Binding Energy per Nucleon trend for fusion vs fission

In summary, the conversation discusses the difference in binding energy and atomic mass between fusion and fission elements, with fusion having a higher energy yield. The reason for this trend is attributed to the Semi-Empirical Mass Formula, which can be used to understand the contribution of each term in the formula. The conversation also touches on the safety and availability of fusion elements compared to fission. The increase in the size of the nucleus with more nucleons is also mentioned.
  • #1
Guest432
48
2
Hello all!

In my Nuclear Power assignment I decided to analyse this graph:

ae534.gif


I mention that
"The difference in atomic mass and binding energy per nucleon for deuterium and helium (fusion elements) is ≈3u and 5.96 MeV respectively. However, for all elements past Iron (fission elements) the difference in any two binding energies is < 1.3 MeV. Such a vast energy yield, even in comparison to fission, is the reason why obtaining net power from fusion is such a holy grail."

However, I am perplexed as to why exactly the difference in binding energy of elements before Iron is so high! I have discussed the fact neutrons increase the distance between protons in nuclei, so I am taking a guess that elements with a low atomic mass have less neutrons, ergo more repulsive force and greater binding energy. However, this logic seems weak and doesn't really explain why the trend of binding energy per nucleon is what it is.

Thanks :)
 
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  • #3
Trontor said:
I have discussed the fact neutrons increase the distance between protons in nuclei,
I don't understand that statement.
Trontor said:
Such a vast energy yield, even in comparison to fission, is the reason why obtaining net power from fusion is such a holy grail.
The energy density is not the key point. The atoms used in fusion are also cheap and available everywhere in the world, their fusion product helium is not radioactive and you have no risk of a runaway reaction.
 
  • #4
mfb said:
I don't understand that statement.The energy density is not the key point. The atoms used in fusion are also cheap and available everywhere in the world, their fusion product helium is not radioactive and you have no risk of a runaway reaction.

Was told this by my physics teacher.
pquuUfW.png


The energy density point is good, but it still doesn't explain to me why exactly the graph trends rapidly upwards then slowly downwards.
 
  • #5
Ah, well, that is a bit hand-waving, because it does not explain why the size of the nucleus increases with more nucleons. Nucleons are not billard balls, they do not occupy a volume.
Trontor said:
The energy density point is good, but it still doesn't explain to me why exactly the graph trends rapidly upwards then slowly downwards.
That was just meant as comment on commercial applications. See @e.bar.goum's answer for a good model of the shape of that curve.
 

What is binding energy per nucleon?

Binding energy per nucleon is the amount of energy required to break apart an atomic nucleus into individual nucleons (protons and neutrons). It is a measure of the stability of an atom and is expressed in units of MeV (mega electron volts).

What is the trend for binding energy per nucleon in fusion?

The trend for binding energy per nucleon in fusion is an increase as the number of nucleons in the nucleus increases. This is because fusion reactions combine smaller nuclei to form larger, more stable nuclei, releasing energy in the process. As the nuclei become larger, the strong nuclear force becomes stronger, resulting in a greater binding energy per nucleon.

What is the trend for binding energy per nucleon in fission?

The trend for binding energy per nucleon in fission is a decrease as the number of nucleons in the nucleus increases. This is because fission reactions split larger, less stable nuclei into smaller, more stable nuclei, releasing energy in the process. As the nuclei become smaller, the strong nuclear force becomes weaker, resulting in a lower binding energy per nucleon.

How does the binding energy per nucleon in fusion compare to that of fission?

The binding energy per nucleon in fusion is generally higher than that of fission. This is because fusion reactions release more energy per nucleon due to the formation of larger, more stable nuclei. In fission, the released energy per nucleon is lower due to the formation of smaller, less stable nuclei.

What is the significance of the binding energy per nucleon trend for fusion vs fission?

The binding energy per nucleon trend for fusion vs fission is significant because it helps us understand the stability and energy release of different nuclear reactions. It also has important applications in areas such as nuclear power and nuclear weapons development.

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