Re: Still haven't graduated from lithium
"They do have a problem with being an attractive target for terrorists."
Only terrorists who really don't know what they're up to. RTGs are hot because they're seriously radioactive and therefore easily detectable from a distance.
Plus they can't be used to make weapons.
- Anything more than slightly radioactive will cause your nuke to start going off too early and cause a fizzle. That's why the US military didn't like Alvin Weinberg's Molten Salt Reactor - the plutonium produced was a mix of desireable and highly undesireable (for bomb making) isotopes that was virtually impossible to separate and so red hot from a radioactivity point of view that any attempts to do so would stick out as a guant "something's going on here" flag
- They're too hot to handle for making a "dirty" (conventional) bomb. Anyone who handled them directly would quickly be dead and in any case a conventional explosion would only scatter the stuff over a limited area that's relatively easy to clean up (see point above about being radioactives being detectable from a distance). Powdering the material for wider dispersal runs into both the "readily detectable" and "soon be dead" issues.
RTGs are nice tools, but attempting to mishandle them is hazardous enough for your health that you'll probably be dead long before being able to do much, or before the armed hazmat team shows up.