Neutrons, fusion and efficiency

In summary: Oh yes one part of the wall is called divertor. @John Plant, do you think the divertor might cause a loss of neutron energy? All the neutrons will be caught somewhere. Nearly all of them in regions that will get hot - and can contribute to the electricity production. A reactor design might decide to discard the heat from some colder regions where it would be uneconomical to use the heat.
  • #1
John Plant
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TL;DR Summary
capturing only a percentage of the fusion neutrons in the thermal blanket to generate energy.
Regarding electricity generation from a fusion reactor:
I can't seem to find any discussion about the percentage of fusion product neutrons that can be realistically caught in the thermal blanket to utilise the energy they carry from the fusion reaction.
The neutrons from fusion have to be slowed to change their kinetic energy into heat so electrical power can be generated at a steam turbine. Thermal blanket may be the wrong term but I think it's obvious what my enquiry concerns.
So how comprehensive is the coverage of said ' thermal blanket' and what percentage of fusion energy is expected to be lost by neutrons that escape through the areas not covered by this thermal blanket ?
I can't imagine it is anywhere even close to 100% of the fusion product neutrons being caught in the "thermal blanket" to extract the KE they carry.
Nevermind catching the energy from neutrons that have been used to produce more tritium.
 
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  • #2
As neutrons move straight, they will not get out through a tunnel that is not straight.

Is there any need to have a straight hole going through the blanket?
(To answer my question: No there isn't. So, if 100% blanket coverage is needed, then it can be quite easily achieved. Oh, yes 100% coverage is needed to protect the superconductors, so there will be 100% coverage then.)
 
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  • #3
jartsa said:
As neutrons move straight, they will not get out through a tunnel that is not straight.

Is there any need to have a straight hole going through the blanket?
There is lots of room between nuclei, so a "hole" is not relevant. Number of neutrons escaping without interaction decreases exponentially with thickness. However more neutrons can get through (at lower eneergy) after scattering.
 
  • #4
mathman said:
There is lots of room between nuclei, so a "hole" is not relevant. Number of neutrons escaping without interaction decreases exponentially with thickness. However more neutrons can get through (at lower eneergy) after scattering.
By hole I mean an area not covered by the blanket. Like a hole through which a supporting concrete pillar goes through, or hole for electric wiring, or holes for cooling pipes, or a path trough which an engineer can walk into the reactor.

Actually blanket is the same as the inner wall. I just looked it up. I thought it was some thick blanket behind the inner wall, sorry. :smile: So how could part of the inner wall be missing?

Oh yes one part of the wall is called divertor. @John Plant, do you think the divertor might cause a loss of neutron energy?
 
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  • #5
All the neutrons will be caught somewhere. Nearly all of them in regions that will get hot - and can contribute to the electricity production. A reactor design might decide to discard the heat from some colder regions where it would be uneconomical to use the heat.
 

1. What are neutrons?

Neutrons are subatomic particles that have no charge and are found in the nucleus of an atom. They have a mass similar to that of protons, but they do not have a positive or negative charge.

2. What is fusion?

Fusion is a nuclear reaction in which two or more atomic nuclei combine to form a heavier nucleus. This process releases a large amount of energy and is the same process that powers the sun and other stars.

3. How does fusion produce energy?

In fusion, the nuclei of two atoms are forced together at high speeds, overcoming their natural repulsion. This causes the nuclei to fuse together, releasing a large amount of energy in the form of heat and light.

4. What is efficiency in the context of fusion?

Efficiency in fusion refers to the amount of energy produced compared to the amount of energy required to initiate and sustain the reaction. Scientists are constantly working to increase the efficiency of fusion reactions in order to make it a viable energy source.

5. What are the potential benefits of using fusion as an energy source?

Fusion has the potential to provide a nearly limitless source of clean and sustainable energy. It produces no greenhouse gases or radioactive waste, making it a much more environmentally friendly option than traditional energy sources. It also requires very little fuel and has the potential to be more efficient than current energy sources.

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