Table of Contents
In the recent years society faced with the numerous environmental issues related to the irrational use of natural resources and excessive pollution. Increasing consumption rates cause the activation of the production process that is inextricably linked with the energy. People’s daily need in electricity and the growing desire to minimize the harm to the environment are the primary reasons for heated discussions on the challenges related with the use of existing and alternative sources of the energy. Nuclear power plant is one of the most controversial means of producing electricity as of today because of its high-risk, especially in the countries that are likely to experiences earthquakes, tsunamis, etc. Along with this, there are a lot of advantages of using the nuclear power plant. That is why it is necessary to know the history of nuclear reactor technology’s development, its pros and cons to make a wise choice in terms of the further utilization of the nuclear power plant energy. To this end, the paper seeks to explore the history of use and principles of functioning of the nuclear power plant.
The History of the Nuclear Power Plant’s Usage
Originating and the First Experience of Use
The development of atomic energy is the result of a merger of scientific, technology and commercial interests. Traditionally scientists were the first to discover the notion of “radioactivity” and investigate the properties of uranium and other radioactive elements such as radium and polonium. In 1930s nuclear fission was achieved when Otto Hahn and Fritz Strassma, who were German physicists, bombarded the nucleus of an uranium atom with neutrons and caused its splitting along with the energy release (Murray & Holbert 2015). Then, the group of scientists continued to develop their theories at the University of Chicago. Fermi, who was at the head of this group, suggested the uranium chain reactor’s possible design. Thus, in 1942 the first nuclear reactor, known as Chicago Pile-1, appeared (Golub 2014). However, the start of the World War II shifted the accents from the researching possibilities of the use of nuclear energy to the military needs. All efforts were aimed at creating the atomic bomb. Further investigation and experiments scientists and engineers continued only after war’s end.
In the after-war period between the 1950s and 1960s, a fast economic growth was observed (Murray & Holbert 2015). Economy recovery and production intensification required energy. A lot of countries had no deposits or reserves of cheap domestic sources such as coal or oil. Thus, the need for cheap energy resulted in a search of the way of its production and spread around the world. Then, in 1953, President Eisenhower addressed the United Nations with his speech “Atoms for Peace” and emphasized the need for international cooperation aimed at the development of nuclear technology for peaceful purposes (U.S. Department of Energy n. d.).
Creating of “very powerful reactor of the channel type” (RBMK) became the first practical result reached by the Soviet Union that developed a graphite moderated reactor fuelled by natural uranium with a water-cooled system (Murray & Holbert 2015). Thus, the Obninsk nuclear power plant in the Soviet Union started the operation in 1954 and was the first commercial practice of nuclear reactor use in the world (IEAE 2015). Since that time, the number of countries using such way of producing electricity grew rapidly. Reactors' boom reached its peak in 1979 when 234 reactors around the world were under construction, and a share of nuclear power in total global electricity industry reached 17% (IEAE 2015).
The Main Milestones in the Development
Thus, summarizing the period of research, it is worth to emphasize the most ignificant milestones. Discovery of X-ray (1895, Wilhelm Rontgen), radioactivity (1896, Henri Becquerel), radioactive element radium (1898, Marie Curie), the neutron (1932, James Chadwick), nuclear fission (1938, Otto Hahn and Fritz Strassman) and creating first fission reactor (1942, Fermi) are the most meaningful among others (U.S. Department of Energy n.d.). After the first commercial practice of the nuclear reactor, further evolution of nuclear power plants is inextricably linked with its technological transformations. Thus, it is not surprising that designs of the reactor are usually categorized by “generation” and named as Generation I, II, III, III+, and IV (Goldberg & Rosner 2011). Increasing the rate of safety and efficiency of the previous version is the crucial task for each next generation.
Generation I, called prototypic reactors, was developed in 1950-60s and included Shippingport (Pennsylvania), Dresden-1 (Illinois), and Calder Hall-1 (United Kingdom) (Golub 2014). Generation II started operating in the late 1960s and presented the class of the commercial reactors that designed for the operational lifetime of 40 years (Murty & Charit 2013). It includes such systems as PWR - pressurized water reactors and BWR - Boiling water reactors, CANDU - CANada Deuterium Uranium reactors, AGR - Advanced gas-cooled reactors, and VVER - Vodo-Vodyanoi Energetichesky Reactors (Goldberg & Rosner 2011). Generation III represents the improved Generation II reactors. The majority of these improvements are related to the standardized design and modularized construction, fuel technology and thermal efficiency (Murty & Charit 2013). Particular attention is paid to safety of the nuclear power plant with an accent on the use of passive systems and 20 years longer operational time (Goldberg & Rosner 2011). This generation appeared in the middle of 1990s (Murty & Charit 2013). It was not in the extensive use yet, and only a few of advanced reactors operates today. Generation III+ is the new evolutionary level of Generation III reactors that offers efficient development in terms of safety over its previous version (Murty & Charit 2013). Generation IV rectors, that are still being designed, are supposed to start operating after 2020 and have closed fuel cycles increasing safety through shortening the time needed for radioactivity’s fall (Golub 2014).
