[oceanview]

the context for that statement comes from the preceding paragraph - note the term "nuclear improvised bomb" used there. I read that as dirty bomb.

[cyncooper]

It was stated explicitly by Comey. See the second paragraph that I posted. Here is just the bolded part:

Zubaida...did think as well that another kind of radiological device was very feasible: uranium wrapped with explosives to create a dirty bomb.

~snip~