From what I understand, they're merely a modified version of a Radioisotope Thermoelectric Generator. They'll use thermocouples to directly produce electricity from the heat emitted from the radioactive decay. Ordinary RTG's are generally more complicated, but that's because they're launched into space and there's no simply switching out the generator if something goes iffy.

I imagine how they'd be installed would be inside a concrete bunker of sorts. The company would build a underground container with connections leading to the outside installed when the concrete is setting like most foundation works and then place a multi-tonne concrete slab on top so that only someone with a back-hoe and crane can even get to them and open the things. They could easily be placed somewhere even more secure like installed on police property in small communities.