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How thorium can burn nuclear waste and generate energy

Posting in Design

A horse called Thorium? Ben Lindley's supervisor Geoff Parks believes that thorium represents a way to ride into the energy future.

There's a growing movement to make nuclear power safer, more efficient and less weapons-prone by replacing today's uranium fuel with another element, thorium.

And within the thorium push, there are different technological ideas for how to deploy. One camp says that the best way to optimize thorium's many advantages is to put it into liquid form in a molten salt reactor (MSR), which is a radically different design compared to today's solid fueled reactors.

Some thorium pragmatists, however, advocate another step that would get thorium onto the power scene sooner: Put it into existing reactors.

That's the message coming from the University of Cambridge in England, where PhD candidate Ben Lindley has discovered another potential advantage: Reactor operators could burn a thorium fuel that is mixed with plutonium and thus would provide a useful way to eliminate troubling nuclear waste.

Fabricators can already mix uranium with plutonium into a fuel called "MOX" (mixed oxide), which France uses in some of its nuclear reactors.

Youth isn't wasted on the young. Ben Lindley is in his early 20s, and has discovered an additional beneficial quality of thorium.

But according to Lindley, a thorium-plutonium mix could power reactors almost forever in a reusable fuel cycle, a huge improvement over the limited number of years that a mixed uranium-plutonium fuel lasts. For more on why this is true, see my Weinberg blog.

Lindley made the discovery while a masters student at Cambridge, under senior lecturer Geoff Parks.

There's one main catch: Those conventional reactors would work best if they were altered. Lindley recommends putting the mixed thorium fuel into conventional reactors that use less water than today's reactors - water serves as a coolant and also as a "moderator" that slows down neutrons and thus facilitates nuclear reactions.

Hitachi, Toshiba, Mitsubishi and the Japan Atomic Energy Agency all have designs for "reduced-moderation water reactors", and Toshiba's Westinghouse has shown interest in Lindley's ideas.

Lindley is also in contact with Norway's Thor Energy, which is examining thorium-plutonium fuel at the Halden test reactor with help from Westinghouse.

Photos from Geoff Parks and Ben Lindley

Another idea: mix a thorium-plutonium liquid in a molten salt reactor:

Or you could put liquid uranium and nuclear waste into a molten salt reactor:

Other ways to use nuclear waste and nuclear:

SmartPlanet has written extensively on thorium and other alternative nuclear technologies including fission and fusion. Enter "thorium" or "alternative nuclear" in the search box above. Or sift through this archive.

— By on April 17, 2013, 10:07 PM PST

Mark Halper

Contributing Editor

Mark Halper has written for TIME, Fortune, Financial Times, the UK's Independent on Sunday, Forbes, New York Times, Wired, Variety and The Guardian. He is based in Bristol, U.K. Follow him on Twitter. Disclosure