To explain the history of nuclear energy we could distinguish three major stages:
- Physical and chemical scientific studies of the elements.
- The development of the nuclear bomb during World War II.
- Use of nuclear energy in the civil field.
Scientific studies cover this whole period since the first Greek philosophers began to define atoms, until the development of the first nuclear bomb. In this process, different scientists discover the presence of electrons, neutrons and protons and properties that make one atom more radioactive than another.
Subsequently and seeing the danger of nuclear weapons the governments began to establish treaties to regulate their use and promote the use of nuclear energy in the civilian field. It is at this moment when the first nuclear power plants for the generation of electricity begin to appear.
First scientific advances
The Greek philosopher Democritus of Abdera was the first in history to give a definition of atom as the smallest constituent of matter, in the V century B.C. The term "atom" is a Greek word that means "not divisible". But later, with the arrival of nuclear fission it's possible to split atoms to obtain energy.
Later in 1803, the British chemist John Dalton stated in his book A New System of Chemical Philosophy that elements are formed from certain combinations of atoms and all atoms of the same element were identical. That is, all the atoms of the iron or uranium are identical.
From here the work of scientists focused on identifying and classifying all elements. The first to propose an arrangement was the English chemist Newlands. A proposal that different scientists as Lothar Meyer, Dimitri Mendeleev or Moseley undertook to study and modify it and obtain the current Periodic Table.
Discovery of the electron
In 1897, JJ Thompson announced the discovery of a negatively charged particle which he called electron. It could also deduce the relationship between the charge of a particle (e) and the mass (m). Electrons are elements with a negative charge orbiting around a nucleus like planets orbiting around the Sun. As Rutherford discovered, assembly nucleus and electrons form the atom.
The discovery of radioactivity
In 1896, the French physicist Antoine-Henri Becquerel found that certain substances, such as salts of uranium, produce penetrating radiation from an unknown source. This phenomenon was known as radioactivity .
Becquerel was working in his lab and carelessly left some uranium salts beside some photographic plates which were subsequently exposed, despite being protected from light. After research he realized that the deceased were the plates was the uranium .Thanks to his discovery Becquerel became the "father of nuclear energy".
At the same time, the French marriage of Pierre and Marie Curie in their research found the existence of another element higher than the activity uranium, in honor to his country they called it polonium. They also discovered a second element called radio.
As a result of investigations of Rutherford and Soddy, we discovered that uranium and other heavy elements emit three types of radiation: alpha, beta and gamma. The first two were made up of charged particles, proving that alpha particles were helium nuclei of atoms and beta particles were electrons. Furthermore, it was found that the gamma radiation was electromagnetic origin.
Rutherford's atomic model
The discovery of the nature of radiation allowed Rutherford to study the structure of matter. In his experiments he could infer that the atom consisted of a positive central area where all the mass was concentrated and the electrons revolving in orbits around the nucleus, like a small solar system. This meant that the atom was not solid as they believed.
The discovery of Planck's constant and quantum theory
In 1900, the German physicist Max Planck stated that the energy is emitted in small individual units called quantum. He discovered a universal constant known as Planck's constant, represented as h.
The Planck law states that the energy of each quantum equals the frequency of electromagnetic radiation multiplied by said universal constant.
Planck's findings represented the birth of a new field for the physic, known as quantum mechanics and provided the basis for research in fields such as nuclear energy.
The theory of relativity of Albert Einstein
Albert Einstein is the most important scientist of the twentieth century. Einstein proposed the famous equation E = mc2. This equation was a revolutionary equation for further studies in nuclear physics, but in those days it was unavailable to prove it experimentally. Thus, E represents the energy and m represents the mass, both interrelated by the speed of light c. This equation related the mass conversions of energy, so it could be assumed that both entities were different manifestations of the same thing.
Bohr's atomic model
In 1913, the Danish physicist Niels Bohr developed a hypothesis according to which the electrons were distributed in distinct layers (or quantum levels) some distance from the nucleus. Thus the electronic configuration of the various elements are constituted.
For Bohr, the electrons revolved stationary orbits from which no radiation is emitted. Thus, the old concept of the atom as indivisible, inert and simply be buried, and the hypothesis of a complex structure that later would give complicated energy manifestations.
The discovery of the neutron
The discovery of the neutron was made by James Chadwick in 1932. Chadwick "measured" the mass of the new particle deducing that was similar to the mass of the proton but with an electrically neutral charge.. It was thus observed that the atomic nucleus consisted of neutrons and protons, the number of protons equal to electrons.
With his discovery, Chadwick got a "projectile" with ideal characteristics to cause nuclear reactions.
The discovery of artificial radioactivity
The marriage of Frederic Joliot and Irene Curie were the discoverers of artificial radioactivity.
The conclusions reached by marriage Joliot-Curie were based on the idea that radioactivity, hitherto natural character, could be produced by man, building radioactive elements by bombardment with alpha particles of some chemical elements.
The discovery of nuclear fission
In 1938, on the eve of World War II, a team of German researchers at the Kaiser Wilhelm Institute in Berlin, with Otto Hahn, Fritz Strassmann, Lisa Meitner and Otto Frisch, interpreted the phenomenon of nuclear fission, identifying the barium element as a result of the split core of uranium.
Early studies on nuclear fission were conducted by Otto Hahn and Lise Meitner, based on the results obtained by marriage Joliot-Curie, who through careful analysis found an element of atomic number intermediate in a sample of uranium bombarded with neutron.
Lise Meitner and Otto Frisch could infer that by bombarding uranium with neutrons, the uranium nuclei captured one neutron and was divided into two fragments, emitting a large amount of energy. It was the discovery of the nuclear fission.
The atomic bomb
Many of the great inventions in history have milirtar origin. The case of the nuclear energy is no an exception.
