Radioactive radiation

Radioactivity refers to the property of certain atomic nuclei to transform into other nuclei without external influence, and to emit high-energy radiation in the process. This process produces stable and/or radioactive decay products, which can also decay further.

Various types of so-called ionising radiation can be released during such nuclear decay: Alpha and beta radiation are particles that can be easily shielded. These radiations pose a health threat when the emitters are inhaled or ingested, as they will continue to radiate in the human body. Gamma radiation is high-energy electromagnetic radiation, and is more difficult to shield than alpha and beta radiation. Containers made of mainly heavy (dense) materials such as steel, concrete or lead are used for shielding.

Neutron radiation can penetrate these heavy materials, but is slowed down (moderated) by water, graphite or certain plastics, for example, and can be trapped by certain materials (often boron).

Radioactivity occurs naturally, and can also be produced by humans. Human civilisation produces a large number of radioactive (waste) substances - for example through nuclear fission in nuclear power plants. Their hazard potential requires elaborate safety systems. The Atomic Energy Act and the Radiation Protection Ordinance contain numerous regulations to protect people and the environment from the harmful effects of these substances.

Effect of ionising radiation on humans

All life has evolved under the influence of natural radioactivity. Today we know that ionising radiation, regardless of whether it is of natural or artificial origin, can have a damaging effect on cells by altering or destroying the genetic material (DNA) of living cells.

Even though the organism has the ability to recover from radiation damage, its defence and repair systems can fail or become overwhelmed.

Long-term and short-term radiation effects

As far as low radiation doses are concerned, there is a certain probability that radiation effects will occur years or decades after exposure. Depending on whether it is a germ cell or a body cell, the genetic make-up may change or cancers such as leukaemia may develop. The radiation dose cannot be used to make any statements about radiation damage, but it can be used to make statements about the probability that radiation damage will occur. For information: For people living in Germany, the average radiation dose from natural sources is 2 millisieverts per year.

However, situations may arise in which people are exposed to a high radiation dose for a short time, e.g. during the clean-up work in the immediate vicinity of the Chernobyl and Fukushima reactors that suffered accidents. In such cases, health damage will occur immediately or within a few weeks. This type of damage – experts speak of deterministic radiation effects – only occurs following a high radiation dose above a certain threshold. For humans, this is around 500 millisieverts. If this threshold is exceeded by a factor greater than ten, this will usually lead to death.