Last week Neil de Grasse Tyson was on Bill Maher's show and the topic of nuclear weapons came up.
Tyson said, "modern nukes don't have the radiation problem.... They're a different kind of weapon than Hiroshima and Nagasaki." When pressed by Maher, he said, no, there is no radiation issue "if it's hydrogen bombs."
With all due respect to Dr. Tyson, does anyone know what in blazes he's talking about?
My understanding is that ALL thermonuclear or "hydrogen" bombs still have a fission primary that uses at least as much fissile material as Fat Man, and therefore even the smallest TN bomb would be at least as irradiative as the original fission bombs, albeit with more "bang for the buck". However, AFAIK most also utilize a shell of additional fissile material which undergoes fission as a result of the huge neutron flux from the fusion, rendering these much dirtier than the original bombs. Wikipedia says specifically that retrofitted W87 warheads use a U235 shell to make the second fission stage even more powerful (and more radioactive).
Is there anything known about "newer" post-cold war weapons designs and/or trends that could justify what he said? My only thought was that he might have been talking about relative "dirtiness" per unit of yield being smaller with modern bombs, but I'm not even sure that much is true when you factor in the fissile shell which seems to be a common feature. Otherwise I'm at a loss to understand why he would say what he said.