Analysis on Permeation Leakage Through Rubber Sealing Ring for Radioactive Material Transport Packages

Abstract To ensure the containment of radioactive contents, IAEA SSR-6 specifies graded requirements on released radioactivity of transport packages. The O-ring sealing rubber is usually used in the radioactive material transport container to achieve the containment of the contents and air-tightness requirements. However, there are two unexpected phenomena occurring with rubber material. The first one occurs during leakage testing of transport packages containing non-radioactive gaseous contents, helium which is typical tracer gas will penetrate through the O-ring to the side with smaller pressure, thus interfering with the true leakage rate, in addition to helium leakage caused by cracks or defects between the flange and the O-ring. The second unwanted phenomenon is radioactivity release through penetration process, for transport packages containing radioactive gaseous contents. The helium permeation goes through three main processes: dissolution, diffusion and desorption. This paper designed one experimental apparatus and utilized typical rubber material as sealing rings to observe and analysis the gas permeation process and mechanism. Based on the outcome of test results, addressing the issues arisen from permeation leakage, this paper proposed recommendations on improvements of gas leakage testing method and procedures, and one calculation model of radioactivity permeation release source term.