Although uranium-238 cannot be made to undergo a continuous chain reaction, firing neutrons at it causes some atoms to split, producing a burst of heat.

ECONOMIST: Nuclear power

But fuel rods also contain uranium-238.

ECONOMIST: Nuclear power

The Russians perfected a far less energy-hogging method that uses centrifuges to spin the uranium hexafluoride at 50, 000rpm so that heavier u-238 separates from lighter u-235.

FORBES: Energy & Genius