Tuesday, December 16, 2008

Used Nuclear Fuel and the Fission-Fusion Cycle

fusion-reactor-5 President-elect Obama often mentions the "safety" of used nuclear fuel as a block to a whole-hearted embrace of nuclear energy, so we wondered what thinking was going on that seeks to mitigate or even eliminate permanent or even (long-term) interim storage.

We might be all aboard the Yucca Mountain Limited, but recognizing the skittishness that some feel about it, what else might we do?

The NYT's Green Inc. blog reports on a notion to use fusion energy to further split and essentially put to immediate use plutonium and the transuranic elements to generate more energy - instant recycling, if you will:

But what if these “transuranics” could themselves be split? Yet more energy would be derived — but perhaps more importantly, the resulting waste, while still radioactive, would be far less long-lived. [note: which might forestall all the science fiction work Washington has done on how to warn people of the far future - or their ape successors -  that radiant elements are present.]

...

At the heart of the concept — which exists only on paper — is what the scientists call a “compact fusion neutron device.”

The compact nature of the reactor is key, as the immensity of previously designed fusion reactors - and the immense amount of energy they need to operate effectively - has kept them off the boards. But considering this is coming from academics still at the preparing-a-paper-for-a-journal phase, this is, at best, a long way from any sort of practical application - which, come to think of it, is true of fusion projects in general. But it is the percolation of ideas that has value.

Read the whole thing - it actually proved tough to excerpt - and see what you think.

Cutaway of an ITER Tokamak fusion reactor. See here for more on it. What the gentlemen in Austin have in mind hasn't seen publication yet.

4 comments:

Anonymous said...

Guys, See the IAEA's paper on fusion / fission breeder reactor:

http://www.iaea.org/programmes/ripc/physics/pdf/ftp_16.pdf

and

http://www.iaea.org/inisnkm/nkm/aws/fnss/cs/meeting_reports/summaryreport6.pdf

I read an article about this back in 1977 when I was an RO on a submarine. This never took off because fusion could never be made self-sustaining and economical. Kirk Sorensen's molten salt thorium reactors or Carlo Rubbia's energy amplifiers are much better ideas:

http://www.nea.fr/html/trw/docs/saturne8/sat15.pdf
http://einstein.unh.edu/FWHersman/energy_amplifier.html

Luke said...

Interestingly, the fission-fusion hybrid reactor concept dates at least as far back as an essay published in Physics Today in 1979 by the illustrious Hans Bethe.

http://www.physicstoday.org/vol-32/vol32no5p44_51.pdf

donb said...

Looks to me like someone is fishing for more research money for a fusion reactor (which has been only 10 years off for the last 50 years).

At least one way of destroying actinides has already been demonstrated - the IRF, though the fuel fabrication cycle was not fully demonstrated (thank you Bill Clinton). This reactor could also burn up the many tons of depleted uranium we have around, both in used fuel from light water reactors and from the U235 enrichment process.

The molten salt thorium reactor mentioned above is also very interesting, and has already been demonstrated.

I say we first spend our money on things we already know work in order to make it commercially viable. Then we can go after more "speculative" solutions like Carlo Rubbia's energy amplifier.

I say we wait until we have working fusion reactors (I'm not holding my breath) before using their excess neutrons from fusion to destroy unwanted products from fission reactors.

M. Simon said...

There are other ways to fusion that might prove quicker and less expensive:

Easy Low Cost No Radiation Fusion

IEC Fusion Technology blog