Difference between revisions of "Moderator"
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: [[Moderator]]s [[Absorb (Physics)|absorb]] some of the [[energy]] of fast moving [[neutron]]s which slows them down to a [[speed]] where they are called [[Thermal Neutron|thermal neutron]]s which are able to be captured by [[Nuclear Fission|fissionable]] [[isotope]]s. | : [[Moderator]]s [[Absorb (Physics)|absorb]] some of the [[energy]] of fast moving [[neutron]]s which slows them down to a [[speed]] where they are called [[Thermal Neutron|thermal neutron]]s which are able to be captured by [[Nuclear Fission|fissionable]] [[isotope]]s. | ||
: Without a [[moderator]] in a [[Nuclear Reactor|nuclear reactor]] the [[neutron]]s released from each [[Nuclear Fission|fission]] event would be moving too fast to cause a second [[Nuclear Fission|fission]] event so a [[Nuclear Chain Reaction|chain reaction]] would not be possible. | : Without a [[moderator]] in a [[Nuclear Reactor|nuclear reactor]] the [[neutron]]s released from each [[Nuclear Fission|fission]] event would be moving too fast to cause a second [[Nuclear Fission|fission]] event so a [[Nuclear Chain Reaction|chain reaction]] would not be possible. | ||
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| + | |[[File:Moderator.png|center|400px]] | ||
| + | | style="height:20px; width:200px; text-align:left;" |As a fast moving [[neutron]] passes through a [[moderator]] it collides with [[atom]]s in the [[moderator]] passing on some of their [[energy]] and slowing down. After several collisions a [[neutron]] becomes slow enough to be captured by a [[Nuclear Fission|fissionable]] [[isotope]]. At this point it is called a [[Thermal Neutron|thermal neutron]]. | ||
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| + | ===References=== | ||
| + | ====AQA==== | ||
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| + | :[https://www.amazon.co.uk/gp/product/0008158770/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=0008158770&linkCode=as2&tag=nrjc-21&linkId=ec31595e720e1529e49876c3866fff6e ''Moderator, page 129, GCSE Physics; Student Book, Collins, AQA ''] | ||
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| + | ====Edexcel==== | ||
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| + | :[https://www.amazon.co.uk/gp/product/1782948163/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1782948163&linkCode=as2&tag=nrjc-21&linkId=0fdbfd5dd397d6e24a9dfb250f08587f ''Moderators, page 174, GCSE Physics, CGP, Edexcel ''] | ||
Latest revision as of 18:41, 22 November 2019
Key Stage 4
Meaning
A moderator is a substance used in nuclear fission reactors to slow fast moving neutrons to become thermal neutrons.
About Moderators
- Moderators absorb some of the energy of fast moving neutrons which slows them down to a speed where they are called thermal neutrons which are able to be captured by fissionable isotopes.
- Without a moderator in a nuclear reactor the neutrons released from each fission event would be moving too fast to cause a second fission event so a chain reaction would not be possible.
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As a fast moving neutron passes through a moderator it collides with atoms in the moderator passing on some of their energy and slowing down. After several collisions a neutron becomes slow enough to be captured by a fissionable isotope. At this point it is called a thermal neutron. |