uranium-238
Sign in to saveAlso known as 238U, U-238, ²³⁸U
Uranium-238 (' or U-238') is the most common isotope of uranium found in nature, with a relative abundance above 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 abso
Key facts
- Isotope.image
- Uranium03.jpg
- Isotope.image_caption
- 10-gram sample
- Isotope.mass_number
- 238
- Isotope.symbol
- U
- Isotope.num_neutrons
- 146
- Isotope.num_protons
- 92
- Isotope.abundance
- 99.274%
- Isotope.decay_product
- Thorium-234
- Isotope.decay_mass
- 234
- Isotope.decay_symbol
- Th
- Isotope.parent
- Plutonium-242
- Isotope.parent_mass
- 242
- Isotope.parent_symbol
- Pu
- Isotope.parent_decay
- a
- Isotope.parent2
- Protactinium-238
- Isotope.parent2_mass
- 238
- Isotope.parent2_symbol
- Pa
- Isotope.parent2_decay
- b-
via Wikipedia infobox
Wikidata facts
- Mass
- 238.050786996
- Image
- Uranium238.jpg
Show 9 more facts
- atomic number
- 92
- neutron number
- 146
- half-life
- 4468000000
- natural abundance
- 0.992742
- spin quantum number
- 0.0
- parity quantum number
- 1
- mass excess
- 47307.783
- binding energy
- 1801689.75
- Commons category
- Uranium-238
via Wikidata · CC0
~14 min read
Article
12 sectionsContents
- Nuclear energy applications
- Breeder reactors
- CANDU reactors
- Radiation shielding
- Downblending
- Nuclear weapons
- Decay
- Radioactive dating
- Health concerns
- See also
- References
- External links
Uranium-238 (' or U-238') is the most common isotope of uranium found in nature, with a relative abundance above 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.
The isotope has a half-life of 4.463 billion years (). Due to its abundance and half-life relative rate of decay to other radioactive elements, 238U is responsible for about 40% of the radioactive heat produced within the Earth. The 238U decay chain contributes six electron anti-neutrinos per 238U nucleus (one per beta decay), resulting in a large detectable geoneutrino signal when decays occur within the Earth. The decay of 238U to daughter isotopes is extensively used in radiometric dating, particularly for material older than approximately 1 million years.