Chernobyl: A Nuclear Accident That Changed the Course of History. Then Came Fukushima.

Editor’s note: This article is part of a collection of expert commentary on nuclear safety published on the tenth anniversary of the Fukushima disaster, produced in a collaboration between the Project on Managing the Atom at Harvard Kennedy School and the Bulletin.

On April 26, 1986, during a planned safety system test at Chernobyl Power Plant’s Unit 4 that involved an electricity shutdown, a series of operator errors led to the meltdown of the graphite-moderated RBMK-type reactor core. Since the reactor was not protected by a containment chamber, the resulting steam explosion tore through the roof of the Unit 4 and rained chunks of fuel rods and radioactive graphite on the surroundings. The fires, spewing clouds of radioactive smoke into the atmosphere, raged for over a week.

Chernobyl still stands for the world’s worst nuclear accident. The full impact of a nuclear disaster on this scale is difficult to compute, not least because the effects that count most are often those that are most difficult to count. Beyond the number of lives lost and people displaced, beyond the money spent on accident mitigation and remediation, there are long-term health, environmental, social, economic, and political consequences that defy quantification. Thirty-five years on, we are still grappling with the full extent of Chernobyl’s impact on the world. Yet in a very real sense, we live in a world shaped by Chernobyl.

As Chernobyl’s radioactive plumes blew over the Soviet border across much of Europe, they brought with them one simple and daunting truth: A nuclear accident anywhere is a nuclear accident everywhere. Chernobyl was a global-scale nuclear event before the world was global, as International Atomic Energy Agency Director-General Rafael Grossi noted during the Nuclear Safety and Security conference at Harvard Kennedy School’s Belfer Center. It jolted the nuclear community into action and much of today’s international regulatory framework on nuclear security emerged in its wake, including the Convention on Nuclear Safety, Convention on Early Notification of a Nuclear Accident, and Convention on Assistance in the Case of a Nuclear Accident or Radiological Emergency.

Today, the nuclear community attributes the Chernobyl accident to a faulty reactor design and an abysmal safety culture. At the time, however, for many Soviet citizens from the leadership to the masses, Chernobyl became symptomatic of the entire Soviet system’s dysfunction, where initiative was punishable, responsibility evaded, and truth inconvenient. And if the Soviet system brought about Chernobyl, Chernobyl brought down the Soviet system.

Then-Soviet leader Mikhail Gorbachev, who hoped to reform the Soviet Union, considered Chernobyl one of the major causes that led to its demise. The accident undermined Gorbachev’s faith in much-touted Soviet technological prowess and its ability to compete with the West, strengthening his commitment to pursue ambitious arms control with the United States. This, in turn, pitched him against the powerful military-industrial sector, whose leaders would conspire against him in August 1991. The August coup and its failure would send the Soviet Union spiraling toward disintegration.