Alikriittistä

Alikriittistä is a Finnish term that translates to "subcritical" in English. It is primarily used in the field of nuclear physics and engineering to describe a state where a nuclear chain reaction cannot be sustained. In a nuclear reactor, a chain reaction occurs when neutrons released from the fission of one atom trigger the fission of other atoms. For a chain reaction to be sustained, a sufficient number of neutrons must be produced to compensate for those that are lost through absorption or escape.

When a nuclear reactor is in an alikriittistä state, the rate of neutron production is less than the rate of neutron loss. This means that the number of fissions per generation decreases, and the chain reaction eventually dies out. This state is important for reactor safety and control. Reactors are designed to operate in a supercritical state, where the chain reaction is sustained and produces power. However, various safety mechanisms are in place to ensure that the reactor can be brought to an alikriittistä state if necessary, for example, during shutdown or in emergency situations. Maintaining an alikriittistä state is crucial for preventing uncontrolled nuclear reactions.