If the smaller reactors can take advantage of easier fabrication and logistics they might be cheaper, but that is an unknown.
Cubic volume increase vs. quadratic surface area increase means larger sizes are more effective.
Here's a simple argument about why that's true:
https://yarchive.net/space/launchers/fuel_tank_scaling_laws....
> Take any plane that slices through the pressure vessel, and consider the problem of trying to prevent the vessel from separating at that plane. The pressure load trying to cause such a separation is proportional to the surface area of the slice. The wall length available to resist it is the outer edge of the slice. The load scales with the square of size, the wall length only linearly... so as the size goes up, the wall thickness must grow as well. Chase it through the math, and wall mass is simply proportional to volume.
It's also a consequence of the virial theorem of mechanics.
Below a certain size you run into code minimums, but nuclear power plants will be well above that size.
The sensible way to deploy these would be in groups close to existing infrastructure in places that can be easily secured. For example de-commissioned coal plants or nuclear plants. Security also raises the cost of operation of course. Just because it is small physically does not mean the risk is smaller. So, same level of security as with a big nuclear plant. Same level of cost. But less energy. Co-locating allows you to reduce that cost.
