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PostPosted: May 21, 2013 4:49 pm 
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According to the paper by Ellis & co.,
Quote:
The comparable TWR requires an initial core load that in the early TWRs may contain on the order of two times as much fissile material as an LWR first core.
However, because the TWR core lifetime can be achieved using only the initial fuel load, no reloads would be needed. Even based on the present value of
the avoided reloads, the TWR would enjoy a fuel cost advantage of several hundred million dollars.


From another document,

Fuel Cycle Analysis of Once-Through Nuclear Systems
Prepared for
U.S. Department of Energy
Systems Analysis Campaign
T. K. Kim and T. A. Taiwo
August 10, 2010

Quote:
3.6 TerraPower Traveling Wave Reactor Concept

~14 % enriched uranium is used for the igniter fuel

Also, the metallic fuel is an alloy with ~8% Zr.


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PostPosted: May 21, 2013 8:36 pm 
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Quote:
According to the paper by Ellis & co.,
Quote:
The comparable TWR requires an initial core load that in the early TWRs may contain on the order of two times as much fissile material as an LWR first core.
However, because the TWR core lifetime can be achieved using only the initial fuel load, no reloads would be needed. Even based on the present value of
the avoided reloads, the TWR would enjoy a fuel cost advantage of several hundred million dollars.


Thanks Jaro, but might that only be a quote for the original traveling wave reactor that started with only a small fraction of the big core with fuel and the majority DU? This "shuffling" reactor concept has mostly fissile fuel elements with just some DU on the outside that they shuffle into the central positions to even out burnup. 18 m3 of core with 14% U235 sounds like an awful lot of fissile to me for 500 MWe.

David


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PostPosted: May 22, 2013 11:32 am 
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My understanding of this seminar given by the TerraPower people
http://www.youtube.com/watch?v=U0oqZX6LXrA
is that TerraPower's differentiating strategy is to forego the benefits of molten salts, and solve the metal-casing-degradation challenge -- with heavy reliance on computer simulations.
This appears to me to be a huge gamble, not a gamble on which I would put my money. Do you guys agree?

Independently, I don't think that it makes sense to disparage Myhrvold and Intellectual Ventures. They are playing by the rules, as written. It's like Apple's taxes. Given the rules, which include the "constructive reduction to practice", guys exactly like participants in this blog should be applying for patents covering ideas (as opposed to demonstrated technologies).

Art Williams


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PostPosted: Jun 24, 2013 7:29 am 
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Cyril R wrote:
Interestingly, vented fuel will release large amounts of iodine fission product to the sodium coolant, which will then bind to sodium iodide. Which is a highly radioactive molten halide salt; it's a molten salt reactor already! 8)


Perhaps, this should not be in the Liquid-Metal-Cooled Reactor section, but if I recall correctly, General Atomics follows the same strategy with their EM2 (Energy Multiplier Module) helium-cooled fast neutron reactor. Conceptually, it appears to be competing with the TerraPower reactor. General Atomics also intends to use fuel venting for the breed-burn cycle of the reactor core, which will have a life-cycle of 30 years.


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PostPosted: Jun 28, 2013 5:00 am 
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The figure shows a large, presumably fission gas plenum at the top. Might they have sodium added in the fuel pin for heat transfer, but not fill the sodium much into the plenum? Might they also only vent the gasses to the cover gas system? Is there any advantage in minimizing release to plenum retention and/or not getting as much FP in the separate coolant Na?

The plenum/trap is a cooler area where condensibles can be trapped, and may have porous carbon to trap or at least hold up some of the FP gasses. Maybe they periodically heat this region up and off gas the trapped materials in a batch clean up mode so it is not in continuous clean up which has more risks for release than batch, and continuous clean up would have to handle very low levels making it harder to operate.


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PostPosted: Jun 29, 2013 12:06 pm 
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Ed P wrote:
The figure shows a large, presumably fission gas plenum at the top. Might they have sodium added in the fuel pin for heat transfer, but not fill the sodium much into the plenum? Might they also only vent the gasses to the cover gas system? Is there any advantage in minimizing release to plenum retention and/or not getting as much FP in the separate coolant Na?

The plenum/trap is a cooler area where condensibles can be trapped, and may have porous carbon to trap or at least hold up some of the FP gasses. Maybe they periodically heat this region up and off gas the trapped materials in a batch clean up mode so it is not in continuous clean up which has more risks for release than batch, and continuous clean up would have to handle very low levels making it harder to operate.


Liquid metal cooled reactors operate at low coolant pressures, so not venting fuel with high burnup (needed for good economics) results in high positive pressure in the fuel cladding. Either a large plenum or a very thick cladding will solve this, but it comes at a cost. Large plenum means bigger fuel elements which is not attractive, thick cladding means more losses to cladding (plus high internal pressure means more potential for leaks).

Vented fuel comes in a bunch of different designs. One can use a diving bell type top plenum, essentially a pressure equalized design with the sodium bond never getting out of the fuel rod and sodium coolant never getting to the bond. Or one can use a filtered vent, with a filter plug at the end.

