Okay, imagine you have a big, magic box that can make electricity. This box is called a nuclear reactor.
Inside this box, there are small things called atoms that are swimming around. Normally, atoms don't like to be near each other because they have the same charge and they repel each other. But in the nuclear reactor, we make some special atoms that like to stick together.
When these atoms stick together, they create energy, which is like magic electricity that we can use to light up our homes and power our phones.
The Topaz nuclear reactor is a special kind of box that uses a rare type of fuel called polonium-210. This fuel makes it possible for the reactor to create a lot of energy in a very small space, kind of like a tiny magic box that does a lot of work.
But because the polonium fuel is very rare and hard to find, the Topaz reactor was only used for certain special missions, like sending satellites to space. It's like a superhero that only comes out for very important jobs.
Overall, the Topaz nuclear reactor is a powerful and impressive invention that helps us create energy in a safe and efficient way.