nuclear reactor

American  

[noo-klee-er ree-ak-ter, nyoo-] / ˈnu kli ər riˈæk tər, ˈnyu- /

noun

Physics.

1. an apparatus in which a nuclear-fission chain reaction can be initiated, sustained, and controlled, for generating heat or producing useful radiation.

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nuclear reactor British  

noun

1. Sometimes shortened to: reactor.  Former name: atomic pile.  a device in which a nuclear reaction is maintained and controlled for the production of nuclear energy See also fission reactor fusion reactor

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nuclear reactor Scientific  

1. A device used to generate power, in which nuclear fission takes place as a controlled chain reaction, producing heat energy that is generally used to drive turbines and provide electric power. Nuclear reactors are used as a source of power in large power grids and in submarines.

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nuclear reactor Cultural  

1. A device in which the energy released by the fission of nuclei of uranium or another element is used to produce steam to run an electrical generator or other device.

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Pronunciation

See nuclear ( def. ).

Closer Look

A nuclear reactor uses a nuclear fission chain reaction to produce energy. The cylindrical core of a reactor consists of fuel rods containing pellets of fissionable material, usually uranium 235 or plutonium 239. These unstable isotopes readily split apart into smaller nuclei (in the fission reaction) when they absorb a neutron; they release large quantities of energy upon splitting, along with more neutrons that may be absorbed by the nuclei of other isotopes, causing a chain reaction. The neutrons are expelled from the fission reaction at very high speeds, and are not likely to be absorbed at such speeds. Moderators such as heavy water are therefore needed to slow the neutrons to a speed at which they are readily absorbed. The fuel rods contain enough fissionable material arranged in close enough proximity to start a self-sustaining chain reaction. To regulate the speed of the reaction, the fuel rods are interspersed with control rods made of a material (usually boron or cadmium) that absorbs some of the neutrons given off by the fuel. The deeper the control rods are inserted into the reactor core, the more the reaction is slowed down. If the control rods are fully inserted, the reaction stops. The chain reaction releases enormous amounts of heat, which is transferred through a closed loop of radioactive water to a separate, nonradioactive water system, creating pressurized steam. The steam drives turbines to turn electrical generators.

Etymology

Origin of nuclear reactor

First recorded in 1940–45

Example Sentences

The combined entity now possesses 55 gigawatts of generating capacity, including 21 nuclear reactors and over 50 natural gas plants.

From Barron's

TOKYO—On a sandy coastline 180 miles from Tokyo, a giant nuclear reactor will soon come back to life after more than a decade offline.

From The Wall Street Journal

The auction came up 6.6 gigawatts short, or about the amount of electricity that can be produced by six large nuclear reactors.

From Barron's

But the company’s plan for bringing small modular nuclear reactors to market has captured investors’ imagination.

From MarketWatch

It has 34 nuclear reactors under construction, according to the World Nuclear Association, and nearly 200 others planned or proposed.

From The Wall Street Journal

Related Words

• reactor