Why build many nuclear plants instead of a single big one?

Is there a specific reason for not putting multiple reactors into a single big central nuclear plant that would generate as much energy as multiple smaller plants? That way, there wouldn’t be a need to construct the buildings and infrastructure for every single plant, only for the big central one.

It’s already done that way.
Palo Verde (the largest installation in the country) has three reactors.

But, there are limits to how far power can be sent economically, so you can’t have all your generation for the entrée country coming from one spot.

Single point of failure is usually bad, and current electrical distribution methods are very, very inefficient.

There is a lot of loss of power in transmission over long distances and superconductors are not going to change that anytime soon.

Plus, when one reactor goes into full meltdown, getting the workers to continue working at the others is a bit difficult. Consider that Fukushima has six reactors and that this has been done. http://en.wikipedia.org/wiki/Fukushima_Daiichi_nuclear_disaster