The train is hauling a so-called CASTOR convoy, named after the type of container carried: Cask for Storage and Transport Of Radioactive material. These trademarked casks have been used since 1995 to transport nuclear waste from German power plants to France for reprocessing, then back to Germany for storage.
"High-level waste is in fact hot," said nuclear energy and proliferation expert Matthew Bunn. "It doesn’t mean anything in particular in terms of how dangerous it is."
A CASTOR railcar glows ominously in a thermal image, but the scene shows only that the cars' contents are warm—no hotter than a sweltering summer day—said Matthew Bunn, of Harvard University's Belfer Center for Science and International Affairs.
The intent seems to be to try and get people to think that the casks are emitting something dangerous, but I think they do quite the opposite.