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| [[File:Laufwellenreaktor.gif|thumb|Numeric simulation of a TWR. Red: uranium-238, light green: plutonium-239, black: fission products. Intensity of blue color between the tiles indicates neutron density]]
| | The main advantage of using the blog is that anyone can use the Word - Press blog and customize the elements in the theme regardless to limited knowledge about internet and website development. If you adored this post and you would certainly like to obtain additional information pertaining to [http://GET7.pw/backup_plugin_983796 backup plugin] kindly go to the web-page. You can either install Word - Press yourself or use free services offered on the web today. The effect is to promote older posts by moving them back onto the front page and into the rss feed. Hosted by Your Domain on Another Web Host - In this model, you first purchase multiple-domain webhosting, and then you can build free Wordpress websites on your own domains, taking advantage of the full power of Wordpress. provided by Word - Press Automatic Upgrade, so whenever you need to update the new version does not, it automatically creates no webmaster. <br><br>These folders as well as files have to copied and the saved. The higher your blog ranks on search engines, the more likely people will find your online marketing site. You are able to set them within your theme options and so they aid the search engine to get a suitable title and description for the pages that get indexed by Google. Furthermore, with the launch of Windows 7 Phone is the smart phone market nascent App. Many times the camera is following Mia, taking in her point of view in almost every frame. <br><br>Your Word - Press blog or site will also require a domain name which many hosting companies can also provide. The nominee in each category with the most votes was crowned the 2010 Parents Picks Awards WINNER and has been established as the best product, tip or place in that category. Are you considering getting your website redesigned. Our skilled expertise, skillfulness and excellence have been well known all across the world. Article Source: Stevens works in Internet and Network Marketing. <br><br>It is the convenient service through which professionals either improve the position or keep the ranking intact. Quttera - Quttera describes itself as a 'Saa - S [Software as a Service] web-malware monitoring and alerting solution for websites of any size and complexity. re creating a Word - Press design yourself, the good news is there are tons of Word - Press themes to choose from. If you choose a blog then people will be able to post articles on your site and people will be able to make comments on your posts (unless you turn comments off). Look for experience: When you are searching for a Word - Press developer you should always look at their experience level. <br><br>Millions of individuals and organizations are now successfully using this tool throughout the world. s ability to use different themes and skins known as Word - Press Templates or Themes. Useful Plugins Uber - Menu Top Megamenu Now it is the time of sticky Top navbar. Working with a Word - Press blog and the appropriate cost-free Word - Press theme, you can get a professional internet site up and published in no time at all. 95, and they also supply studio press discount code for their clients, coming from 10% off to 25% off upon all theme deals. |
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| A '''traveling-wave reactor''' (TWR) is a type of [[nuclear reactor]] that nuclear engineers anticipate can convert [[fertile material]] into usable fuel through [[nuclear transmutation]] in tandem with the burnup of fissile material. TWRs differ from other kinds of [[neutron temperature|fast-neutron]] and [[breeder reactor]]s in their ability to use fuel efficiently without [[uranium enrichment]] or [[nuclear reprocessing|reprocessing]], instead directly using [[depleted uranium]], [[natural uranium]], [[thorium]], [[spent nuclear fuel|spent fuel]] removed from [[light water reactor]]s, or some combination of these materials.
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| The name refers to the fact that fission does not occur throughout the entire TWR core, but remains confined to a boundary zone that slowly advances through the core over time. TWRs could theoretically run, self-sustained, for decades without refueling or removing any spent fuel from the reactor.
