What are the main factors that prevent a feedback loop being created by using a hybrid method of fission and fusion. Fusion building up to fissionable materials, and fission breaking down till fusion is possible. Ex: numbers of neutrons, cross section for interaction, the gap between elements, amount of energy needed, probability of correct species being generated.

Further, would it be possible to at least get a few occurrences of the fission/fusion cycle.

  • $\begingroup$ reasons for down votes? $\endgroup$ – Numoru Mar 24 at 19:01

There is no fission/fusion cycle. Fusion never produces fissionable nuclei. It doesn’t produce anything beyond iron. This is because of how nuclear binding energy works.

  • $\begingroup$ All fissionable nuclei were made by some form of fusion. Although those processes were endothermic, not exothermic. $\endgroup$ – Jon Custer Mar 24 at 17:42
  • $\begingroup$ @JonCuster Excellent point! Thank you for correcting my overly simplistic answer. $\endgroup$ – G. Smith Mar 24 at 17:47

The cycle you wish to form can be outlined like this.

More massive nuclei are produced from less massive nuclei (fusion) with the net output of energy and this type of process continues to be exothermic until nuclei of approximately the mass of a iron nucleus are being produced.

To produce even more massive nuclei there must be an input of energy (and an abundance of neutrons) and such reactions are endothermic. These sort of processes occur in stars and supernova explosions.

Having produced these more massive nuclei they can decay via a number of processes including fission with the release of energy. These reactions are exothermic. Some of the less massive nuclei which are produced are stable which means that energy is required to split them up further into even less massive nuclei and these are endothermic reactions.

The process of splitting the massive nuclei (less in mass than iron) into less massive nuclei again requires a net input of energy ie such reactions are endothermic.

The production of nuclei whose masses move towards the mass of iron nuclei and the production of nuclei more massive than that of iron does occur naturally but the production of less massive nuclei from those nuclei which have a mass less then that of iron nuclei is very unlikely to happen.

The fission/fusion cycle that you have described is not really feasible.


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