Nuclear Reactor Simulator
Take the operator’s seat of a simplified pressurized-water reactor. Pull or insert the control rods to steer reactivity while the core responds with real physics: point-kinetics with six groups of delayed neutrons, fuel and coolant temperature feedback (Doppler and moderator coefficients), and xenon-135 poisoning that builds up hours after a power change and fights your rod moves. Strip charts track power, reactivity, temperatures and xenon; alarms warn as you approach limits, and the SCRAM button drops every rod at once. Scenarios include a cold start-up, load-following, a xenon transient after shutdown and a runaway you must catch before the fuel overheats.
Runs 100% in your browser — simulations are computed locally on your device.
Read the full guide to this tool
Notes
- Power follows the point-kinetics equations with six delayed-neutron precursor groups — the ~0.65% of neutrons that arrive seconds late are the only reason a reactor is controllable at all.
- Negative temperature coefficients make the core self-stabilizing: hotter fuel (Doppler broadening) and hotter coolant both remove reactivity, so power excursions tend to throttle themselves.
- Xenon-135, produced from iodine-135 decay, is a powerful neutron absorber: after a shutdown it peaks for ~11 hours and can make restart temporarily impossible — the same effect that trapped the operators at Chernobyl into pulling too many rods.
- Runs 100% in your browser — simulations are computed locally on your device.
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