Passive safety

A safety feature that does its job using physics alone (gravity, natural circulation of hot and cool coolant, conduction of heat, or reactivity feedback) with no outside power, pumps or operator action. Some systems described as passive still need one active step to start them, such as a battery-powered valve opening, and that difference is worth checking. A claim of passive safety is always a claim about a specific set of accidents and usually a specific length of time, such as three days with no action needed; it is not a claim of safety against every possible event indefinitely. It depends on numbers that a reader is entitled to ask for: chiefly the reactor's decay heat, the path that heat takes out of the core, and its reactivity coefficients. A design being passively safe does not remove the need for regulation, maintenance or security around the radioactive material it still holds.

Vocabulary id

concept:passive-safety

Scheme

Concepts

Back to the glossary.