Science Interviews

Nuclear Energy: Fission And Fusion

Dr Jeffery Lewins, University of Cambridge

Chris - Nuclear power has had a mixed reception from the public and certainly a hostile reception this week in the wake of the government's publication of what they think should happen on the nuclear debate. But first of all, what actually is nuclear power, how does it work and what's the future?

Jeffery - We've heard about the fusion going on in the Sun and that's that great nuclear reactor in the sky. The light and the heat we get from the Sun is essential to the Earth already. You could hope to build a fusion reactor on Earth, but it's a real problem because we don't have the mass of the Sun, the gravity to make it work. We have to substitute it with a magnetic field and that's expensive. It's great science and challenging engineering but I think having been in the business for fifty years, I'd still say that success is fifty years away if you mean by success that you get useful electricity back from fusion power. Now the other end from what Chris said is fission power. In the Sun they're putting very light elements together and getting energy out of it. But here on Earth we get heavy elements like uranium and thorium and if you split them up into fission products you also get neutrons left over, these are what cause the fission in the first place, and energy. It's that energy that for the last fifty years people have employed. Of course, some of this has been in weapons and we don't want to see that, but some has been employed in nuclear power stations to make electricity, which we have a substantial amount of in this country and other places in the world.

Chris - But why is fusion viewed as better than fission?

Jeffery - Perhaps because it's fifty years further down the line is one answer. But it doesn't produce the associated materials such as plutonium, which comes out of fission reactors when uranium is converted into plutonium. Plutonium can also be burned in fission reactors but it is also one of the roots into nuclear weapons, and I think there's a concern there. But to be fair, fusion energy produces a lot of neutrons, it produces a lot of radioactivity and don't think that's it's the clean thing that some people would like you to think it is.

Kat - Nuclear power is very controversial and over the past nine weeks or so I've been involved in writing a blog for the Institute of Physics which is looking at all the issues surrounding nuclear power, especially in light of the UK's energy review. So you can go and have a look yourself and hear all the arguments. It's at www.potentialenergy.iop.org and it's looking into the science, the economics, the politics, so go along and make some of your own comments.

July 2006