There were 6 variations on the Uranium Cell, 3 that served as fuel and 3 that could be used for create new cells.
Uranium Cell: The Standard Reactor Fuel.
Dual Uranium Cell: Twice as powerful as the Uranium Cell.
Quad Uranium Cell: 4 times as powerful as the Uranium Cell.
Near-Depleted Uranium Cell: Sometimes when a Uranium Cell died out, this stayed behind
Depleted Isotope Cell: Crafted from a Near-depleted Uranium Cell, could be re-enriched
Re-Enriched Uranium Cell: When a Depleted Isotope cell was placed in a breeding reactor, this is what it would turn into, and could be crafted into a Uranium Cell