Nuclear Fission

Fission is the process of splitting atoms apart. It involves using neutron "bullets" to make isotopes of uranium unstable and therefore split apart, releasing more neutrons and heat energy. A nuclear power plant can convert this released energy into electricity.

Nuclear Fission Process

Mined uranium is enriched to increase its 235U count, the uranium isotope best suited for fission. Generally when uranium is mined, it has a high concentration of the nonfissible isotope 238U. The uranium can be enriched using many different methods varying from lasers, centrifuges, and diffusion. (Fig. 1)

Fig. 1: Enriched uranium, ready to be processed into fuel pellets.
Fig. 2: These fuel rods are the fuel source for the fission reaction.

The uranium is formed into pellets and placed into fuel rod assemblies.
Many of these fuel rods are placed into the core of a nuclear power station. (Fig. 2)

Fission reactions are maintained by neutron-capturing fuel rods called control rods. Using these rods, which are attached to machines above, workers can increase or decrease the amount of fusion reactions that take place in the core. When fission does occur, energy and more neutrons are released and the reaction grows exponentially. (Fig. 3)

Fig. 3: This diagram shows a fission reaction at the atomic level. This reaction is the key for nuclear power.

The released heat energy from the nuclear reaction is used to heat water which turns to steam.
This steam is used to turn the turbine, which then creates electricity. (Fig. 4)

Fig. 4: This is a basic diagram of a nuclear power station. Note the fuel rods located in the containment building. This is where fission takes place.

When fuel assemblies are spent, they are carefully removed and replaced, while the waste is sent to secure holding areas.

The following video shows a 3D animation of a fission reaction.