It was quite well done.
A group of US anti-nuclear activists (or some such) had some how stolen a bunch of plutonium and fashioned a crude bomb and had it on a boat in Charleston, SC's (IIRC) harbor. They intended to use it to force the US to disarm its weapons, or something of the sort.
They had a portable TV camera which let them broadcast their demands, etc., (and let the movie take place). It becomes a media circus, as you might imagine.
The main actor had gotton plutonium poisoning, so he was a gonner no matter what happened....
The bomb on the boat is booby-trapped. Anti-terrorist commandos raid the boat, but are unable to disarm the bomb...
It goes off. Thousands are killed....
A few days pass, and life goes on...
It was a good show. I wish I could recall the title. :-( I think it was on NBC in the very early '80s, when the nuclear missile debate was very intense, especially in Europe.
Cheers,
Scott.