How geologists are using history’s worst nuclear disaster to open up earth’s history

Chernobyl released more than 400 times as much radioactive material as the Hiroshima atomic bomb

Thirty-seven years ago, on April 26 1986, the reactor of the Chernobyl nuclear power plant suffered a catastrophic meltdown. In the weeks that followed, the deadly event drove hundreds of thousands of people to relocate from the surrounding area, which is still a deserted “exclusion zone” today.

The Chernobyl nuclear accident was caused by an unfortunate cocktail of human error and flawed reactor design. It was the worst nuclear disaster in history, releasing more than 400 times as much radioactive material as the Hiroshima atomic bomb.

An uncontrollable chain reaction inside the reactor caused a sharp increase in temperature that ultimately resulted in the fusion of the fuel rods, a steam explosion and a fire. The melted fuel rods pooled temporarily at the bottom of the reactor chamber before making their way into the deeper levels of the power plant.

This hellish molten soup has proved an unexpected source of insight for geologists like me. In new research published in American Mineralogist, my colleagues and I show tiny zircons formed at Chernobyl change our understanding of how these crystals behave – and what they tell us about Earth’s past.

Molten reactor material is called corium, and it’s a serious contender for the most dangerous substance on Earth.

Nearby radiation exposure to corium can kill within minutes, but that is not all. Corium is extremely hot and generates its own heat from radioactivity. It’s very difficult to cool it down.

The corium at Chernobyl reached 2,600℃, almost twice as hot as the surface temperature of the space shuttle during atmosphere re-entry or half the temperature at the surface of the Sun. For comparison, the temperature of natural lava from volcanoes ranges from 500 to 1,000℃.