After the accident at the Fukushima No.1 Nuclear Power Station in the wake of the Great East Japan Earthquake, decontamination of radioactive substances is under way mainly around the area of Fukushima Prefecture. However, there are many places that are difficult to decontaminate, such as roofs, under flooring, and cracks in concrete and asphalt, due to structural and other problems, and this has become the cause of rising amounts of air-transmitted radiation being present both indoors and in surrounding areas.Shin-Etsu's Radibarier Series of liquid silicone rubbers was developed by mixing a radiation-shielding material with liquid silicone rubber to add the function of attenuating gamma rays. The accumulation of long-term exposure to doses of radiation can be greatly reduced by using this product in places that need to decontaminate radioactive materials such as private residences and facilities where radioactive materials are stored.
The "Radibarrier Series" consists of "Radibarrier 101," which has low viscosity and can be poured into a small opening, and "Radibarrier 102," which has high viscosity and is a suitable sealant for vertical and other surfaces. After both of these new products are hardened at room temperature, the new products demonstrate superior heat resistance, cold resistance and weather resistance - characteristics that are similar to those of existing silicone rubbers - and they are superior in long-term reliability. In addition, application products such as shielding silicone rubber sheets ("Radibarrier sheets"), which are molded in the shape of sheets, and shielding storage containers are already developed.
The research and development of this product was initiated based on a request from EARTH Corporation, a Japanese company, headquartered in Koriyama City in Fukushima Prefecture, which performs decontamination of radioactive materials and measurement / analysis of environment. With regard to the development process of this product, performance verification of this product has been carried out in collaboration with major general contractor companies and Fukushima Prefecture's local governments. For example, in the case of gamma radiation that emanates from Cesium 137, Shin-Etsu's new product achieved about 70% radiation attenuation with a sample thickness of 3 cm.
