Nuclear power is uniquely reliable: it works day and night, at all times of the year.
This reliability is important because of how energy demand works. Throughout every day, energy demand rises and falls: offices draw power to run lighting during work hours, residents turn appliances on when they get home from work, and so on. There are seasonal fluctuations as well, as buildings need more heating and air conditioning during extreme temperatures.
During times when electricity demand is higher, more electricity is needed on the grid. This is known as “peak load.” Yet even during periods of lower demand, there are many people and businesses using electricity; this minimum amount of power required is referred to as “baseload.”
Most utilities use fossil fuels, such as natural gas, to meet peak load demand because they can be started up and shut down relatively quickly. In this way, the utilities waste as little power as possible, without overburdening the grid or causing brownouts.
Some utilities are also able to harness newer forms of power generation such as wind and solar, but the power output of these methods depends on the wind blowing and the sun shining.
Because nuclear power is not intermittent, and because Canadian nuclear plants do not have to be shut down for refuelling, it provides a reliable baseload supply of electricity.