A station blackout is the loss of the offsite grid together with failure of the emergency diesel generators, leaving only batteries and any non-AC systems. Turbine-driven pumps and battery-powered instruments must carry decay heat removal for a defined coping time while power is restored or portable equipment is connected. A prolonged blackout that also loses DC power led to core damage at Fukushima Daiichi.
Loss of offsite power and both diesels failed to load, declare station blackout and start the coping strategy.
Coping time depends as much on battery life and room heat-up as on water supply, which is why DC load shedding is drilled.
Also heard as
- station blackout
Related terms
Decay heat
Heat produced by radioactive decay of fission products after a reactor shuts down, which must be removed.
Beyond design basis accident
An accident more severe than those the plant's safety systems were explicitly designed to handle.
Severe accident
An accident involving significant damage to the reactor core, with possible fuel melting and large releases.
Diversity
Using different designs, technologies or physical principles for the same safety function to guard against common-cause failure.