So I made this spreadsheet a while ago and tweeted it to you. One of the things I noticed is that maximum waste depends on the number of fuel rods avaiable. I also noticed that there is not realy much of a reason to build a reactor higher then 3 because of the way radiation works. As a result flat is pretty much boss.

So my suggestion would be to make waste per colom. So that a fuel rod colom of 5 high has a minimal ejection waste of 5% but 5 one high coloms still have a minimal of 25% waste before it can eject. This would give an incentive to build upwards and reduce the variation in power/steam output.

The spreadsheet for reverence: https://docs.google.com/spreadsheets/d/1df7-8OqdOeWppfr1xZsV5eFqBWUeGGvtyQ6e1agJN2s/edit?usp=sharing

No. Fuel was merged into a single container for a reason in the 0.1 >> 0.2 transition.