Criticality

The state of a nuclear chain reaction in which each generation of fissions is exactly as large as the one before it, so the reaction is self-sustaining at a steady rate rather than dying away or growing. A reactor operating at steady power is critical continuously; this is its normal state. To raise power, operators make it slightly supercritical for a while, and to lower power, slightly subcritical. First criticality, the first time a specific reactor achieves this, is a distinct commissioning milestone, tracked in this dataset as a regulatory stage.

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concept:criticality

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