I think there should be a way to re-use the iron from the spent fuel cell casing.
But why? That iron is all sorts of nuclear waste.
The iron cost is so minor (1 iron for 10 fuel lasting over half an hour) that it barely registers on the radar. Or are you making a funny? Because it seems like you're making a funny.
Nuclear reactions are VERY binary- they tend to not work at all, or they work WAY too much. When a fuel cell runs out, that only means it lacks the critical mass of flying neutrons to stay on knife edge of being useful. There's still good fuel in it, but it needs to be reprocessed back up to critical mass to work again. If this were included in game terms it would mean:
- Harvest 0.7% U235 from the earth as current. This is fine and gives enough nuclear fuel to get your feet wet.
- Reharvest <1 U235 per 10 spent fuel cells with reprocessing tech. Any value from 30-60% U235 return (prod3 fuel is self sustaining at 71%) will let the player expand their nuclear ability such that they still have spare U238, but not boxes and boxes full of the stuff. Players no longer have to focus on rushing enrichment just to get large scale nuclear power.
- Reharvest 1 or more U235 with enrichment tech. This ultimately gives the last U235 push for unlimited reactors and nukes.
Currently we can only get the 0.7% U235 base or the steep, exponential growth with kovarex. The middle step will help a lot and make harvesting the catalyst less of a hard wall. After all banking 40 U235 means giving up a full day's supply of fuel! That's a lot of nuke time you have to give up, so I understand why players might completely skip the early reactor until Kovarex is online.
Kovarex using spent fuel cells
This would be a HUGE hit and a major nerf to Kovarex for sure, but at the same time it wouldn't be so bad if fuel processing was a stronger tech. The process of enriching fuel IRL basically means running a hot reactor and not really caring about the energy it produces; we don't care about it so we throw it away. We can do the same thing in game by simply dunking fuel in a reactor- it will keep burning and it won't stall if we leave it at 1000C. So the solution for mass producing nukes still exists, but you have an intermediate step of producing a large scale wall of reactors to get it rolling. It may feel wasteful to burn all that fuel for nothing, but at least the green glow will keep you warm at night! Think of it as a lamp MK2.
But if we can't spam Kovarex, how will we build huge glowing green fields of centrifuges???
I feel your pain, man. But a centrifuge isn't just about separating nuclear materials. The devs have pondered the option of making some kind of ore enrichment where "dirty ore" is mined and useful materials are extracted out of it. For the sake of argument I will call this dirty ore "stone", which players tend to have a large excess of. The only stone demand is for Electric Furnaces in production science, which is by far the lowest demand at a mere 10K stone per rocket. The excess stone gets mined, prepared(with some kind of liquid recipe?), and separated in the centrifuge. The end result is bonus iron ore and copper ore, maybe even some uranium, with some junk that might only be good as cooked brick. It's a nice way to use all that excess stone, and it gives an excuse to build large centrifuge farms.