Uranium-238

  • uranium-238, 238u
    uranium03.jpg
    10 gram sample
    general
    symbol238u
    namesuranium-238, u-238
    protons92
    neutrons146
    nuclide data
    natural abundance99.2745%
    half-life4.468 billion years
    parent isotopes242pu (α)
    238pa (β)
    decay products234th
    isotope mass238.05078826 u
    spin0
    decay modes
    decay modedecay energy (mev)
    alpha decay4.267
    isotopes of uranium
    complete table of nuclides

    uranium-238 (238u or u-238) is the most common isotope of uranium found in nature, with a relative abundance of 99%. unlike uranium-235, it is non-fissile, which means it cannot sustain a chain reaction in a thermal-neutron reactor. however, it is fissionable by fast neutrons, and is fertile, meaning it can be transmuted to fissile plutonium-239. 238u cannot support a chain reaction because inelastic scattering reduces neutron energy below the range where fast fission of one or more next-generation nuclei is probable. doppler broadening of 238u's neutron absorption resonances, increasing absorption as fuel temperature increases, is also an essential negative feedback mechanism for reactor control.

    around 99.284% of natural uranium's mass is uranium-238, which has a half-life of 1.41×1017 seconds (4.468×109 years, or 4.468 billion years).[1] due to its natural abundance and half-life relative to other radioactive elements, 238u produces ~40% of the radioactive heat produced within the earth.[2] 238u decay contributes 6 electron anti-neutrinos per decay (1 per beta decay), resulting in a large detectable geoneutrino signal when decays occur within the earth.[3] the decay of 238u to daughter isotopes is extensively used in radiometric dating, particularly for material older than ~ 1 million years.

    depleted uranium has an even higher concentration of the 238u isotope, and even low-enriched uranium (leu), while having a higher proportion of the uranium-235 isotope (in comparison to depleted uranium), is still mostly 238u. reprocessed uranium is also mainly 238u, with about as much uranium-235 as natural uranium, a comparable proportion of uranium-236, and much smaller amounts of other isotopes of uranium such as uranium-234, uranium-233, and uranium-232.[4]

  • nuclear energy applications
  • nuclear weapons
  • radium series (or uranium series)
  • radioactive dating
  • see also
  • references
  • external links

Uranium-238, 238U
Uranium03.jpg
10 gram sample
General
Symbol238U
Namesuranium-238, U-238
Protons92
Neutrons146
Nuclide data
Natural abundance99.2745%
Half-life4.468 billion years
Parent isotopes242Pu (α)
238Pa (β)
Decay products234Th
Isotope mass238.05078826 u
Spin0
Decay modes
Decay modeDecay energy (MeV)
alpha decay4.267
Isotopes of uranium
Complete table of nuclides

Uranium-238 (238U or U-238) is the most common isotope of uranium found in nature, with a relative abundance of 99%. Unlike uranium-235, it is non-fissile, which means it cannot sustain a chain reaction in a thermal-neutron reactor. However, it is fissionable by fast neutrons, and is fertile, meaning it can be transmuted to fissile plutonium-239. 238U cannot support a chain reaction because inelastic scattering reduces neutron energy below the range where fast fission of one or more next-generation nuclei is probable. Doppler broadening of 238U's neutron absorption resonances, increasing absorption as fuel temperature increases, is also an essential negative feedback mechanism for reactor control.

Around 99.284% of natural uranium's mass is uranium-238, which has a half-life of 1.41×1017 seconds (4.468×109 years, or 4.468 billion years).[1] Due to its natural abundance and half-life relative to other radioactive elements, 238U produces ~40% of the radioactive heat produced within the Earth.[2] 238U decay contributes 6 electron anti-neutrinos per decay (1 per beta decay), resulting in a large detectable geoneutrino signal when decays occur within the Earth.[3] The decay of 238U to daughter isotopes is extensively used in radiometric dating, particularly for material older than ~ 1 million years.

Depleted uranium has an even higher concentration of the 238U isotope, and even low-enriched uranium (LEU), while having a higher proportion of the uranium-235 isotope (in comparison to depleted uranium), is still mostly 238U. Reprocessed uranium is also mainly 238U, with about as much uranium-235 as natural uranium, a comparable proportion of uranium-236, and much smaller amounts of other isotopes of uranium such as uranium-234, uranium-233, and uranium-232.[4]