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NNadir

(33,368 posts)
Fri Feb 25, 2022, 03:00 AM Feb 2022

An interesting chemical reaction with applications beyond the context in which it's being studied.

Many of the modern breed and burn fast nuclear reactors now under rapid development to address climate change utilize old fashioned sodium coolants. I'm personally not a big fan of sodium coolants, but any kind of nuclear reactor is superior to any dangerous fossil fuel plant.

As I informed my son, people are building sodium cooled reactors so it's best to understand them to be a competent nuclear engineer.

I came across this paper this evening in one of the journals I regularly read: Thermally Stimulated Liquid Na–CaCO3 Reaction: A Physicogeometrical Kinetic Approach toward the Safety Assessment of Na-Cooled Fast Reactors Nobuyoshi Koga and Shin Kikuchi Industrial & Engineering Chemistry Research 2022 61 (7), 2759-2770.

The purpose of this paper is to discuss the reaction kinetics, in particular the Arrhenius constant, for the reduction of concrete by liquid or gaseous sodium metal.

The reaction is described in one of the figures from the paper, this one:



The caption:

Figure 9. Geometrical reaction model for the liquid Na–CaCO3 pellet reaction.


I look at this reaction beyond its safety implications in sodium cooled reactors, to see that this reaction represents a thermal reduction of carbonate, obtained from CO2 (in the case of concrete captured from air), to elemental carbon.

It suggests (although sodium itself will not work as well as its higher congeners) a thermochemical cycle for the production of elemental carbon from CO2 gas.

This terrible war of aggression that disgusts the whole world, the Russian attack on Ukraine, will pass; but climate change will be with us long afterward, particularly because the reliance on dangerous natural gas to back up so called "renewable energy," is now obviated by political danger as well as the physical danger of dumping dangerous fossil fuel waste into the atmosphere.

It is time to free energy in order to free people. In our disgust, we should not be distracted from a greater threat.
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An interesting chemical reaction with applications beyond the context in which it's being studied. (Original Post) NNadir Feb 2022 OP
why are you not a fan of sodium cooled reactors? texasfiddler Feb 2022 #1
In recent years, many of the earlier issues connected with sodium cooled reactors have been solved. NNadir Feb 2022 #2
Thanks for the explanation. texasfiddler Feb 2022 #3
You're welcome. Thermal storage in many cases is superior to batteries for a lot of reasons. NNadir Feb 2022 #4
The lead cooled Russian BREST-300 is under construction. hunter Feb 2022 #5
Russian engineers were pioneers in LBE cooled reactors. NNadir Feb 2022 #6

texasfiddler

(1,986 posts)
1. why are you not a fan of sodium cooled reactors?
Fri Feb 25, 2022, 03:11 AM
Feb 2022

I am just curious. I have been following the progress of the TerraPower Natrium reactor. I am an electrical engineer not a nuclear engineer. I have been trying to educate myself with regards to Generation IV designs. I am ready for nuclear to have a renaissance for the sake of our planet. I am just trying to understand the safety and design issues.

NNadir

(33,368 posts)
2. In recent years, many of the earlier issues connected with sodium cooled reactors have been solved.
Fri Feb 25, 2022, 03:28 AM
Feb 2022

This said, it is still a highly flammable coolant and is, in my view, thus not ideal.

Sodium has significant, albeit not particularly high (less than 1 barn), neutron capture resonances from 1 keV to 0.5 MeV and thus small amounts of Na-24 are formed. This isotope has a half-life of around 15 hours, not long enough to be a long term hazard, but long enough to be a major concern for the short term, in the event of a leak. (These kinds of leaks have happened, for example at the Monju fast reactor in Japan, and, if I recall correctly, the Superphenix in France. They were not catastrophes, but basically, they sucked.)

I think it is now possible to manage sodium coolants, but I think their utilization is based more on tradition than on being a requirement for the utilization of the fast neutron spectrum.

In the last 50 years we have identified many superior coolants. If I were to insist on a liquid metal coolant, I would choose lead, which has a different set of problems, but for many other reasons is superior.

I like liquid metal fuels very much - although no one is currently talking about them right now - but I favor salts as heat transfer tools.

texasfiddler

(1,986 posts)
3. Thanks for the explanation.
Fri Feb 25, 2022, 03:37 AM
Feb 2022

I do like the idea of utilizing salts as heat transfer tools. The TerraPower plant uses the hot molten salt tank as basically big battery to augment the output of the reactor to help support renewables.

NNadir

(33,368 posts)
4. You're welcome. Thermal storage in many cases is superior to batteries for a lot of reasons.
Fri Feb 25, 2022, 09:10 AM
Feb 2022

This said in general I oppose so called "renewable energy." A thermal storage tank to "support" "renewables" represents an unnecessary expense in my view, a redundant system that adds expense and in fact, environmental impact, by adding to the onerous materials requirements that make "renewable energy" unsustainable. .

I am, however, aware that the Terrapower reactor has this feature.

I do read a lot of papers on thermal storage that are nominally about "solar thermal" plants. Solar thermal plants, even after nearly half a century of talking about them, and the construction of awful facilities like Ivanpah, have proved useless. However, if one is applying for a grant, one cannot say "nuclear." At Ivanpah the back up is not thermal storage but rather dangerous natural gas, which is environmentally unacceptable. It is wasteful in the extreme to try to store four or five hours of intense sunlight to run a generator for 24 hours. It simply will not work. For the long term, when dangerous fossil fuels have been completely phased out, it may be useful to utilize the technology for thermal storage developed for solar thermal plants for nuclear plants.

These days, for cultural reasons, everyone has to pretend that they support "renewable energy." However renewable energy will never be as sustainable and as clean as nuclear energy; the largest single reason being land use, followed by materials constraints.

A better way to store energy from nuclear plants would be manufacture chemical fuels like DME and replacement for petroleum based materials by capturing what is now waste heat. This approach might actually make direct air capture - perhaps via sewater - economically viable. It's not clear that this is true, but it may be at some point.

All this can be accomplished using very high temperatures, temperatures at which sodium will not work for heat transfer or storage. This is a materials science question, and one on which I am encouraging my son to look into during his doctoral research. Only nuclear plants can supply this heat reliably, economically and cleanly.

hunter

(38,264 posts)
5. The lead cooled Russian BREST-300 is under construction.
Fri Feb 25, 2022, 02:00 PM
Feb 2022

Completion is likely to be delayed with all these economic sanctions.

https://en.wikipedia.org/wiki/BREST_%28reactor%29

With any luck the next Russian leader will be a boring technocrat, not a Soviet relic trying to rebuild a fallen empire.

NNadir

(33,368 posts)
6. Russian engineers were pioneers in LBE cooled reactors.
Fri Feb 25, 2022, 02:18 PM
Feb 2022

They have exhibited some problems, but surely these are surmmountable.

The Russians have successfully marketed their VVER reactors for which there has been considerable interest.

This disastrous decision to become a pariah state does not bode well for addressing climate change, since we really need all hands on deck.

History will hold Putin in contempt.

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