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PostPosted: Jul 21, 2014 8:57 am 
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jagdish wrote:
Fast MSR is the best way I can think of to reduce costs and recycle the used LWR fuel. However 99.995% 7Li may create some problems of procurement. An alternate salt like NaF or NaF-ZrF4 eutectic would be a better choice and material balances should be worked out.


I don't have the wherewithal to determine whether it'd be possible to simultaneously achieve isobreeding and an extremely low reprocessing requirement with a different solvent salt but my instincts say it's pretty unlikely.

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PostPosted: Jul 22, 2014 8:56 pm 
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Here's the as-sent revised MS. In addition to incorporating your latest suggestions, I've decided that I could make a good case for building the equivalent of "10,000 to 30,000" full-sized (not modular), one GWe, reactors ASAP...and did.

In my opinion, it should be possible to build/break a full sized MSFR (9 cubic meter active volume) in(to) pieces small enough to be "trucked".

This paper gores almost everyone's ox but the World's current situation requires that effort/attention become focused on long term solutions to real problems.


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BEST MSBR final ESR revised.doc [814.5 KiB]
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PostPosted: Jul 25, 2014 12:50 am 
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Combine it with Japanese ideas on Fluorex processing and you have the ideal way to recycle used LWR fuel! uranium and plutonium hexafluorides are volatile and can be extracted from used LWR fuel. Dissociated to tetrafluorides, they can be used for such an MSR. DOE could have made use of it.


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PostPosted: Jul 25, 2014 7:38 am 
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darryl siemer wrote:
This paper gores almost everyone's ox but the World's current situation requires that effort/attention become focused on long term solutions to real problems.


I know it is not the preferred solution here, but what is the key problem with the liquid-metal (sodium) fast breeder, e.g. the BN800 (soon BN1200). Is it that it simply takes too long to startup? Is that actually the case? Any other important issues?


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PostPosted: Jul 25, 2014 10:31 am 
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SteveK9 wrote:
darryl siemer wrote:
This paper gores almost everyone's ox but the World's current situation requires that effort/attention become focused on long term solutions to real problems.


I know it is not the preferred solution here, but what is the key problem with the liquid-metal (sodium) fast breeder, e.g. the BN800 (soon BN1200). Is it that it simply takes too long to startup? Is that actually the case? Any other important issues?


The fundamental problem with the IFR concept is that it's highly unlikely that it could produce cheap electricity. The reasons include 1) an extremely complex/expensive fueling system (e.g., France's 250 MWe Phenix LMFBR had a total of about 300,000 individual fuel/blanket/reflector rods within it all of which would eventually require some sort of "reprocessing") 2) "pyrochemical" reprocessing of those rods is intrinsically arty and therefore intrinsically expensive, 3) the refabrication of fuel/blanket rods from the so-recovered U/TRU is also intrinsically arty and therefore also expensive, and 4) almost all of the sodium cooled reactors ever built (quite a few) have experienced sodium leaks most which such incidents resulting in fires/explosions. The best-ever performing such reactor - Russia's BN 350 - experienced many such "events" most of which would have totally shut down any reactor operated under the auspices of the NRC (Russia doesn't let little things like fires shut down its reactors). It was finally shut down because the country which had "inherited" it when the USSR broke up , Kazakhstan, couldn't afford to pay for its fuel.

To learn more about the foibles of today's reactors including LMFBRs, read James Mahaffey's (retired PhD NE) latest book, "Atomic Accidents" (Amazon hard cover $22, kindle $15). Its last chapter ("Falling into the Rickover Trap") concludes that the MSR concept deserves a great deal more attention.

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PostPosted: Jul 28, 2014 8:50 am 
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darryl siemer wrote:
I've decided that I could make a good case for building the equivalent of "10,000 to 30,000" full-sized (not modular), one GWe, reactors ASAP...and did.
I suspect 30,000 will be a bit low. I arrived at 70,000 myself. Of course, a bit of it was for water.

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PostPosted: Jul 28, 2014 1:47 pm 
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darryl siemer wrote:
SteveK9 wrote:
darryl siemer wrote:
This paper gores almost everyone's ox but the World's current situation requires that effort/attention become focused on long term solutions to real problems.


I know it is not the preferred solution here, but what is the key problem with the liquid-metal (sodium) fast breeder, e.g. the BN800 (soon BN1200). Is it that it simply takes too long to startup? Is that actually the case? Any other important issues?


