Shielding materials in the compact spherical tokamak

Area of Science:

• Materials Science
• Nuclear Engineering
• Plasma Physics

Background:

• Neutron shielding is crucial for nuclear fusion technology, especially in compact spherical tokamaks with limited space.
• The central column shield must protect superconducting magnets from radiation damage and heating, impacting cryogenic system energy consumption.

Purpose of the Study:

• To assess structure-property relationships of tungsten carbide (WC) and its composites for neutron shielding in fusion devices.
• To evaluate WC and a new WC-FeCr cermet as potential materials for central column shielding.

Main Methods:

• Review of fundamental material properties of monolithic tungsten carbide (thermal transport, mechanical properties, plasma interaction).
• Presentation of recent results on accident safety, thermo-mechanical properties, and irradiation behavior of WC-FeCr cermet.
• Assessment of structure-property relationships relevant to plasma-facing materials challenges.

Main Results:

• Monolithic tungsten carbide (WC) exhibits favorable properties compared to metallic tungsten for shielding applications.
• The WC-FeCr cermet demonstrates promising accident safety, thermo-mechanical, and irradiation behavior.
• Key structure-property relationships for WC-based materials in fusion environments were identified.

Conclusions:

• Tungsten carbide and its composites are attractive neutron-attenuating materials for compact tokamak central column shielding.
• Further research is needed on irradiation damage and hydrogen trapping in these advanced shielding materials.
• WC-based materials offer a viable solution for enhancing shielding efficiency under severe space constraints in fusion reactors.