The 1986 Chernobyl disaster was the worst nuclear accident of its era, eclipsing the radiation leak at Three Mile Island and at other sites. What have we learned from the death and destruction of the Chernobyl accident? Judging by the 2011 nuclear disaster at Japan's Fukushima plant, not much.
A Disaster Waiting to Happen
The Chernobyl nuclear power plant was built in the 1970s and 1980s in northern Ukraine, which at the time was a Soviet republic. The nearby city of Pripyat was a bustling center of nearly 50,000 residents, while the town of Chernobyl had about 12,500 people living in it; the rest of the area was mostly forest or farmland.
Four nuclear reactors had been built at Chernobyl; all were a Soviet-designed and -built model named RBMK-1000. The RBMK series uses the mineral graphite as a moderator to make the nuclear fission process more efficient.
On April 25, 1986, the plant operators began to prepare for a one-time shutdown of Chernobyl reactor number 4. To do that, they disabled some equipment, including the plant's automatic shutdown mechanisms. When very hot nuclear fuel rods were lowered into cooling water, a massive amount of steam was produced, greatly increasing pressure within the reactor core.
The seriously flawed design of the RMBK reactor then caused a chain of events that resulted in the facility's destruction: Shortly before 1:30 a.m. on April 26, as alarms were sounding all over the nuclear plant because of the intense pressure building inside reactor core number 4, a steam explosion blew the cover plate of the reactor partially off, releasing radiation into the atmosphere. A few seconds later, another explosion threw fuel rods and superheated graphite out of the reactor core, causing a number of immense fires to break out all over the Chernobyl facility.
While two plant workers died as a result of the explosions and fires, the worst was yet to come: For the next 10 days -- as emergency crews scrambled desperately to contain the fires and radiation leaks -- the largest uncontrolled release of radiation ever recorded rained radioactive iodine-131, strontium-90 and caesium-137 over hundreds of square miles. Ukraine and neighboring Belarus bore the brunt of the radioactive fallout, though Russia, Scandinavia and other parts of eastern and northern Europe were also affected.
Thirty-one people are believed to have died as a direct result of the Chernobyl nuclear accident, mostly firemen and emergency workers. Many of these workers knew they were sacrificing their lives by exposing themselves to massive doses of radiation; indeed, many tales of personal heroism and sacrifice have emerged from the Chernobyl disaster. By dawn on April 26, all fires had been extinguished, except for the fire raging inside the core of reactor 4, which burned unabated for many days.
The town of Pripyat was not evacuated until the afternoon of April 27 -- roughly 36 hour after the nuclear disaster at the Chernobyl plant. Before that, however, many residents complained about severe headaches, vomiting and other effects of radiation poisoning. Advised that their evacuation would last about three days, residents left behind almost all of their belongings -- these remain sealed in what is today an off-limits ghost town.
Soviet authorities were slow to announce the Chernobyl accident, and quick to downplay the rumors of radiation leaks that were swirling throughout the U.S.S.R. and elsewhere. Only after radiation alarms started going off at a nuclear plant in Sweden -- prevailing winds after the accident carried the fallout west and north into Europe -- did the Soviet government cautiously announce the truth about the disaster.
The enormous plume of radioactive material that escaped from Chernobyl contaminated over 38,000 square miles -- an area larger than the state of Indiana -- falling mostly in Ukraine and Belarus. An estimated five million people were exposed to high levels of radiation, over 200 people were determined to have acute radiation sickness, and 31 died of it. Most of Europe, from Greece to Finland to the British Isles, was also contaminated with some level of radiation.
But as in all cases of tremendous nuclear and chemical disasters, like Bhopal, Fukushima and others, the exact number of deaths and injuries will probably never be known. Some 4,000 cases of thyroid cancer, particularly among children, are believed to have resulted from the Chernobyl disaster. Because radiation-caused cancer can take decades to develop, an estimated 4,000 to 9,000 eventual deaths could result from Chernobyl. Additionally, hundreds -- or perhaps thousands -- of children in the region were born with severe deformities.
These estimates, however, don't even begin to tell the whole story of the impact of Chernobyl. Many women were advised to abort their pregnancies, due to fears of radiation-induced mutations, though these fears were probably unfounded. The mental health problems of millions of affected people -- especially the region's 116,000 evacuees -- will never be assessed adequately. And the environmental impact was, of course, catastrophic: Contamination of lakes, rivers and groundwater, deaths and mutations among millions of animals, and the wholesale destruction of the area's forest.
In the aftermath of the Chernobyl accident, a concrete "sarcophagus" was hastily created around reactor 4. However, this isn't considered a safe or sturdy containment structure, and there are plans to create a more permanent containment, though those plans have yet to be fully implemented -- even decades after the disaster. Though the facility remains highly contaminated, the other three reactors at Chernobyl were allowed to continuing operating for many years; in December of 2000, the last reactor was finally shut down, ending the facility's time as a nuclear power plant.
The Chernobyl plant today sits in the middle of an exclusion zone, also called a "zone of alienation," that extends 19 miles in all directions around the facility. The zone is completely uninhabited except for a handful of residents who stubbornly refuse to leave. After reverting to wilderness, the area is now home to a teeming population of wolves, deer, foxes and other animals -- some people have even compared the area to a wildlife refuge.
Tourists are now able to visit the Chernobyl exclusion zone, but only for a brief tour. Because of the intensity of the area's radiation, and the longevity of that radiation, the area around Chernobyl won't be safe for human habitation for about 20,000 years.