The fundamental problem with the IFR concept is that it's highly unlikely that it could produce cheap electricity. The reasons include 1) an extremely complex/expensive fueling system (e.g., France's 250 MWe Phenix LMFBR had a total of about 300,000 individual fuel/blanket/reflector rods within it all of which would eventually require some sort of "reprocessing") 2) "pyrochemical" reprocessing of those rods is intrinsically arty and therefore intrinsically expensive, 3) the refabrication of fuel/blanket rods from the so-recovered U/TRU is also intrinsically arty and therefore also expensive, and 4) almost all of the sodium cooled reactors ever built (quite a few) have experienced sodium leaks most which such incidents resulting in fires/explosions. The best-ever performing such reactor - Russia's BN 350 - experienced many such "events" most of which would have totally shut down any reactor operated under the auspices of the NRC (Russia doesn't let little things like fires shut down its reactors). It was finally shut down because the country which had "inherited" it when the USSR broke up , Kazakhstan, couldn't afford to pay for its fuel.

To learn more about the foibles of today's reactors including LMFBRs, read James Mahaffey's (retired PhD NE) latest book, "Atomic Accidents" (Amazon hard cover $22, kindle $15). Its last chapter ("Falling into the Rickover Trap") concludes that the MSR concept deserves a great deal more attention.


Thanks for the response. I don't think I've read much detail on the fueling process. I understood that reprocessing will have costs, but from what you have written here it seems you believe they would be much greater than mining uranium and enriching it for fuel to use in a PWR or BWR.

On the fear of accident side, I'm not so sure I'm convinced. It is often reported that the BN600 had the best capacity utilization of any Russian reactors (not true?). I think they had a couple of fires with it as well. But, actually I'm quite happy that Russia doesn't let things like a sodium fire stop everything. That's the way we used to work, and I think it's pretty hard to do something new without problems. You may be right, but I'm glad they stuck with it. And, they claim they've learned a few things (I think that is likely to be true), and that the problems with sodium were exaggerated. And, of course this is not just a 'Russian' thing, there are supporters here (Till etc.), and GE did finish the design of the Prism reactor.

In a recent story the Russians said they hope to have 10 of the BN1200's running by 2030. I guess time will tell.


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PostPosted: Jul 28, 2014 1:56 pm 
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SteveK9 wrote:
darryl siemer wrote:
This paper gores almost everyone's ox ....


Thanks for the response. I don't think I've read much detail on the fueling process. I understood that reprocessing will have costs, but from what you have written here it seems you believe they would be much greater than mining uranium and enriching it for fuel.

On the fear of accident side, I'm not so sure I'm convinced. It is often reported that the BN600 had the best capacity utilization of any Russian reactors (not true?). Also, I'm quite happy that Russia doesn't let things like a sodium fire stop everything. That's the way we used to work, and I think it's pretty hard to do something new without problems. You may be right, but I'm glad they stuck with it.

I'm not sure why they don't agree with your assessment. In a recent story the Russians said they hope to have 10 of the BN1200 running by 2030. I guess time will tell.
[/quote]

Maybe the Russkies will do as they say. If so, good luck to them.

Are you going to read Mahaffey's book?

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PostPosted: Jul 28, 2014 2:09 pm 
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Even if the fuel cycle costs of sodium cooled reactors are two or three times that of conventional reactors, the capital costs will still be the deciding factor.

So if you can turn out SFRs cheap, then they will be cheaper.


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PostPosted: Jul 28, 2014 7:31 pm 
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The Russians are running a fast reactor for a long time and finding it as feasible as their other designs. No wonder they have started up another and are building/planning for more. They will finalize IFR before anyone else.
India might well be the next.
Fast MSR will have better synergy with pyro-processing.


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PostPosted: Feb 07, 2015 7:20 pm 
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Here's the really final version of my "Energy Science & Engineering" opinion piece. It's going to be coming out soon & will be "open access" (free). The last/final round of corrections can be viewed by clicking Adobe's "correction" feature.

For some reason ESE insists upon putting footnotes at the end which (to me anyway) complicates reading. One of those footnotes (& the last correction) points out that DOE had to fork out $88,000/kg ($234 million altogether) to have ANL/INL's pyroprocessing experts reprocess the last of EBR II's driver fuel (to date, EBR II represents the one & only "IFR"). Since that work is being done with a "4th generation" system, it's not "first of a kind" & the reprocessing costs are representative of those that a utility's CEO would have to ponder before committing to that nuclear fuel cycle.


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PostPosted: Feb 07, 2015 8:33 pm 
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I've done some more doodling about how to actually implement a practical MSFR. The key point is that it must be both "maintainable" (we can't assume that the walls of the barrier (tank or tanks) surrounding its core will last for more than a few years) and "sustainable" (able to "isobreed" with so little reprocessing that the simplistic scheme proposed in my ESE article -see my last post - is viable).