The Manhattan Project
In 1939, at the beginning of World War II, Albert Einstein recommends to the President of the United States, FD Roosevelt, to develope the atomic bomb. Einstein explained that through the research conducted by Enrico Fermi and Leo Szilard, in the United States, and Frédéric Joliot and his wife Irene Joliot-Curie in France, soon would be possible to trigger a reaction nuclear chain that would release a large amount of energy. This procedure would also allow the construction of a new kind of bombs.
Einstein also mentioned the shortage of uranium reserves in the United States and that mines of this mineral were in the former Czechoslovakia and in the Belgian Congo. Einstein proposed the collaboration between scientists and industry to develop this atomic bomb as soon as possible.
In Addition, he reported that Germany had stopped the sale of uranium from the Czech mines, which the Reich had taken over. This could mean that scientists of Kaiser Wilhelm Institute could be experimenting in nuclear fission, too.
The fear of Albert Einstein about the nuclear war was a result of his deep knowledge of the progress of research in this field. He had to emigrate to the United States in 1933 from Germany at the beginning of the persecution of the Jews.
Part of a letter writen by Albert Einstein:
"Recent work by E. Fermi and Szilard LS ... let me assume that the chemical element uranium ... can become a very important new energy source ... For the past four months the possibility of creating a nuclear reaction chain using a large amount of uranium has increased. This reaction would result in large amounts of energy and new elements similar to radius... This new phenomenon also lead to the construction of bombs...
Given this situation I recommend to maintain some contact between the Government and the group of physicists working together on nuclear chain reactions in America.
One possible way to achieve this might be that you could assign this responsability to a person you trust on.
Your task in this regard could be the following: ... ensure the supply of uranium to the United States... speed up the experimental work... raise funds... "
Roosevelt received this letter without excessive illusion, and he created a commission to take charge of all issues mentioned by the scientist.
Between 1940 and 1941 some measuring systems held uranium graphite. Glen Seaborg discovered an artificial element in 1940: plutonium-239, which could be used for the subsequent manufacture of the atomic bomb.
Te construction of the bomb was entrusted to the army, in a war project that would cost around 2,500 million dollars.The program included two alternatives: the separation of uranium-235 from uranium-238 and the production of plutonium-239 in the graphite reactors.
The 2nd of December 1942 a group of European nuclear physicists, who emigrated to the United States and operated by the Italian physicist Enrico Fermi, put up the first nuclear chain reaction produced by the man with the intention of applying for the first time nuclear energy. The nuclear reactor used, called Chicago Pile (CP-1), was a simple structure and it was settled under the grandstand football stadium at the University of Chicago. The fuel used was uranium, such as that Fermi used in their experiments in Rome and graphite moderator.
The preparations for this experiment were carried out with great secrecy. The aim of the research was obtaining a chain reaction, theoricaly controled, to allow the study of their properties and develope an atomic bomb.
The fission chain reaction started once they carefully extracted the control bars. At this time, the first nuclear reactor in the history of nuclear power became operational .
In 1943 were lifted three cities full of research facilities: Oak Ridge (Tennessee) to separate uranium-235 from uranium-238, Hanford for the establishment of nuclear reactors, and Los Alamos to build the atomic bomb. Robert Oppenheimer became director of the Los Alamos laboratory, getting together about a thousand scientists taht they would remain there until six months after the war finished.
The 16th of July 1945 was held the first test of plutonium atomic bomb in the desert of Alamogordo (New Mexico), with a complete success.
The uranium and plutonium atomic bomb were ready at the same time. The first atomic bomb, called Little Boy, consisted of two masses of uranium-235 that were projected one over the other with conventional explosives. The second, called Fat Man, consisted of a plutonium hollow sphere that was collapsing around its center by the action of conventional explosives.
The 6th of August 1945, the two atomic bombs that would alter the course of history were dropped. Little Boy was dropped on Hiroshima from the Enola Gay, and the 9th of August Fat Man was dropped on Nagasaki.
The conditions for the construction of an atomic bomb, on which some Soviet physicists (as Igor Vasilievich Kurchatov) worked unsuccessfully during World War II, were more stringent than required for the successful operation of a nuclear reactor.
The energy released by detonation is distributed approximately 35% of thermal radiation, 50% of pressure and 15% of nuclear radiation. This process could reach temperatures up to 14 million degrees Celsius. The Hiroshima atomic bomb released 23.2 million KWh.
Use of nuclear energy for peaceful uses
With the intention of softening this situation, a series of international conferences of a technical nature on the peaceful uses of nuclear energy were organized. On this occasion, conversations between developed countries with significant atomic potential were a complete success.
Taking advantage of the new situation, US President Eisenhower then presented his international cooperation program "Atoms for Peace" at the United Nations. From this program, a series of scientific and technological knowledge was released that would allow the subsequent commercial exploitation of nuclear energy. The speech proposed an agreement between the great powers to stop and reduce the manufacture of nuclear weapons and to make known to all mankind the knowledge and material means, especially nuclear fuels, for use for peaceful purposes. In addition, the creation of regulatory bodies was favored.
However, countries such as the United Kingdom and the former Soviet Union had already begun their research aimed at the commercial deployment of nuclear energy.
Definitive Treaty of Nuclear Non-Proliferation
In 1967, the IAEA organized an analysis group of all those technical problems that could be contained in a Nuclear Non-Proliferation Treaty, which would enter into force in 1972.
The signatory countries agreed not to transfer nuclear weapons or collaborate to manufacture them, and pledged to establish the necessary safeguards for compliance.
The development of nuclear energy was promoted at all times by the interest aroused about the production of electricity using this energy source. Throughout the 1960s and 1970s, several nuclear programs were initiated in various countries.