Though they are neat.

For someone who has concerns about fluorine, I'd think you'd be worried about strontium 90 - it [link|http://tms.physics.lsa.umich.edu/214/other/news/100101UKBones.html|gets in bones] too...

[link|http://mmae.iit.edu/~MAE442/powrprg3.htm|RTGs] - Radioisotope Thermoelectric Generators - use the heat given off by radioactive decay to generate electricity directly (using something like a thermocouple operated in reverse). The usual usage for these things is satellite power at distances from the sun where solar cells are impractical. Shielding is an issue in other applications....

Another neat technology is to use the large thermal gradient in the oceans to generate electric power - [link|http://www.nrel.gov/otec/what.html|Ocean Thermal Energy Conversion]. It's very cold very deep, and warm up at the top and if you design a power plant correctly you could generate a lot of power that way - but not cheaply. It might be good for some tropical islands....

Cheers,
Scott.