Funny thing you mention that.

We had a nuclear meltdown in an experimental reactor in Lucens (https://en.wikipedia.org/wiki/Lucens_reactor).

It raises cost, makes access difficult in case a recoverable accident happens and there's still possibility of groundwater contamination if things go wrong.

Sure, but it makes cooling extremely difficult. And due to the confined environment any kind of incident response is needlessly difficult.

As if construction cost wasn't the biggest expense already.