Demo simulation — physics simplified for education. No real radiation involved.
Live Readouts
Reaction Rate
0 f/s
k-effective
—
Energy
0 MJ
Neutrons
0
Atoms Left
100
Reactor Mode
Subcritical
Neutron Source
Control Rods (2 rods)
Withdrawn0% insertedFull
Absorb neutrons → lower reaction rate
Moderator Blocks
Slow neutrons → raise fission probability
Initial U-235 Atoms
Legend
U-235 Atom
Fissioned Nucleus
Fast Neutron
Slow Neutron (moderated)
Control Rod
Moderator Block
Reactor Modes (k-eff)
Subcriticalk < 0.8 — dies out
Criticalk ≈ 1 — stable
Supercriticalk > 1.2 — runaway!