Nuclear power stations are designed to deliver a reliable level of power over long periods of time. The new plants proposed for the UK are expected to generate electricity as much as 90% of the time during normal operation. Plants delivering similar levels of availability are already operating in several countries including the US.
This means that nuclear power stations can provide reliable 'baseload' power – the amount that can be reasonably expected to meet customer demands.
In 1990, only a quarter of the world's nuclear plants had load factors over 75% – that is, only a quarter ended up generating more than 75% of their theoretical maximum electrical output. Today, nearly two thirds of nuclear plants have load factors over 75%, and a quarter have load factors higher than 90%.
The planned new generation of nuclear power stations in the UK aims to set a new standard, with shorter outage periods and reduced fuel consumption per kilowatt-hour (kWh) of electricity generated meaning they need less fuel and have to refuel less often.