Radioactive Waste
United States Atomic Energy Commission public information booklet, circa 1972.
We admit to curiosity about the phrase “it remains potentially dangerous for hundreds of thousands of years”. The fission products segregate naturally into two groups (nobody knows why), one with half–lives of less than thirty years, and one with half–lives of more than a hundred thousand years. The radiotoxic hazard is almost entirely in the former, and is effectively spent within a few hundred years.
It is possible that what is meant is that, if the waste were to be dispersed into the environment after a long period of cooling, some unknown geochemical process could possibly concentrate some of these long–lived fission products into a hazardous form. But the likelihood of this is vanishingly remote, especially because for any element except technetium, dilution with non–radioactive forms of the same element would almost certainly occur. Indeed, the “permissible body burden” given for iodine–129 (half–life 15·7 million years) in a 1959 regulatory guidebook is greater than the total amount of iodine normally present in the human body!
