SMRs are still in their first development stage, but their low cost and high practicality is attracting the attention of all those who believe nuclear energy is worth investing in. Their development is starting from the different models used to power nuclear submarines for more than a half-century.
Ranging in size from 25 megawatts to 125 megawatts or more, and no bigger than a small railroad car, an SMR can be built in a factory instead of at a nuclear site for a fraction of the cost and in less than half the time of a large nuclear plant. Though a conventional nuclear plant is cheaper on a cost-per-kilowatt basis than a cluster of SMRs with the same power output, SMRs are more affordable if ordered and built one at a time, as the demand for electricity arises.
Importantly, most SMRs would be located underground for security, and placed one next to another.
In other words, since modules using a standardized design could be built in series over a number of years, SMRs would be much easier to pay for than a large power plant, whether nuclear or fossil fuel.