# I How much energy does a fission nuke actually release?

So I was trying to debunk a conspiracy theory involving bombs and I realized that I have a small problem with Einstein's equation: E=mc2
To be honest I haven't really understood how it's used... I mean, how far should the fission go until as much energy as E=mc2 is released?
Does the matter have to completely disappear into the strings of energy the String Theory studies or every time an atom goes through fission, that much energy is released?( For example the same amount of energy is released in fission of 1kg of Mg into Li as in the fission of 2kg of Mg into C)
If it's the first case, how much energy does each kg of 80% enreached uranium actually release in a nuclear explosion?

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#### mfb

Mentor
Fission converts about 0.1% of the mass of its fuel to energy that is released in the explosion. The other 99.9% of the total energy are in the mass of the fission products.
Does the matter have to completely disappear into the strings of energy the String Theory studies
There is no such thing.
( For example the same amount of energy is released in fission of 1kg of Mg into Li as in the fission of 2kg of Mg into C)
Mg=magnesium? Splitting that needs energy, it doesn't release anything.
If it's the first case, how much energy does each kg of 80% enreached uranium actually release in a nuclear explosion?
$9\cdot 10^{16} \frac{J}{kg}$ total energy content, 0.1% of 80% of 1 kg are $7.2\cdot 10^{13} J$, or about 17 kT TNT equivalent.
A more precise calculation leads to 18 kT per kg of pure U-235, or 14.4 kT per kg of 80% enriched uranium.

Little Boy had about 80% enrichment with 64 kg uranium, a bit less than one kg of its U-235 was split in the explosion with an estimated yield of 15 kT.

• Fission converts about 0.1% of the mass of its fuel to energy that is released in the explosion. The other 99.9% of the total energy are in the mass of the fission products.There is no such thing.Mg=magnesium? Splitting that needs energy, it doesn't release anything.$9\cdot 10^{16} \frac{J}{kg}$ total energy content, 0.1% of 80% of 1 kg are $7.2\cdot 10^{13} J$, or about 17 kT TNT equivalent.
A more precise calculation leads to 18 kT per kg of pure U-235, or 14.4 kT per kg of 80% enriched uranium.

Little Boy had about 80% enrichment with 64 kg uranium, a bit less than one kg of its U-235 was split in the explosion with an estimated yield of 15 kT.
I am very sorry I took so long. Somehow I must have forgotten to. :(
Please accept my very late appreciation

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• berkeman

#### Auston Louis

How is the energy stored in the molecules and atoms to represent Einstein's conservation of mass and energy equation? Fission of enriched U is only tapping into one atomic energy source and via chain reaction it yields energy representing only 0.1 % of the original mass. Therefore, one would naturally ask, "How, or, in which form is the remaining energy stored in the atoms that have already been utilized but remain as mass?" This question leads to a review of the various forces and energies involved with every atom. Thus, one of my questions is, what is the "mass to energy" equation that is applicable for calculating the energy in joules that is released from a mass in grams in a Coulomb explosion?

#### mfb

Mentor
The fission products, lighter nuclei, have 99.9% of the mass of the uranium nuclei. The total number of protons plus neutrons stays the same, only binding energies change (and some neutrons are converted to protons). The binding energy per nucleon is small compared to the rest energy of a nucleon.