why couldn’t we get an infinite loop of energy by repeatedly doing nuclear fission and fusion

Question

If my mind serves me correctly, fission is splitting a particle into two, and fusion is bringing those two together, and nuclear fission and fusion produce huge amounts of energy, so why couldn’t we theoretically create a reactor that alternates between those two sometime way in the future?

In: Physics

Answer 1

Fission works with heavy elements, such as uranium and plutonium.

Fusion works with light elements such as hydrogen.

You can see the energy chart [here](https://openstax.org/resources/6cadef770ccd570f45d1641892c6035fb8edd0ed). You only gain energy if you go up the chart, for example from hydrogen to helium (fusion). If you try to break helium to hydrogen, you lose energy.