What is the power of fusion or fission bombs?

Answer 1

The maximum yield for a nuclear weapon varies depending on the type of weapon and ignition mechanism.

For pure-fission weapons, the most powerful weapon built is the Ivy King, at a yield of approx. 500 Kt, compared with approx. 15kt for Hiroshima or 22kt for Nagasaki. The Ivy King bomb uses a core consisting of some 60 kg of highly enriched uranium. Pure fission weapons are limited in yield by the difficulties in dealing with large critical masses of uranium and/or plutonium. In pure-fission weapons, masses required for a larger yield tend to be disrupted before a chain reaction can spread through them. With a fission weapon the rule is 77grams of weapon grade U235 or 78 grams Pu239 per kiloton of yield. Generally these days fissile uranium or Plutonium is first ignited by compression of Deuterium or Tritium to give a fusion boost. These are called third generation nuclear weapons and their criticality is not dependant on the mass or isotope purity of the fissile material.

Fusion weapons have no theoretical limit, although the mass/yield ratio imposes some practical limits. The highest-yield fusion weapon to have ever been detonated is the Soviet Union's Tsar Bomba, at 57 Mt, about 4500 times Hiroshima. This bomb was originally designed to have about twice that yield, for a weight of approx. 27 metric tonnes. Fusion bombs generally referred to as Hydrogen bombs actually us a tapered chamber called Hohlraum to compress a shock wave in a mass of deuterium and can be scaled upwards as desired to increase the yield.

Answer 2

The power of fusion bombs, also known as hydrogen bombs, can range from tens to hundreds of megatons of TNT equivalent. Fission bombs, also known as atomic bombs, typically have a power in the range of kilotons to tens of kilotons of TNT equivalent.