is there a lower limit on the size of a nuclear bomb?

Question

And if so, what factors determine it?

I know that the scale of the explosion is an insane amount larger than the teeny molecules causing it, but I’m wondering if there could ever be nuclear explosions small enough to take out a single house or block, rather than a whole city from high above.

In: Physics

Answer 1

Theoretically if you had something strong enough to compress and contain it you could make a ‘fusion’ weapon consisting of a proton boron atom that generates an energetic alpha particles.

For a thermonuclear weapon of the conventional sort the smallest that could be made would be pretty expensive, as it would require 5kg of Californium 251.

The world’s production of Californium is about 500mg a year. This might take a while.

Then you’d have a hollow sphere of subcritical Cf151. Crush it with a bomb into a prompt critical configuration surrounded by a tamper and fusion fuel and you’ve got a nuclear bomb somewhere between 8 and 12kg that would have a yield equivalent of maybe 5 tons of TNT.