Core Concepts
Rigorous, accessible articles on the physics that powers stars and reactors.
Foundations
Atomic Structure
Protons, neutrons, electrons — the building blocks and the forces that bind them.
→DecayRadioactive Decay
Alpha, beta, gamma — modes of decay, half-lives, and the chart of nuclides.
→FissionNuclear Fission
How heavy nuclei split, release energy, and sustain chain reactions.
→DataNeutron Cross-Sections
What cross-sections measure, why they depend on energy, and how they drive reactor design.
→Reactor PhysicsCriticality & k-effective
The conditions under which a chain reaction becomes self-sustaining.
→FeedbackDoppler Broadening
How temperature broadens absorption resonances and provides inherent reactor safety.
→Interactive
The Reactor Simulator
Control temperature, fuel composition, and neutron flux inside a contained fission environment. Watch k-effective respond in real time as you adjust parameters.
Launch Simulator118 Known Elements
3000+ Known Isotopes
~200 MeV Energy per U-235 Fission
10⁻²⁴ cm² Unit of a Barn (cross-section)