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PostPosted: Apr 23, 2014 2:38 pm 
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the MSFR is the concept actually followed by Europe and other countries. The papers I did see till now show a playground for nuclear physicists payed by taxpayers money.

Are there any new studies/papers from 2013/2014 available on the MSFR concept????
Does anyone know what the chinese are doing concerning MSFR, MSR?

Please find attached my latest critic on the concept.


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1301 Fast Chloride vs Fast Fluoride MSR France.pdf [1.93 MiB]
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PostPosted: Apr 23, 2014 5:47 pm 
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Nice overview! ....thanks for sharing!

I guess you haven't posted this in the "Chloride Reactor Design" section because you cover both fluoride and chloride concepts.

Nevertheless, you must be aware of discussions in the "Chloride Reactor Design" section.

For materials considerations, this might be of interest:
viewtopic.php?f=5&t=4264

For neutronics:
viewtopic.php?f=3&t=4197&p=55577#p55589

On page 5 you mention that "During the operation the following neutron induced reactions occur."
An important reaction that is missing from your list is Cl35(n,p)S35.
As you can see in the attached graph, the x-section is quite significant: Looks to me like Cl35 must be avoided, unfortunately.


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PostPosted: Apr 23, 2014 6:49 pm 
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Looks like you haven't had a chance to consider design options for the MCFR core yet: I see just sketches comparing to the French MSFR concept.

A good reference on this topic is the Doctoral Dissertation of CARLO FIORINA:
https://www.politesi.polimi.it/bitstrea ... iorina.pdf

People in the EVOL group, as well as C. Fiorina, have used thermal-hydraulic models for optimizing core geometry to avoid flow re-circulation and stagnation zones inside the core, that leads to great temperature variations, reactor vessel hot spots, and flow instabilities.

Beyond that, none of the MSFR work to-date combines thermal-hydraulic models with 3D neutronics.
The safe way out of that problem is to put a few hundred fuel channels inside the core.
The problem then becomes a mechanical engineering issue, considering differential thermal expansion and creep, materials & installation details, etc.


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MSFR_thermal-hydraulic_Fiorina_and_EVOL.jpg
MSFR_thermal-hydraulic_Fiorina_and_EVOL.jpg [ 526.07 KiB | Viewed 4187 times ]
Holger_Narrog_MCFR_28-I-2014_mod.jpg
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PostPosted: Apr 24, 2014 12:21 am 
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Isotopic separation of chlorine should be easier than U or Heavy water and definitely the Li-7. Chlorides are also more volatile than fluorides and it should be easier to distill and fraction-ate the Th-233U fuels. ThCl4 and UCl4 can be distilled below 1000C and less volatile components can be discarded as waste making reprocessing simpler.


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PostPosted: Apr 24, 2014 2:36 am 
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jaro wrote:
Beyond that, none of the MSFR work to-date combines thermal-hydraulic models with 3D neutronics.


That is incorrect. M. Aufiero successfully defended his Ph.D. thesis last month which included such (excellent) work, notably:

Aufiero, Manuele, Mariya Brovchenko, Antonio Cammi, Ivor Clifford, Olivier Geoffroy, Daniel Heuer, Axel Laureau, et al. 2014. “Calculating the Effective Delayed Neutron Fraction in the Molten Salt Fast Reactor: Analytical, Deterministic and Monte Carlo Approaches.” Annals of Nuclear Energy 65 (March): 78–90. doi:10.1016/j.anucene.2013.10.015.
http://www.sciencedirect.com/science/ar ... 4913005458

and

Aufiero, Manuele, Antonio Cammi, Olivier Geoffroy, Mario Losa, Lelio Luzzi, Marco E. Ricotti, and Herv Rouch. 2014. “Development of an OpenFOAM Model for the Molten Salt Fast Reactor Transient Analysis.” Chemical Engineering Science. doi:10.1016/j.ces.2014.03.003. http://www.sciencedirect.com/science/ar ... 0914001146.
http://www.sciencedirect.com/science/ar ... 0914001146


Unfortunately the thesis is not available yet online.


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PostPosted: Apr 24, 2014 12:49 pm 
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Hi Jagdish,

Isotopic separation of chlorine should be easier than U or Heavy water and definitely the Li-7. Chlorides are also more volatile than fluorides and it should be easier to distill and fraction-ate the Th-233U fuels. ThCl4 and UCl4 can be distilled below 1000C and less volatile components can be discarded as waste making reprocessing simpler.

The idea is to make a realistic cost optimized reactor. Chlorine enrichment would increase costs without a significant benefit. Hence I do not see any reason for a chlorine isotopic enrichment.

a. If the fuel treatment and reprocessing is done in a cost optimized way with limited separation efficiency the waste fractions to be disposed will contain fission product chlorides, remaining actinide chlorides and some Cl36. The waste contains residues of long lasting actinides. A few mols of Cl36 a year will not make a significant difference.

b. In such a reactor there is some ppm free chlorine due to fissions, some 1-3 ppm oxygen remaining from salt cleaning, a few additional mols of sulphur (less than a ppm) that might react with fp or cause grain boundary corrosion. It is not welcome but will most probably not add significantly to the challenges for the structure material. The Cl35(n,p)S35 reaction with its large cross section is not yet mentioned.

c. The breeding ratio of a fast chloride MCFR is far beyond 1 (based on the concept studies of the 60ies with a low fp share). For practical reasons it should be slightly above 1. As Cl36 and Cl35 has a higher neutron absorption than Cl37 it is not a significant disadvantage.


Last edited by HolgerNarrog on Apr 24, 2014 2:58 pm, edited 4 times in total.

