Going to be controversial here and say I think that the controls are absolutely fine. I think they are just different from the norm, which isn't necessarily bad, just different. After playing for 10 minutes it was pretty natural, the only thing I found difficult sometimes was collecting the coolant as the speed was a little too fast to line up with it correctly.
I mentioned in another comment that the way the coolant works prevented me from completing the game for a while, as I had assumed that any neutron (rather than just my own) passing through the clouds would reduce the temperature. Once I noticed this, I was able to get to the end.
With those two points out of the way; I think this is my favourite game of the jam that I've played so far! I love how it puts you right in the middle of the simulation and allows you to influence it from the inside as well as the outside. I also think it's brilliant how all the particles are simulated and that lowering control rods into the reactor doesn't just adjust some weighting in the background, you can actually see the rods lower into the chamber and see that more particles bash into it. Awesome job!