Magazine article New Statesman (1996)

A Nuclear Overreaction

Magazine article New Statesman (1996)

A Nuclear Overreaction

Article excerpt

There is an old joke that physicists like to wheel out every now and then. It goes like this: fusion power is just 20 years away and it always will be. The gag has been doing the rounds again, because the US defence research contractor Lockheed Martin has spoiled the punchline. It announced that it already has a small-scale fusion energy generator. In ten years' time, it says, it will have developed a reactor large enough to power a city and small enough to sit on the back of a truck.

Make of this claim what you will; there is little evidence to support it. Most experts dismiss it as improbable after all, we've been trying to achieve this since the 1920s; why would Lockheed Martin suddenly have the answer? (Cynics respond by muttering about share prices.) Common sense suggests we should just shrug our shoulders and wait and see. In a decade, we'll know whether the claim was valid. Common sense, though, can be a dangerous guide: a decade is far too long to keep such a disaster-prone dream alive.

Nuclear fusion reactors subject hydrogen atoms to extremely high temperatures and pressures, fusing them together into one particle. This releases enormous amounts of energy. It's not beyond us to do this--we achieved such "ignition" decades ago. The problem is that the energy release is not easy to control and it is even harder to sustain.

Fusion creates a hot, writhing cloud of electrically charged gas called a plasma. This is, in effect, corrosive to the reactor that created it and has to be kept away from the walls of its container using magnetic fields. Any contact with the walls also dissipates the plasma's power and ends the fusion reaction. Even if the plasma is successfully confined, the bursts of high-energy neutrons released during the fusion process eat into the container walls, weakening them significantly. …

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