[ RadSafe ] Curiosity query

[Maury]

Can anyone tell me or suggest a link to description of the size and 
weight of the radioactive components of the Hiroshima bomb?  Also would 
like to know weight and size of the shielding required to handle this 
material.  How did they load this material onto the USS Indianapolis 
without lethal irradiation of handlers?  Am wondering if these answers 
would shed any light on what would be required to attempt a practicable 
so-called dirty bomb if not a practicable nuclear weapon.

Seems to me that terrorist groups would be hard pressed to handle a 
nuclear weapon even if any of our opponents saw fit to give them one 
...?  The implication to me is that a dirty bomb of any serious yield 
would not be feasible?

Thanks for comments.
Maury&Dog