Boosted fission weapons improve on the implosion design.

The key to reducing that girth was the two-point implosion design.

A very inefficient implosion design is one that simply reshapes an ovoid into a sphere, with minimal compression.

Later versions were based on the implosion design.

The Mark 10 project was cancelled prior to introduction into service, replaced by the much more fissile material efficient Mark 12 nuclear bomb implosion design.

This possibility is sometimes referred to as bubble fusion and is likened to the implosion design used in the fusion component of thermonuclear weapons.

The document led media to report that Iran has tested a two-point implosion design.

Unlike the implosion design, which required sophisticated coordination of shaped explosive charges, the gun-type design was considered almost certain to work.

The implosion design acquired a new urgency in April 1944, when studies of reactor-produced plutonium confirmed that it could not be used in a gun-type weapon.

Designing a workable implosion design becomes the top priority of the laboratory.