The reactor has quite a few rules to teach in a short amount of time- it's definitely the weakest part of the tutorial. Basically, CYCLE multiplies the FUEL value, so it's easier if you start with CYCLE very close to zero, and work from there. Same for the second step- setting FUEL close to zero, and then ramping up CYCLE. I might end up including a recording of the 'quick method' of starting the reactor in the files.
You also have the option to enable Skip Tutorial in Settings- after the reactor, you're just taught to switch the orange "black-boxes" between their holders, and that clicking the character's 'entrances' allows you to block entry & exit of 'passengers'.