Fission Chain Reaction Simulator

Nuclear fission releases roughly 200 MeV per event by splitting a heavy uranium-235 nucleus into two lighter fragments plus 2–3 new neutrons. This simulator visualizes the chain reaction those neutrons drive: fire a single seed neutron into a lattice of intact nuclei and watch each fission spawn fresh neutrons that fly outward, some absorbed by control rods, some escaping the core, and some striking a neighbouring nucleus to repeat the process. Adjust control-rod absorption, fuel density and neutron speed to move the reaction between subcritical (k<1, dies out), critical (k=1, self-sustaining) and supercritical (k>1, exponential growth) regimes — the same balance real reactors maintain with automated control rods.