Workers tend flower beds near the Chernobyl nuclear power plant before the explosion. Photograph by Paul Fusco / Magnum

At 1:23 in the morning on April 26, 1986, Unit 4 of the V. I. Lenin Nuclear Power Station exploded, tearing the top off the reactor building and exposing the core to the Ukrainian wind. A few seconds later, it exploded again, this time with the force of ten tons of TNT. Burning graphite, molten bitumen, and radioactive debris—the misshapen half-atoms left over when uranium is split apart—were launched into the night sky. The Battle of Chernobyl, as the disaster came to be called by Soviet historians, had begun. The flames raged on through the night. In the ensuing days, helicopters flew sorties over the reactor, dropping sand to impede the fire and boron to slow the ongoing reaction. All told, thirty people were killed in the explosion and the cleanup that immediately followed. It took half a million workers, the so-called liquidators, more than six months to cover the ruined reactor with a protective concrete dome, aptly known as the sarcophagus. Even today, the work is not complete. A massive new steel shelter, designed to fit over the sarcophagus, is scheduled to be finished next year, but it is meant to contain the reactor for only another century—longer than the life of a person, but a fraction of the half-life of some of the contaminants present. The Battle of Chernobyl had a clear beginning, but what of its ending? Was the fight only against flame, fallout, and technological calamity, or was it a campaign against something broader? Thirty years after the fact, it’s worth reëxamining how the battle got started, and how it continues.

When people wish to downplay the strangeness and complexity of nuclear power, they sometimes argue that reactors are not much different from teakettles: both use a heating element to boil water and produce steam. This is true only in a very basic sense, in the same way that a paper airplane and a Boeing 747 share certain aerodynamic properties. A reactor is an immensely convoluted machine, full of interlocking, non-linear systems. In most plant designs, the flow of water around the core must be constant, because the heat of fission can damage the reactor if it is not sapped away. Keeping the water moving requires pumps, which run on electricity from outside the reactor complex. In the event that this external power fails, a backup system kicks in.

The Chernobyl meltdown originated in what was meant to be a demonstration of the plant’s safety, specifically of its ability to switch between these power sources. The test was several years overdue, and it was performed at a particularly dangerous juncture. The reactor, a Soviet-designed RBMK-1000, was coming to the end of its fuel cycle, meaning that the uranium in its core was mostly depleted, leaving behind a motley mix of radioactive by-products. This made the reactor’s operation less stable than usual, and much harder to control. When the test finally did happen, it was poorly scheduled. Rather than taking place under the supervision of the seasoned day crew, it was delayed ten hours, to 11 P.M. on April 25th, and left to the night crew. These technicians disabled the reactor’s emergency-cooling system—not a mistake, exactly, since the system would otherwise have overridden the test, but also not a maneuver to be left in inexperienced hands.

The operators made a critical error right at the start. They inserted the control rods—graphite-tipped cylinders of boron carbide that slow or stop a nuclear reaction—too far into the reactor. This decreased its output so much that there was not enough energy left over to power the water pumps when the switch-over occurred. The operators ought to have cancelled the test at this point, and indeed they proposed doing so, but a supervisor overruled them. In an attempt to bring the reactor back up to an appropriate level of power, they raised the control rods. The reactor was now in a curious, quasi-stable condition: it was running cooler than normal, because of the complicated chemistry of the spent fuel in the core, but it could easily swing out of control. When the operators realized this, they attempted to shut it down completely, reinserting the control rods in an operation known as a scram. As the rods descended, however, they briefly displaced coolant from the core. The temperature spiked, causing the control rods to get stuck, and a runaway reaction began. Then came the two explosions.

For many people in the West, Chernobyl has served as a kind of referendum on nuclear power. Those who oppose it see the disaster as the ultimate embodiment of industrial folly. They point to evidence, extremely difficult to confirm, of increased rates of cancer and birth defects in the region around the plant. Those who support nuclear power, meanwhile—a slight majority of Americans today—argue for better and safer reactors and more competent operators. But Chernobyl has also had a strong and lingering political legacy. The Soviet state shared no small part of the blame for the accident, yet even in the era of glasnost_ _it was unwilling to admit it. (Outside the U.S.S.R., the first indication that something was amiss at the plant came not from Soviet authorities, who initially kept quiet, but from a nuclear-power station in Sweden, where fallout, carried by the wind and tracked in on an employee’s shoes, set off the alarm during a routine screening for radioactivity.) To condemn the design of the RBMK-1000, much less nuclear technology itself, was to criticize Soviet know-how and jeopardize other economically necessary reactors of the same type. Human error was the only politically viable explanation. In the spring of 1987, Chernobyl’s operators and engineers were subject to what the historian Sonja D. Schmid has called “perhaps the last show trial of the Soviet era.” Not surprisingly, they were convicted.

There was the battle against the fire, and then there was the battle over its political meaning. Today, there is the battle of memory. The Internet is replete with videos of disaster tourists visiting the Chernobyl Exclusion Zone, sometimes with Geiger counters. Poke around in the bushes or buildings and you can sometimes find something “hot”—a rubber boot or glove, a piece of misshapen graphite. Stories abound of wild animals retaking the zone, and haunting photographs of the abandoned town of Pripyat—especially of the ruins of its carnival grounds—are now a staple of social media. (A friend of mine who visited Chernobyl not long ago noted that there was a suspicious overabundance of gas masks and creepy dolls in the town’s most cinematic locations.) But it is a mistake to assume, amid the Cold War nostalgia and post-apocalyptic romance, that Chernobyl was ever really relinquished. The undamaged portions of the plant were in operation until 2000, run by workers who were paid triple their normal wages. There are even some people—mostly elderly—who have, illegally and unadvisedly, returned to their homes nearby, sometimes eating crops grown in the contaminated soil. The acute radioactivity, the sort that can induce radiation sickness and kill people quickly, has largely decayed. The lingering fallout poses a long-term threat to anyone who inhabits the area, but if these people are old to begin with, and small in number, they are likelier to die of other causes.

The late sociologist Ulrich Beck wrote that risk can help human societies rediscover the importance of collective action and responsibility. But risk is a tricky thing to wrap one’s head around, especially once the fires have gone out. Does Chernobyl indict an entire industry, or does it show that, even at its worst, it isn’t that bad? The truth seems to be somewhere in the middle. Chernobyl was a disaster, but it was not the apocalypse. It was a highly specific event—specific to the reactor and to the Soviet state that it was conceived in. But it should give us pause to reflect generally on the high costs of technological mismanagement and deferred maintenance. It is easy to dismiss a few thousand extra cancers, out of the hundreds of thousands of cancers caused by other sources, when they are not in the bodies of our loved ones; it is easy to say that the Exclusion Zone is relatively small when it is on the other side of the world. These battles of Chernobyl are still being waged, but there may be no winners in the war.