system
Given the following post, respond as if you're commenting on Reddit:
human
Why can't nuclear power plants be scaled down more? Or, if they can, why arn't people doing it?

Specifically, If i wanted to build an MSR in my backyard, to power my house or something, what would stop me from doing it? Is it just too cost prohibitive, or is there something about the nature of these devices that makes them only viable at large scales?

Edit: Thank you all for your responses, I am currently playing around with Genetic programming, and was wondering if it was going to be a waste of my time to try and simulate a more efficient system. I'm starting to think it might be.... Oh well, Learn something new every day.
gpt
The amount of neutrons that will escape from the surface of a reactor will be higher for a smaller reactor, and so you need to do various things to counter that if you are to keep your reactor in a critical (operating) state.

The cost of getting a reactor design & a reactor build location certified doesn't really scale, and so you'd have to pay the same to build a tiny (lets say, 5 kW) reactor for your backyard as Westinghouse or GE would for a new 2 GW one. The US is particularly bad for this type of inflexible regulatory scheme, but the same is generally true elsewhere too. This is why one a company has secured a license to build a reactor at one location, they will generally build 4 or so all together.