Recycled hybrid material for use as shielding in operations with ionizing radiation

One of the most efficient measures to prevent gamma radiation is shielding, which can take the form of protection barriers, storage containers, wall coating, bunkers, or many others aimed at minimizing the exposure of people to radiation. The materials used to this end have not changed much since the invention of X-rays, when materials with high attenuation capacity were employed, such as lead, tungsten, or concrete. These are all high-density materials and, therefore, also very heavy, and some of them are expensive and not environmentally friendly, as they do not have many possibilities with regards to their recycling. Circular economy provides an opportunity to reintroduce subproducts and waste in the same production processes that generated them or as raw matters in others. The use of sustainable materials is one of these options; however, there is little research in the field of radiation protection about the use of recycled material to this end, and there are few alternative sustainable options different from conventional materials that show similar behaviour. In our study, we have designed and built shielded panels called Mixlead® for gammagraphy, made of 100 % recyclable materials with sandwich structures combining polymeric fractions of electric cables and lead-alloy protection sheets used in the packaging of radiographic plates. With a methodology combining shielding calculations and a series of thermomechanical-radiological tests, it was possible to accurately determine the thickness of Mixlead® necessary to perform the tests with security guarantees and meeting sustainability requirements for radioactive sources of Iridium (192Ir) and Selenium (75Se), the use of the former being predominant, with an average activity of 1 GBq. In order to reduce this activity 2 and 10 times, the necessary thickness would be 24 and 79 mm respectively, which represents 3 or 4 layers of Mixlead® material.