Heck, they use tritium for a lot of "glow in the dark" items these days.

For far future SF (like Traveller) I've always thought that RTGs are a great power source for settlers on frontier worlds. Dif a hole, drop it in, and you've steady (if slowly decreasing) power for decades. No muss, no fuss.

And as I said above, I think they *really* should look into TIMMs for venus landers.