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PostPosted: Apr 24, 2014 12:59 pm 
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Hi Jaro,

one of the major challenges of the MSFR and MCFR is the corrosion by hot salt mixtures and neutron damage of the structure material.

The safe way out of that problem is to put a few hundred fuel channels inside the core.

The reactor core has the max. neutron density. To fill it with thin structures is from the engineers point of view the worst that can be done. A hot spot most probably in the upper center of the reactor will not disturb as long as it is not in contact with the structure material (mixed at the outlet with cold salt from the outside) and the fuel does not evaporate. The boiling points of the used salts are at 12 bar at or bejond 1800°C. From engineers point of view the optimum is to have some velocity and a turbulent flow in the reactor but not thin structures of structure material.

I added the reaction Cl35(n,p)S35 to the list. Thank you very much!!


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PostPosted: Apr 24, 2014 4:42 pm 
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HolgerNarrog wrote:
The boiling points of the used salts are at 12 bar at or bejond 1800°C.
Sorry, I missed the part about the high operating pressure. Can't say that I like it, however. The big advantage of MSRs is that they can be run at ambient pressure or even slightly negative gauge pressure, to ensure that any potential leak path is in the inward direction.

HolgerNarrog wrote:
From engineers point of view the optimum is to have some velocity and a turbulent flow in the reactor but not thin structures of structure material.
I guess you don't share my concern about MSFRs that lack any sort of internal structure inside the core -- the concern being the potential for rapid neutron flux oscillation, accompanied by acoustic vibration that may shorten the life of the mechanical equipment.
I agree that the addition of an internal structure comprising fuel channels or flow guides, whose main function is to impede propagation of acoustic waves driven by flux oscillations, is tough on component endurance, but it may turn out to be unavoidable (To put it another way, will you be able to prove to the regulatory authority that a design without any internal structure will NOT suffer from flux-driven vibrations?)

Anyway, in case you ever change your mind, I figure that a minimal fuel flow guide structure might comprise simple rigid beams of triangular crossection, as shown in the illustration. This might be sufficient to achieve the desired damping effect, without having to deal with problems that would result with fuel channels that are in contact with each other or, even worse, joined rigidly together throughout the core.


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PostPosted: Apr 24, 2014 5:22 pm 
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Hi Jaro,

The structure you designed is a very clever design.

Thin structures in the core of a reactor with its high neuron flux have a limited lifetime. As proposed for the 1970 MSR it would require regular replacement and might limit power density. It would take a major advantage from MSFR perhaps kill the concept.

The reactor will suffer from vibrations from the pumps and other causes anyway. It is to avoid potential vibration resonances. According to my todays knowledge it is to optimize the mounting, absorbers, adding weight, perhaps if required modify shape and dimensions.

My knowledge about neutron flux oszillations is limited. If you have some details about expected neutron flux oszillations I would be very pleased if you could share it with me.

A 12 bar salt pressure will avoid cavitation of the pumps, avoids evaporation of the salts* and makes the fuel treatment easier. The pressure is low compared to the pressure of LWR up to 170 bar, SCWR 250 bar, or gas cooled reactors 40 bar.

Holger

*Chloride salt fission products have lower boiling points than fluorides. That makes reprocessing easier but requires a bit pressure in the reactor.


Last edited by HolgerNarrog on Apr 25, 2014 11:03 am, edited 1 time in total.

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PostPosted: Apr 25, 2014 3:53 am 
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12 bar is a lot when it comes to the thermal and radiation creep regime this reactor vessel is in.

You may wish to go for a bit more conservative design, lower temp and lower pressure, to manage materials/thicknesses and accidents. Molten chloride reactors are themselves highly unconservative.


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PostPosted: Apr 25, 2014 10:04 am 
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Scratch what I said, Dr. Aufiero's thesis is openly available since yesterday:

https://www.politesi.polimi.it/handle/10589/89364


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PostPosted: Apr 25, 2014 10:59 am 
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Hi Boris,

nice to see you..

Are there any new reports from Grenoble or the Euratom about the MSFR project.... Salt reprocessing, engineering, design, cost estimates???

Best regards

Holge r


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PostPosted: Apr 25, 2014 11:30 am 
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Boris H wrote:
Scratch what I said, Dr. Aufiero's thesis is openly available since yesterday:

https://www.politesi.polimi.it/handle/10589/89364

Thanks !

I note the following comments in the Conclusions section:
Quote:
In the nominal MSFR conditions, a certain fraction (1%) of the core volume is occupied by small gas bubbles.
In these conditions, the fuel mixture is likely to present a relatively high compressibility and a very low speed of sound (compared to the pure fuel salt).
...In this direction, consistent transient analyses are desirable, at least to exclude any meaningful difference with respect to incompressible simulations.


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PostPosted: Apr 25, 2014 2:57 pm 
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Cyril R wrote:
12 bar is a lot when it comes to the thermal and radiation creep regime this reactor vessel is in.

You may wish to go for a bit more conservative design, lower temp and lower pressure, to manage materials/thicknesses and accidents. Molten chloride reactors are themselves highly unconservative.

OR you could have a pool type reactor and keep the pool at a similar pressure but cooler.


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PostPosted: Apr 25, 2014 3:22 pm 
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Lars wrote:
Cyril R wrote:
12 bar is a lot when it comes to the thermal and radiation creep regime this reactor vessel is in.

You may wish to go for a bit more conservative design, lower temp and lower pressure, to manage materials/thicknesses and accidents. Molten chloride reactors are themselves highly unconservative.

OR you could have a pool type reactor and keep the pool at a similar pressure but cooler.


12 bar is a lot of hydrostatic head. If buffer salt is used of 2 g/cc then it is 60 meters of buffer salt!


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