Supercriticality

Definition

Supercriticality occurs when a nuclear chain reaction becomes self-sustaining and the neutron population increases exponentially. It is a state where each fission event causes more than one subsequent fission event.

5 Must Know Facts For Your Next Test

1. Supercriticality is crucial for the operation of nuclear reactors and nuclear weapons.
2. It is achieved when the effective multiplication factor, k, exceeds 1.
3. In medical applications, controlled supercritical states are used in radioisotope production for diagnostic imaging.
4. Uncontrolled supercriticality can lead to dangerous levels of radiation and reactor meltdowns.
5. The transition from subcritical to supercritical involves careful balancing of fuel, moderator, and neutron absorbers.

Review Questions

• What happens to the neutron population during supercriticality?
• Why is the effective multiplication factor (k) important in determining supercriticality?
• How can uncontrolled supercriticality be dangerous in a nuclear reactor?

Related terms

Subcritical: A state where each fission event causes less than one subsequent fission event, leading to a decrease in the neutron population.

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

Neutron Moderator: A material used in a nuclear reactor to slow down fast neutrons, making them more likely to cause further fission events.