What would the world be like if nuclear reactors exploded simultaneously?

In an article titled "The Second Nuclear Apocalypse" published in the journal Special Subjects of Physics, researchers from the University of Leicester in England specifically referred to the science fiction television series The 100.

Researchers say the film depicts "a small crew leaving Earth by rocket to escape the apocalypse, which occurs when all the nuclear power plants on Earth melt down almost simultaneously. This event is known as 'Praimfaya'. Another group survives by hiding in underground bunkers."

According to Sputnik, researchers say they decided to "assess the accuracy of the claims" made by Clarke, the leader of the group of survivors. Clarke is radiation-immune and had previously stated that returning to Earth would be safe about a decade after the apocalypse.

Using data collected after the Chernobyl and Fukushima nuclear disasters, scientists have attempted to calculate how much radioactive nuclide was released into the atmosphere when the nuclear reactors melted down and how long the planet would remain uninhabitable.

"Clarke suggested that radiation levels would decrease to safe levels five years after Praimfaya. From our model, we believe there was a serious underestimation, and we conclude that habitability on Earth would only be possible 156 years after Praimfaya," the researchers pointed out.