CanopyCo wrote:

On Sep 22, 1:19 pm, (Ralph) wrote:
According to Cresson Kearny (in his videos I think) the biggest chunks
are the most dangerous because they hit the ground first, but the finest
dust takes the longest to reach the ground, up to a year. Therefore, the
radioactive dust will be the last to reach the ground and be very widely
dispersed.


Isn't anything that is in the blast zone now radioactive once the bomb
hits?
The dust from the blasted building would float around right off.
The dust from crushed up bigger chunks that you mentioned would also
be there.

It's the type of nuke and what the fireball hits. The two that were
dropped on Japan were air bursts, but inefficient nukes. They generated
some fallout which would also be true of a nuke built by terrorists or a
rogue nation and be few in number, but nukes built by a super-power
would be much more efficient, but in greater numbers.

Air bursts are detonated at about 3,000 feet for maximum destruction to
surface structures. The effect is called a Mach-Y stem in which initial
and reflected blast waves are combined at ground level. Since the
fireball doesn't touch buildings or the ground, very little radioactive
fallout is produced.

But in a ground burst, detonated at ground level for use against
hardened military targest, the nuclear fireball vaporizes tons of earth
which is ejected into the atmosphere. This is the radioactive fallout to
be worried about.