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PostPosted: Jul 23, 2013 10:08 pm 
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Their design is at 40 MWe now:

New Spec: 40/40/40

and they want to put them in Detroit:

An Offer To The City Of Detroit

They also have a press release to this end:

Tennessee Nuclear Power Plant Manufacturer Offers Economic Boost To Detroit

I seem to remember a 60 MWe fast-breeder reactor installed near Detroit, oh, about fifty years ago. Didn't go too well:

We Almost Lost Detroit

I wonder if they've read that book?


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PostPosted: Jul 24, 2013 1:29 am 
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Anyone, including Americans, can make mistakes or do shoddy work. Fast reactors are part of ongoing reactor development in Russia, China and India.
http://www.forbes.com/sites/kirksorense ... -digester/
Anyone, other than the Chinese, with a stomach for a prototype fast MSR?


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PostPosted: Jul 24, 2013 9:14 pm 
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Lars wrote:
Cyril R wrote:
.

Agreed. But the comment that LFTRs are more similar to fast solid fuel reactors than LWRs due to delayed neutron fraction I think is wrong and that is what I was rebutting. The safety margin to super criticality is very good for LFTRs as the French team as shown. But I'd remind folks that while the threat of super criticality accidents are the press bogey man the real challenge is dealing with decay heat as you pointed out. We have to solve both to be successful.


My intent was not to say that MSR's were not safe. My point was that from a criticality safety perspective the the removal of the delayed neutorns for thermal reactors and fast made them very similar in that performance and we really shouldn't distinguish them like that, unless I am missing something. Both, thermal and fast MSRs can have the needed negative temperature coefficient. Even a transient positive total coefficient can be accomodated for some time because of the large margin to boiling. Again, I am not recommending pursuing that. I like to keep a fully negative temperature coefficient.

Distinguishing them for fuel load requirements is a legit difference, but that is just inital load, so in my mind that is not that big a factor either.


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PostPosted: Jul 31, 2013 3:16 pm 
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Ed P wrote:
Lars wrote:
Cyril R wrote:
.

Agreed. But the comment that LFTRs are more similar to fast solid fuel reactors than LWRs due to delayed neutron fraction I think is wrong and that is what I was rebutting. The safety margin to super criticality is very good for LFTRs as the French team as shown. But I'd remind folks that while the threat of super criticality accidents are the press bogey man the real challenge is dealing with decay heat as you pointed out. We have to solve both to be successful.


My intent was not to say that MSR's were not safe. My point was that from a criticality safety perspective the the removal of the delayed neutorns for thermal reactors and fast made them very similar in that performance and we really shouldn't distinguish them like that, unless I am missing something. Both, thermal and fast MSRs can have the needed negative temperature coefficient. Even a transient positive total coefficient can be accomodated for some time because of the large margin to boiling. Again, I am not recommending pursuing that. I like to keep a fully negative temperature coefficient.

Distinguishing them for fuel load requirements is a legit difference, but that is just inital load, so in my mind that is not that big a factor either.


Another big safety difference is under unforeseen accident conditions where the fuel gets massively spilled. A thermal reactor requires extra special moderators that are not found in nature to go critical. No matter where the fuel flows it won't get to be critical except with the ultra pure graphite moderator and the quasi-spherical configuration. A fast reactor though has a much higher fissile/fertile ratio and could become critical again in the presence of a moderator. I don't know the answer whether a major fuel spill from a fast reactor could become critical again if it gets adjacent to a concrete wall, or water. Since the answer isn't really obvious if a fast reactor has a major fuel spill it will be a major ratings boost for TV news as they ask various scientists what is the worst case scenario. Hence, my inclination is that we have relatively few fast reactors operated by the very best and let the vast majority of reactors be thermal machines.


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PostPosted: Jul 31, 2013 9:50 pm 
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The rhetoric on their blog (which I assume is written by Jack Campbell) is getting a bit shrill:

Nuclear Power Economics

Quote:
We have previously stated our conclusion that no currently pursued SMR project has a prayer of a chance of evolving into a successful commercial venture. And, we named them — by name: GE-Hitachi, B&W, NuScale, Gen 4 Energy, TerraPower, Holtec, and the rest. This is not an insult nor some competitive posturing. It is a dry, analytical research conclusion based on our market and economics study.


