nuclear reactor

[ noo-klee-er ree-ak-ter, nyoo- ]

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.

nuclear reactor

noun

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

nuclear reactor

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.

nuclear reactor

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.

Pronunciation Note

See nuclear ( def ).

Word History and Origins

Origin of nuclear reactor¹

First recorded in 1940–45

A 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.

Example Sentences

Despite calls from progressives to invest in renewable energy sources like solar and wind power, the bill aims to boost the struggling nuclear power industry through a four-year, $6 billion program to keep nuclear reactors in operation.

From Time

The US military’s first attempts at land-based portable nuclear reactors didn’t work out well in terms of environmental contamination, cost, human health, and international relations.

From Popular-Science

Researchers at the Nuclear Regulatory Commission and the National Academy of Sciences have previously questioned the risks of nuclear reactors being attacked by terrorists.

From Popular-Science

With physicist Eugene Wigner, Wilkins began laying the theoretical physics groundwork for nuclear reactors.

From Science News

In a nuclear reactor, energy is released when uranium atoms fission, or split, after being hit by a neutron.

From Science News

When Israel did not admit in the '60's to establishing a nuclear reactor in Dimona, it claimed it was a 'textile factory.'

From The Daily Beast

This is not the story of a future Israeli strike against Iran; this is Israel's attack on a Syrian nuclear reactor in 2007.

From The Daily Beast

In 2007, the Bush administration had the location of a suspected nuclear reactor in Syria.

From The Daily Beast

From nuclear-reactor makers to dictators, see who else BM has worked for.

From The Daily Beast

In 2007, it signed an agreement with Russia for the construction of a small nuclear reactor on Burmese soil.

From The Daily Beast

Another kind, which can be made in a nuclear reactor, is called tritium.

From Project Gutenberg

This ship is powered by a nuclear reactor—in other words, an atomic pile.

From Project Gutenberg

"Even without a nuclear reactor or any potential atom bombs," Rick added.

From Project Gutenberg

He would report that country Y had a secret atomic pile—nuclear reactor, that is—in the mountains of West China.

From Project Gutenberg

Nevertheless, a nuclear reactor is well beyond such experiences.

From Project Gutenberg

Related Words

• reactor