Editing Neutron moderator (section)

{{Short description|Substance that slows down particles with no electric charge}}
{{Science with neutrons}}
In [[nuclear engineering]], a '''neutron moderator''' is a medium that reduces the speed of [[Neutron temperature#Fast|fast neutrons]], ideally without [[neutron capture|capturing]] any, leaving them as [[Neutron temperature#Thermal|thermal neutrons]] with only [[Thermal energy|minimal (thermal) kinetic energy]]. These '''thermal neutrons''' are immensely more susceptible than '''fast neutrons''' to propagate a [[nuclear chain reaction]] of [[uranium-235]] or other [[Fissile material|fissile]] [[Radionuclide|isotope]] by colliding with their [[atomic nucleus]].

[[Water]] (sometimes called "light water" in this context) is the most commonly used moderator (roughly 75% of the world's reactors). Solid [[graphite]] (20% of reactors) and [[heavy water]] (5% of reactors) are the main alternatives.<ref>{{cite book
  | last = Miller, Jr.
  | first = George Tyler
  | title = Living in the Environment: Principles, Connections, and Solutions
  | publisher = [[The Thomson Corporation]]
  | year = 2002
  | location = Belmont
  | pages = 345
  | isbn = 0-534-37697-5| edition = 12th
 }}</ref> [[Beryllium]] has also been used in some experimental types, and [[hydrocarbon]]s have been suggested as another possibility.