Efficiency:
Physicists say increasing the size of a reactor increases the thermal efficiency by an epxonential factor of three.
Manufacturers say (when they tell the truth) mass production of units can provide a fourfold reduction in costs.
So big nuclear plants make sense. The devil is in the details, however since the thermal efficiency is not being fully developed and realized.
Not by a long shot. It makes economic sense to build smaller nuclear reactors and really get the technology down.
I hope the President studies this issue while funding the nuclear expansion.