Why does 135Xe have a high thermal neutron cross section?

In summary, 135Xe is considered a fission product because it is produced as a byproduct of nuclear fission reactions. It has a high thermal neutron cross section due to its large nuclear size and high number of neutrons, which can cause "Xenon poisoning" in nuclear reactors. While it can be used in certain types of breeder reactors, it is not as efficient as other isotopes for nuclear energy production.
  • #1
pierce15
315
2
Title says it all. Made a few google searches and couldn't find any information. Is there a reason why it is so large, or is it just a coincidence of nature?
 
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  • #2
It would seem to be a coincidence of Nature. Isotopes Xe-134 and Xe-136 have very low absorption cross-sections, and are stable.

One has to look at certain rare Earth isotopes of Sm-149, -151 and Gd-155, -157 to find comparable absorption cross-sections.
 
  • #3
And a common underlying cause for such coincidences seem to be the presence of suitable excited states (real or virtual).
 

1. Why is 135Xe considered a fission product?

135Xe is considered a fission product because it is produced as a byproduct of nuclear fission reactions. When uranium or plutonium atoms undergo fission, they split into smaller fragments, including xenon isotopes such as 135Xe.

2. What is a thermal neutron cross section?

A thermal neutron cross section is a measure of the probability that a neutron will be absorbed by a nucleus when it is moving at the same speed as the surrounding atoms, also known as thermal energy. It is a characteristic property of each isotope and is dependent on its nuclear structure.

3. What makes 135Xe's thermal neutron cross section high?

135Xe has a high thermal neutron cross section because of its large nuclear size and high number of neutrons. This makes it more likely to interact and absorb thermal neutrons, compared to smaller and lighter isotopes.

4. How does 135Xe's high thermal neutron cross section affect nuclear reactors?

The high thermal neutron cross section of 135Xe can cause a phenomenon known as "Xenon poisoning" in nuclear reactors. When 135Xe absorbs too many neutrons, it can reduce the number of neutrons available for fission reactions, leading to a decrease in reactor power. This can affect the stability and efficiency of the reactor.

5. Can 135Xe be used for nuclear energy production?

While 135Xe is not commonly used for nuclear energy production, it can be used in certain types of breeder reactors that are designed to produce more nuclear fuel than they consume. In these reactors, 135Xe is converted into fissile 136Xe, which can then undergo fission and release energy. However, this process is not as efficient as using other isotopes such as uranium or plutonium.

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