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PostPosted: Aug 09, 2013 12:28 am 
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http://www.youtube.com/watch?v=w2KzC3LC2AI

Today's reactor technologies depend on solid fuel rods leading to a
complex fuel cycle. The operation of liquid-fueled homogeneous reactors
(i.e. molten-salt reactors) leads to a tradeoff between optimal fuel
processing and coolant handling.

The Dual Fluid Reactor (DFR), developed by the Institut für
Festkörper-Kernphysik gGmbH (Institute for Solid-State Nuclear Physics),
combines the advantages of a lead-cooled fast reactor with the fuel
processing capabilities of the molten-salt reactor, gaining a very high
level in safety and economy. The DFR is being designed with respect to
the Energy Return on Invested (EROI) measure and passive safety
standards according to the KISS principle and with attention to the
state of technology in mechanical, plant and chemical engineering for a
speedy implementation.

For more information, refer to http://festkoerper-kernphysik.de/dfr

Dipl.-Phys. Daniel Weißbach, Dipl.-Ing. Nico Bernt
Institut für Festkörper-Kernphysik
Leistikowstraße 2
D-14050 Berlin
Germany

http://www.the-weinberg-foundation.org/ ... t-reactor/
As much I want "pro-solar/pro-wind/pro-coal/anti-nuclear germany" to be cursed to buy energy from nuclear france and nuclear russia for all eternity , I hope germany can make this project, and in the process solve the worlds energy problem once and for all.

Any one think germany might beat china to MSR?


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PostPosted: Aug 09, 2013 9:39 am 
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The DFR concept sounds interesting.
But I'm sure I'm not the only one with doubts about the technical feasibility.
Because the UF4 fuel is quasi-static - not circulated through heat exchangers like MSR - the heat transfer to the lead coolant depends on the surface area of the fuel tubes: The DFR requires on the order of ten thousand small-diameter fuel tubes, similar to the number of individual fuel rods in ordinary solid-fuel reactors.
The trouble is that ALL those thousands of tubes are interconnected, to allow the core fuel load to be drained, and to perform on-line processing.
Those thousands of connections must of course withstand decades of use in a harsh environment: Its not at all obvious that this can be made to work.


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PostPosted: Aug 09, 2013 9:59 am 
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Agree with Jaro. This durability issue is very difficult. A single leak of the many thin walled tubes and connections could lead to decommissioning of the entire reactor.

A fuel assembly approach, with liquid fuel in tubular fuel assemblies, seems more reasonable. Fuel assemblies could be shuffled online, and drained of fuel outside the core, the fuel is then reprocessed in small batches and put into a new fuel assembly. More similar to an IFR approach, but with a potentially simpler reprocessing step. Or just go metallic fuel, even more similar to IFR.


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PostPosted: Aug 09, 2013 10:27 am 
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jaro wrote:
The DFR concept sounds interesting.
But I'm sure I'm not the only one with doubts about the technical feasibility.
Because the UF4 fuel is quasi-static - not circulated through heat exchangers like MSR - the heat transfer to the lead coolant depends on the surface area of the fuel tubes: The DFR requires on the order of ten thousand small-diameter fuel tubes, similar to the number of individual fuel rods in ordinary solid-fuel reactors.
The trouble is that ALL those thousands of tubes are interconnected, to allow the core fuel load to be drained, and to perform on-line processing.
Those thousands of connections must of course withstand decades of use in a harsh environment: Its not at all obvious that this can be made to work.


http://dual-fluid-reactor.org/faq

Low pressure fuel/coolant isn't a risk. Strong walled fuel pipes will be used.

Q4 Isn't the corrosion at 1000 °C a big problem?
No. Most material problems exist for thermal reactors, but since the DFR is a fast reactor, the choice of materials opens widely. In principal the material problems were already solved by the MSRE development. In the past more durable and resistant materials were applied in industry. Those materials are rarer and rather expensive. Indeed they are affordable for the DFR because of the high powered small core and the abandonment of fuel elements the required amounts are low.


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PostPosted: Aug 09, 2013 11:35 am 
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I wouldn't say the problems of materials don't exist with fast spectrum. Graphite for example, isn't bothered by thermal neutrons, but is damaged by fast neutrons. All physical dislocation based damage processes are exagerbated. This is unfortunate since all carbon bearing materials will be affected and carbides are the most promising group of materials for containing both lead and molten salt in a radiation environment....

Some neutron reactions are also dependent on neutron speed.

The problems of fast neutron damage are different, but they are there.

Leaks are a problem if you have complicated thin walled geometry in a high flux environment. All sorts of weird effects occur, causing radiation creep and such. This could well develop into a leak over decades of operation. The entire core container would have to be replaceable to be safe.


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PostPosted: Aug 09, 2013 11:51 am 
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Cyril R wrote:
I wouldn't say the problems of materials don't exist with fast spectrum. Graphite for example, isn't bothered by thermal neutrons, but is damaged by fast neutrons. All physical dislocation based damage processes are exagerbated. This is unfortunate since all carbon bearing materials will be affected and carbides are the most promising group of materials for containing both lead and molten salt in a radiation environment....

Some neutron reactions are also dependent on neutron speed.

