Here is the full list of all 17 Rainbow Reactor achievements.
Complete the 1st shift
Complete the 2nd shift
Make a Quadruple Reaction
Score Over 9000
Get the highest Reward at the end of a shift
Complete the 3rd shift
Complete the 4th shift
Complete the 5th shift
Complete the 6th shift
Complete the 7th shift
Complete the 8th shift
Complete the 9th shift
Make a Quintuple Reaction
Make a Sextuple Reaction
Make a Septuple Reaction
Reach Max Multiplier
Mix a brown C-Ball