Axial Xenon Oscillation Simulator (2D)

This 2D simulator resolves the same Iodine-135/Xenon-135 physics as the 3D reactor-poisoning simulator, but spatially: the core is divided into 24 axial slices, and a real finite-difference neutron-diffusion eigensolver recomputes the axial power shape every simulated tick from each slice's local xenon absorption. That spatial resolution reveals a genuinely different phenomenon than the lumped 3D model's single "iodine pit" — the axial xenon oscillation, a slow top-to-bottom power tilt that migrates back and forth across the core over tens of hours. Insert a rod pulse into just the top or bottom half to seed the tilt, then compare how quickly it dies out on a tightly neutronically coupled (small) core versus how persistently it rings on a loosely coupled (large) one — the exact distinction that makes large commercial PWRs, but not small tightly-coupled reactors, require active axial-offset control.