- Small footprint, quick and easy to deploy in the wilderness
- High energy density compared to solar or accumulators
- Limited energy supply rates
- Uranium fuel cells for life span required in advance
- Eventually becomes depleted and must be refurbished
- Efficiency penalty compared to running power lines from main grid
And since this is Factorio, Cons are just another person's Pros :-)
- Supply priority is tertiary, same as accumulators, so an SMR on the main electricty grid is like a high-capacity accumulator that can't recharge.
- SMRs retain fuel level if picked up and moved. Fuel reserve is visible as a health bar when in an inventory.
- Current fuel level can be read by the circuit network, like an accumulator.