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  1. critical mass

    noun

    1. The smallest mass of a fissionable material that will sustain a nuclear chain reaction at a constant level.
    2. The total mass of matter needed to generate sufficient gravitational force to halt the current expansion of the universe.
    3. An amount or level needed for a specific result or new action to occur.

    noun

    1. The smallest mass of a fissionable material that will sustain a nuclear chain reaction at a constant level.
    2. The total mass of matter needed to generate sufficient gravitational force to halt the current expansion of the universe.
    3. An amount or level needed for a specific result or new action to occur.
    4. The amount of fissile material that is needed to support a self-sustaining nuclear chain reaction.
    5. A quantity or amount required to trigger a phenomenon.
    6. The minimum mass of fissionable material that can sustain a chain reaction.
    7. The minimum amount (of something) required to start or maintain a venture.
      "there is now a critical mass of successful women to take the lead"
    The American Heritage® Dictionary of the English Language, 5th Edition • More at Wordnik
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  2. en.wikipedia.org

    The critical mass for lower-grade uranium depends strongly on the grade: with 45% 235 U, the bare-sphere critical mass is around 185 kilograms (408 lb); with 19.75% 235 U it is over 780 kilograms (1,720 lb); and with 15% 235 U, it is well over 1,350 kilograms (2,980 lb). In all of these cases, the use of a neutron reflector like beryllium can ...
  3. britannica.com

    Critical mass, in nuclear physics, the minimum amount of a given fissile material necessary to achieve a self-sustaining fission chain reaction under stated conditions. Its size depends on several factors, including the kind of fissile material used, its concentration and purity, and the
    Author:The Editors of Encyclopaedia Britannica
  4. allthescience.org

    May 21, 2024If critical mass is not achieved, then the neutrons present will overtime decrease, making a nuclear reaction less and less likely over time. Strictly speaking, the term critical mass is used to describe the state of equilibrium in which there is enough fissile material present to keep the amount of neutrons roughly the same, but the reaction ...
  5. atomicarchive.com

    The amount of a fissionable material's critical mass depends on several factors; the shape of the material, its composition and density, and the level of purity. A sphere has the minimum possible surface area for a given mass, and hence minimizes the leakage of neutrons. By surrounding the fissionable material with a suitable neutron "reflector ...
  6. The critical mass of a fissionable substance is the minimum amount of fissionable material that will support a self-sustaining chain reaction. At this mass the neutrons released as a product of one fission reaction can cause neighboring atoms to fission. A mass of material that is made to exceed the critical mass and fissions at an increasing ...
  7. library.fiveable.me

    Critical mass refers to the minimum amount of fissile material needed to maintain a nuclear chain reaction. This concept is fundamental in nuclear physics, as it determines whether a fission reaction can become self-sustaining or will fizzle out. Understanding critical mass is crucial for designing safe and effective nuclear reactors, as well as for managing the risks associated with nuclear ...

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    Critical mass

    In nuclear engineering, a critical mass is the smallest amount of fissile material needed for a sustained nuclear chain reaction. The critical mass of a fissionable material depends upon its nuclear properties, density, shape, enrichment, purity, temperature, and surroundings. The concept is important in nuclear weapon design. Wikipedia

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