Peak uranium is a term that refers to the point in time when the world's production of uranium (a type of mineral) hits its highest level. After that point, production of uranium will start to go down. Uranium is an important mineral because it is used to make nuclear energy and to make some other kinds of energy. We use nuclear energy to generate electricity in many places all over the world. That means that if the production of uranium starts to go down, it can be harder for us to get electricity from nuclear power.