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For optimal efficiency, nuclear reactors require materials that will perform under high heat conditions. Beryllium can meet those requirements. Pure beryllium metals S-65 and S-65-H are light weight with high strength. S-65 has the lowest impurity levels of commonly made grades of beryllium, which reduces the amount of transuranic elements, so that the material needs less storage time after being removed from reactors.

S-65 and S-65-H beryllium metals maintain their properties at elevated temperatures, thereby increasing usefulness in fusion energy applications over conventional graphite materials. These metals increase nuclear reactor efficiency and help reduce the hazardous waste production, which can help reactors run longer.


Nuclear reactors require high purity beryllium that offers unique properties. S-65 and S-65-H provide high neutron flux, making them ideal for neutron reflector and moderator applications. Other nuclear property advantages of these beryllium metals include:

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

For more details on nuclear grade beryllium, for vacuum hot pressed, download the S-65 spec. sheet.

For additional information on nuclear grade beryllium that is hot isostically pressed, download the S-65-H spec. sheet.


Our nuclear grade beryllium is the reference grade for the International Thermonuclear Experimental Reactor (ITER), a cutting-edge fusion energy program. S-65 beryllium metal was chosen for the walls in ITER and for breeder pebbles because it offers superior resistance to cracking under high heat flux thermal cycling.

Our beryllium nuclear grade metals were also used for nuclear reflector tiles for the walls in the Joint European Torus (JET), the world’s largest plasma physics experiment focused on nuclear fusion energy production.

Other applications that use S-65 & S-65-H are:

  • Neutron reflectors and moderators
  • Neutron filter assemblies
  • Nuclear test reactors
  • Medical isotope reactors


  • S-65 is available in rod, bar or custom pressing. It is vacuum hot pressed.
  • S-65-H is available in rod or bar forms that are cut from a hot isostically pressed block.
  • Special sizes and shapes based on the part shape can be made upon request.

Contact our engineers to find the right beryllium specification for your application.

Additionally, you can work with our Special Products and Application Development Engineering (SPADE) team and they will ensure that you get optimum results when using our beryllium metals for nuclear applications. SPADE can help manage projects and provide engineering support from design inception to project completion.

Work with Materion’s SPADE group for engineering assistance on advanced applications.