The problems of fast neutron damage are different, but they are there.

Leaks are a problem if you have complicated thin walled geometry in a high flux environment. All sorts of weird effects occur, causing radiation creep and such. This could well develop into a leak over decades of operation. The entire core container would have to be replaceable to be safe.


I like the idea of replacable core containers. It could make things so much easier long term.


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PostPosted: May 26, 2014 1:45 pm 
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For anyone who may be in Vancouver in August:

http://pbnc2014.org/


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PostPosted: May 26, 2014 2:27 pm 
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While I welcome all efforts in promoting MSR and in general good nuclear technology, I think the idea of having chloride salts and lead at 1000 deg C separated by silicon carbide in a molybdenum alloy is... questionable, from a feasibility point of view. Sure, from a pure reactor physics point of view, it makes sense to separate the fuel and the coolant, while minimizing parasitic absorptions and having a very hard neutron spectrum. But materials and chemistry are stubborn adversaries.


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PostPosted: May 26, 2014 11:56 pm 
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In for a penny, in for a pound (make it a cent and a dollar/euro if it helps).
Just consider having water for the second fluid. It will be a moderator-coolant in place of the lead coolant. The advantages are
1. It is cheaper.
2. It provides limited moderation resulting in a dual mode reactor.
3. It directly produces steam for use for the purpose you want it.
4. Areas near the water tubes get moderated neutrons and act as a neutron source.
5. Areas further away have neutrons in fast/resonance spectrum and act as fast reaction area/neutron sink resulting in higher conversion.
The problem is the thermal shock but it is routine in boilers. Have the tubes of a heat exchanger.


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PostPosted: May 29, 2014 2:59 am 
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German media is dominated by left wing and green journalist. Even in the governmental run TV stations there are reports about the 20000 death from Fukushima. The global warming or climate hoax is responsible for any storm, flooding and inconvieniance. The future are "renewable energies". The high costs and other disadvantages are not caused by reality but by big corporations or capitalism.

The "Dual Fluid Reactor" is the only new reactor concept that received positive attention by the German mass media within the last 10 years.

The main initiator was formerly promoting "cold fusion" and has excellent communication skills. The initiators do a very successful communication based on phantastic promises. This reactor does not create nuclear waste, does not have any safety issues and costs less than any other power plant. .....
The technical informations are vague and in many aspects inconsistant. I assume it is similar to other political science to avoid points for attack.

From the technical point of view it is according to my knowledge perhaps the poorest MSR concept published. For example there is no detailled information which structure material will be used in contact with a 1200 - 1300°C chloride salt* mixture in the center of the reactor ....The few technical data is not consistant.

The biggest success of this group was to join a "Green Award" by asking for votes in some pro nuclear blogs. They got the 1st prize...they were excluded as the Green does not really appreciate nuclear...they went to court and thus got a lot of media attention.

Holger


*An average coolant outlet temperature of 1000°C means coolant temperatures within hot spots of up to perhaps 1100°C and about 1200 - 1300°C (guess without calculation) in the structure material of the thin pipes that separate fuel and coolant in this concept.

I would bet that there is no structure material available on this planet that is resistant as thin structure against lead corrosion at 1100°C, a chloride salt mixture including Fp chlorides, Cl2 at 1200°C good heat transfer properties, good mechanical properties, very high neutron flux....


Last edited by HolgerNarrog on May 30, 2014 5:12 pm, edited 4 times in total.

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PostPosted: May 29, 2014 10:32 am 
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Does anyone understand why they want to go for such an insane temperature? Thermodynamic efficiency? Or do they hope for self-healing of neutron damage? Using chlorides has the particular advantage of low melting eutectics being available.


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PostPosted: May 29, 2014 1:25 pm 
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Hi Burghard,

I was a bit in contact with the group some 3 years ago. None of them is an engineer.

If you study their papers you will not find a lot of technical data. They mentioned to use uranium- or thorium chlorides. UCL3 has a melting point of 837°C, PuCl3 767°C. The binary phase diagram does not show a strong decline in the melting temperature. I did not read anything about a carrier salt that would decrease the melting temperature. That means from the technical point of view you will have to have very high operating temperatures.

If you do not have to stay within the limitations of a technical concept ....


PS: Very interesting is that many qualified poeple give so much attention to such a concept.


Last edited by HolgerNarrog on May 30, 2014 5:13 pm, edited 1 time in total.

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PostPosted: May 29, 2014 7:51 pm 
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Is there any way to get a molten salt reactor that operates at LWR temperatures?
These are sufficient for power generation and would reduce the materials challenges significantly.


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PostPosted: May 30, 2014 1:01 am 
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There may be discussion but will the govt permit any type of nuclear reactor?
As regards the lower temperature MSR, a fuel based on NaF-ZrF4 and no moderator may be the best MSR. It will burn the used and processed LWR fuel and work safely at low pressure in the core. It could have a clean salt as secondary coolant and use PWR generating sets after a steam generator.


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PostPosted: May 30, 2014 1:50 am 
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How about an NaCl-MgCl2 eutectic salt - apparently with significant TRU loading it will be usable (in viscosity terms) as low as 770K.

500 Celsius sounds far less insane to engineer for than the operating temperatures often suggested.


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