Okay kiddo, so there's a place called the Marcoule nuclear site. It's like a big place where grown-ups use special machines called reactors to make electricity. These reactors use something called uranium and it's very powerful.
Now, when the grown-ups are done using the uranium, it leaves behind something called radioactive waste. This waste is very dangerous and can make people sick or hurt the environment.
At Marcoule, they have special buildings and tanks to keep the radioactive waste safe so it doesn't hurt anyone. The grown-ups also wear special clothes and follow strict rules to make sure they're safe too.
The people who work at Marcoule are very smart and work hard to make sure everything is safe and done right. That way, we can have electricity and stay cozy in our homes without getting hurt.