The thing is, you could probably create something FAR more horrific by simply mixing spent nuclear fuel with TNT...

Not that I want to give anyone any ideas.

> The thing is, you could probably create something FAR more horrific by simply mixing spent nuclear fuel with TNT...

Nope. It turns out you need astronomical amounts of spent waste to noticeably impact a large population.

The trial of Jose Padilla (aka "the dirty bomber") has the best data on this. He went to Al Qaeda, offering to build and detonate a dirty bomb. Al Qaeda wasn't at all interested. They had run the actual numbers from an engineering standpoint (unlike everyone else who had just said "ooh scary bad!"), and demonstrated clearly that dirty bombs aren't actually a viable mass casualty weapon.

Before the Jose Padilla trial, we used to hear lots about dirty bombs. Since then, not at all. It's not that people forgot about them. They just aren't actually a credible engineering threat. It's too hard to get enough material distributed over a large enough area to measurably impact health outcomes for the impacted population. That was a surprise that came out of the trial.

There are lots of attack types to worry about. Dirty bombs are very far down that list.