Editing Graphite (section)

===Neutron moderator===
{{main|Nuclear graphite}}
Special grades of synthetic graphite, such as Gilsocarbon,<ref name="arregui17">{{cite journal |last1=Arregui-Mena |first1=José David |last2=Bodel |first2=William |last3=Worth |first3=Robert N. |last4=Margetts |first4=Lee |last5=Mummery |first5=Paul M. |title=Spatial variability in the mechanical properties of Gilsocarbon |journal=Carbon |date=December 2016 |volume=110 |pages=497–517 |doi=10.1016/j.carbon.2016.09.051 |bibcode=2016Carbo.110..497A |url=https://pure.manchester.ac.uk/ws/files/47000433/47000378.Spatial_variability_in_the_mechanical_properties_of_Gilsocarbon_manuscript.pdf }}</ref><ref name="arregui18">{{cite journal |last1=Arregui-Mena |first1=José David |last2=Edmondson |first2=Philip D. |last3=Margetts |first3=Lee |last4=Griffiths |first4=D.V. |last5=Windes |first5=William E. |last6=Carroll |first6=Mark |last7=Mummery |first7=Paul M. |title=Characterisation of the spatial variability of material properties of Gilsocarbon and NBG-18 using random fields |journal=Journal of Nuclear Materials |date=December 2018 |volume=511 |pages=91–108 |doi=10.1016/j.jnucmat.2018.09.008 |bibcode=2018JNuM..511...91A }}</ref> also find use as a matrix and [[neutron moderator]] within [[nuclear reactor]]s. Its low [[neutron cross-section]] also recommends it for use in proposed [[fusion reactor]]s. Care must be taken that reactor-grade graphite is free of neutron absorbing materials such as [[boron]], widely used as the seed electrode in commercial graphite deposition systems – this caused the failure of the Germans' [[World War II]] graphite-based nuclear reactors. Since they could not isolate the difficulty they were forced to use far more expensive [[heavy water]] moderators. Graphite used for nuclear reactors is often referred to as [[nuclear graphite]]. Herbert G. McPherson, a Berkeley trained physicist at  National Carbon, a division of Union Carbide, was key in confirming a conjecture of Leo Szilard that boron impurities even in "pure" graphite were responsible for a neutron absorption cross-section in graphite that compromised U-235 chain reactions. McPherson was aware of the presence of impurities in graphite because, with the use of Technicolor in cinematography, the spectra of graphite electrode arcs used in movie projectors required impurities to enhance emission of light in the red region to display warmer skin tones on the screen. Thus, had it not been for color movies, chances are that the first sustained natural U chain reaction would have required a heavy water moderated reactor.<ref name="Figure11" >{{cite book | last = Weinberg | first = Alvin M. | title = The First Nuclear Era| publisher = American Institute of Physics | place = New York, N.Y.|year = 1994 |at=Figure 11| isbn =  978-1563963582}}</ref>