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Physics · Nuclear science

Atom Core

Build a nucleus, watch a thousand atoms decay, hold a chain reaction at exactly critical and see how the Sun fuses hydrogen.

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The course

7 worlds · 27 lessons

World 1 · Inside the Nucleus

FREEThe tiny core that holds almost all of the atom
  1. 01From atom to nucleus: how small is small?Zoom in by a factor of a hundred thousand · 11 min
  2. 02Protons, neutrons and isotopesThree numbers that name every nucleus · 12 min
  3. 03The strong force and the push-apartWhat holds a nucleus together against its own repulsion · 12 min
  4. 04Mass defect: the missing massWhy a helium nucleus weighs less than its parts · 13 min

World 2 · Stability and Decay

PROWhy some nuclei last for ever and others do not
  1. 01The band of stabilityA map of every nucleus, with neutrons on one axis and protons on the other · 12 minPRO
  2. 02Alpha, beta and gammaThree kinds of decay and three kinds of radiation · 14 minPRO
  3. 03Half-life with a thousand diceRandom for one atom, predictable for a crowd · 14 minPRO
  4. 04Decay chains and radonWhen the product of a decay is itself radioactive · 14 minPRO

World 3 · Radiation, Dose and Safety

PROBecquerels, grays and sieverts, in proportion
  1. 01Becquerel, gray, sievertThree units, three different questions · 13 minPRO
  2. 02Background radiation and everyday numbersYou are always being exposed, and that is normal · 13 minPRO
  3. 03Time, distance, shieldingThe three levers of radiation protection · 12 minPRO
  4. 04Radiation in medicineSeeing inside the body and treating disease · 14 minPRO

World 4 · Splitting the Atom

PROWhere nuclear energy comes from, and how a chain reaction is held steady
  1. 01The binding energy curveOne graph that explains fission, fusion and why stars shine · 13 minPRO
  2. 02Fission of uranium-235Why one neutron can release 200 MeV · 14 minPRO
  3. 03Chain reaction and kWhy a reactor can sit still at exactly k = 1 · 13 minPRO
  4. 04Moderators and control rodsThe brake and the accelerator pedal · 13 minPRO

World 5 · Running a Reactor Safely

PROHeat, control, many layers of protection, and the waste question
  1. 01Inside a pressurised water reactorFrom fission heat to electricity in two water loops · 14 minPRO
  2. 02Control, delayed neutrons and SCRAMWhy a chain reaction that doubles in milliseconds can still be steered · 14 minPRO
  3. 03Layers of safety, and what accidents taughtDefence in depth in plain language · 15 minPRO
  4. 04Waste and the fuel cycleA small volume, a long memory · 14 minPRO

World 6 · The Sun's Furnace: Fusion

PROJoining light nuclei, in the Sun and in a magnetic bottle
  1. 01Why fusion needs extreme heatThe barrier between two protons, and the quantum way through · 13 minPRO
  2. 02How the Sun makes lightThe proton-proton chain, step by step · 14 minPRO
  3. 03Deuterium, tritium and the tokamakHolding a plasma hotter than the Sun in a magnetic bottle · 15 minPRO
  4. 04Why isn't fusion power on the grid yet?Gain, records and the engineering gap · 15 minPRO

World 7 · Nuclear in Everyday Life

PROSmoke alarms, old bones and the electricity grid
  1. 01Smoke detectors, tracers and sterilisationQuiet, sealed, useful · 13 minPRO
  2. 02Carbon-14 datingA clock that starts when a living thing stops eating and breathing · 14 minPRO
  3. 03Nuclear and the energy mixPutting the numbers next to each other, with the trade-offs · 14 minPRO
Atom Core — interactive 3D lab · Novareka