By the way ... what is Nuclear exactly?

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Re: By the way ... what is Nuclear exactly?




by sicetaitsimple » 16/11/17, 22:58

Ahmed wrote:To summarize, efficiency is not the answer, since it is the problem!


Good, I pick up, I lack oxygen! Best regards.
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Re: By the way ... what is Nuclear exactly?




by Bardal » 16/11/17, 23:12

The question is not so simple, grelinette, but let's try a little exercise:

- nuclear energy is the implementation of internal forces at the nucleus of atoms, breaking heavy nuclei (it is fission) or by bringing together light nuclei (it is fusion); the material deficit in these two operations leads to a huge energy production, according to the law of restricted relativity E = MC2. It differs from chemical energy (where only electrons are concerned), such as burning oil, coal or wood. The ratio of atomic energy supplied by an atom to chemical energy is of the order of 1 000 000: 1gr of fissioned uranium produces as much as one ton of burnt coal. It is also different from thermal energy (it is the agitation of molecules), electricity (it is the displacement of electrons), potential energy - or inertial, as you want - is the force of attraction of the body)

- nuclear energy is a natural phenomenon, at the source of all other known energies: sun, stars, geothermal energy, biomass, ... It is everywhere (including in our organism) from space to the depths of the ground. Remained to domesticate it, which is not so simple ...

- natural radioactivity is responsible for the heat of the earth (so-called geothermal energy); it is due to the radioactive elements that it contains, in particular uranium 235, which slowly transforms into uranium 238, and thorium, which is also transformed, even more slowly. This process is irreversible, and whether the man intervenes or not, their disappearance is scheduled, for very late reassure us. These are fatal energies, and not fossils.

- As a matter of principle, this nuclear energy does not produce CO2, methane or greenhouse gases. On the other hand, it produces waste, mostly in solid form, for certain radioactive products, fission products or parasitic reactions.
Of course, in order to build the plant, extract the ore, transport it, CO2 was produced because of the necessary gray energy, as is the case for all other forms of energy, whatever they are (including including photovoltaics, whose production is very energy intensive).

- geothermal energy, which is nothing other than nuclear energy degraded into heat, has been known since the dawn of time; but its exploitation is reasonably possible only in a few regions of the world (mainly volcanic regions), its access proving inaccessible, or very expensive, most of the time. Let us quote, among these "geothermal" regions, Iceland, where it constitutes the first source of energy, Italy, where its production is significant, Guadeloupe (where a geothermal power station is installed, and of course Chaudes Aigues, where it has been exploited since prehistoric times Elsewhere, in France at least, only medium-temperature geothermal energy seems accessible, in the form of deep hot water tables; various installations are operational (Maison de la Radio in Paris, various sites the Paris basin, Alsace, Aquitaine, etc.); the results obtained do not always meet expectations (significant investments, rapid depletion of the water table, etc.) but the resource exists and should provide its ecot to renewable energies.

- piercing the earth's crust to reach the magma is not today within the reach of our technologies ... But in the future ... one thing is certain today: apart from the regions privileged on this point, the geothermal energy is one of the most expensive energies of all, much more than nuclear power, and even more than photovoltaics. This may not be the case later, but we are still far from it. Let us not believe either that this energy is very "clean": the seismic manifestations are one of the first causes of CO2 emissions, and SO2, which is hardly better.

Bouf, it's a bit long ... but ...

ps I don't know for whom nuclear energy would be "fabulous", but when it comes to physics or technology, fables hardly have their place; we can always wish that reality was other than what it is, but it remains stubborn, very stubborn ...
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Re: By the way ... what is Nuclear exactly?




by sen-no-sen » 16/11/17, 23:49

Well summarized, however, we must distinguish the fusion (thermonuclear) fission (nuclear), which are the only two sources of energy available in the Universe (I overlooked the possibility very distant vacuum exploitation quantum effect Casimir or black energy that does not consensus).
However, as already stated, nuclear fission will not change much the composition of the global energy mix and will only be a source reserved for the industrialized countries *.
In this sense are role to limit GHG emissions is too limited to consider it as a global solution.
The most likely scenario is that of sustaining nuclear energy * in the industrialized countries without exceeding more than 15% of the global energy mix, fossil fuels (gas and oil) will remain dominant, although in depletion, the everything will be supported by a very large jump in renewable energies the time needed to develop fusion plants.


