Reactor Point Kinetics 2D: Core Glow & Power Strip Chart

This simulator solves the one-group point-kinetics equations exactly — not by numerical integration but by diagonalising the linear neutron-population/precursor system analytically every time reactivity changes — so it stays stable no matter how small the prompt generation time Λ is set. Insert a step reactivity change in dollars (units of β, the delayed-neutron fraction) and watch a top-down 9×9 fuel-rod grid track the resulting power trajectory in real time: the fast "prompt jump" that follows any reactivity step, the slower exponential rise or fall set by delayed-neutron precursors, and — if you push past prompt critical (ρ ≥ β) — the millisecond-scale runaway that real reactors are engineered to keep impossible. A vertical control-rod gauge animates with the reactivity you dial in, a live neutron-spark field pulses with the reaction rate, and a scrollable strip chart on a logarithmic power axis lets you drag back through the last minute of history. An automatic trip scrams the reactor if power exceeds 100× nominal.