Critical Point

Rod depth sets the multiplication factor k between 0.955 (fully in) and 1.035 (fully out), and every simulation tick advances the power through the exact point-kinetics solution N → N · e^((k−1)Δt/τ) with τ = 0.09 s — the effective generation time that delayed neutrons buy a real reactor. Nothing else touches the power: every wobble on the trace is your own hand on the lever.

The ghost dot runs the identical integrator two seconds into the future at your current rod depth. That is exactly the operator’s problem in a real control room: power is an exponential, so where you are matters less than where your current k is taking you. If the ghost is above the scram line, you are already late.

The later levels borrow two genuine reactor headaches. Xenon-135, a fission product that devours neutrons, builds up and quietly drags k down — the game’s poison term — so holding steady power means continuously withdrawing the rod. And grid load steps force the operator to re-settle at a new power smoothly, without letting the exponential get a head start in either direction.