I am hopeful for small modular reactors (SMR's). They have the potential for significant construction cost savings, are less of a risk from terrorism/disaster, and can often be located closer to the load (long power lines lose power).
There have been a number of studies that have SMRs are being as expensive or higher than conventional nuclear, with the added downside of higher levels of waste, anywhere from 2 to 30 times as much as conventional nuclear depending on the tech used.
Part of the reason for scaling up reactors in the first place was the expectation that output would scale faster than costs. That hasn't really panned out to the extent expected.
I guess from a physics standpoint, one would expect an SMR to be somewhat less fuel efficient in that a nuclear reactor is essentially a furnace and the surface area to volume ratio favours a larger design to retain the heat. SMR proponents like to spin this as a "feature", however, in that they would be less likely to meltdown and that safety trumps efficiency in reactor design. Another point they claim from the safety standpoint is that if you had say a dozen SMRs replacing a single traditional reactor, you could routinely take one off-line for inspection/maintenance without a huge hit on power generation.
I don't know enough about this and most of what I read is anecdotal though, so take it with a grain of salt. There may still be a case for them in northern communities, many of which are off the grid and use large diesel/gas generators? I guess it would depend on how well SMRs can follow load, which has tended to be a problem with nuclear power.