Definition

1. Adjective:
   • Capable of undergoing nuclear fission: Describes a material, typically an atomic nucleus or a substance containing such nuclei, that can be split into smaller parts when struck by a neutron, releasing a significant amount of energy.

Usage

• The term fissionable is primarily used in the context of nuclear physics, nuclear engineering, and discussions about nuclear energy or weapons. It describes the inherent property of certain isotopes.
• It is often used attributively (before a noun) to describe materials.

Examples

• Adjective:
  • Uranium-235 is a fissionable isotope used as fuel in nuclear reactors.
  • The laboratory stored fissionable material under strict security protocols.
  • Not all heavy elements are fissionable under normal conditions.

Advanced Usage

• "Fissionable vs. Fissile": In technical contexts, fissile is a more specific subset of fissionable. While all fissile materials are fissionable, not all fissionable materials are fissile. Fissile materials (like U-235, Pu-239) can sustain a chain reaction with slow (thermal) neutrons, whereas some fissionable materials may require fast neutrons to split.
  • Plutonium-239 is both fissionable and fissile.

Variants and Related Words

• Fission (n): The nuclear reaction itself, the splitting of an atomic nucleus.
  • The process of nuclear fission releases immense energy.
• Fissile (adj): A technical term for materials capable of sustaining a fission chain reaction with thermal neutrons.
  • Fissile isotopes are crucial for nuclear power generation.

Synonyms

• Fissile (in many, but not all, technical contexts).
• Cleavable (in a very broad, non-technical sense of "able to be split," but this is not used in nuclear physics).

Antonyms

• Non-fissionable (adj): Incapable of undergoing nuclear fission.
  • Lead is a non-fissionable material used for radiation shielding.
• Fertile (adj, in nuclear physics): Describes a material (like U-238) that is not itself easily fissionable but can be transformed into a fissile material (like Pu-239).
  • Uranium-238 is a fertile material.

Adjective

1. capable of undergoing nuclear fission
   • a fissionable nucleous
   • fissionable material