(This is using all pYmods up to AE):

I noticed that the fusion reactions don't actually produce more power, than what is spent to produce the ingredients.
I tested building separated processes where I supply the precursor ingredients externally, and then build all the buildings to supply a reactor ...

So I am wondering about the two ways you can take to turn Iron Pulp Stage 1 into Iron Pulp Stage 7.

There is the chain turning it into Unslimed Iron after which it will go through Stages 2 to 7.
Or the chain turning it into Iron Concentrate, Fine Iron Concentrate, which can also be turned into Pulp ...