Beat the game! Could have gone on forever but it was running at 1 frame every 2 seconds at this point and I decided to call it quits.
Quick guide: Go for 100% increased base reaction energy early while the reactions are still controllable (If you need cooling at this point, go for increasing the meltdown threshold, it will give you more wiggle room for temps and let you use the control rods more easily). This will give you a shit ton of levels really quickly, then just buy the -5% reaction temp upgrade 20 times and you're free to raise the control rods. There. You beat the game!