During the period of more than one hundred years since the moment of discovering radioactivity in 1896, the science related to nuclear research has developed greatly.
Following the discovery of the neutron in the 1930s, an army of researchers examined nucleus transformations induced by neutrons. The discovery of artificial radioactive elements goes back to the mid 1930s. The first isotope not existing in nature was produced by an Italian physicist Enrico Fermi in 1934: the received transuranium is characterised by a higher atomic number compared to natural uranium and originates in the process of beta decay. In the course of his experiments involving irradiation by neutron, Fermi arrived at artificial radioactive elements. In such a case, excessive neutrons appear and the nucleus tries to get rid of them by means of decay.
Despite the fact that in 1938 Fermi received a Nobel Prize in physics for his discovery, the name nuclear fission derives from Lise Meitner who was the first to provide a theoretical explanation for the first nuclear fission that was obtained by her colleagues Otto Hahn and Fritz Strassmann in 1938.
However, there was still a long way to the creation of the first reactor.
For the first time, the idea of a nuclear chain reaction was approached by Leó Szilárd who patented his concept in 1936. The chain reaction also means that the process becomes self-sustained, since neutrons originating in the process of U-nuclei fission split further U-nuclei. For the purposes of maintaining a chain reaction, neutron moderating media, the so-called moderators are necessary. The role of a moderator can be played, for example, by hydrogen (H2O, i.e. in the form of light water), heavy hydrogen (D2O, i.e. in the form of heavy water), carbon (C, in the form of graphite) and beryllium (Be). The most common among these is water.
The birth moment of nuclear industry can be identified in many ways. The first reactor that could also generate electricity was the EBR (Experimental Breeder Reactor) in the USA, commissioned in 1951.
The first nuclear power plant in the world was connected to the Soviet grid on 27 July 1954. The nuclear power plant in Obninsk operated a graphite-moderated, water-cooled reactor; its electrical power was 5 MW.
The beginning of peaceful commercial nuclear energy is dated by many to 8 December 1953. That was the day when the famous Atoms for Peace speech was delivered by President Eisenhower, after which the US Congress approved the Atomic Energy Act.
Construction of the world’s first commercial nuclear power plant commenced in September 1954 in Shippingport, USA.
A pressurised water reactor was originally developed on the initiative of Admiral Hyman Rickover for the navy, with the purpose of propelling aircraft carriers. Nowadays, this nuclear reactor concept is considered to be the most accepted and safest one.
The first Hungarian reactor was constructed in 1959 at the Central Institute of Physics Research of the Hungarian Academy of Sciences (KFKI). The reactor in Budapest was a research reactor with the thermal power of 2 MW and served research purposes. The reactor was modernized twice and its present nominal power accounts for 10 MW; however, it is not used for generating electricity. The subject of research carried out with the use of this reactor is not connected with the reactor itself. It is focused rather on isotope production, as well as on solid-state physics, chemical physics and nuclear physics.
The teaching reactor of the Budapest University of Technology and Economics was commissioned in 1971 and is still in operation; its thermal power is 100 kWt. Besides teaching purposes, it is used for carrying out technical, radiochemistry, archaeological and medical research.
Reactor physics related research started in the ZR-1 critical system built in 1961 and was followed by the construction of another five critical systems. Among these, the last critical system with the identification number ZR-6 operated for 18 years (1972–1990) and was used for performing measurements supporting the physics of the nuclear reactor type implemented in Paks. The ZR-6 measuring programme was one of the most significant experimental installations on a world scale in the history of reactor physics.
Between 1982 and 1987 four reactors of VVER-440/213 type entered commercial operation in the town of Paks. The Paks Nuclear Power Plant accounts for about 50% of Hungary’s national electricity production and it produces the cheapest electricity in the country.