RADIOACTIVE DECAY: Four Isotopes Put Earth on a Light Simmer

Radioactive Decay

Last Updated: Dec 31, 2018

Radioactive isotopes puts Earth on a light simmer

Radioactive Decay

Four radioactive isotopes inside Earth account for about 50% of Earth’s internal heat.

Like a slow cooker, they constantly release heat within the planet keeping it on a light simmer.

These four isotopes are uranium-238 (238U), uranium-235 (235U), thorium-232 (232Th), and potassium-40 (40K).

The majority of the heat transfer occur at mid-oceanic ridges. Whereas, the least amount of heat transfer is from the continental interiors.

A source of energy for plate tectonics

Certain isotopes of elements are unstable and radioactive. For example, uranium, thorium and potassium isotopes generate 50% of Earth’s radiogenic heat from radioactive decay. The remaining 50% of Earth’s internal heat budget is from primordial heat after its initial formation.

It’s from this radioactive heat in the mantle that makes our planet geologically active. The majority of internal heat transfer occur volcanically at mid-oceanic ridges. This process drives mantle convection and plate tectonic motion on the planet.

These radioactive isotopes have long lifetimes before they decay and release slow amounts of energy. It’s because of these 4 isotopes that Earth maintains a cozy temperature in the mantle.

Radioactive decay in nuclear power plants

We use uranium and thorium in nuclear power plants in order to make fuel for fission reactors. Because of the possibility of overheating, nuclear power plants are usually located close to a source of water to cool down.

Certain elements have isotopes with a specific number of neutrons such as uranium-238 (238U). Each number corresponds to the number of protons and neutrons in its nucleus.

Overall, it’s the weak nuclear force that is responsible mostly for decay. For example, this force can change an electron into a neutrino, and a neutron into a proton. Through this force, atoms will decay or end up unstable and radioactive.

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