uranium 238

American  

noun

Chemistry.

1. the radioactive uranium isotope having a mass number 238, comprising 99.28 percent of natural uranium: used chiefly in nuclear reactors as a source of the fissionable isotope plutonium 239.

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Etymology

Origin of uranium 238

First recorded in 1940–45

Example Sentences

"The ratio of isotopes of uranium 238 to 225 on our planet is different than anywhere else in the universe because the two isotopes decay at different timescales," Brownless said.

From Salon • Sep. 1, 2023

The elements were formed when neutrons from the explosion hit atoms of uranium 238 and were captured by its nucleus.

From Time Magazine Archive

The U-bomb, say the educated guessers, gets much of its energy from uranium 238, the plentiful isotope of uranium that used to be considered inert and nonfissionable.

From Time Magazine Archive

Penetrating into the ICBM's outer shell of uranium 238, they can produce slow fission, causing heat that may deform the warhead or set off its lens charges.

From Time Magazine Archive

About 95 percent of each pellet is uranium 238, an isotope with a half-life of 4.5 billion years.

From "Meltdown" by Deirdre Langeland