Why is the hydrogen bomb the clean bomb?

Answer 1

A hydrogen bomb can be either clean, conventional, or salted depending on the material used for the fusion (secondary) stage tamper and how it interacts with the high energy fusion reaction neutrons.

• a clean hydrogen bomb uses a tamper material that does not capture or fission when hit by the high energy neutrons. Lead is one such material. Significant yield is sacrificed compared to a conventional hydrogen bomb.
• a conventional hydrogen bomb uses depleted or natural uranium as the tamper material, which fissions when hit by the high energy neutrons providing up to 90% of the bomb's yield and fallout.
• a salted hydrogen bomb uses materials in the tamper that readily capture neutrons and produce highly radioactive isotopes in the fallout.

Note a very very clean hydrogen bomb has a tamper material so transparent to neutrons that almost all escape in a flash: this is sometimes called a neutron bomb!

Answer 2

The hydrogen bomb, also known as a thermonuclear bomb, is not considered a "clean" bomb. It releases a vast amount of energy through nuclear fusion, resulting in a devastating explosion with significant radioactive fallout. Despite its high destructive power, it causes substantial environmental and human consequences due to the radiation produced.