This has false flag written all over it.
I majored in Physics, and the last time I encountered anything radioactive was thirty years ago in grad school. Only the Feds would be able to get their hands on large enough quantities of something like Co60 or Cs137 to make a dirty bomb.
How about Americium? Specifically: Am-241?
The amount of americium in a typical new smoke detector is 0.29 micrograms (about one-third the weight of a grain of sand) with an activity of 1 microcurie (37 kBq). Some old industrial smoke detectors (notably from the Pyrotronics Corporation) can contain up to 80 μCi.
-Wikipedia
Granted, one could purchase a couple of hundred such detectors, extract the Am-241, and build an only mildly "dirty" bomb - but it would "spook" some people.
Regards,
BINGO!
Heck, Georgia Tech used to have a pretty serious research reactor on campus. It was shut down in 1995 and decommissioned in 1999, so over two decades ago. To your point.
Only the Feds would be able to get their hands on large enough quantities of something like Co60 or Cs137 to make a dirty bomb.
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Yes, you are so right.