Hello all

Loving the mod, but I have one question related to nuclear power.
In my recipe book i can find Kovarex enrichment process, to create additional 235's. However i can't seem to find the tech anywhere in the research tree.
Am i missing something or is there another way to add additional 235's?
Or do i just have to smack down a load of centrifuges making 235 out of hexaflouride?

Looking forward to a response.

After digging through the tech tree, I think kovarex process is meant to be nonexistent, just like in reality.
In compensation, there is thorium fission fuel, which can be self-sustaining consuming only U238 and Thorium. You can burn U233 rod in normal reactor, and use it to power Thorium rod in high temperature reactor.
Later on there is no use for U235 either. I think with the powerful things added by this mod, even nukes become obsolete. And fusion is much easier to handle than fission.
In vanilla mid-game, it's also possible to use nuclear without kovarex. Just process MOAR uranium, it's how factorio works.

There is no kovarex in EI.

Thorium serves as a compensation but in general nuclear is just more realistic.
Later on Fusion will be your good friend :)

I did some calculation and found out it's actually unnecessary to do thorium fission.
With fission postprocessing, doing U235 and Pu 239 fission is about 1 U235 + 30 U238 -> ~270GJ heat, assuming all fuel is burnt in normal reactor and factoring in the 200% effciency.
Assuming thorium is free, Th232 fission is about 12 U238 -> ~46GJ heat, with U232(Edit:U233) in normal reactor and thorium in high reactor.
This means 1 U235 is worth about 40 U238 in amounts of heat. In vanilla kovarex only need 3 U238 for 1 U235.
With this I prefer not to do thorium fission, and the extra U238 could be used in powerful ammo. In my current playthrough I'm at late electricity era, and I really need these uranium ammo.
While U235 can still be used in nukes, I would rather use heavy minigun with compound magazine. This is available much earlier, and I won't have accidental nuke detonations.
@PreLeyZero
When doing the above calculations, I noticed a problem: for U235, U233, Pu239 fuel, normal reactors are actually more effcient than high temperature reactors.
Burning a U235 rod in a normal reactor is 200% effcient and gives 50GJ heat energy.
Burning a U235 rod in a high temperature reactor gives 600k steam at 500C, which is equivalent to 58.2GJ of heat.
However, burning a rod in a high reactor consumes 150MW x 120s = 18GJ of heat, so it only nets 40.2GJ heat overall.
Considering high temperature reactors are unlocked later than normal reactors, and they are more complex to set up, they should be more effcient instead. I think this is a design oversight.
Edit: fixed typo, thorium fission should use U233 in normal reactor.

My understanding is that high temperature reactors are less efficient and are harder to maintain normal ones, but their purpose is to burn thorium to create a closed loop cycle.

Basically in nuclear stage the problem is not producing enough energy, it's making it sustainable. And U235 fuel on its own is not sustainable (you get much more U238 than U235), and thorium on its own is not sustainable either, because you need at least some other type of nuclear fuel to heat up high temp reactors, so you need to process used U235 as well as used thorium fuel rods to also produce U233 and plutonium to create a closed loop cycle.

In my opinion, this system is pretty amazing, much closer to reality and is far deeper than just covarex process.

I do agree thought that high temp reactors look like they're supposed to be an upgrade over normal ones, but their purpose is just different. I think it might be easier to make them only accept thorium fuel to avoid the confusion? Because currently they're straight up worse at burning other types of nuclear fuels.

You can't really make the system sutainable long-term if you just use U235 fuel from mining and use extra U238 for other types of stuff like science packs and ammo, because eventually you'll either run out of U238 ammo or produce too much of it. You'll also pretty quickly run out of your uranium deposits because they're quite limited in my experience and thorium helps to extend their lifetime tremendously. So you need to have an efficient system that also self-balances to a degree.

I just use tank shell cannons and flamers in nuclear age for defense, then artillery.

My understanding is that high temperature reactors are less efficient and are harder to maintain normal ones, but their purpose is to burn thorium to create a closed loop cycle.

I still think it's a design oversight for the high reactor to be less effcient. Maybe the dev forgot to factor in the 200% effciency of standard reactor when calculating the steam values of the high reactor.

You can't really make the system sutainable long-term if you just use U235 fuel from mining and use extra U238 for other types of stuff like science packs and ammo, because eventually you'll either run out of U238 ammo or produce too much of it. You'll also pretty quickly run out of your uranium deposits because they're quite limited in my experience and thorium helps to extend their lifetime tremendously. So you need to have an efficient system that also self-balances to a degree.