* Including the generation 4.
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Re: By the way ... what is Nuclear exactly?




by Christophe » 16/11/17, 23:51

I like your bardal answer ...

Grelinette wrote:the magma is formed between 70 and 200 km deep, finally it's not so far, it's a distance that I can do by bike


The comparison is funny ... by bike you go rather horizontally ... and in the air ...

Move vertically and ..
in the rock asks let's say a considerably higher energy for every km traveled :)

The deepest drilling did not exceed 12km I think ... Potential deep geothermal sites are quite rare ...
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Re: By the way ... what is Nuclear exactly?




by Ahmed » 17/11/17, 11:26

Outside favorable sites, the thermal gradient is about 3 ° for 100 M => 30 ° per Km ... There would therefore be no need to dig too deep, even taking into account the losses of the return part (it should ask Dedeleco!), but it is true, at the price where is the oil!
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Re: By the way ... what is Nuclear exactly?




by Christophe » 17/11/17, 12:20

Yes but with 30 delta we do not have electricity ... and how much does it cost to drill 1000 m?

When we see that that of a geothermal heat pump of a few tens of m is already charged in the 15-20 000 ...

Otherwise the atmospheric thermal delta is -6 degrees for 1000m ... bin which we do many 1000m tricks now :)
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Re: By the way ... what is Nuclear exactly?




by Ahmed » 17/11/17, 12:27

This is true! Nature does everything to annoy us ... it's discouraging! : Lol:
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Re: By the way ... what is Nuclear exactly?




by Grelinette » 17/11/17, 12:35

Hello and thank you for all these details that have taught me more about nuclear.
(by the way, very interesting the long commentary of Bardal ! thank you for these very clear explanations.)

That being said, what I wanted to highlight through my naive question is the paradox that I perceive between:

- this energy, the nuclear power, whose capacities are phenomenal, and its equally extreme characteristics, in terms of temperatures produced, complexity of the process, the dangers involved, the waste produced, and the costs involved,

and:

- the "minimal benefits" that one derives from it, namely to heat water only a few hundred degrees, if I may say so!

By the way, do you know what temperature from a nuclear reaction is actually used to heat the water that will drive the turbines at the end of the process to produce electricity?

There are some values ​​on the internet, of the order of 300 to 400 degrees in the primary circuit, ie the circuit whose water will directly recover the heat produced by the nuclear reaction, (See the EDF website) ... while the nuclear reaction is capable of producing some 15 000 000 of degrees Celsius. (We "play" with fifteen million degrees to use 300! : Shock: ).

To give a trivial image, it's a bit like I used a 50 tons truck to transport a pea, and again, I have to be far from the proportions of temperatures in the nuclear process.
Well, of course, I hear the objectors remind me that "Who can do the most, can the least", but still, 400 ° it's almost the temperature of my stove when I cook the tartiflette in the oven! ... and Fortunately, every time someone misses the cooking of his tartiflette in the oven, we are still far from creating a global disaster!

It is understandable then why one must be so careful in the implementation of this energy, and why a simple grain of sand in the process (or human negligence) can create a runaway in proportions that we are difficult to control!

And if I'm not mistaken, that's what happened for Chernobyl, and it's also what we feared for Fukushima, the famous "Chinese syndrome".

To end on the analogy with the heat of the volcanoes ... certainly it is an anecdotal example, but finally and all accounts, to simply heat water to 300 ° it would surely cost less to install big turbines in the magma of a volcano than to build a nuclear power plant! And probably also cheaper to transport the electricity produced from the heat of volcanoes even if it comes from some volcanic regions located at the other end of the world!
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Re: By the way ... what is Nuclear exactly?




by Christophe » 17/11/17, 12:42

Capable yes but 15 millions is for fusion ... not fusion ...

I believe that the heart of the sun does not exceed 2 million (memory) ... and that of a fission reactor overheating a few thousand ...
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Re: By the way ... what is Nuclear exactly?




by Did67 » 17/11/17, 12:54

And once again, do not confuse energy and temperature!

A body can be raised at a very high temperature with relatively high energy (if it is isolated). And conversely, our homes dissipate considerable energy without being heated to very high temperatures. One is a stream, the other a stock.

So in a reactor, we control the reaction, with a "diluted fuel", so that the flow of energy is manageable ... In a bomb, we concentrate the fuel. And we fart! But the same amount of "fuel" (eg uranium) will eventually release the same amount of energy! In a fraction of a second (in a bomb). Or in a few years (in a reactor) ...
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