For a blog post about economics, I would hasten to point out that a 40 MWe reactor running at 100% capacity factor and selling electricity at $20/MW-hr can generate a maximum of slightly more than $7M annually. That's a bit more than the yearly NRC fee of $5M.


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PostPosted: Aug 01, 2013 10:51 pm 
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Lars wrote:
Another big safety difference is under unforeseen accident conditions where the fuel gets massively spilled. A thermal reactor requires extra special moderators that are not found in nature to go critical. No matter where the fuel flows it won't get to be critical except with the ultra pure graphite moderator and the quasi-spherical configuration. A fast reactor though has a much higher fissile/fertile ratio and could become critical again in the presence of a moderator. I don't know the answer whether a major fuel spill from a fast reactor could become critical again if it gets adjacent to a concrete wall, or water. Since the answer isn't really obvious if a fast reactor has a major fuel spill it will be a major ratings boost for TV news as they ask various scientists what is the worst case scenario. Hence, my inclination is that we have relatively few fast reactors operated by the very best and let the vast majority of reactors be thermal machines.


If you have a fast liquid fueled MSR reactor with just enough fuel to let it stay critical, is a lot less fissile/reactivity than a fast solid fueled reactor. So, rearranging into a critical configuration with a moderator, and if you make no configurations in the structure below the core that could go critical with that lower fuel load, you should be able to make it stay passively safe. Don't forget if you have Th or U238 in the core, then those become stronger poisons in a moderator too.


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PostPosted: Aug 02, 2013 2:50 am 
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It's a genuine concern, the potential for a recriticality event from a fast MSR having a massive fuel dump into the containment, the moisture present in concrete provides moderation as one example of how fuel rich salt could find an accidental moderator. Now I'm thinking earthquake with water ingress, that could be very challenging.

That said I would like to think that all those accident cases can be examined and technical solutions developed using things like boronated concrete, using a fertile blanket as a reflector, so the unit goes subcritical when the blanket is lost and other fixes that can be simple and passive in nature. Please note that I don't have any experience in this area, however it does look like a genuine problem to me, one with options to solve.


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PostPosted: Aug 02, 2013 4:31 pm 
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Lindsay wrote:
It's a genuine concern, the potential for a recriticality event from a fast MSR having a massive fuel dump into the containment, the moisture present in concrete provides moderation as one example of how fuel rich salt could find an accidental moderator. Now I'm thinking earthquake with water ingress, that could be very challenging.

That said I would like to think that all those accident cases can be examined and technical solutions developed using things like boronated concrete, using a fertile blanket as a reflector, so the unit goes subcritical when the blanket is lost and other fixes that can be simple and passive in nature. Please note that I don't have any experience in this area, however it does look like a genuine problem to me, one with options to solve.

I am confident we can solve it technically. For example, have the core in a pool of buffer salt and make the salts mixable and the buffer salt contain reactivity poisons like 238U or 232Th. Then as long as gravity works we should be good.


My concern is that the PR will be a tough battle. With widespread deployment there will be unplanned accidents. If someone asks "what is the worst case" then answer wants to be that physically we can't go critical again - period. Hopefully, this can be obvious enough that even folks who aren't intimately familiar with the reactor (but know a bit about nuclear science) can agree that it can't happen.

The real danger to people from nuclear power is stupid decisions based on fear.

The real danger to nuclear power is losing PR battles. With Fukushima we barely fought back. Nuclear power was proved safer than hydro and oil in that earthquake/tsunami but we so badly lost the PR battle that nuclear was completely stopped in Japan and fossil fuels were expanded dramatically. (Yet remember the news backdrops before the hydrogen explosions were of a oil refinery burning and nuclear power plant in trouble).