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| ==History==
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| Traveling-wave reactors were first proposed in the 1950s and have been studied intermittently since that time. 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.<ref>S. M. Feinberg, "Discussion Comment", Rec. of Proc. Session B-10, ICPUAE, United Nations, Geneva, Switzerland (1958).</ref> Michael Driscoll published further research on the concept in 1979,<ref>M. J. Driscoll, B. Atefi, D. D. Lanning, "An Evaluation of the Breed/Burn Fast Reactor Concept", MITNE-229 (Dec. 1979).</ref> as did Lev Feoktistov in 1988,<ref>L. P. Feoktistov, "An analysis of a concept of a physically safe reactor", Preprint IAE-4605/4, in Russian, (1988).</ref> Edward Teller/Lowell Wood in 1995,<ref>E. Teller, M. Ishikawa, and L. Wood, "Completely Automated Nuclear Reactors for Long-Term Operation" (Part I), ''Proc. of the Frontiers in Physics Symposium'', American Physical Society and the American Association of Physics Teachers Texas Meeting, Lubbock, Texas, United States (1995); Edward Teller, Muriel Ishikawa, Lowell Wood, Roderick Hyde, John Nuckolls, "Completely Automated Nuclear Reactors for Long-Term Operation II : Toward A Concept-Level Point-Design Of A High-Temperature, Gas-Cooled Central Power Station System" (Part II), Proc. Int. Conf. Emerging Nuclear Energy Systems, ICENES'96, Obninsk, Russia (1996) UCRL-JC-122708-RT2.</ref> Hugo van Dam in 2000,<ref>H. van Dam, "The Self-stabilizing Criticality Wave Reactor", ''Proc. Of the Tenth International Conference on Emerging Nuclear Energy Systems (ICENES 2000)'', p. 188, NRG, Petten, Netherlands (2000).</ref> and Hiroshi Sekimoto in 2001.<ref>H. Sekimoto, K. Ryu, and Y. Yoshimura, "CANDLE: The New Burnup Strategy", ''Nuclear Science and Engineering'', 139, 1–12 (2001).</ref>
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| Since 2001, the Travelling wave reactor was systematically discussed in INES 1, in 2004, INES-2 in 2006 and INES 3 in 2010 meetings in Japan, and was called "CANDLE" Reactor an abbreviation from Constant Axial shape of Neutron flux, nuclides densities and power shape During Life of Energy production reactor, as proposed by Sekimoto in 2001 and 2005, published in Progress in Nuclear Energy.
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| In 2010 Popa-Simil publishes in INES-3 proceeding the paper "advanced Nuclear Reactor from Fiction to Reality", where he discuses the case of micho-hetero-structures improved Travelling Wave Reactor, further detailed in Plutonium Futures meeting,in 2010 the paper "Plutonium Breeding In Micro-Hetero Structures Enhances the Fuel Cycle", describing a TWR with deep burnout enhanced by plutonium fuel channels, and multiple fuel flow.
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| In 2010 a group from Terra Power applies for the patent EP 2324480 A1 following WO2010019199A1 "Heat pipe nuclear fission deflagration wave reactor cooling" where in order to be accepted calls the traveling or singular wave "deflagration" as is mooving with about 1-4 inch per year, and introduces the heat pipe cooling already applied in space reactors built at LANL and INL since 2000, or even earlier, using the flaws and weaknesses of USPTO.
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| No TWR has yet been constructed, but in 2006, [[Intellectual Ventures]] launched a subsidiary named [[TerraPower, LLC]] to model and commercialize a working design of such a reactor, which has since come to be called a "traveling-wave reactor". TerraPower has developed TWR designs for low- to medium- (300 MWe) as well as high-power (~1000 MWe) generation facilities.<ref>K. Weaver, C. Ahlfeld, J. Gilleland, C. Whitmer and G. Zimmerman, "Extending the Nuclear Fuel Cycle with Traveling-Wave Reactors", Paper 9294, ''Proceedings of Global 2009'', Paris, France, September 6–11, (2009).</ref> [[Bill Gates]] featured TerraPower in his 2010 [[TED (conference)|TED]] talk.<ref>{{cite video
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| |url=http://www.ted.com/talks/lang/eng/bill_gates.html|title=Innovating to zero!
