60 second guide to... Nuclear power

With the world’s population rising and resources dwindling, does nuclear power make economic and environmental sense?

Nuclear power is electricity generated from an atomic process known as nuclear fission. Around one fifth of UK electricity comes from nuclear plants, though the figure is higher in some other countries. In France, for example, around three-quarters of power is nuclear.

Nuclear power is a highly controversial topic. Some people see it as an essential tool for tackling climate change and energy insecurity; others see it as dangerous, irresponsible and environmentally unfriendly.

How nuclear power works

The first step in producing nuclear power is the mining of uranium, a naturally occurring metal. Next, the uranium is enriched. This is necessary because natural uranium includes only a tiny proportion of U235, the version of the metal that enables fission to occur.

Once the uranium has a higher proportion of U235 it is made into fuel rods, which are reacted in a power station. This generates huge quantities of heat, which is used to rotate electricity-generating turbines.

Waste and accidents

Enriched uranium is a highly radioactive material that remains dangerous – and potentially useful for terrorists – for hundreds of thousands of years after it has been reacted in a power station. The safe disposal of this waste is a big unsolved problem.

The leading proposal is to bury nuclear waste in deep underground caves, but it remains to be seen whether this will be deemed affordable and safe. Another concern is the possibility of nuclear explosions – either caused by accidents (like the 1986 Chernobyl incident in the Soviet Union) or by terrorist attacks on the power stations.

Many critics of nuclear power acknowledge that a Chernobyl-scale incident is almost impossible in a modern plant with a proper containment shell . But the risk, however small, of any kind of nuclear explosion leaves large parts of the population uneasy with nuclear power.

Nuclear power and climate change

One of the most commonly cited pro-nuclear arguments is the fact that nuclear power stations produce minimal CO2 emissions relative to gas or coal plants. They produce around 2–20 tonnes of CO2 per megawatt of electricity, compared with 356 for gas and 891 for coal.

But not everyone accepts that nuclear is a good way of tackling climate change. It can take decades to build a nuclear plant, which isn’t ideal given the urgency of global warming. Also, building nuclear plants requires big upfront investment, which many environment commentators say would be better put towards energy efficiency and renewable power sources.

Some environmentalists also point out that no one knows exactly how much uranium remains to be mined. They argue that this means that nuclear isn’t a sustainable power source, adding to the case that money would be better invested in renewables.

The state of play

Over the past few years, the UK government has reviewed all these arguments in order to determine whether to allow a new generation of plants. In 2006, industry secretary Alistair Darling gave nuclear the green light, claiming that nuclear allows “electricity without carbon emissions” and “a consistency of energy which wind power cannot”.

But Greenpeace challenged this decision in the high court, which ruled that the consultation process had been seriously flawed. This led to further reviews and consultations in 2007 and, finally, a renewed government commitment to nuclear power in Jan 2008. It remains to be seen when and where the new stations will be built.