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  1. #11
    a scream in a vortex nanook's Avatar
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    Jul 2007


    Traveling wave reactor - Wikipedia, the free encyclopedia

    A traveling-wave reactor, or TWR, is a kind of nuclear reactor that can convert fertile material into fissile fuel as it runs using the process of nuclear transmutation. TWRs differ from other kinds of fast-neutron and breeder reactors in their ability to use little or no enriched uranium, instead burning fuel made from depleted uranium, natural uranium, thorium, spent fuel removed from light-water reactors, or some combination of these materials.

    The concept of a reactor that could breed its own fuel inside the reactor core was initially proposed and studied in 1958 by Saveli Feinberg, who called it a “breed-and-burn” reactor

    No TWR has yet been constructed, but in 2006, Intellectual Ventures launched a subsidiary named TerraPower, LLC to model and commercialize a practical engineering embodiment of such a reactor, which has since come to be called a traveling-wave reactor. TerraPower has developed TWR designs for low- to medium-power (300-MWe) and large power (~1000-MWe) application.[7] Bill Gates featured TerraPower in his 2010 TED talk.[8]

    Reactor Physics:
    The reactor is fueled primarily by depleted uranium, but requires a small amount of enriched uranium or other fissile fuel to initiate fission. Some of the fast-spectrum neutrons produced by fission are absorbed by neutron capture in adjacent fertile fuel (i.e. the non-fissile depleted uranium), converting it into plutonium by the nuclear reaction. The plutonium then fissions to produce two fission products, an average of around 2.5 neutrons, and about 200,000,000 electron volts (eV) of energy, which is converted to electricity using conventional steam turbines.

    Unlike light-water reactors (LWRs), TWRs can be fueled at the time of construction with enough depleted uranium to produce full power for 60 years or more.[11] TWRs consume substantially less uranium than a LWR per unit of electricity generated due to TWRs higher fuel burnup, higher thermal efficiency and higher fuel density. A TWR also accomplishes reprocessing on the fly, without the need for chemical separation that is typical of other kinds of breeder reactors. These features greatly reduce fuel and waste volumes while enhancing proliferation resistance.[10]

    Depleted uranium is widely available as a feedstock. Stockpiles in the United States currently contain approximately 700,000 metric tons of depleted uranium, which is produced as a waste byproduct of the enrichment process.[12] TerraPower has estimated that these stockpiles represent an energy resource equivalent to $100 trillion worth of electricity.[11] Company scientists have also estimated that wide deployment of TWRs could enable projected global stockpiles of depleted uranium to sustain 80% of the world’s population at U.S. per capita electricity usages for over a millennium.[13]

    In principle, TWRs are capable of burning spent fuel from LWRs. This is possible because spent LWR fuel is mostly depleted uranium and, in a TWR fast neutron spectrum, the neutron absorption cross section of fission products are several orders of magnitude smaller than in a LWR thermal neutron spectrum. Additional technical development would be required to realize this capability, however.

    TWRs are also capable, in principle, of reusing their own fuel. The used metal fuel from TWRs will still contain a high fissile content. Recast and reclad into new driver pellets without separations, this recycled fuel could be used to start fission in additional TWRs, thus displacing the need to enrich uranium altogether.

  2. #12
    resonance entropie's Avatar
    Join Date
    Apr 2008


    No the translation made sense.

    The TWR looks indeed really cool, but its in the end only another form of breeder reactor to produce material for nuclear power plants or nuclear power itself.

    Since I am no big fan of nuclear energy, I will not like it, cause it does produce nuclear waste nevertheless and isnt a sustainable form of energy production.

    Judging from the concept tho and the idea its indeed a betterment in the field of breeder reactors.

    What I didnt like about the article is that he said it will produce "no nuclear waste" what is a lie and that he pointed out the advantages of the thing cause it has no CO2 emissions. That's just foul play cause CO2 emissions will be the least of our worries if we concentrate on more nuclear power plants.

  3. #13
    resonance entropie's Avatar
    Join Date
    Apr 2008


    Gonna post my personal opinion now on the topic of nuclear power, cause I feel like it:

    In my opinion there are no real achievements left to be made in the nuclear energy sector. And someone, who talks about revolutionary inventions and masks them as green energy innovations is an idiot.

    The Americans have the luxury to live in a big country. They can like dumb their atomic waste everywhere, free following the slogan "what I dont see, doesnt bother me". In Germany tho, having a much more densely populated area it has always been a precious issue to find a place to dumb the stuff. An issue that even led to the foundation of an own political party, namely the Greens, from activist farmers that protested against the plans of the government to dumb the stuff in their neighbourhood.

    Since that time we have reduced the amount nuclear energy needed to meet the countries energy requirements to 11 % (!!). One has to think about that number, its only 11% and the plans to close all nuclear power plants are long laied out only the energy lobbies tend to destroy them with every new change of political ruling system we have.

    So fact is, Germany can become a role model region presenting that it is possible without nuclear power. So really cool inventions in that field would be for example the container/turbine system that can store electrical current. It's a container filled with a liquid that is changed into a gas thru a turbine electrically powered. The gas then is stored. When then electrical current is needed the gas goes thru the turbine again which then turns and produces power. Has an effect ratio of almost 90%.

    In my opinions those should be great inventions of the future, which can be really called green, not a betterment of breeder reactors.

    In the long term I am hoping for breakthroughs in Quantum Science, so that nuclear fusion may be effective one day. I dont think that this is an impossible thing to do. With new and better super-magnets maybe it will be possible to get the thunneling effect thats going in the sun for billion of years working down on earth aswell.

  4. #14
    Member Schaph's Avatar
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    Mar 2010


    It'll be intereting to know how Bill Gates squeezed a Phd of nuclear physics in his busy schedule.

    I try to be impartial about nuclear energy. Energy source should be selected to fit the end usage. Nuclear energy is great because during operation a nuclear power plant can run on a closed loop system, which is convinent for submarines and stuff. However, nuclear energy does not have zero carbon emission. Production of nuclear fuel requires vast mining and refining operations. Not to mention the current refining process uses pure flurine, which is energy (carbon) intensive to produce and extremely hazardous.
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