None in the DC area I've heard of.
Back in the 70s, though, a broken Soviet satellite powered by a nuclear reactor crashed into Canada, spreading radioactive debris over hundred of miles of forest. Most of the reactor core was never found. So if you're walking through the Canadian wilderness, see a 3-eyed Sqatch and start rhowing up, you may have found some reactor fuel.
https://en.wikipedia.org/wiki/Cosmos_954
When I was a little kid I remember seeing guys in protective gear with geiger counters in the woods on the news looking for this thing.