In my playthrough I'm currently at early computer era, so I'm nowhere near burning out my uranium deposit. I have a total of 2.8M uranium patch within reach. With +20% mining prod and lossless fission running only U235 fission without postprocess, they will yield 2.4k pieces of U235 = ~120TJ. With postprocess I'll get ~600TJ in total, I think I can get to fusion before I use this up.
If I really run out of uranium I can simply centrifuge dirty water for more. The recipe is actually rather efficient: 60 dirty water for 1 crushed uranium, which is about 70MJ of nuclear heat. Running 4 advanced centrifuges should produce enough fuel to sustain a standard reactor. It costs a lot of stone but stone is free anyway.
I build lossless fission reactors, insert fuel rod only when needed, and have enough steam capacity for a full rod. For this mod I have 3 huge tanks, total 600k steam capacity.
I think a lossless build will become way more complex if I use high reactors. I need to make sure there is no wasted heat, no matter how the energy demand fluctuates.
I can use the high reactor itself to buffer some steam, but I'm not sure how much it can store. I expect it to have enough capacity for 2 recipe cycles. If it does have this much capacity, I only need ~200k external steam capacity.
About the U238 balance thing, I can just pile them up. U238 is relatively high value, they take up very little space when put in storage. The above 2.8M uranium patch will give ~340k U238, which is only enough to fill 70 steel chests.

so you need to process used U235 as well as used thorium fuel rods to also produce U233 and plutonium to create a closed loop cycle.

No you don't. If you do thorium fission, you can sustain it without consuming any U235. U233 can be burnt in standard reactor, and thorium rods give more than enough U233 to heat themselves. You can simply pile the U235 up, they won't take up much space.

I just use tank shell cannons and flamers in nuclear age for defense, then artillery.

I also used tank cannon but I found it underwhelming even with U ammo. Maybe it's because the minigun is too OP.
I skipped the flamer tech completely. Partly because of the tech scaling, partly because I've played enough with it in vanilla.
I haven't reached artillery yet. Maybe I'll skip it for the same reason.

Edit: fixed formatting of quotes

I found some mistakes in my previous calculations about thorium fission cycle. I assumed thorium is free. It isn't, and is actually relatively expensive. Thorium takes a significant amount of stone and centrifuging to produce.
1 thorium costs 185 stone, and 463 centrifuge ticks. In comparison, 1 crushed uranium via dirty water costs 12 stone and 2.5 centrifuge ticks.
With a beaconed quarry setup, I think 1 stone is about equivalent to 3 centrifuge ticks. This means 1 thorium costs ~25 crushed uranium = ~5 U238 + 0.035 U235. If there is lots of open land, then it's unnecessary to beacon the quarry, then stone is much cheaper, making thorium much more relatively expensive.
A cycle burning 3 U235 rod and 2 Pu rod is approx ~ 1 U235 + 30 U238 -> 270GJ.
A cycle burning 2 Thor rod and 3 U233 rod is approx ~ 4 Thor + 26 U238 -> 112.2GJ.
With 1 Thor = 3.5 U238 + 0.025 U235, this is 0.14 U235 + 46 U238 -> 112.2GJ.
Subtracting the U235 then this is 42 U238 -> 74.4GJ.
This is 1.8 GJ per U238, and 216 GJ per U235. 1 U235 is worth about 120 U238.

I'm back : I reached fusion power generation and now I have a running fusion plant.
I have burnt through 15TJ of fission rods (530 U235 rod + 60 Pu rod), including those burnt in personal reactor and the spidertron. I didn't make any high temperature reactor, and no Thorium / U233 rods.
I didn't try to save energy. Uranium is as plentiful as expected. I used a lot of prod modules, and left a lot of beacons running without affecting anything. I only used a circuit to make the reactor lossless, which is a design ported from my vanilla reactor. My fission reactor is 600MW before I tear it down.
I have now dismantled my fission reactor and uranium extraction, and now the only thing that consumes fission fuel is my personal reactor. I think I will replace it soon.
In theory 15 TJ of fission fuel only needs ~80k uranium chunk, burning only U235 and Pu rod and with full rod recycling. In practice, I processed ~780k uranium chunk, and still have 350 U235 and 200 Pu remaining. I also had 64k U238, which fits in a storehouse. With the uranium plant repurposed for neodymium, I will slowly use up the U238.