I love the spare silence of this game (at least until the reactor goes critical). It is an unbelievably stressful game, having to bounce between all the levels.
Depending on how much information you want to block or withhold from the player, I would make the readouts much larger than they currently are (also make sure your game defaults to full-screen), and elevate them above the player's head. I would also include some UI elements to show the player how much power they've generated (maybe have a soft goal for them to reach) and how much time is left on their shift (could just be an analog clock with an hour hand that goes around once).
I really liked the experience you captured here. I'd love to play this again after you've had a chance to revisit it. Great work!