Supercritical mass

Definition

Supercritical mass is the amount of fissile material needed to maintain a self-sustaining nuclear chain reaction with increasing rate. It occurs when there is enough mass and density to ensure that more than one new neutron from each fission event causes further fission.

5 Must Know Facts For Your Next Test

1. A supercritical mass results in an exponentially growing number of fission reactions.
2. It is crucial for the operation of nuclear reactors and atomic bombs.
3. The concept hinges on the probability that emitted neutrons will cause further fissions, which depends on factors such as material purity and geometry.
4. Achieving supercritical mass requires careful control of neutron reflectors and moderators.
5. If not controlled, it can lead to a runaway reaction causing an explosion.

Related terms

Critical Mass:

The minimum amount of fissile material needed to maintain a self-sustaining nuclear chain reaction.

Subcritical Mass: An amount of fissile material that cannot sustain a chain reaction because each fission event does not produce enough neutrons to continue the process.

Neutron Moderator: $\text{A substance used in a nuclear reactor to slow down fast neutrons, thereby increasing the likelihood of further fission events.}$