Safety Apparatus for a Nuclear Reactor

a system of arrangements designed for quick shutdown of a chain reaction in the core of a nuclear reactor.

The safety apparatus is activated automatically in the case of an accident in a nuclear reactor or when one of the parameters attains a value that can lead to an accident. These particularly important parameters include temperature, pressure, and release of coolant and the power level and rate of power increase. The active parts of the reactor safety equipment usually consist of a rod with a neutron absorber (boron or cadmium, for example) which is inserted in the core a fraction of a second after a sensing device for some parameter transmits a danger signal. Other methods are used much less frequently—for example, the injection of an absorbing solution into the coolant circuit. The fundamental requirement stipulated for safety equipment is reliability and rapid action.