Are tritium runway lights widespread in remote areas? There was some interest in the 80s and 90s in providing runways in remote areas with tritium lighting (which requires no external power, since the radioactive decay in a sample of tritium gas induces radioluminescence in a suitable material). However, apart from this failed trial in Alaska (pdf) and various vague mentions of it on the internet, I can't establish if this every became a viable technology.

Has it become widely-used (perhaps for military airstrips, if not for civilian ones)? And if so, how did the technology improve in the last couple of decades to make it work?
I think it's a major headache to heave radioactive material in remote areas. Soviet union used RTG for lighthouses. A lot of countries were worried about that. You can find articles on the internet. So probably it's not very good idea due to threats.