Unlike the US navy reactors, civilian reactors don't swim in coolant.

Yes, power levels make difference there, but there is no inherent advantage of smaller sizes in this context.

If reactor explosion happens even with small reactor sizes, containment building makes no difference unless you size it to contain even an explosion, which will make it even more expensive. And you will still have to deal with meltdown products in the end.

If you have enormous amounts of coolant at hand, you can equally well cool a bigger reactor too.

From the point of view of safety smaller reactors that -can't- go into critical mass by the design are far superior to the older huge reactor designs that we have currently. Sure it's usually cheaper to go bigger but the public just is not going to have allow it with designs that can potentially go critical mass and make the next Chernobyl no matter how many times you tell them you can handle any situation.

> From the point of view of safety smaller reactors that -can't- go into critical mass by the design

Man, any reactor is critical, by the definition.

You know exactly what I was talking about. Sorry I'm not a nuclear scientist. In common parlance "going critical" means losing control of the reaction and having to run away at a fast rate of speed before you become a victim of radiation poisoning.

Modern reactor designs physically CAN'T explode. Modern reactors are designed with a HEAVILY negative coefficient.

https://en.wikipedia.org/wiki/Void_coefficient

> Modern reactor designs physically CAN'T explode.

You have a few gigawatt water heater, and an extremely large pressure vessel.

Modern reactors physically can explode, with, or without positive void reactivity coefficient.

I urge you to disable the control system on any working PWR reactor, and stand by to test your hypothesis.

Rapid power excursions with, or without coolant inside come from many phenomena, not just void reactivity coefficients.