Uranium enrichment in Factorio

Playing with nuclear technology is one of the (many) great moments in Factorio. However, the uranium enrichment process (the famous “Kovarex” process) is often confusing for newcomers. We will see here how to set up a simple and scalable enrichment system to get basically infinite fuel for your nuclear plants.

Kovarex

The Kovarex process consist in converting 40 U-235 and 5 U-238 into 41 U-235 and 2 U-238. (Have a look at the official Wiki page for more details about the enrichment process).

The main pain points are:

you need at least 40 U-235 to start the process.
it burns U-238
it is very slow (60 seconds), and you only get one additional U-235 per cycle.

One problem, one solution:

Before starting the Kovarex setup, you need to mine a lot of uranium and filter natural U-235.

Uranium mining

With a big enough mining setup, you don’t really care about the U-238. Also, it can be recycled from empty cell fuels.
To compensate the very slow gain in U-235, you will need to put in place several enrichment pipelines

Setup

Here is a picture of 3 pipelines running in parallel:

Kovarex setup

U-238 side

The U-238 arrive from the top into the left loop. It is fed into each centrifuge by an inserter. Output of Kovarex process (the 2 U-238) are put back on this loop via a filter inserter, but on the EXTERNAL side of it. At the top of the loop, the external part is put back into the internal part first. Therefore, the output U-238 has always priority above new U-238 from input. This is the neat part of this design, and as you can see no wire/calculator/complexity is required.

U-235 side

Use a filter inserter to put back U-235 on the right side ABOVE another inserter in charge of taking back the 40 U-235 required for the process. After each run of the Kovarex process, the centrifuge will reuse 40 of the 41 U-235 it generates, and leak one extra U-235.

Bootstrap

To bootstrap a lane, manually put 40 U-235 in the top centrifuge. It will start the process, gradually leak U-235 for the next centrifuge that will also start once it gets 40 U-235, etc. Once all the centrifuge on the lane are producing, you’ll get some extra U-235 at the bottom of the lane to be used elsewhere (nuclear plant, weapons, etc.)

Blueprint

Here is the blueprint for one line of production in the layout described above:

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Conclusion

We have seen how to create a simple Kovarex enrichment process to get as much U-235 as required. The benefit of this setup is that each line can be extended as required, and you can put many lines in parallel. The only drawback is that, after setting up your enrichment pipelines, you will have to wait quite a long time for the production to ramp up, but it will eventually be worth it.

Kovarex setup in Factorio