One way to improve EVOL's reference system would be surround the whole core (not just its sides) with blanket salt. This would simultaneously enhance CR & eliminate axial reflector wear & tear. (Improving CR would reduce the amount of "new" uranium & U enrichment needed to get a fleet of them started up)

The ATTACHMENT describes one way to accomplish this which retains the ref MSFR's right circular cylindrical core configuration. The core is surrounded by/defined by the innermost surfaces of three "supermetal" blanket salt tanks - a disk-like top, a right circular ring-shaped center tank, & a disc like bottom tank. Since it would probably would be better to situate the heat exchangers above the core (enhances thermosyphoning) I've assumed that the 10 cm wide slots through which fuel salt would enter/leave the core should be tilted upwards.

It should be possible to pull/lift all three of them straight up & and out with an overhead crane - the heaviest tank would weigh under 6 tonnes.

I haven't depicted the bottom tank's core dump valve or worked out how o go about connecting the blanket salt tanks to their HX's.

This system would require about 25 cubic meters of blanket salt vs the 7.3 m3 assumed for EVOL's.

I welcome constructive comments & advice.


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top, bottom and side blanketed MSFR.xls [21 KiB]
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PostPosted: Feb 08, 2015 1:12 am 
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Thanks for sharing your work Darryl.

A few observations.....

Quote:
ORNL’s molten salt research program [7], shifted emphasis to the graphite moderated13 /two-salt system depicted in Figures 2, 3.
In principle, a full-sized (~1 GWe) reactor featuring that concept’s complex interlaced graphite pipe core configuration could achieve a CR > 1 utilizing a relatively easy-to-reprocess (meaning thorium-free) fuel salt. Unfortunately, like many “paper reactors”,14 it would have been virtually impossible to either build or operate due to graphite’s physical characteristics (e.g., highly anisotropic, unweldable, modest strength, poor ductility, etc.) and its propensity to first shrink and then swell upon fast neutron irradiation.

Figures 2 & 3 don’t cover all the design options investigated by ORNL for the two-fluid MSBR.
Apparently Flibe’s concept is more like the attached images……

Quote:
Another drawback is the fact that the ~300 tons of radiologically contaminated, neutron-damaged graphite within its core would have to be replaced every 3–4 years, which, in the absence of a suitable repository, raises significant waste issues.

That would seem to be even worse for the two-fluid graphite moderated design – simply because the complexity of the fuel channel arrangement will likely lead to scrap graphite even sooner than “every 3–4 years.”

Quote:
because it soon became apparent that both CR and reactor durability21 would be improved by surrounding its entire core region with blanket salt rather than just along its sides, recent EVOL papers [14] often describe optimized MSFRs that look much like ORNL’s original sphere-within-sphere concept – compare Figures 7 and 1.22

Interesting that the “tube-in-tube” concept never re-appeared.
Care to guess why ?
Can similar issues affect a high-power-density spherical core ? (if not, why not?)


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PostPosted: Feb 08, 2015 3:24 am 
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Dear Darryl,

the MSFR is as mentioned in my critic more a scientific concept. The radial blankets were made as fertile blanket the axial blankets metal Neutron reflectors.

From an engineering point of view it would be ideal to put a tank in a tank. The inner tank for the fuel and the outer tank for the blanket. The neutrons from the fuel are used to breed new fuel in the blanket. The breed Ratio might be >1. The surplus could be sold. Even in the far future there will be plenty of reactors with a breeding <1.

A main issue in terms of maintenance is the plating out of noble metal fission products. The reactor and all components of the primary circuit of a MSR/MSFR/MCFR are very radioactive. It requires remote controlled devices to handle them. In order to handle a blanket element (your design) you need to disconnect it from in/out pipes and sensors first then you can pull it out by a crane. If you have a complete 2 Zone reactor it is 40 tons without neutron reflector. It is better if it can run for some > 30years replacing the pumps only.

Best regards

Holger


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PostPosted: Feb 08, 2015 2:22 pm 
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KitemanSA wrote:
darryl siemer wrote:
I've decided that I could make a good case for building the equivalent of "10,000 to 30,000" full-sized (not modular), one GWe, reactors ASAP...and did.
I suspect 30,000 will be a bit low. I arrived at 70,000 myself. Of course, a bit of it was for water.


Sorry to go back a bit, but ....

Isn't world wide primary power production about 16TW. About 8TW of that is used to make 2-3TW of electricity. The other 8TW of heating and locomotive power could be replaced by 2-3TW of electricity so a total of 5TWe, less current Hydro, wind and solar which will be cheaper.

How about if the world gets richer? The UK uses an average of about 45GWe - and this is not increasing as the economy grows. Double that for heating and electric cars. 90GWe, for a little under 1% of the world's population, gives about 12TWe (less hydro) to give everyone western levels of comfort.

Of course, if you cut prices significantly, then demand might rise further. But hard to see a need for 30TWe - without high velocity space applicatoins.


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