Radiation can be harmful to humans and the environment. Protecting staff against its effects is particularly important in nuclear facilities, as well as in medicine and research. Shielding against radiation involves placing radiation-absorbing materials between humans and the radioactive source – anything from simple slabs and walls to entire anti-radiation casings. The Steinbeis Innovation Center for Application-oriented Material-, Production-, and Process-Technology and imq-Ingenieurbetrieb für Materialprüfung, Qualitätssicherung und Schweißtechnik GmbH teamed up to investigate the radiation protection properties of a variety of composite materials.
The level of a radiation dose depends on the type of radiation and its intensity, as well as the duration of exposure, the distance from the source, and the effectiveness of protective materials. Shielding against alpha and beta radiation (ionizing radiation) is relatively straightforward, requiring only basic measures and simple materials. However, shielding against gamma radiation (high-energy, shortwave radiation) demands thick layers of lead or concrete. Shielding against ionizing radiation not only protects humans and other life forms, but also objects and equipment. It also reduces background noise during radiation measurements. Radioactive waste must be stored according to radiation protection regulations and transported in suitable containers.
Of course, the key factor in radiation protection is choosing the right protective materials. Recently, composite materials filled with metal fibers or powdered metal have become a major area of research. The Steinbeis Innovation Center for Application-oriented Material-, Production-, and Process-Technology teamed up with the firm imq-Ingenieurbetrieb für Materialprüfung, Qualitätssicherung und Schweißtechnik GmbH to investigate composite materials using a new inspection technique based on eddy currents. The partners analyzed the effectiveness of different composites filled with highly absorbent metal fibers or powder in shielding against ionizing radiation.
This innovative solution has a number of benefits. Composites are much simpler to manufacture than pure metals, and the technology to do so is already offered by all composite manufacturers. Composite materials are highly diverse and can be manufactured with high precision in almost any conceivable form.
In initial experiments, lead fibers were introduced into a resin mixture. Absorptiveness tests determined the attenuation coefficient μ. Upon increasing the fiber content of the mixture, the attenuation coefficient μ also increased (allowing for an error margin of 5 per cent), indicating a rise in the level of gamma radiation absorption. Compared to a sample of pure lead with an attenuation coefficient of 0.5 1/cm, the composite with 60 per cent lead fibers demonstrated a value of 0.23 1/cm.
Using these new lightweight custom composites, the shielding properties of radiation protection products can be optimally adjusted to radiation emissions, allowing the best possible protection. As well as thermoplastics and duroplastics, elastomers can also be used as a substrate for the lead fibers, as they have higher elasticity. This means flexible membranes or components can be manufactured, allowing objects with unusual or complex shapes to be fully protected. Materials which strongly absorb x-rays could also be used in composites. The study was conducted as part of a research project funded by the German Federation of Industrial Research Associations (AiF).
Dipl.-Ing. Alexandru Söver
Dipl.-Ing. (FH) Stephanie Seidel
Prof. Dr.-Ing. Lars Frormann
Steinbeis Innovation Center for Applicationoriented Material-, Production-, and Process- Technology
Dipl.-Ing.(FH) Christopher Seidel
Dr. rer. nat. Antje Zösch
Dr. sc. techn. Dr. rer. nat. Martin Seidel
imq-Ingenieurbetrieb für Materialprüfung, Qualitätssicherung und Schweißtechnik GmbH