Definitions

from The American Heritage® Dictionary of the English Language, 5th Edition.

  • noun The uranium isotope with mass number 235 and half-life 7.04 × 108 years, fissionable with slow neutrons and capable in a critical mass of sustaining a chain reaction that can proceed explosively with appropriate mechanical arrangements.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

  • noun physics An isotope of uranium, used for energy generation and in atomic weapons, containing one hundred and forty-three neutrons. It has a half-life of 7·038×108 years, whereupon it decays into thorium-231.

Etymologies

from Wiktionary, Creative Commons Attribution/Share-Alike License

uranium + 235 the atomic mass of this isotope.

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Examples

  • But President Obama is talking about building new ones, massive gigawatt-sized reactors, and even smaller ones that would use thorium, rather than uranium-235.

    Lee Schneider: Will We See Nuclear Progress in Japan? Lee Schneider 2011

  • Today's reactors use dried wood—enriched uranium-235—that burns hot and quickly.

    A Window Into the Nuclear Future Robert A. Guth 2011

  • Richard Wakeford of the Dalton Nuclear Institute, at the University of Manchester, called such fears science fiction, pointing out there is not enough uranium-235 in the reactor to create a nuclear blast.

    Blast rocks Fukushima reactor No. 2; radioactive leak feared 2011

  • But they would still rely on uranium-235, a limited resource with safety and proliferation concerns.

    Calculating the speed of light; building nuclear reactors Post 2010

  • But President Obama is talking about building new ones, massive gigawatt-sized reactors, and even smaller ones that would use thorium, rather than uranium-235.

    Lee Schneider: Will We See Nuclear Progress in Japan? Lee Schneider 2011

  • These numbers compare with 200-210 MeV released by the fission of one uranium-235 or plutonium-239 atom.

    Accelerator-driven nuclear energy 2009

  • As uranium-235 molecules are lighter than the uranium-238 molecules, they move faster and have a slightly better chance of passing through the pores in the membrane.

    Uranium enrichment 2009

  • Uranium found in nature consists largely of two isotopes, uranium-235 (235U) and uranium-238 (238U).

    Uranium enrichment 2009

  • The essence of a conventional nuclear power reactor is the controlled fission chain reaction of uranium-235 (235U) and plutonium-239 (239Pu).

    Accelerator-driven nuclear energy 2009

  • Natural uranium has the same elemental composition as when it was mined (0.7% uranium-235 (235U), over 99.2% uranium-238 (238238U)), whereas enriched uranium has the proportion of the fissile isotope 235U increased by a process called enrichment, commonly to 3.5 - 5.0%.

    Nuclear power reactor 2009

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