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Uranium powers nuclear plants globally, providing essential electricity. Image by Visoot Uthairam / Getty ImagesKey Insights
- Uranium-235 (U-235) is ideal for nuclear energy because it undergoes induced fission, where its nucleus splits after absorbing a neutron, releasing considerable energy (around 200 MeV) and generating additional neutrons to sustain the process.
- The fission of U-235 generates substantial heat and gamma radiation, with byproducts that are lighter than the original atom.
- For nuclear power production, natural uranium needs to be enriched to raise its U-235 content to at least 3 percent, as natural uranium contains only about 0.7 percent U-235, making enriched uranium crucial for long-term nuclear energy generation.
In the U.S., nuclear plants supply around 20% of the country’s annual electricity needs. In France, nuclear power provides about 77% of the nation's electricity each year [source: NEI]. What essential element, abundant on Earth, do these nuclear plants rely on to generate such vast amounts of power? The answer is uranium.
Nuclear fission happens when an atom splits into two, releasing energy. Spontaneous fission occurs naturally, though at a very slow rate, with uranium emitting radiation. Uranium-235 (U-235), which makes up only about 0.7% of naturally occurring uranium, is highly effective for nuclear energy. This is because U-235 decays through alpha radiation, releasing an alpha particle (two neutrons and two protons). Another reason U-235 is ideal for nuclear power is that, unlike most materials, it can undergo induced fission. When a free neutron strikes a U-235 nucleus, it captures the neutron and splits rapidly, releasing around 200 MeV (million electron volts).
When a uranium atom splits, it releases significant heat along with gamma radiation (high-energy photons). The two resulting atoms also emit gamma radiation, as well as beta radiation (fast-moving electrons). The fission byproducts, along with their neutrons, weigh less than the original U-235 atom. This difference in mass is converted into energy, which can be quantified using the equation E=mc².
For uranium to be used in nuclear power plants, it must be enriched to contain at least 3% of U-235.
