I set up a nuclear reactor after automating the first four sciences. But even though I researched everything I could up to that point, there is seemingly no way to set it up in a sustainable way. Both U-238 and spent fuel cells are piling up.

Naturally, the spent fuel cells are so little that they are less of a problem, but the U-238 requires a lot of steel chests to store.

It seems like without automating further sciences, I am unable to solve the U-238 problem. Is there any other way out, or do I need to automate more sciences before actually using nuclear?