#10239
Viable blood samples can be found on the bodies of certain enemies. They seem to appear on any enemies that could be exposed to radiation, namely:
Feral ghouls
Mirelurks
Bloodbugs
Deathclaws
Mongrels
Super mutants
Yao guai
Radscorpion
There is, however, no guarantee that a viable blood sample will appear on a corpse, and they do not appear in the game until the related quest is started.
#10239