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.
Wherever the fissionable material (e.g., some isotope of Uranium, or of Plutonium) is located.
No nuclear fission occurs in the body.
chain reactions
A critical assembly of fissile material
number of control rods
Currently, it can't. May be it could be in future.
In the reactor core, which is the volume filled with the fuel assemblies
Nuclear energy
No nuclear fission occurs in the body.
The dangerous condition that can occur in a nuclear reactor and due to overheating is a nuclear meltdown.
There are many ways a nuclear accident may occur, however most nuclear power plant accident occur due to problem in an reactor.
chain reactions
A critical assembly of fissile material
number of control rods
Currently, it can't. May be it could be in future.
The term fission generally means to split into parts. When we talk about splitting the atom, we generally apply the term nuclear fission to the process. Nuclear fission, the breaking apart of an atomic nucleus, can occur spontaneously, or it can occur as the result of the bombarding of a nucleus with radiation. Nuclear fission is covered in another related question, and it is linked below.
No place, we have not yet determined how to make a fusion reactor. Only fusion bombs.
Nuclear fission splits an atom of one element into two atoms of two different elements. This is not usually called transmutation. However, fission is accompanied by subsequent steps, which usually include transmutation.