Throttling
The 1950s designed reactors in operation today, don’t throttle up or down very well, they can indeed throttle if needed, but in practice, they are run up to full power and operate at that level until it is time to refuel. This has made them great baseload plants, but inflexible in the modern wholesale market. With more and more hours each year with negative prices, reactors that produce baseload power find themselves struggling to break even.
Renewables don’t always produce and can’t be forced to run. If there is no wind and no sunshine, then some other source of low-carbon electricity is needed.
Adding the ability to throttle to a plant that has fuel available and can run anytime it is called upon can provide for that need.
Many SMR designs can provide this capability. Ramp rates on those designs vary but can be in the same range as combined cycle natural gas turbines.
Black Start
Some SMR designs can black start and some need assistance. Some need pumps, compressors or other equipment that run to overcome the passive safety measures.
These ancillary devices can be powered from auxiliary power units at the site of the SMR.
Black start is critical for restarting the grid, regardless of why the grid stopped working.
Inertia
SMR provide inertia at a level that Inverter Based Resources (IBR) do not provide. While IBR can provide inertia, it takes more watt of IBR to provide the same level of inertia that the synchronous generator (like SMR) can provide.
SMR I - Announcement of Small Modular Reactor Series
SMR II - Major types of reactors
SMR III - Why is 300 megawatts the dividing line for SMR?
SMR IV - Foundation independent designs & Power Conversion
NEXT: SMR VIII- Process Part 1