Gizmodo has, thanks to the Freedom of Information Act, obtained a copy of a 1986 training video developed by the National Nuclear Security Administration, which is a federal agency responsible for, well, preventing this sort of catastrophe. This video was used as part of a large, multi-agency exercise dubbed "Mighty Derringer" that simulated responses to a nuclear terrorist attack on Indianapolis, Indiana.
So far, Gizmodo has published only this segment, which depicts local reporters in Indianapolis discussing the terrorists’ threats. This is high drama in the spirit of Threads and The Day After that I dearly hope Gizmodo publishes in full.