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| |people=[[Bill Gates]]
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| |accessdate=2010-07-13
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| |publisher=[[TED (conference)|TED]]
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| }}</ref>
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| ==Reactor physics==
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| Papers and presentations on the TerraPower TWR<ref>R. Michal and E. M. Blake, "John Gilleland: On the traveling-wave reactor", ''Nuclear News'', p. 30–32, September (2009).</ref><ref name="Wald">{{Cite journal | last = Wald | first = M. | title = 10 Emerging Technologies of 2009: Traveling-Wave Reactor | publisher = MIT Technology Review | date = 2009-March/April}}</ref><ref name="Gilleland">{{Cite conference | author = [http://www.nuc.berkeley.edu/Gilleland-bio Gilleland, John] | title = TerraPower, LLC Nuclear Initiative | publisher = University of California at Berkeley, Spring Colloquium | date = 2009-04-20 | url = http://www.nuc.berkeley.edu/node/1077 | accessdate = October 2009}}</ref> describe a pool-type reactor cooled by liquid sodium. The reactor is fueled primarily by depleted uranium-238 "fertile fuel", but requires a small amount of enriched uranium-235 or other "fissile fuel" to initiate [[nuclear fission|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), which is "bred" into [[plutonium]] by the nuclear reaction:
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| :<math>\mathrm{^{238}_{\ 92}U + \,^{1}_{0}n \;\rightarrow\; ^{239}_{\ 92}U \;\rightarrow\; ^{239}_{\ 93}Np + \beta \;\rightarrow\; ^{239}_{\ 94}Pu + \beta}</math>
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| Initially, the core is loaded with fertile material, with a few rods of fissile fuel concentrated in the central region. After the reactor is started, four zones form within the core: the depleted zone, which contains mostly fission products and leftover fuel; the fission zone, where fission of bred fuel takes place; the breeding zone, where fissile material is created by neutron capture; and the fresh zone, which contains unreacted [[fertile material]]. The energy-generating fission zone steadily advances through the core, effectively consuming fertile material in front of it and leaving spent fuel behind. Meanwhile, the heat released by fission is absorbed by the molten sodium and subsequently transferred into a closed-cycle aqueous loop, where electric power is generated by steam turbines.<ref name="Wald"/>
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| ==Fuel==
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| Unlike light-water reactors (LWRs), TWRs use only a small amount (~10%) of enriched uranium-235 or other fissile fuel to initiate the nuclear reaction. The remainder of the fuel consists of natural or depleted uranium-238, which can generate power continuously for 40 years or more and remains sealed in the reactor vessel during that time.<ref name="Gilleland"/> TWRs require substantially less fuel per kilowatt-hour of electricity than do LWRs, owing to TWRs' higher fuel burnup, energy density and thermal efficiency. A TWR also accomplishes most of its reprocessing "on the fly"{{cn|date=November 2011}} within the reactor core. Spent fuel can subsequently be recycled after simple "melt refining", without the chemical separation of plutonium that is required by other kinds of breeder reactors. These features greatly reduce fuel and waste volumes while enhancing proliferation resistance.<ref name="Wald"/>
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| 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 left as a byproduct of the [[nuclear enrichment|enrichment]] process.<ref>United States Department of Energy, [http://web.ead.anl.gov/uranium/mgmtuses/storage/index.cfm "Depleted UF<sub>6</sub> Inventory and Storage Locations"]. Accessed October 2009.</ref> TerraPower has estimated that the [[Paducah Gaseous Diffusion Plant|Paducah enrichment facility]] stockpile alone represents an energy resource equivalent to $100 trillion worth of electricity.<ref name="Gilleland"/> TerraPower has 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 energy usages for over a millennium.<ref>L. Wood, T. Ellis, N. Myhrvold and R. Petroski, "Exploring The Italian Navigator's New World: Toward Economic, Full-Scale, Low Carbon, Conveniently-Available, Proliferation-Robust, Renewable Energy Resources", 42nd Session of the Erice International Seminars on Planetary Emergencies, Erice, Italy, 19024 August (2009).</ref>
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| In principle, TWRs are capable of burning spent fuel from LWRs, which is currently discarded as radioactive waste. Spent LWR fuel is mostly depleted uranium and, in a TWR fast-neutron spectrum, the neutron absorption cross-section of fission products is several orders of magnitude smaller than in a LWR thermal-neutron spectrum. While such an approach could actually bring about an overall reduction in nuclear waste stockpiles, additional technical development would be required to realize this capability.
