Why is uranium 235 used in nuclear reactors

Two or three neutrons are released along with the heat. These neutrons may hit other atoms, causing more fission. A series of fissions is called a chain reaction. If enough uranium is brought together under the right conditions, a continuous chain reaction occurs. This is called a self-sustaining chain reaction. This is because it decays naturally by a process known as alpha radiation. This means that it releases an alpha particle two neutrons and two protons connected together.

Another reason that U is ideal for producing nuclear power is that unlike most materials, U can undergo induced fission. When a free neutron collides with a U nucleus, the nucleus will usually capture the neutron and split extremely quickly. The splitting of a single U atom can release roughly MeV million electron volts. When the uranium atom splits, lots of heat is released, as well as gamma radiation high-energy photons. The resulting two atoms also release gamma radiation, in addition to beta radiation very fast electrons.

U- does not undergo fission with lower-energy neutrons, while U- does. U- is a fissile isotope, meaning that it can split into smaller molecules when a lower-energy neutron is fired at it. U- is a fissionable isotope, meaning that it can undergo nuclear fission, but the neutrons fired at it would need much more energy in order for fission to take place.

U- has an even mass, and odd nuclei are more fissile because the extra neutron adds energy - more than what is required to fission the resulting nucleus. Why is U used more in nuclear reactors than U? How is uranium made into nuclear fuel? Nuclear fuel pellets, with each pellet — not much larger than a sugar cube — contains as much energy as a tonne of coal Image: Kazatomprom The mining of uranium Uranium is found in small amounts in most rocks, and even in seawater.

A bank of centrifuges at an enrichment plant Image: Urenco The making of nuclear fuel The enriched uranium is transported to a fuel fabrication plant where it is converted to uranium dioxide powder. Nuclear fuel in its powder and pellet form Image: Urenco About 27 tonnes of uranium — around 18 million fuel pellets housed in over 50, fuel rods — is required each year for a MWe pressurized water reactor.

A fuel assembly, usually several metres long, can spend years in a reactor, generating immense amounts of low-carbon electricity Image: Framatome Share. Japan: Nuclear Power. China: Nuclear Power. Canada: Uranium.