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S-65 grade beryllium is a vacuum hot pressed material with 99.2% minimum beryllium content. S-65 has the lowest impurity levels of any of the commonly made grades of beryllium and is commonly used in neutron reflector and moderator applications.

This lower level of impurities reduces the amount of transuranic elements so that the material needs less storage time after being removed from the reactor. S-65 is an approved material per the ITER specification.


Beryllium Assay, % minimum 99.20
Beryllium Oxide, % maximum  0.900
Al, % maximum 0.050
C, % maximum 0.090
Fe, % maximum  0.080
Mg, Cr, each % maximum 0.010 
Ni, Cu, Ti, Zr, each, % maximum  0.025 
Zn, Mn, Ag, Co, Pb, Ca, Mo, each, % maximum  0.005 
Silicon, % maximum  0.045  
U, % maximum  0.015 
Other Metallic Impurities, each, % maximum  0.040 


  • Low neutron absorption
  • Reduces neutron kinetic energy in nuclear reactors
  • High neutron scattering cross section
  • High thermal conductivity under fusion conditions
  • Excellent neutron thermalization
  • Transparent to most forms of radiation
  • Superior cracking resistance under high heat flux thermal cycling
  • Maintains characteristics at elevated temperatures


  • Available in rod or bar.
  • Several size pressings can be made.