destroyed facility, displacing roughly 160,000 people. Some of these evacuees may never return to their homes or businesses.
Fallout from the Fukushima Disaster
As the Fukushima disaster unfolded, scientists and government officials began to assess the complete impact of the crisis. Though it was initially rated as a Level 4 accident on the International Nuclear Event Scale by Japanese officials, that rating was eventually raised to 7, the highest value in the scale.
Only one other nuclear crisis compares to Fukushima in terms of intensity and impact: the Chernobyl disaster. Officials have determined that Fukushima released only one-tenth the radiation that was released by Chernobyl, but some conflicting reports have found that the amount of caesium-137 from Fukushima was as high as 40 percent of that released from Chernobyl.
Radioactive contamination of the region surrounding the plant -- as well as the Pacific Ocean, where radioactive water was dumped after the disaster -- caused the government to ban the use of food and tap water throughout Japan. Indeed, radioactive isotopes were detected in eastern Russia and the west coast of the United States in the days following the disaster; soon, radioactivity levels spiked at detection units in Canada, Europe and all over the northern hemisphere.
Who's at Fault?
Fortunately, there were no human deaths from radiation sickness from the Fukushima disaster. Because of the evacuation and disaster response, the overall number of cancer deaths related to the accident are expected to be in the range of 100 to 1,000 over the next several decades. Those numbers could have been much higher -- the number of eventual cancer-related deaths from Chernobyl, by comparison, could be almost 10,000.
Following the Fukushima accident, the usual amount of finger-pointing, hand-wringing and litigation ensued. In July of 2012, a government investigation determined that, rather than a natural disaster, Fukushima "was a profoundly man-made disaster -- that could and should have been foreseen and prevented."
A vast array of errors, omissions, miscalculations, hubris, arrogance and plain-old sloppy engineering were documented, with TEPCO as the primary responsible party, because the company failed to invest time, money or energy into improving plant safety -- despite overwhelming evidence that the plant was wholly unprepared for even a small tsunami wave. TEPCO "mishandled its response to the crisis and nuclear regulators failed to prepare sufficient disaster-mitigation measures as they were overly confident about the safety of nuclear power," according to an independent investigation.
Cleanup and remediation at Fukushima are expected to continue for several decades, and the area immediately surrounding the plant will remain unsafe for many years due to high levels of radiation. It will also be many years before the full environmental impact of the disaster is known, though early reports are troubling: Scientist have already reported that butterflies in the Fukushima area have severe mutations, including abnormal wings, legs and antennae.