Flexible Composite Shields Fusion Reactors From Radiation While Sealing Tritium

Researchers from the Hefei Institutes of Physical Science, part of the Chinese Academy of Sciences, have developed a flexible silicone rubber composite designed to both contain tritium and shield against nuclear radiation, offering a potential material solution for radiation protection in future fusion facilities.

The team, led by Dr. Huo Zhipeng, published its findings in the Journal of Materials Research and Technology.

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

For the study, the researchers built a silicone rubber composite reinforced with lead tungstate (PbWO4) and boron carbide (B4C). Spindle-shaped PbWO4 particles were first prepared using a water-based precipitation method, then combined with B4C and silicone rubber to form the composite.

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

The material also proved resistant to aging. PbWO4's ability to absorb ultraviolet radiation helped limit degradation during accelerated aging tests, with only a small loss in tensile strength recorded.

The researchers went on to evaluate the material's ability to shield against neutron and gamma radiation through both simulations and experiments. The composite provided effective shielding against both types of radiation while also helping to reduce the production of secondary gamma rays.

"The composite blocked 93.13 percent of neutrons and 82.76 percent of gamma rays at a thickness of 15 cm," said Dr. Huo. "Its shielding performance was comparable to or better than that of concrete used for radiation protection."

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

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