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Splitting atoms to boil a kettle

How Does Nuclear Power Work?

A nuclear station is an ordinary steam power station with an extraordinarily strange fire.

1 A heavyatom issplit2 The piecesfly apartas heat3 The heatboils water4 Steam spinsa turbine
An unusual fire, an ordinary kettle.

  1. Step 1 of 5

    Splitting a heavy atom releases heat.

    A kilogram of woodwarms a roombrieflyA kilogram of coala little betterA kilogram of uraniumas much as alorry of coal

    Hit a uranium atom with a loose particle and it splits into two smaller atoms that fly apart. That flying apart is heat — and a scrap of uranium releases as much as a lorryload of coal.

  2. Step 2 of 5

    Each split sets off more splits.

    One atom splits Its particlessplit severalneighbours

    A splitting atom throws out loose particles that split their neighbours. Left alone that doubles and doubles; a reactor's whole design is about not letting it.

  3. Step 3 of 5

    Control rods eat the spare particles.

    A reactor held at asteady rateRods further in— the reactiondies downRods furtherout — itspeeds up

    Rods that soak up loose particles are pushed in among the fuel. Deeper in means fewer splits and less heat; pulled out means more. The reaction is held at exactly one split per split.

  4. Step 4 of 5

    The waste stays dangerous for a very long time.

    Very little of ita few metrescubed per yearDangerous for millenniafar longer thanany country haslastedSo it is sealed andburiedin stable rock,deep down

    The fragments left over keep throwing out particles for thousands of years. There is not much of it by volume, but it must be kept away from everything alive for longer than any country has existed.

  5. Step 5 of 5

    It makes no smoke at all.

    A coal station Soot and carbon dioxideA nuclear station Only water vapour

    No burning means no soot and no carbon dioxide. What comes off the towers is water vapour. The arguments about nuclear power are about waste, cost and accidents — never about smoke.

    The Sun runs the opposite way — squashing small atoms together rather than splitting heavy ones. That releases even more energy, and we cannot yet do it usefully.

The short version

Nuclear power splits heavy atoms to make heat, held at a steady rate by control rods, and then boils water like any other station.

Try it yourself

Stand dominoes so each knocks over two. That runaway is what control rods stop, by holding it to one for one.

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