Today thorium is used as nuclear fuel only in India; very probable the future will be different.
Uranium, plutonium, or thorium.
The next possible nuclear fuel is actually Thorium, but will likely remain Uranium
Uranium (as uranium dioxide, uranium carbide, uranium metal, uranium alloys, etc.), plutonium and thorium.
In this type of nuclear reactor the fertile isotope thorium-232 is transformed in the fissile isotope uranium-233 and this act as a nuclear fuel.
Uranium (as metal, dioxide, carbide, etc.) is the nuclear fuel for nuclear power reactors; plutonium is obtained also from uranium 238 and thorium 232 generate uranium 233.
A nuclear reactor is a device to initiate, control, and sustain a nuclear chain reaction. Nuclear power is energy produced from controlled nuclear reactions. When it comes to just standard fuel across the table it would have to be: Plutonium, Uranium, and Thorium.
Thorium is and can be used as a fuel in nuclear reactors. It just happens to be not fissile, so it needs a neutron flux to create Uranium-233, which is fissile. There are pros and cons of using Thorium. For more information, please see the Related Link below.
According to the United States Nuclear Regulatory Commission, nuclear fuel is from three different kinds of fuel. The special one consists of uranium-233, uranium-235, enriched uranium, or plutonium. The Source is from natural uranium or thorium. It can also come from depleted uranium not suitable as a reactor fuel. The byproduct can come from radioactive material. They also contain waste and tailings made by extracting or concentrating the uranium or thorium from an ore processed mainly for its content of source material.
Mostly Uranium and sometimes thorium also. Uranium is obtained from Australia, France, Russia etc and thorium is found in India along with other Asian countries.
Not as fuel, but it can be used in breeder reactors as breeding material to make fissile Uranium-233.
Most nuclear fuel for nuclear reactors in power plants is enriched uranium, though there are some plants that use "regular" uranium, like the plants using heavy water. There are also plants that use plutonium.Research and development is being done on nuclear plants using thorium as fuel.Surf on over to the Wikipedia articles to mine more data. You'll find links to them below.
Uranium. There is some interest in using thorium in the future. Thorium cannot be used directly as fuel in a reactor as it does not fission, it requires a fast breeder reactor to convert it to Uranium-233 which does fission.