The functioning of the organizations that tried control and support the research and use of the nuclear energy with the peaceful purposes is also the significant part of the nuclear power’s history. In this regard, one should outline the establishment of the Atomic Energy Commission (AEC) in 1946, The International Atomic Energy Agency (IAEA) in 1957, World Association of Nuclear Operators in 1986 (U.S. Department of Energy n.d.).
The Principles of Work of the Nuclear Power Plant
Reactor and Its Components
Nuclear power plant is a factory that transforms nuclear energy into electricity where a nuclear reactor is the generator of this energy and the central element of the production process (Murray & Holbert 2015). The fission reaction has the place in the nuclear reactor releasing the energy in the form of heat that is used for generating electricity. There are the following components in the reactor used to recover and transform the heat: fuel assemblies, a coolant fluid, a moderator, the control rods and steam generator (Murty & Charit 2013).
Fuel is the source of nuclear energy because it contains fissile atoms, such as uranium 235, plutonium 239 and plutonium 241, which are capable of giving up the energy by the means of the fission reaction (Murray & Holbert 2015). Uranium 235 is the primary fissile atom that the nuclear power plants use because it is the only one that can occur in a natural way (Murty & Charit 2013). The fuel is placed in the fuel assemblies, which are loaded into the core of the reacctor.
The chain reaction is held continuously in the reactor and it should be controlled. The control rods, containing the materials that can absorb neutrons and allow for regulation of the number of neutrons, are used to provide the control of this process (Murty & Charit 2013). They can be moved out of the reactor’s core if the reaction should not be slowed and return in the heart of the reactor in case of an accident, when the need to stop the reaction appears (Murray & Holbert 2015).
The energy released in the process of the chain fission reaction should be carried to be used for producing electricity. The coolant, that is the liquid circulating the rods of uranium fuel, plays the role of heat carrier providing functions of taking up the energy from the fuel and bringing it out of the reactor’s core (Murty & Charit 2013).
To provide better control of the speed of neutrons most reactors contain the moderator besides fuel rods, the control rods, and the coolant. Its task is to slow down the neutrons to avoid new fission reactions. Taking into account that neutrons may be slowed by the means of material containing the atoms with nuclei that do not absorb the neutrons, the moderator is of such a material (Murty & Charit 2013). It consists of light nuclei whose mass is similar to the neutron’s mass (Murray & Holbert 2015).
The steam generator is a yet another very significant component of the reactor whose primary task is regulating the temperature of the coolant (Murty & Charit 2013). The coolant heats up when it contacts with the fuel. Its temperature reaches 300- 550°C when it leaves the reactor’s core (Murray & Holbert 2015). In such condition, the coolant can be used for heating the steam generator. The water boiling in the steam generator by the means of coolant produce the steam that drives the turbine connected to the alternator that generates electricity.
Types of the Reactors
Despite the fact that all nuclear power plants in the world share the same fundamental operational principle, they may differ one from another with the different families of nuclear reactors. The combinations of chosen fuel, coolant, and moderator determine the type of the reactor’s family to which the power station belongs. Thus, a pressurized water reactor (PWR), a fast neutron reactor (FNR) and a gas cooled reactor (GCR) exist and are used in the operation of the nuclear power plants (Murty & Charit 2013). PWR or pressurized water reactor belongs to the most widely used reactors’ type worldwide, and it produces nearly half of the world’s nuclear electricity. The fast neutron reactors were designed to improve the use of fissile material in the fuel (Murray & Holbert 2015).
After all, one can see that development of the nuclear energy happens rather fast. Even one century of its use has not passed yet, but the nuclear power plants are the essential element of world energy industry. Moreover, a lot of investigations have been held for such a short period, and numerous improvements were made. Being characterized by a constant chemical process that is used for producing electricity, the nuclear power stations are continuously transforming to ensure safety and efficiency of the process. Despite various controversies and the issue of radioactive waste, as well as high operational risk causes, the use of the nuclear energy remains one of the most widespread sources. Obviously, there are a lot of urgent issues to be solved, such as the environmental impact, the influence of a radioactive element on the human health, ensuring safety in different geographical locations, etc. However, all these warnings and discussions build significant ground for improvements that can minimize all the negative aftermaths and develop new advanced generations of the nuclear reactors.