Uranium enriched to about 5% U-235, in oxide form UO2
The fission happens in the fuel, which is usually in fuel rods inside the reactor. The rods are spaced at a particular distance apart and fill the reactor.
The fission reactor is composed of:Nuclear fuel,reactor coolants,neutron moderator (optional)control elementsshieldingmeasurement instrumentssupporting structures... etc
a fission nuclear reactor -binky
Nuclear fission takes place in the nuclear fuel rods that are placed in the reactor core that is situated in the reactor pressure vessel. The reactor pressure vessel is usually situated inside the reactor containment.
The uranium 235 atoms in the nuclear fuel are what actually fission, or split into two other atoms. The uranium is in ceramic fuel pellets that are inserted into fuel rods, that make up fuel elements, that are in the reactor core that is located in the reactor vessel of the nuclear power plant. After the fuel has been in the reactor it begins to produce plutonium 239 atoms within the fuel which will also undergo a fission reaction.
Nuclear fission occurs in the reactor core of a nuclear reactor. This is where nuclear fuel, typically uranium, is arranged in such a way that it sustains a chain reaction of splitting atoms, releasing energy in the process.
The nuclear fuel is typically contained in the reactor core, which is a central part of the nuclear reactor where the fission reaction takes place. The fuel rods, which contain the nuclear fuel pellets, are inserted into the reactor core during operation.
The reactor(s) at Chernobyl are fission reactors, and fission of fuel and fission products following the fire and the overheating of the core melted it down.
After nuclear fission occurs in fuel rods in a nuclear reactor, the next step is to control the reaction by regulating the rate of fission through control rods. These control rods absorb neutrons to maintain a steady and safe level of nuclear chain reactions in the reactor core.
The neutrons produced by fission in a nuclear fission reactor during the process of thermalization to be available for a new generation of fission could be subject to:absorption in fuelabsorption in non fuel reactor components (moderator, clad, structural material, ...)fast leakageresonance capture in U-238fast fission in U-238thermal leakage
The nuclear fuel is found in the fuel rods. These fuel rods are formed into fuel bundles called fuel assemblies, and together they make up the reactor core.
If you mean a nuclear reactor, and not a chemical one, there is only one way, and that is by nuclear fission in the fuel