Fission Chain Reaction and Reactor

Also called

nuclear fission · chain reaction · nuclear reactor · uranium-235 · U-235 · slow neutron · thermal neutron · control rods · cadmium rods · moderator · heavy water · graphite · critical mass · fuel rods · fission fragments · nuclear energy · turbine · multiplication factor · नाभिकीय विखंडन · श्रृंखला अभिक्रिया · नाभिकीय रिएक्टर

Topics

• A slow neutron absorbed by a U-235 nucleus makes it split into two lighter nuclei, such as barium and krypton.
• Each fission releases about 200 MeV of energy and two or three fresh neutrons.
• If those neutrons split more nuclei, the reaction multiplies: one, three, nine… a chain reaction.
• A lump smaller than the critical mass leaks too many neutrons from its surface for the chain to continue.
• Fission neutrons are fast; a moderator (heavy water or graphite) slows them so U-235 can capture them.
• Cadmium or boron control rods absorb neutrons: pushed in, the reaction slows; pulled out, it speeds up.
• In a steady reactor each fission leads to exactly one more (multiplication factor K = 1).
• The heat released boils water; the steam turns a turbine and the turbine drives a generator.
• Uncontrolled, the same chain reaction is the nuclear bomb; controlled, it lights cities.

About this model

A GLB file of about 414 KB, shown in Lably's 3D viewer and, on a phone, placed in your room with AR. Credit: Model, science and animation: Lably (built procedurally with three.js; no downloaded meshes). | CC BY 4.0. Original geometry and animation made for Lably.

More in Physics

A

AC generator and transformerClass 123D model

AC generator and transformerClass 123D model

Artificial neural networkClass 8–123D model

Button cell cutawayClass 123D model

C

Capacitor and DielectricsClass 123D model

Capacitor and DielectricsClass 123D model