Comment by Animats
10 hours ago
This isn't about radioactivity at all. It's about the millions of pounds of mercury used at the Y-12 plant at Oak Ridge,[1] resulting in a lot of low-level mercury contamination.
[1] https://ehss.energy.gov/ohre/new/findingaids/epidemiologic/o...
It's highly likely that the waste is mixed waste, meaning rad + mercury. Much tougher to treat than just rad or mercury.