Eli5: Before the first atom bomb was detonated, there was some speculation that the chain reaction would keep continuing and lead to burning up the atmosphere. So what actually limits the size of the explosion?

Question

Eli5: Before the first atom bomb was detonated, there was some speculation that the chain reaction would keep continuing and lead to burning up the atmosphere. So what actually limits the size of the explosion?

In: Physics

Answer 1

For the bomb that destroyed Hiroshima, roughly 64 kilograms of enriched uranium were employed. About one kilogram of the uranium split into its decay products; iodine, cesium, strontium, xenon and barium. About a half a gram was converted into energy. This was the energy that produced the massive explosion, estimated at around 16 kilotons.

The energy release occurred in about one millisecond, almost completely destroying the bomb’s containment. If one could theoretically contain the core of the bomb longer, the yield would go up. Simple math suggests that converting all 64 kilos of the Hiroshima bomb would result in a yield of about 1,024 kilotons, or on megaton.

That is for an atomic bomb, a fission weapon where uranium is split up.