Energy From Thorium Discussion Forum

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PostPosted: Dec 16, 2014 7:54 am 
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jaro wrote:
HolgerNarrog wrote:
There are plenty of pro`s and con`s for both options...
To me the worst "con" for MCFRs is that you need isotopically pure Cl37.
That's almost as bad as pure Li7 in FLiBe.


A more practical concern I have is that chloride reactors are complete paper reactors. No one has ever gone beyond desk studies, not even a serious engineering experiment... nothing. That is not a good start. Its a blank. Basically you have to go and build a MSRE for chloride, operate for years, then study things and solve the many problems that no doubt will surface... you're over 2030 before you can even consider any power plant demonstrator and that is with good funding which you won't attract because of the time frame that is too long. We already have long term dead end pet peeve projects like ITER, and you can't compete with that funding. You have to offer some near term prospect or it will sink before it can swim.


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PostPosted: Dec 16, 2014 12:36 pm 
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There are plenty of questions left for the MCFR and as well for the MSFR.

The actual studies of MSFR and other advanced reactor concept cannot promise any real and significant advantage compared to LWR. Thus nobody in the OECD is willing to spend a significant budget in favor of advanced reactor concepts. If progress goes on in the current pace it will need at least a century to develop a commercial MSFR/MCFR.

If there is a concept that can promise a significant benefit this might hopefully change. In the 50ies/60ies the USA and other OECD countries built plenty of different test reactors. Test reactors were bulit within 2 - 3 years.

The main and first point is to develop a concept that promise a real benefit doesn`t matter if metallic fuel, chloride salt or whatever.


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PostPosted: Dec 16, 2014 2:36 pm 
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Light water breeder experiment is a proved case.
Further improvements could include use of heavy water for greater fuel economy.
Building on a successful trial could cut the development time and expense of a thorium breeder.


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PostPosted: Dec 16, 2014 3:08 pm 
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Cyril R wrote:
A more practical concern I have is that chloride reactors are complete paper reactors. No one has ever gone beyond desk studies, not even a serious engineering experiment... nothing. That is not a good start. Its a blank.
I would say that MCFR concepts have one big thing going for them, which is that much work is currently being done on high-temperature chloride salt chemistry, as part of research on pyroprocessing of spent fuel.
That can hardly be called "nothing" or "blank".
It's a good deal more than is being done on fluoride salts.
But fluorine doesn't have to be isotopically separated.


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PostPosted: Dec 21, 2014 3:35 pm 
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jaro wrote:
To me the worst "con" for MCFRs is that you need isotopically pure Cl37. That's almost as bad as pure Li7 in FLiBe.


Should we send URENCO an inquiry for a price indication?
http://www.urenco.com/about-us/company- ... e-isotopes

While I trust your experience, we will never know for sure whether it's a show stopper, if we don't ask. I would volunteer to send the inquiry, but I fear they will not take me seriously.


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PostPosted: Dec 22, 2014 8:32 pm 
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Another concern is that MCFR is a very fast reactor. One would need to look closely at the neutronics to see if there is a fast enough control mechanism should any accident bring the reactor to prompt criticality. You also have the challenges with the vessel first wall more severe than a fast fluoride reactor. So, overall I'd say a fast chloride reactor is more of a challenge than the fast fluoride reactor which is harder than a thermal fluoride reactor.


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PostPosted: Dec 23, 2014 5:46 pm 
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Dear Burghard,

as mentioned ago the only serious reason to for a 37Cl enrichment for a MCFR is the risk of corrosion by sulphur. It is acc. to Merle Lucotte about 10 moles/yr. for a large reactor.

Sulphur tends to place in the grain boundaries and might create grain boundary corrosion. 10 moles/yr. should not be a major thread. The most critical areas are the thin structures of the HX. At the end it is an issue that requires a practical test for a year to find out.

Other questions concerning the sulphur generation are... what happens with the generated sulphur...will it form sulphides with the fission products as SrS..? How stable are These sulphides? Is it possible to get it out by the fuel treatment?

In General it should be far less expensive to make an isotopic Separation by gas centrifuge for 37 Cl, HCl = 36/38 rather than UF6 349/352.

But anyway please do not hesitate to ask them for a Price indication. It would be helpful and provide some Facts to the discussion.


Last edited by HolgerNarrog on Dec 24, 2014 6:22 am, edited 2 times in total.

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PostPosted: Dec 23, 2014 5:54 pm 
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Dear Lars,

all nuclear reactors are controlled by the delayed Neutrons doesn`t matter if it is a fast or a moderated reactor. A main difference is in the isotopic composition of the fuel.

Another aspect is the fluctuation of the criticality. In Germany the Fast Sodium cooled Reactor was evaluted less critical compared to a BWR due to the lower fluctuation of criticality (KfK Marth).


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