Thursday, September 13, 2012

Fusion-Fission Fandango in Texas

Super Divertor XIt’s like the doublemint twins at the University of Texas at Austin.

The researchers — Mike Kotschenreuther, Prashant Valanju and Swadesh Mahajan of the College of Natural Sciences — have patented the concept for a novel fusion-fission hybrid nuclear reactor that would use nuclear fusion and fission together to incinerate nuclear waste. Fusion produces energy by fusing atomic nuclei, and fission produces energy by splitting atomic nuclei.

How does it work?

The researchers’ patent covers a tokamak device, which uses magnetic fields to produce fusion reactions. The patented tokamak is surrounded by an area that would house a nuclear waste fuel source and waste by-products of the nuclear fuel cycle. The device is driven by a transformational technology called the Super X Divertor.

The Super X Divertor is a crucial technology that has the capacity to safely divert the enormous amounts of heat out of the reactor core to keep the reactor producing energy.

I guess this means – well, I’m not sure what it means. It sounds as though the fuel rods would need to find their way to the tokamak via the Super X Divertor or perhaps the system would use something other than a fuel rod. Or I’m all wet. Let’s look for more detail.

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This illustration (also above – click for larger) suggests a two part process – a fission/fission-fusion fandango - with light water reactors operating as they normally do, and the used fuel then further processed in the fission-fusion reactor.

This second reactor can also produce energy and presumably can be rated much as fission reactors are now done, so the result will be more electricity and perhaps a good deal of process heat, which theoretically has impressive industrial applications. Perhaps the use of the Super X Divertor, which diverts the heat so as to avoid it melting the containment, gives that use added plausibility.

This article provides a few more details. I admit I’m still lost on some elements of it; for example, what would seed the fusion reaction? ITER is using deuterium (heavy water) and tritium – but I’m not sure about this project. (The reason to care is to understand better the cost implications). But there are a lot of good details here.

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Anyway, the professors have gotten some attention for their work:

Several groups are considering implementing the Super X Divertor on their machines, including the MAST tokamak in the United Kingdom, and the DIIID (General Atomics) and NSTX (Princeton University) in the U.S. Next steps will include performing extended simulations, transforming the concept into an engineering project, and seeking funding for building a prototype.

Which keeps it firmly in the university/lab sphere, for now. In describing fusion projects, I sometimes think of them as  “Today’s Technology Tomorrow,” because fusion always seems two years away from a major breakthrough. It always has, as long as I’ve followed the subject.

But one can’t help but be impressed by the amounts of ingenuity and enthusiasm being poured into fusion projects. Maybe that’s  motivated by a potentially enormous payoff for the team who can make a project practical – that is, scalable and affordable – but maybe also, even largely, for love of ingenuity and enthusiasm. Those qualities have carried the world a long ways. 

2 comments:

Paul Studier said...

It must be D-T fusion because it is by far the easiest and produces 14 Mev neutrons which can burn up nuclear waste and are also good at destroying the reactor. After decades of fusion research, no fusion device has achieved "breakeven", that is, more energy produced than is consumed starting the reaction. In other words, Q<1. This concept is quite speculative.

Engineer-Poet said...

Fusion? Why bother?
Fast protons break atoms too.
Do a bang-up job!