Understanding Neutron Diffusion in Nuclear Reactions

In summary, neutron diffusion refers to the movement of neutrons through a medium, where they can either react with nuclei or scatter. In cases where there is no nuclear reaction, the neutrons will travel in a straight line and diffusion will not be a good approximation. Neutron diffusion is explained by the law that governs neutron flux, which can be simplified as a high number of moving balls spreading around a space with less balls. This is a simplification, as it does not take into account absorption, material properties, and generation of new neutrons. The textbook also mentions that even without nuclear reactions, there can still be neutron diffusion due to scattering. However, scattering does not count as a nuclear reaction. The source for this information is
  • #1
Physicsissuef
908
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Is neutron diffusion, traveling neutrons from the nucleus, to direction outside of the nucleus? In my textbook says that there is neutron diffusion, where there is not nuclear reaction. In that case are neutron bouncing off the nucleus?
 
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  • #2
Neutrons moving through a medium can either react with it or scatter. In all cases the interactions are with nuclei. The electrons are too small to have any effect.

When neutrons are going through thick media, i.e. lots of scattering, the transport can be modeled as diffusion.
 
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  • #3
In this case, it says that it doesn't react with the nucleus, but there is neutron diffusion. What that means?
 
  • #4
heeelp please! urgent! :D
 
  • #5
In this case, it says that it doesn't react with the nucleus, but there is neutron diffusion. What that means?
I presume the text means that nothing happens except elastic scattering with the nuclei. There is no nuclear reaction, such as absorption or inelelastic scattering.

When there is no reaction at all, the neutron travels in a straight line, so diffusion will not be a good approximation.
 
  • #6
Netronic diffusion explain how neutron will move inside a material, neutrons will move due to a difference of density of neutron from higher density neutron zone to a lower neutron density zone, due to that in a high density neutron zone there will be more scattering collision than in a lower density zone , so there will be a neutron current.
This under certian condition like , isotropic scattering, no neutron source inside the material and costant flux.
Well at least this is what I remember...may be there is something wrong.
 
  • #7
So there will be just, elastic collision? But can anybody explain what is neutron diffusion with simpler words??
 
  • #8
Well it's the "law" that explain the neutron flux.
It's like ..humm...a space with a high number of moving balls, those will spread around the space to zone where there are less balls, you can see that the moving balls will spread around in zone where there are less balls, this because you will have less collision betwen balls ( elastic scattering) in that zone.
This is a semplification of diffusion, because in this case it dosen't keeps in count absorbion, material proprietiesù and generation of new neutron inside the material and
 
  • #9
Physicsissuef said:
heeelp please! urgent! :D

is this a course work question??
 
  • #10
PhilippH said:
Well it's the "law" that explain the neutron flux.
It's like ..humm...a space with a high number of moving balls, those will spread around the space to zone where there are less balls, you can see that the moving balls will spread around in zone where there are less balls, this because you will have less collision betwen balls ( elastic scattering) in that zone.
This is a semplification of diffusion, because in this case it dosen't keeps in count absorbion, material proprietiesù and generation of new neutron inside the material and

But why in my textbook says that there isn't any nuclear reaction, but there is nuclear diffusion?

malawi_glenn said:
is this a course work question??

No it is not. I was just bumping the thread...
 
  • #11
Because diffusion is composed by a sum of different terms, and if your temrs ( assorbtion and generation) that describe the nuclear reaction are 0, there still a term that describe the neutron collision and this term involves the "Flick law" so there still neutron diffusion also without nuclear reacion.
 
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  • #12
scattering does not count as a nuclear reaction (at least not in general).

Can u please cite the book?
 
  • #13
malawi_glenn said:
scattering does not count as a nuclear reaction (at least not in general).

Can u please cite the book?

No, it dosen't count as nuclear reaction.
My english is not very good so may be wasn't much clear.
I ment that if asobtion and generation ( S) are nill, there still diffusion due to scattering.

The text is: "B. Montagnini - Lezioni di Fisica del Reattore Nucleare - Università di Pisa, 1983"
 
  • #14
How is that nuclear diffusion is not nuclear reaction, but it changes the number of nucleons in the nucleus?
 
  • #15
The neutrons that are taken in consideration aren't the neutron of nucleus, but "free" neutrons coming from some source.
 
  • #16
But does the nuclear reaction is made just using one neutron?
 

What is neutron diffusion?

Neutron diffusion is the movement of neutrons through a material or substance. Neutrons are uncharged particles that are found in the nucleus of an atom. In neutron diffusion, these particles move from areas of high concentration to areas of low concentration, creating a flux or flow of neutrons.

How is neutron diffusion different from other types of diffusion?

Neutron diffusion is different from other types of diffusion because it involves the movement of neutrons, rather than other particles such as molecules or atoms. Additionally, neutron diffusion occurs in nuclear systems and is primarily driven by nuclear reactions rather than thermal energy.

What are the applications of neutron diffusion?

Neutron diffusion has many applications in nuclear engineering and physics. It is used in nuclear reactors to control the rate of nuclear reactions and to produce energy. It is also used in nuclear weapons, as well as in the study of nuclear fission and fusion processes.

What factors affect neutron diffusion?

Several factors can affect neutron diffusion, including the density and composition of the material through which the neutrons are diffusing, the energy and speed of the neutrons, and the presence of other particles, such as absorbers, that may interact with the neutrons.

How is neutron diffusion studied and modeled?

Neutron diffusion is studied and modeled using mathematical equations and computer simulations. These models take into account the various factors that affect neutron diffusion and can help predict the behavior of neutrons in different materials and scenarios.

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