The Pu is from an old soviet smoke detector, containing roughly 40μg of Pu, which creates a few μCi of radiation needed for smoke detection. For fission, you need at least several kg of pure Pu239. For a "dirty bomb", any amount will do, of course.
> For a "dirty bomb", any amount will do, of course.
By that logic, one smoke detector is enough?
I probably wouldn't want to eat a smoke detector, but if one was added to a bomb I probably wouldn't be very concerned about the impact of the smoke detector.
Using that definition of dirty bomb, a firecracker inside a banana is enough. Perhaps it should include a minimal threshold, like it's enougt to kill 1 person in the linear no threshold model.