Vented fuel will release most of the noble gasses to the coolant, and then to the cover gas (or directly to the cover gas if a gas vent line to cover gas is provided). A proper design will not release meaningful amounts of the non-volatile (rare earths, strontium etc.) and chemically reactive stuff (iodine, bromine).

Too much FP in the coolant means the reactor is more difficult to service. But it's probably not such a big deal, considering you have Na-24 all over the place already. Huge activity from that source.


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PostPosted: Sep 29, 2013 4:50 am 
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Here's more recent information on TerraPower from the NY Times:

http://www.nytimes.com/2013/09/25/busin ... d=all&_r=0

The research facilities of TerraPower are shared with other projects of Intellectual Ventures. I wonder, if they really want to get this off the ground, why they don't enter into a CRADA with Idaho National Laboratory to develop a prototype, which could be backed by Bill Gates' billions.


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PostPosted: Oct 02, 2013 3:17 am 
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A travelling wave implies a move of fission space with time. That will require a shift of heat extraction too. It could possibly be done but the complications may make it uneconomical. It has to be a fast reactor in any case.
One interesting variation could be an expanding dome. A 3D lattice can be devised so that the fission space is expanding out from center of a hemisphere. The entire lattice could transfer the heat to a gas coolant.
Any MSR with monitoring of reaction and corrective reprocessing, though initially designed to be balanced, is a less complicated idea.


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PostPosted: Sep 23, 2015 11:26 am 
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Dan Yurman's article on today's news of deal between Terrapower and CNNC to prototype and commercialize the "Traveling Wave" reactor.

Terrapower inks deal with China’s CNNC to build fast reactor


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PostPosted: Sep 25, 2015 4:46 am 
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AP1000 design of US origin has been developed in China before being approved by the US NRC. Outsourcing of development to China after the initial design seems to be an expedient arrangement. There is no reason why the Terrapower should not follow the Westinghouse example. In case of MSR, even the design has been undertaken by the Chinese.
I hope the Terrapower will popularise the design as a means to dispose off the used LWR fuel stocks. They need to develop an economical reprocessing method too.
The UK, the holders of a large fissile fuel stocks, are stuck with costly French systems. Could they possibly take the lead with a fast MSR breeder? Moltex could be starting point.
If the rest of the world stumbles, Russia and China are quite steady on their nuclear feet.


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PostPosted: Oct 03, 2017 6:53 am 
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TerraPower Establishes Joint Venture with CNNC for TWR Co-Development


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PostPosted: Oct 04, 2017 9:57 am 
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Puts China firmly on fast reactor path. I wonder if they will buy up the RG recovered plutonium stocks quickly?


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PostPosted: Oct 05, 2017 1:00 pm 
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'Traveling Wave Reactor' has become somewhat of a misnomer. As I understand the TerraPower design is now more like a standing wave reactor, where they try to shuffle the fuel around during the lifetime of the reactor. But it's really just a sodium-cooled fast reactor, which has already been tried and tested in several countries (EBR-II, Phenix, BN-800...)


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PostPosted: Oct 06, 2017 7:11 pm 
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Fast reactors are a new technology currently in progress only in India, Russia and China. Nothing wrong in an American company developing it in China.


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PostPosted: Jun 02, 2018 9:24 am 
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TerraPower’s Nuclear Reactor Could Power the 21st Century

Quote:
Feinberg imagined what we now call a breed-and-burn reactor. Early proposals featured a slowly advancing wave of nuclear fission through a fuel source, like a cigar that takes decades to burn, creating and consuming its fuel as the reaction travels through the core. But Feinberg’s design couldn’t compete during the bustling heyday of atomic energy. Uranium was plentiful, other reactors were cheaper and easier to build, and the difficult task of radioactive-waste disposal was still decades away.

The breed-and-burn concept languished until Edward Teller, the driving force behind the hydrogen bomb, and astrophysicist Lowell Wood revived it in the 1990s. In 2006, Wood became an adviser to Intellectual Ventures, the intellectual property and investment firm that is TerraPower’s parent company. At the time, Intellectual Ventures was exploring everything—fission, fusion, renewables—as potential solutions to cutting carbon. So Wood suggested the traveling-wave reactor (TWR), a subtype of the breed-and-burn reactor design. “I expected to find something wrong with it in a few months and then focus on renewables,” says John Gilleland, the chief technical officer of TerraPower. “But I couldn’t find anything wrong with it.”

That’s not to say the reactor that Wood and Teller designed was perfect. “The one they came up with in the ’90s was very elegant, but not practical,” says Gilleland. But it gave TerraPower engineers somewhere to start, and the hope that if they could get the reactor design to work, it might address all of fission’s current shortcomings.

The TerraPower team, led by Wood and Gilleland, first tackled these challenges using computer models. In 2009, they began building the Advanced Reactor Modeling Interface (ARMI), a digital toolbox for simulating deeply customizable reactors. With ARMI, the team could specify the size, shape, and material of every reactor component, and then run extensive tests. In the end, they came away with what they believe is a practical model of a breed-and-burn TWR first proposed by Feinberg six decades ago. As Levesque recalls, he joined TerraPower when the team approached him with remarkable news: “Hey, we think we can do the TWR now.”


Attachment:
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twr-cutaway.jpg [ 229.69 KiB | Viewed 745 times ]


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