Parts Of Nuclear Power Plant And Its Function Pdf

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A nuclear reactor , formerly known as an atomic pile , is a device used to initiate and control a fission nuclear chain reaction or nuclear fusion reactions.

What are the different types of power plants used to generate energy?

Nuclear reactor , any of a class of devices that can initiate and control a self-sustaining series of nuclear fission s. Nuclear reactors are used as research tools, as systems for producing radioactive isotope s, and most prominently as energy sources for nuclear power plants. Nuclear reactors operate on the principle of nuclear fission, the process in which a heavy atomic nucleus splits into two smaller fragments.

The nuclear fragments are in very excited states and emit neutron s, other subatomic particle s, and photon s. The emitted neutrons may then cause new fissions, which in turn yield more neutrons, and so forth. Such a continuous self-sustaining series of fissions constitutes a fission chain reaction. A large amount of energy is released in this process, and this energy is the basis of nuclear power systems. In an atomic bomb the chain reaction is designed to increase in intensity until much of the material has fissioned.

This increase is very rapid and produces the extremely prompt, tremendously energetic explosions characteristic of such bombs. In a nuclear reactor the chain reaction is maintained at a controlled, nearly constant level. Nuclear reactors are so designed that they cannot explode like atomic bombs. Most of the energy of fission—approximately 85 percent of it—is released within a very short time after the process has occurred. The remainder of the energy produced as a result of a fission event comes from the radioactive decay of fission products, which are fission fragments after they have emitted neutrons.

Radioactive decay is the process by which an atom reaches a more stable state; the decay process continues even after fissioning has ceased, and its energy must be dealt with in any proper reactor design.

The course of a chain reaction is determined by the probability that a neutron released in fission will cause a subsequent fission. If the neutron population in a reactor decreases over a given period of time, the rate of fission will decrease and ultimately drop to zero. In this case the reactor will be in what is known as a subcritical state. If over the course of time the neutron population is sustained at a constant rate, the fission rate will remain steady, and the reactor will be in what is called a critical state.

Finally, if the neutron population increases over time, the fission rate and power will increase, and the reactor will be in a supercritical state. Before a reactor is started up, the neutron population is near zero. During reactor start-up, operators remove control rods from the core in order to promote fissioning in the reactor core, effectively putting the reactor temporarily into a supercritical state.

When the reactor approaches its nominal power level, the operators partially reinsert the control rods, balancing out the neutron population over time. At this point the reactor is maintained in a critical state, or what is known as steady-state operation. When a reactor is to be shut down, operators fully insert the control rods, inhibiting fission from occurring and forcing the reactor to go into a subcritical state.

A commonly used parameter in the nuclear industry is reactivity, which is a measure of the state of a reactor in relation to where it would be if it were in a critical state. Reactivity is positive when a reactor is supercritical, zero at criticality, and negative when the reactor is subcritical. Reactivity may be controlled in various ways: by adding or removing fuel, by altering the ratio of neutrons that leak out of the system to those that are kept in the system, or by changing the amount of absorber that competes with the fuel for neutrons.

In the latter method the neutron population in the reactor is controlled by varying the absorbers, which are commonly in the form of movable control rods though in a less commonly used design, operators can change the concentration of absorber in the reactor coolant.

Changes of neutron leakage, on the other hand, are often automatic. This decrease in coolant density will increase neutron leakage out of the system and thus reduce reactivity—a process known as negative-reactivity feedback. Neutron leakage and other mechanisms of negative-reactivity feedback are vital aspects of safe reactor design. Fortunately, reactor control is aided by the presence of so-called delayed neutrons, which are neutrons emitted by fission products some time after fission has occurred.

The concentration of delayed neutrons at any one time more commonly referred to as the effective delayed neutron fraction is less than 1 percent of all neutrons in the reactor. However, even this small percentage is sufficient to facilitate the monitoring and control of changes in the system and to regulate an operating reactor safely. Nuclear reactor Article Media Additional Info. Article Contents.

Home Technology Industry Nuclear reactor device. Print print Print. Table Of Contents. While every effort has been made to follow citation style rules, there may be some discrepancies.