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| TWRs are also capable, in principle, of reusing their own fuel. In any given cycle of operation, only 20–35% of the fuel gets converted to an unusable form; the remaining metal constitutes usable fissile material. Recast and reclad into new driver pellets without chemical separations, this recycled fuel can be used to initiate fission in subsequent cycles of operation, thus displacing the need to enrich uranium altogether.
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| ==Traveling wave vs. standing wave==
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| The breed-burn wave in [[TerraPower]]'s TWR design does not move from one end of the reactor to the other<ref name="Ellis">{{Cite conference | author = T. Ellis, R. Petroski, P. Hejzlar, G. Zimmerman, D. McAlees, C. Whitmer, N. Touran, J. Hejzlar, K. Weaver, J. Walter, J. McWhirter, C. Alhfeld, T. Burke, A. Odedra, R. Hyde, J. Gilleland, Y. Ishikawa, L. Wood, N. Myrvold, W. Gates III | title = Traveling-Wave Reactors: A Truly Sustainable and Full-Scale Resource for Global Energy Needs | publisher = American Nuclear Society, Summer Meeting | date = 2010-06-14 | url = http://terrapower.com/uploads/docs/ICAPP_2010_Paper_10189.pdf | accessdate = October 2013}}</ref> but gradually from the inside out. Moreover, as the fuel's composition changes through nuclear transmutation, fuel rods are continually reshuffled within the core to optimize the neutron flux and fuel usage at any given point in time. Thus, instead of letting the wave propagate through the fuel, the fuel itself is moved through a largely stationary burn wave. This is contrary to many media reports,<ref name="nyt1">{{Cite news | author = M. Wald| title = Developer of Novel Reactor Wins $35 Million Infusion | newspaper = The New York Times | date = 2010-06-14 | url = http://www.nytimes.com/2010/06/15/business/energy-environment/15nuke.html | accessdate = June 15, 2010}}</ref> which have popularized the concept as a candle-like reactor with a burn region that moves down a stick of fuel. By replacing a static core configuration with an actively managed "standing wave" or "[[soliton]]", however, TerraPower's design avoids the problem of cooling a highly variable burn region. Under this scenario, the reconfiguration of fuel rods is accomplished remotely by robotic devices; the containment vessel remains closed during the procedure, and there is no associated downtime.
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| ==Concept criticism==
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| [[Kirk Sorensen]] of [[Flibe Energy]] has criticized the TWR as "a particularly difficult implementation" of the [[fast breeder reactor]], which he characterizes as "already hard to build in the first place." As well, he has emphasized the enormous difficulties and risks associated with the eventual [[nuclear decommissioning]] of a TWR reactor.<ref>[http://www.youtube.com/watch?&v=P9M__yYbsZ4#t=01h00m25s THORIUM REMIX 2011] (YouTube video; comments begin about 1:00:25)</ref> Dr. Robert Hargraves, who is on the Flibe Energy Board of Advisors,<ref>[http://flibe-energy.com/company/boa/ Board of Advisors :: Flibe Energy]</ref> lauded the goal of addressing [[energy poverty]] globally with the TWR, but briefly highlighted that its projected [[Cost of electricity by source|cost of energy production]], "competitive with [conventional] nuclear power", wasn't as low as [[fossil fuel]]s (e.g. coal).<ref>[http://www.youtube.com/watch?v=Aeejr4M_gxI#t=29m30s IThEO 2011 - New York - The Way Forward] "Closing panel from [http://itheo.org/thorium-energy-conference-2011 IThEO 2011], International Thorium Energy Organisations annual conference which was held in New York" in October 2011. (YouTube video; Hargraves' comments begin about 29:30)</ref>
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| ==References==
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| {{Reflist|30em}}
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| == External links ==
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| * [http://intellectualventureslab.com/?page_id=532 "TerraPower Reactors Approach the Nuclear Ideal"] by [[Intellectual Ventures]] Lab.
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| * [http://earth2tech.com/2010/02/15/terrapower-how-the-travelling-wave-nuclear-reactor-works/ TerraPower: How The Traveling Wave Nuclear Reactor Works], inc 4 diagrams from IV.
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| * [http://www.terrapower.com/ Terrapower.com company website]
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| {{Nuclear fission reactors}}
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| [[Category:Nuclear power reactor types]]
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