An interactive, browser-based model of an RBMK-1000 nuclear reactor, the Soviet design behind the 1986 Chernobyl accident. It is detailed enough to show why that accident happened: the positive void coefficient, xenon-135 poisoning, the graphite-tipped control rods, and the AZ-5 emergency shutdown that briefly raised power before it dropped.
Live: https://natozenbilek.github.io/rbmk/
Educational model. The physics is simplified for teaching and intuition, not for engineering analysis, and is not validated against real plant data.
- Run the reactor by hand or in auto mode: move the control rods (with a realistic belly-shaped differential-worth curve) and watch power, temperature, pressure, void fraction, reactivity (pcm), and turbine output respond live.
- See the physics that mattered at Chernobyl: the full iodine → xenon-135 chain and the "xenon pit", a positive void coefficient, Doppler feedback, decay heat after shutdown, and the graphite-tip reactivity spike during a SCRAM.
- Explore the plant: an annotated, zoomable diagram of the primary heat circuit (core, drum separators, main circulation pumps, HP/LP turbines, generator, condenser, cooling tower), each with real engineering data.
- Run scenarios and faults: a guided Chernobyl reconstruction, an MCP (pump) trip, and a pipe rupture, across four modes (Free Play, Normal Ops with safety limits, Safety Training drills, Accident Analysis).
- Review the run: a debrief with peak values, an event timeline, and an operator rating. Share a run as a URL, trip AZ-5 (SCRAM), toggle sound, or read the built-in physics notes and references.
Plain HTML, CSS, and JavaScript in a single, self-contained index.html — no
framework, no build step. The plant diagram and its animation are drawn on a
<canvas>; the live readouts are plain HTML, and sound is synthesized with the
Web Audio API. Installable and offline-capable as a PWA.
index.html the whole simulation (UI, physics, scenarios, help)
manifest.json PWA manifest
sw.js service worker (offline cache)
The software is mine, but the nuclear engineering is theirs. I'm grateful to H. Nur Atmaca and Zehra Nur Şirin, nuclear engineering students at Hacettepe University, who taught me the reactor physics behind this simulation, guided the model from the start, and patiently walked me through the fundamentals.
Released under the MIT License.
Made by Nezih Arhan Tözenbilek, for learning.