Chernobyl Reactor Was Destroyed By a Nuclear—Not Steam—Explosion

An analysis of xenon isotopes created four days after the Chernobyl explosion of 1986 in Kiev, Ukraine is challenging our understanding of what happened on that catastrophic day.

It’s long been accepted that the explosion, which killed 30 people, was a steam one—not nuclear. A group of scientists from the Swedish Defense Research Agency, Swedish Meteorological and Hydrological Institute, and Stockholm University says that an assessment of the isotopes shows that they’re the products of nuclear fission—meaning they could have originated from a nuclear explosion.

The Chernobyl nuclear reactor

Here’s Andrew Masterson, writing for Cosmos Magazine:

The team, led by Lars-Erik De Geer, concludes that the first of two explosions reported by eyewitnesses was in fact a nuclear one—or rather, a very rapid series of nuclear ones—followed three seconds later by a secondary steam explosion.

The nuclear explosions, the researchers conclude, sent a jet of debris very high into the sky. The steam explosion immediately afterwards ruptured the reactor and sent still more debris into the atmosphere, but at lower altitudes.

The investigators noted that the first blast generated temperatures hot enough to melt a thick plate beneath the core of the reactor. A steam explosion wouldn’t have had this much energy.

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