Definition

1. Adjective:
   • Not fissile: Describes a material, typically a nuclear substance, that is not capable of sustaining a nuclear fission chain reaction. It cannot be split by neutrons into smaller atoms with the release of energy.

Usage

• The word nonfissile is a technical adjective primarily used in nuclear physics, engineering, and materials science. It describes the property of a material, often in contrast to fissile materials like Uranium-235 or Plutonium-239.
• It is used attributively (before a noun) or predicatively (after a linking verb).

Examples

• Attributive use (before a noun):
  • Uranium-238 is a nonfissile isotope used in breeder reactors.
  • The reactor design incorporates a nonfissile blanket to absorb excess neutrons.
• Predicative use (after a linking verb):
  • This particular form of thorium is nonfissile.
  • The material was confirmed to be nonfissile and therefore safe for transport under the regulations.

Advanced Usage

• In nuclear fuel cycles: The term is often used to describe fertile materials, which are nonfissile but can be converted into fissile materials through neutron absorption (e.g., Thorium-232 converting to Uranium-233).
  • The nonfissile thorium fuel cycle presents potential advantages in waste reduction.

Variants and Related Words

• Fissile (adj): Capable of sustaining a nuclear fission chain reaction. (Antonym)
• Fertile (adj): In nuclear physics, describes a nonfissile material that can be transmuted into a fissile material.
• Nonfissionable (adj): Often used synonymously with nonfissile, though sometimes with a broader meaning of not being able to undergo fission at all.

Synonyms

• Nonfissionable: Not capable of undergoing nuclear fission.
• Infertile (in a specific nuclear context): Not capable of being transformed into a fissile material. (Note: This is less common and context-specific.)

Notes on Meaning

• The meaning of nonfissile is highly specific and technical. It does not have common idiomatic or figurative uses. Its core meaning is the direct negation of the property "fissile."
• It is important to distinguish it from non-radioactive; a nonfissile material can still be radioactive (e.g., some isotopes of uranium or plutonium).

Adjective

1. not fissile