Nuclear fission Simulation — Description
Simulation
Three tabs showing nuclear fission at increasing scale:
Single Fission — a ²³⁵U nucleus absorbs a slow neutron, becomes excited [²³⁶U]*, then splits into ⁹²Kr + ¹⁴¹Ba + 3 neutrons + ~200 MeV. Watch the shockwave, fragment separation, and neutrons streaming out.
Chain Reaction — each fission triggers more, generation by generation. The exponential growth is visible as the canvas fills with splitting nuclei.
Controlled — a reactor core with boron control rods. The slider adjusts rod insertion; the status flips between UNCONTROLLED → CONTROLLED k≈1 → SHUTDOWN as neutron density changes in real time.
Class Activity — “Control the Reactor” (10 min, KS4 pairs)
Setup: Open the Controlled tab.
Task: Students adjust the slider and record what happens to fission rate and energy output at three rod positions.
| Rod insertion | Status | Fissions observed |
|---|---|---|
| 0% | ||
| 50% | ||
| 100% |
Questions:
- What does inserting the rods further do to the neutron population?
- Why must the reactor maintain k ≈ 1 rather than k > 1?
- Switch to Chain Reaction — how does this differ from the controlled tab?
Exit question: Name the material used in control rods and explain how it reduces the chain reaction.