[The Raven]

I think the critical mass of a nuke is somewhere around 80-90 lbs. Then add in the weight of the bomb itself. So how could the suitcase weigh 60 lbs?

Also..... Later in the above article they say they need 110kg (220 lbs) of material - confusing the reader by mixing english/metric units.

[Sender]

One critical mass of plutonium is only about 10.5 kilos I believe. So they wouldn't need much more than that. But even if they only have a handful of highly radioactive dust taped to a stick of dynamite it's going to cause a mess much bigger than the anthrax scare.

[Vinnie]

Also..... Later in the above article they say they need 110kg (220 lbs) of material - confusing the reader by mixing english/metric units.

That is confusing. No only that, but there has to be some shielding between the components to prevent a premature critical mass. And there must be shielding around the whole thing to stop radioactivity from leaking.

IF a small nuke was detonated, then we would have to retaliate with same. But what target?

[Robert A Cook PE]

Not so. Your numbers are immaterial because there are too many variables. So ANY weight value you care to mention, I could "design" a bomb that would work..down to a limit.

Or I could "prove" that such a bomb couldn't work equally easily.

Critical mass is funcion of density, geometry, implosion speed (or linear speed for a Tallboy style bomb - recall that it weighed (total bomb) something over 12,000 lbs and was the size of a good-sized van), packing material, reflector material, and purity/quality/density/enrichment of the fissile material. Etc. Etc.

[Don Joe]

"I think the critical mass of a nuke is somewhere around 80-90 lbs. Then add in the weight of the bomb itself. So how could the suitcase weigh 60 lbs?"

Now subtract the weight of the core material no longer needed when they reinforce it with tritium.

Oops!