The article give the source for the comments as a link embedded in the text.
The article is using the U.S. Department of Homeland Security's National Capital Region Key Response Planning Factors for the Aftermath of Nuclear Terrorism (2011)as the source of its information.
The Lawrence Livermore National Laboratory released a report in 2011 that spells all this out. It hasn't gotten nearly the attention it deserves.
It's called the "National Capital Region Key Response Planning Factors for the Aftermath of Nuclear Terrorism" and it makes for fascinating reading.
Did you know, for example, that: