Power CBMs are VERY VERY VERY common - take those apart for plutonium.
Also, manhacks occasionally drop some - lock up the scientists until they’ve dropped all their manhacks, kill the manhacks…
And yes, labs tend to have a good bit of it.
Seriously, though, Power CBMs… I’ve got over 20,000 power on my current character, and I’ve still got lots of Power CBMs… shockers, shocker brutes, scientists, technicians, broken cyborgs, bio-operators… just the scientists in a decent-sized lab can give you 10-20 of them, easy.