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PostPosted: Aug 03, 2013 12:31 am 
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http://www.nucleartownhall.com/wp-conte ... 08-021.pdf.
Another SMR proposal from General Atomics.
Energy multiplier module in the name obviously means input of power to create neutrons to achieve criticality. I wonder if the neutrons of required energy can be created in a truck load of equipment.
The smallest neutron machine would be a U-233 powered reactor like the Indian KAMINI. which, however, is not an 'Energy Multiplier'.
The smallest practical reactor in a short term would be a BWR with a closed circuit of heavy water and thorium-U233 or thorium-Pu fuel. May be a higher enriched, heavy water cooled compact version of Indian AHWR.
http://dae.nic.in/writereaddata/.pdf_37


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PostPosted: Aug 04, 2013 11:36 am 
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Lars wrote:
I am confident we can solve it technically. For example, have the core in a pool of buffer salt and make the salts mixable and the buffer salt contain reactivity poisons like 238U or 232Th. Then as long as gravity works we should be good.

My concern is that the PR will be a tough battle. With widespread deployment there will be unplanned accidents. If someone asks "what is the worst case" then answer wants to be that physically we can't go critical again - period. Hopefully, this can be obvious enough that even folks who aren't intimately familiar with the reactor (but know a bit about nuclear science) can agree that it can't happen.

The real danger to people from nuclear power is stupid decisions based on fear.

The real danger to nuclear power is losing PR battles. With Fukushima we barely fought back. Nuclear power was proved safer than hydro and oil in that earthquake/tsunami but we so badly lost the PR battle that nuclear was completely stopped in Japan and fossil fuels were expanded dramatically. (Yet remember the news backdrops before the hydrogen explosions were of a oil refinery burning and nuclear power plant in trouble).

I agree, I believe that that there are technical solutions that should easily meet that rational/scientific safety assessment, but when we get to the talking heads citing all sorts of nonsense scenarios in the public debate, that's when it gets tough, I mean look at the quality of the public debate around the steam generator leaks at San Onofre, and the early retirement of those units, what an egregious waste of good assets and billions of dollars. (Grrr)


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PostPosted: Sep 09, 2013 8:03 pm 
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American Atomics is "crowd-funding" now:

World's Cheapest Electricity

Quite a claim...


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PostPosted: Sep 11, 2013 1:00 am 
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Kirk Sorensen wrote:
I seem to remember a 60 MWe fast-breeder reactor installed near Detroit, oh, about fifty years ago. Didn't go too well:

We Almost Lost Detroit

I wonder if they've read that book?


That book was total bunk. See the reasons why in the classic book by Petr Beckmann called "The Health Hazards of Not Going Nuclear"? If you haven't read this book yet, I highly recommend it. It is both amusing and informative, although I'm sure most people here already know just about everything in it.


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PostPosted: Sep 16, 2013 7:35 pm 
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I'm aware of the book, but have never read it. I have read some other documents discussing LMFBR development and real-world performance and off the cuff I'd say that 60 - 80% of them have had significant problems. Some of those included partial core melts which is quite unacceptable if that has the potential to create an uncontrolled criticality event. I can only recall two or maybe three successful LMFBR's (I hope that there are more just two or three).


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PostPosted: Sep 17, 2013 1:21 am 
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Petr Beckmann gives several reasons why Detroit was never in any danger, but here's the kicker:

Quote:
And Fermi I in October 1966, as pointed out by Prof. W. Meyer of the University of Missouri, had not been in operation long enough to have sufficient fission products to undergo a meltdown, after it was shut down, under any circumstances.


The book painted a tense, dramatic situation as you might expect in a Hollywood thriller, but in the real world they actually had a birthday party at one point during the big drama.

There was also a paper that I read many years ago called "We Did Not Almost Lose Detroit," but I do not recall who wrote it. You can google it if you are interested.


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PostPosted: Oct 01, 2013 3:07 am 
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"American Atomics" appear to have folded the tent. Attempts to link to their main page or blog now redirect here:

http://www.aboutjack.com/

where their former CEO can help you make a "hit product." I should have grabbed the text from the more audacious posts when I had the chance.

Their Indiegogo effort also has concluded, having raised $101.


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