Okay kiddo, let me tell you a story about a very bad thing that happened at a nuclear power plant in Chernobyl.
A long time ago, in 1986, there was a big explosion at a power plant in Ukraine. The power plant made electricity by using special things called nuclear reactors. Nuclear reactors are like a big machine that can make a lot of heat and energy from tiny things called atoms.
But something went really wrong at Chernobyl. There was a big fire and lots of smoke and a lot of dangerous things came out of the nuclear reactor. These dangerous things are called radiation. Radiation is like little tiny invisible bullets that can hurt people and animals and plants.
Lots of people were very scared and had to leave their homes and live somewhere else. They couldn't go back, because the radiation was still there and it wasn't safe to be near it. But some people were really brave and stayed to help clean up the mess.
Now, many years later, Chernobyl is still a sad place. People can't live there because it's still not safe. But scientists and doctors are working hard to make things better and help people who were hurt by the radiation. They want to make sure something like this never happens again.
So, that's the story of Chernobyl. It's a reminder that even though nuclear power can be very helpful, we have to be very careful with it and make sure nothing bad happens.