At that point, the recycling begins. A spent fuel rod is a collection of potentially valuable radioactive isotopes embedded in a filler of uranium. Ninety-five per cent of a spent fuel rod is uranium-238, the relatively benign isotope that is only mildly radioactive. It could be put right back into the ground without doing any harm. Another 1 per cent is the fissionable uranium-235, which does the actual work.

U-235 constitutes only 0.7 per cent of natural uranium. In order to make a bomb, it must be enriched to 90 per cent. For a nuclear power plant, you only need to enrich it to 3 per cent - which is why a nuclear plant can't blow up like a bomb.

By the time the fuel rod has been in the reactor for three years, the U-235 is back down to 1 per cent. That can be extracted and enriched again for more fuel. The same holds true of the plutonium, an artificial element formed in reactors that comprises another 1 per cent. At its Melox facility in Avignon, the French combine spent uranium and plutonium to form a mixed-oxide fuel, which can also be burned into reactors.

By now we're down to the last 3 per cent of the fuel rod. These are very highly radioactive isotopes, which might have some industrial or medical use. This is the material stored beneath the floor at La Hague. It is first vitrified - dissolved in glass that will last for thousands of years. Then it is encased in steel and lowered into manholes in the floor.

The French decided to go nuclear in the late 1950s under Charles de Gaulle. They foresaw energy problems long before the Arab oil boycott awakened the rest of the world. They had a slogan: "We may not have any oil, but we have ideas." By contrast, Britain's attitude has been: "We may not have any ideas, but we've got plenty of North Sea oil." That has proved to be a losing hand.