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Physics of fission

Atoms consist of an electron cloud and a nucleus. The electrons each have the same mass and the same negative electric charge. The mass of an atom is given almost entirely by the nucleus which consists of protons and neutrons. Protons have a positive electric charge and neutrons have no electric charge. The chemical properties of atoms are governed by the number of electrons in the cloud. These match the number of protons in the nucleus and the electric charge of the electron and proton balance exactly.

One nucleus will spontaneously transform into a different nucleus if the final state nucleus is more stable and if the laws of physics allow the transformation. This process is usually accompanied by the release of ionizing radiation and is often called "radio-active decay". Nuclei that exhibit this behaviour are said to be "unstable" or "radioactive". Most of the matter found naturally on Earth is stable and does not undergo this transformation. Some examples of common radiactive isotopes found naturally that have this property are ⁴⁰K (potassium-40) which is present in seawater and many salts, ¹⁴C (Carbon-14) and Uranium and Thorium.

Nuclear Fission energy is released when a very heavy atomic nucleus absorbs a neutron and splits into two lighter fragments. The energy release in this process is enormous. It is 10 million times greater than the energy released when one atom of carbon from a fossil fuel is burned.

As this process happens, heat is produced. The heat is converted into electricity via conventional steam and gas turbines like those used at Fossil-fuel based power plants. Harnessing this heat is an engineering problem.

There are 3 nuclear isotopes of importance to nuclear power that exhibit this behavior.

These are: ²³⁵U (Uranium-235) , ²³⁹Pu (Plutonium-239) and ²³³U (Uranium-233). Of the 3, only ²³⁵U is found naturally on Earth. Natural Uranium found on Earth consists of 99.3 % ²³⁸U and 0.7% ²³⁵U. The two other isotopes, ²³⁹Pu and ²³³U can be created from the far more abundant ²³⁸U and Thorium nuclei via advanced Nuclear techniques.

Some basic Nuclear Physics