What Is a Nuclear Reactor?
European Nuclear Society webpage, http://www.euronuclear.org/info/energy-uses.htm LIGHT WATER REACTOR (LWR) Currently, the LWR is the main reactor type employed in the U.S. In LWRs, light water (H2O) is used as both the coolant and the moderator. There are two main types of LWRs; pressurized water reactors (PWRs) and boiling water reactors (BWRs) PWR Energy from the fission reactions can cause the temperatures in the reactor core to reach 300 degrees Celcius (2). This is way above the temperature that would cause the light water coolant to boil if the pressure were that of the atmosphere (101kPa). To prevent the water from boiling and thus vaporizing, the coolant is forced to flow around the reactor core at an exceedingly high pressure of approximately 15 to 16 MPa (See Primary water in Figure 3) (3). A disadvantage of the PWR is that it must shut down regularly for routine check ups – under such high pressure, it is wise to regularly check that there is no wear and tear on the system’
A nuclear reactor is a piece of scientific equipment which is designed to generate controlled chain reactions of fissionable elements like uranium. Nuclear reactors can be used for a number of purposes, including the generation of electrical power, the production of nuclear fuels, and scientific research. Nuclear reactors of various designs can be found in many regions of the world, from scientific labs in the United States to the French countryside, with the French relying on nuclear power for around 75% of their power needs as of 2009. Nuclear reactors rely on a process known as fission, which occurs when a heavy element absorbs a neutron and breaks apart into two lighter elements. In the process, the element releases energy. In a controlled fission reaction, this energy can be harnessed for various activities, and coaxed into establishing a chain reaction which encourages the rest of the fissionable element to break apart as well. An uncontrolled reaction creates a nuclear bomb. Ins
A nuclear reactor is a system that contains and controls sustained nuclear chain reactions. Reactors are used for generating electricity, producing radionuclides (for industry and medicine), conducting research, and military purposes. All of the various designs of power-producing reactors accomplish the same simple task: spinning a generator. Many commercial reactors pass water over heat-producing fuel rods to generate steam and run a turbine. Some designs call for the passage of helium over a pile of heat-producing fuel pebbles. Yet another design uses liquid sodium as a coolant.
A nuclear reactor a device designed to release, under controlled circumstances, the energy stored in the nucleus of an atom. Although engineers talk of ‘burning’ nuclear fuel, the process is fundamentally different than the chemical process of combustion. In combustion, the atoms or molecules of the fuel (coal, oil, wood, etc.) are joined to molecules of oxygen in a process that releases heat. In a nuclear reactor, the fuel atoms themselves are split into smaller atoms in a process called fission. Pound for pound, the amount of energy released in a fission reaction is over a million times larger than that released during a combustion reaction. A single thimble sized pellet of uranium dioxide typically remains in a reactor for up to 3 years and produces the energy equivalent of a ton of coal.
