HISTORY OF RADIOACTIVITY
The beginning of the knowledge of ionizing radiation in history, began with the hand of Wilhelm Conrad Röntgen, German engineer and physicist. After successive experiments, on November 8, 1895, he produced and detected electromagnetic radiation at a wavelength generating a photo of his wife’s hand and skeleton, called X-rays, “temporarily” to designate something unknown.
A year later in 1896 Henri Becquerel discovered that uranium salts generated similar rays naturally. Although he discovered the phenomenon, it was his PhD student Marie Curie who named it ‘Radioactivity’.
First half of the 20th century
Röntgen won the Nobel Prize in physics in 1901. Henri Becquerel, Marie’s husband, Pierre Curie and Marie, won the Nobel in 1903 for their work on radioactivity, in 1911 Marie won the Nobel Prize in chemistry for her discovery of the elements polonium and radio, and his eldest daughter, Irene (1897-1956), also won the 1935 Nobel Prize in chemistry for their discovery of artificial radioactivity. Both died with severe symptoms of radioactive poisoning, leukemia, and their bodies are considered radioactive material. Marie always denied the health risks of radiation exposure.
In 1938 the Germans Otto Hahn and Fritz Strassmann discovered nuclear fission, opening the possibility of creating nuclear chain reactions. Since the early 1930s, the race of the 20th century began, a race to develop atomic energy and obtain nuclear weapons to obtain world hegemony. At a time where the tensions generated after the First World War could anticipate an escalation of a major conflict, due to the military and civil technological development produced in this period.
The first artificial nuclear reactor on Earth was the Chicago Pile-1, its construction was part of the Manhattan project (a project developed by the United States, Canada and the United Kingdom to manufacture the first nuclear bombs). The Chicago Pile-1 succeeded in producing the first self-sustaining, human-generated nuclear chain reaction on December 2, 1942. Shortly after this reactor was reconfigured as Chicago Pile-2, and it was deactivated in 1954. In 1945 the United States dropped the first nuclear bombs in the cities of Hiroshima and Nagasaki, ending the Second World War, and becoming the first world power indisputably during the second half of the century.
Second half of the 20th century
In 1954, the first civil nuclear power plant in the history of Russia, the Obninsk nuclear power plant, was inaugurated. It was deactivated in 2002 and is in the process of being dismantled.
During the decades of the 50s, 60s and 70s, nuclear energy will become an essential source of energy, economic, military and political power. Energy that despite successive accidents, waste management problems, and scientific demonstrations in relation to the increase in the incidence of cancer, was considered a talisman of civilization until the Chernobyl accident in 1986, which sparked a debate around the safety of this energy. Italy closed its nuclear power plants in 1987 and Belgium in 1999.
Early 21st century
In 2003, the Finnish company TVO together with the Franco-German consortium Areva-Siemens commissioned the first nuclear power plant built in Europe, after the Chernobyl accident. The first decades of the 21st century have seen the flourishing of the Nuclear industry and its expansion to the development of projects in Africa, Latin America, the US, the Middle East and Asia (especially in China) where more than 20 nuclear reactors are currently being built .
On March 11, 2011, an earthquake in Japan irreversibly damaged the reactors at the Fukushima-Daichi Nuclear Power Plant, causing 3 hydrogen explosions and three complete reactor meltdowns, plus damage to a fourth reactor. This caused the largest nuclear crisis in history, which is now out of control. Being dumped every day since the accident between 300-400 tons of highly radioactive water into the Pacific Ocean and emitting radioactive nano-particles into the atmosphere.
In September 2011 Germany was the first country to announce the decommissioning of all its nuclear power plants due to concerns raised in the wake of Fukushima. Sweden, South Korea and Taiwan have banned food imports from Japan. And there is a challenge for the world scientific community to find a solution to this accident, since not even the best-designed robots are capable of surviving the radioactivity generated by damaged reactors.
The proliferation since the Iraq war, commercialization and use of DU Weapons (Depleated Uranium Weapons or enriched uranium weapons), the problem of waste management (which today is not known how to manage them), and the increase in Radiology in cancer treatments, together with the increase in environmental ionizing radiation due to the dropping of nuclear bombs, military tests and civil accidents such as Three Mile Island, Chernobyl and Fukushima have caused a notable increase in radiation exposure by the world population in the last century.
According to the EPA (US Environmental Protection Agency) the average American receives 6.2 millisieverts per year of ionizing radiation (environmental, industrial and medical) at the beginning of the 21st century. The following graph shows the evolution in the last 117 years of the average ionizing radiation received by a citizen, in this case in the United States.
Evolution of exposure to ionizing radiation – millisieverts per year
Source EPA (US Environmental Protection Agency) https://www.epa.gov/radiation/radiation-sources-and-doses
Ionizing radiation per capita at the beginning of the 20th century was 0, in the 50s, after the launching and testing of the first nuclear bombs it began to rise slightly, after the Chernobyl and Fukushima accident, environmental ionizing radiation has risen to 3 millisieverts / year of exposure for the United States population, the other half of the increase corresponds to per capita exposure in recent years from new nuclear medicine treatments.
MEANING OF RADIOACTIVITY
Radioactivity is a physical phenomenon, which develops in nuclei of unstable atoms, these nuclei are capable of transforming or decaying, spontaneously, into atomic nuclei of other more stable elements.
As there is instability between the number of neutrons and protons in the atomic nucleus, electromagnetic energy or particles with kinetic energy are released that are capable of passing through bodies opaque to ordinary light, producing fluorescence, impressing radiographic plates, ionizing gases, or modifying the DNA of living cells, among others. Radioactivity ionizes the medium it passes through.
Radioactivity is used to obtain nuclear energy, it is used in medicine (radiotherapy and radiodiagnosis) and in industrial and military applications.
Radioactivity can be Natural (manifested by isotopes found in nature) or Artificial (manifested by radioisotopes produced in artificial transformations). Most of the current ionizing radiation is the result of artificial transformations generated by man, radioisotopes that were not present in nature, and that are the result of synthetic elements produced by the nuclear industry.
4 TYPES OF RADIATION
ɣ GAMMA RADIATION
Penetrating electromagnetic radiation, arising from the radioactive decay of atomic nuclei.
Natural sources of gamma rays originating on Earth are mainly due to radioactive decay and secondary radiation from atmospheric interactions with cosmic ray particles. However, there are other rare natural sources, such as terrestrial gamma ray flashes, that produce gamma rays from the action of electrons on the nucleus.
Notable man-made sources of gamma rays include fission, such as that which occurs in nuclear reactors, and high-energy physics experiments, such as the decomposition of neutral pions and nuclear fusion.
ß BETA PARTICLES
Beta particles are a type of ionizing radiation and for radiation protection purposes they are considered more ionizing than gamma rays, but less ionizing than alpha particles. The greater the ionizing effect, the greater the damage to living tissue.
Beta particles can be used to treat health conditions like eye and bone cancer and are also used as tracers.
α ALPHA PARTICLES
Alpha radiation is an average of about 20 times more dangerous, and in experiments with inhaled alpha emitters, up to 1000 times more dangerous  than an equivalent activity of beta or gamma emitting radioisotopes.
It is used in some smoke detectors, for radioisotope thermoelectric generators used for space probes and artificial cardiac pacemakers.
X ELECTROMAGNETIC RADIATION
X-rays form X-radiation, a form of high-energy electromagnetic radiation, which can pass through opaque bodies and print photographic film.
X-rays, digital radiographs, and CT scans
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