Unauthorized Experiments Caused the Meltdown
On April 26, 1986, some workers at the Chernobyl nuclear plant decided to perform some experiments that had not been authorized. They wanted to test if the reactors would cool with a specific procedure. To complete the process, they had to run one of the reactors on meager power.
There were design flaws in this reactor, so running it on such low power began a runaway thermodynamic reaction. Instead of cooling, the reactor heated up so much that it caused a massive power surge and an explosion inside the plant.