Moderator (Nuclear)

	Main Article	Discussion	Related Articles  [?]	Bibliography  [?]	External Links  [?]	Citable Version  [?]
	This editable Main Article is under development and subject to a disclaimer. [edit intro]

In nuclear engineering, a moderator is a material that restricts the free flow of various particles, such as neutrons, or of radiation, such as X-rays. In general, materials with a low-Z (i.e., low atomic number, such as beryllium or hydrogen) restrict the flow of particles (e.g., neutrons) while high-Z materials (e.g., lead, uranium) block radiation).