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Chernobyl, 25 Years Later: It’s Not Over Yet

A tour guide measures radiation near the Chernobyl plant. Levels are still high decades after the disaster.

On the morning of April 28, 1986, radiation detectors began spiking off the charts at the Forsmark nuclear power plant in the Uppland region in east-central Sweden. The obvious and terrifying initial conclusion: somehow, the plant’s safety systems had failed, releasing radioactive material into the surrounding environment. But as engineers ran one diagnostic after another, it quickly became clear that the problem lay elsewhere -- and while the government tried to deny it at first, "elsewhere" was soon revealed to be Reactor no. 4 at the Chernobyl power plant near the town of Pripyat, in Ukraine, which was then part of the Soviet Union.

Engineers at Chernobyl had been performing a systems test on the antiquated reactor when a power surge triggered explosions, followed by a raging fire in the exposed reactor core, spewing radioactive smoke and soot in a massive plume that spread north and west to contaminate a huge expanse of territory, most of it in the former U.S.S.R. The radioactive plume eventually hitched a ride via prevailing winds and circled the globe, although most regions were not exposed to unsafe radiation levels.

The explosion itself, and the searing radioactivity that bathed plant workers and emergency crews who desperately fought the fire, killed 64 people outright; a massive evacuation began that eventually forced hundreds of thousands of people to move out of affected areas; and the Soviet government, under intense international pressure, soon came clean about a disaster it couldn’t possibly hush up. Indeed, then-premier Mikhail Gorbachev later acknowledged that the accident forced him to get serious about his fledgling policy of "glasnost," or openness. Chernobyl, he has suggested, was the straw that finally broke the back of the Soviet Union.

It was all so momentous, but also so long ago that it seems like a part of history -- a relic of the Cold War, along with the Vietnam War, the Bay of Pigs invasion and the Berlin Wall. But while the worst nuclear accident on record began during the Reagan administration, it didn’t end then, or during the first Bush administration, or Clinton, or even the Presidency of George W. Bush. The reactor site itself is still highly radioactive, and the cleanup, even a quarter of a century later, continues. Ukrainian and international officials haven’t yet figured out how to secure the most highly radioactive debris in a safe and permanent way. And the accident’s toll on the people and ecosystems of Ukraine, Belarus and Russia, where the radioactive fallout mostly settled, is still unfolding.

Differing Estimates of Lives Lost

That toll is highly uncertain. It was pretty straightforward to count the fatalities from the blast itself, and from the intense bath of radioactivity that doused the first responders; acute radiation sickness is grimly easy to diagnose. But while it’s well known that radioactivity can also cause cancer, only thyroid cancer has been definitively linked to ingesting contaminated food in the fallout zone. By 2002, according to a U.N.-sponsored report titled "Chernobyl’s Legacy: Health, Environmental and Socioeconomic Impacts," more than 4,000 children who drank radioactive milk soon after the accident ultimately came down with this generally treatable disease.

The radioactive iodine released in nuclear accidents, including the one still going on at the Fukushima complex in Japan, decays to harmless levels within a few weeks. Other byproducts of nuclear energy, though, including radioactive cesium, remain potent for decades. That’s why the area around the plant was evacuated -- but not before hundreds of thousands of people were exposed. Many of them have almost certainly gotten, or may still get, other forms of cancer as a result of the accident. However, says the report: "It is impossible to assess reliably, with any precision, numbers of fatal cancers caused by radiation exposure due to the Chernobyl…. Small differences in the assumptions concerning radiation risks can lead to large differences in the predicted health consequences, which are therefore highly uncertain." The best anyone can give is a ballpark estimate.

According to this report, at least, whose authors included representatives from the affected governments and also the World Health Organization, the International Atomic Energy Agency, the United Nations Environment Program and several other high-profile groups, that ballpark is an extra few percent of fatal cancers -- which amounts to a few thousand extra cases -- above the 100,000 you'd ordinarily expect in the affected populations during the 50 years after the accident.

But others have come up with higher estimates. "When you're in Ukraine," says environmental historian John Perkins, a professor emeritus at Evergreen State College in Washington, "you'll find plenty of scientists and physicians who think that number is way too low."

The problem, according to some critics, is twofold. First, the Soviet penchant for secrecy kept scientists from gathering good information on the actual amount of radioactive contamination that blanketed the affected area.

Second, the conventional approach to predicting long-term effects from radiation exposure is to assume that acute radiation exposure -- the kind suffered by people just downwind of Chernobyl -- is much more dangerous than the kind of long-term, very low-dose exposure experienced by much larger populations in Western Europe. If you assume otherwise, you get different numbers. Some extreme estimates put the potential death toll as high as a quarter-million. In a study published in the International Journal of Cancer in 2006, which includes Western Europe as well as the 600,000 or so "liquidators" who were brought in from other areas of the USSR over the years to help in the cleanup, the total number of cancer deaths is pegged at somewhere between 6,000 and 38,000 -- attesting to the difficulty of coming up with a precise figure.

