8. Atomic energy (No playing outside!)

Atomic energy and living things
Atomic nuclei consist of positively charged protons and uncharged neutrons. They are held together by atomic bonding forces. Radioactive nuclei such as cesium-137 are unstable and decompose. This leads to a release of atomic energy in the form of high-energy ionizing radiation. If this radiation penetrates living cells, it can trigger chemical reactions that can cause cancer, leukemia or mutations in the genetic material. The more radiation, the greater the risk.
Although cells have an in-build repair system for genetic material and the entire organism is protected by an immune system, both can be overwhelmed if many damages occur in a short time.

Natural radioactivity
Radioactivity is also found in nature, for example uranium, which is finely distributed in rocks. It decays into other unstable atoms, which continue to decay and thereby emit further radiation until, eventually, only stable atoms remain. Most of this radiation is well shielded by the surrounding rocks. The released energy contributes to the geothermal energy. Only a very small amount of radioactive substances reaches the earth's surface, mostly the noble gas radon.
Almost everywhere the natural radiation of radon and its decay products is low. But in some places, for example here in the southern Black Forest, radon from the ground can penetrate into poorly ventilated basements and from there into indoor areas. If radiating particles accumulate too much in the breathing air and no countermeasures are taken, even natural radioactivity can increase the cancer risk of the residents.

Artificially concentrated atomic energy
In order to use nuclear energy to generate power, a lot of fissile material such as uranium-235 or plutonium-239 must be confined in a very tight space. If the so-called critical mass is exceeded, an atomic chain reaction can be triggered: The fission of uranium-235 atomic nuclei releases two to three neutrons, which in turn hit other nuclei, that subsequently also split, and so on.
This process releases a tremendous amount of energy. 1 g of natural uranium, containing only about 0.7% fissile uranium-235, has the same energy content as 12.6 litres of crude oil or just under 19 kg hard coal.

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