Please refer to the appropriate style manual or other sources if you have any questions. Facebook Twitter. Give Feedback External Websites. Let us know if you have suggestions to improve this article requires login. External Websites. See Article History. Sequence of events in the fission of a uranium nucleus by a neutron.

Get a Britannica Premium subscription and gain access to exclusive content. Subscribe Now. Chain reaction in a nuclear reactor at a critical stateSlow neutrons strike nuclei of uranium, causing the nuclei to fission, or split, and release fast neutrons.

The fast neutrons are absorbed or slowed by the nuclei of a graphite moderator, which allows just enough slow neutrons to continue the fission chain reaction at a constant rate.

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Nuclear power plant

Published Jul 27, Updated Jan 29, Atoms are constructed like miniature solar systems. At the center of the atom is the nucleus; orbiting around it are electrons. The nucleus is composed of protons and neutrons, very densely packed together. Hydrogen, the lightest element, has one proton; the heaviest natural element, uranium, has 92 protons. The nucleus of an atom is held together with great force, the "strongest force in nature. Because uranium atoms are so large, the atomic force that binds it together is relatively weak, making uranium good for fission.

Not a MyNAP member yet? Register for a free account to start saving and receiving special member only perks. The Committee was requested to analyze the technological and institutional alternatives to retain an option for future U. The Committee consisted of members with widely ranging views on the desirability of nuclear power. Nevertheless, all members approached the Committee's charge from the perspective of what would be necessary if we are to retain nuclear power as an option for meeting U.

This page is about the main conventional types of nuclear reactor. A nuclear reactor produces and controls the release of energy from splitting the atoms of certain elements. In a nuclear power reactor, the energy released is used as heat to make steam to generate electricity. In a research reactor the main purpose is to utilise the actual neutrons produced in the core. In most naval reactors, steam drives a turbine directly for propulsion. The principles for using nuclear power to produce electricity are the same for most types of reactor. The energy released from continuous fission of the atoms of the fuel is harnessed as heat in either a gas or water, and is used to produce steam.


the plant and its components. To control these functions the nuclear power plant is divided into structural and functional entities, i.e. sys- tems. A system's safety.


Nuclear reactor

Nuclear reactor , any of a class of devices that can initiate and control a self-sustaining series of nuclear fission s. Nuclear reactors are used as research tools, as systems for producing radioactive isotope s, and most prominently as energy sources for nuclear power plants. Nuclear reactors operate on the principle of nuclear fission, the process in which a heavy atomic nucleus splits into two smaller fragments. The nuclear fragments are in very excited states and emit neutron s, other subatomic particle s, and photon s.

Nuclear power plants produce electricity from the heat created when atoms are split within a nuclear reactor. This process is called fission. Uranium is the fuel most widely used in nuclear reactors at power plants. Nuclear energy is created when uranium atoms are split in a process called fission.

Nuclear plants split atoms to heat water into steam. The steam turns a turbine to generate electricity. In most power plants, you need to spin a turbine to generate electricity. Coal, natural gas, oil and nuclear energy use their fuel to turn water into steam and use that steam to turn the turbine. The nuclear reactors currently operating in the United States are either boiling water reactors or pressurized water reactors.

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This page is about the main conventional types of nuclear reactor. A nuclear reactor produces and controls the release of energy from splitting the atoms of certain elements.

Components of a nuclear reactor

Nuclear power and hydropower form the backbone of low-carbon electricity generation. Together, they provide three-quarters of global low-carbon generation. However, in advanced economies, nuclear power has begun to fade, with plants closing and little new investment made, just when the world requires more low-carbon electricity. This report focuses on the role of nuclear power in advanced economies and the factors that put nuclear power at risk of future decline. It is shown that, without action, nuclear power in advanced economies could fall by two thirds by

We use them to give you the best experience. If you continue using our website, we'll assume that you are happy to receive all cookies on this website. We have recently upgraded our technology platform. Due to this change if you are seeing this message for the first time please make sure you reset your password using the Forgot your password Link. Power Nuclear Plant. As a number of countries continue to move away from high-polluting fossil fuels towards low-carbon alternatives, the dynamic of how and where power plants operate is constantly changing. Nuclear, coal and wind are just three types of energy that are used to generate electricity in power plants across the world.

Nuclear reactor

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