A report titled "The Other Report on Chernobyl," produced by two scientists from the United Kingdom, also claims that radiation can cause cardiovascular problems, and that the stress caused by anxiety (or terror) regarding the accident itself and by the massive evacuation of the area (some 350,000 people have been relocated so far) can cause health problems as well. But again, nobody knows for certain. "If you cite any number for illness or fatality," says Perkins, "someone will jump on you and say it's wrong, that the study was poorly done. Everything you can say is likely to be contested."

Mutated trees, returning animals

As for Chernobyl's environmental toll, there's not a lot of good information there either. James Morris, a biologist from the University of South Carolina, has been to the area five or six times to study the uptake of radioactive carbon released when the graphite burned.

"One pine forest within sight of the reactor was known as the 'red forest,'" Morris says, because radiation killed all the trees and turned their needles red. The timber was bulldozed and left to rot. Now a new forest has sprung up again, and, he says, "all the trees are clearly mutated." They’ve lost the internal signals that make a Christmas tree taper toward the top. Instead, he says, "they don’t seem to know which way is up."

But that sort of aberration isn’t seen everywhere. In fact, Perkins says some forms of wildlife, including wolves, bears and white-tailed eagles have returned to the forests where they haven’t been seen since being exterminated by hunters decades ago. "One interpretation," he says, "is that humans are more dangerous than radiation."

Biologists documented plenty of mutated animals in the years shortly after the disaster, but these have diminished in later generations. Biodiversity, however -- the variety of species -- has also declined.

As for the Exclusion Zone, also known as the Zone of Alienation, an approximately Rhode Island-sized area surrounding the plant, Perkins has ventured inside four times with students from Evergreen State.

"You have to get special permission," he says, "but once you’re inside you can drive around freely, although you have to have a guide and be out by sundown. You can see the abandoned city -- lots of reinforced concrete, slowly crumbling. You see abandoned villages, with the forest overtaking them."

Or not quite abandoned, perhaps. Because they probably won’t live long enough to develop cancer from any exposure they get at this point in their lives, says Morris, the old people who lived in villages within the Exclusion Zone have been allowed -- unofficially -- to return. "They're interesting places," he says, "full mostly of women, because they tend to outlive men by quite a lot. Whole villages full of old, old women."

You need special permission to enter the sarcophagus, the ominously named concrete shell that’s been built around the remains of Reactor no. 4, but anyone who’s been allowed into the Exclusion Zone can tour the visitor center about 300 yards away. "I heard a presentation from some Ukrainian physicists who were somewhat dismayed," says Perkins. The sarcophagus isn’t watertight, they told him, and there’s some fear that the molten fuel remaining inside may include some water-soluble material that could leak out. The poorly built sarcophagus is starting to crumble in any case, which is why a huge, hangar-like concrete structure known at the "New Safe Confinement" is now being built to keep the worst of the remaining radioactive material under wraps.

But the Ukrainian scientists Perkins met with aren’t convinced it will work. The shelter won’t be watertight either, they told him, and, like the sarcophagus within, it will itself eventually become irradiated and dangerous. "Their sense," he says, "is that this won’t last forever. It’s just kicking the can down the road, creating a problem for future generations."

That’s a lesson Japanese officials will surely keep in mind as they continue to grapple with their own nuclear mishap at Fukushima. The accident itself hasn’t been as disastrous as Chernobyl (at least so far), and Japan in 2011 is way ahead of the USSR in 1986 in terms of resources, technical expertise, and transparency.

Even so, experts have suggested that the cleanup there could take as much as a century, and that Fukushima may have to be encased in its own version of a sarcophagus, at the center of its own Zone of Alienation, for at least that long. Until engineers can get a look at the 1,000 metric tons of fuel deep inside the reactors, however -- something that might not be possible for years -- there’s no real way of knowing.

Half a world away, in now-independent Ukraine, there’s undoubtedly plenty of sympathy for what the Japanese are going through. But the Ukrainians are still dealing with their own disaster. Chernobyl is not only still unfolding: it will continue to unfold for many decades to come. Along with Fukushima and Three Mile Island, whose 32nd anniversary was noted at the end of last month, it’s a reminder that while nuclear power could help limit the carbon emissions that are already altering the climate, it’s hardly without potential dangers of its own.

This story originally appeared at OnEarth partner Climate Central.

image of Mike Lemonick
Mike Lemonick is the senior science writer at Climate Central. He has covered science and the environment for TIME magazine for nearly 21 years, and has also written for Discover, Scientific American, Wired, New Scientist and The Washington Post. L... READ MORE >