NuclearCraft adds nine different ores to the game. They are copper, tin, lead, silver, uranium, thorium, plutonium, lithium, boron, and magnesium.
Copper and tin are useful starting in early game for tools and other basic necessities and are still necessary in the later game. Lead also becomes useful during construction of machines and reactors.
Uranium and Thorium are found in the over world and serve primarily as fuel for Fission reactors. Plutonium is a rare nether ore that is also extremely useful for fission. Mining Plutonium will normally yield 1 small pile of Plutonium-239, or it can be silk-touched to double the output with a crusher.
Lithium and Boron are both fairly useful in the fueling of Fusion reactors. In addition, boron makes a good substitute for iron armor.