Flexible Composite Offers Tritium Containment and Radiation Shielding for Fusion Facilities

Future fusion facilities need materials that can provide reliable radiation shielding while also maintaining gas tightness and allowing components to be easily removed for maintenance. This is particularly important for areas where pipes and other components pass through radiation shielding structures.

In a study published in Journal of Materials Research and Technology, a team led by Dr. HUO Zhipeng from the Hefei Institutes of Physical Science of the Chinese Academy of Sciences developed a flexible silicone rubber composite that can both contain tritium and shield against nuclear radiation, offering a potential solution for radiation protection in future fusion facilities.

Researchers developed the silicone rubber composite reinforced with lead tungstate (PbWO4) and boron carbide (B4C). They first prepared the PbWO4 particles with a spindle-like shape using a water-based precipitation method, and then combined these particles with B4C and silicone rubber to make the composite.

The spindle-shaped PbWO4 particles bonded well with silicone rubber and helped improve the material's stability and mechanical properties. The composite remained stable at high temperatures and showed good resistance to thermal expansion. It also had sufficient strength and flexibility to maintain a gas-tight seal while allowing components to be detached when needed.

Besides, the composite showed good resistance to aging. The ability of PbWO4 to absorb ultraviolet radiation helped reduce degradation during accelerated aging tests, with only a small loss in tensile strength.

Through simulations and experiments, researchers evaluated the composite's ability to shield against neutron and gamma radiation. It showed effective shielding against both types of radiation while helping reduce the production of secondary gamma rays. "The composite blocked 93.13% of neutrons and 82.76% of gamma rays at a thickness of 15 cm. Its shielding performance was comparable to or better than that of concrete used for radiation protection," said Dr. HUO.

The findings of this study suggest that the flexible composite could be used in tritium containment and radiation protection systems in future fusion facilities, particularly where sealing, shielding, and ease of maintenance are all required.

Schematic illustration of the sealing and radiation shielding mechanism of micron spindle-shaped PbWO4 filler-reinforced flexible silicone rubber for penetration holes in nuclear fusion facilities. (Image by HUO Zhipeng)