Cobalt-60 has a half-life of 5.2714 years.
After 35,000 years, one unit of Co-60 would be reduced to only
1/2(35000/5.2714) = 1/26640
of its original mass.
In other words: Even if the entire observable universe consisted solely of Co-60, after 35,000 years, not even a single atom of it would be left.
In fact, the last atom of Co-60 would have decayed into harmless Nickel-60 millennia earlier.
Regards,
thanx...got me to looking for something a tad clearer
interesting here:
Don’t screw with cobalt 60 even if you believe it has a short half life. Those Mexican scroungers that stole the x-ray machine cask back in 1984 died, along with a couple of their neighbors , for spilling a few pellets in the street. The machine was about 20 years old and had been stored for lack of a skilled operator. But the poor wetbacks never got the memo about how it should have been low risk.
We sent a crew of guys from Hanford to help track down the contaminated re-bar that the cask got melted into. By the time they found the stuff it was all over Mexico and the US Southwest.
When we refuel Naval reactors we treat the whole spent package as tho it will be dangerous for 30+ thousand years. The PUREX guys sniggle out the parts they want and the rest gets buried deeply.
My main point is that the stuff is still used in medical applications, is Ionizing radiation, Is lifetime exposure, and it’s use must be accounted for and minimized as much as practical. I’m aware of medical applications that resulted in overdosing, burning as it were, that resulted in death. 600 REMS and you’re done. A little less and you’re done, just slowly. The indications are obvious but are always blamed on stage 5 cancer, witchcraft, voodoo, or some other convenient, fashionable boogeyman.