A Permeation System for the Mitigation of Hydrogen Gas Accumulation
Within Hazardous Material Packages

We propose a new method to alleviate hydrogen (H2) gas accumulation in hazardous material packages using a simple permeation system. The system accelerates H2 permeation from enclosed packages while maintaining regulatory compliance. The proposed system can be used in new designs or for retrofits of commercial packages for shipping and storage, as well as other commercial applications. H2 generation occurs via radiolysis in radioactive materials packages. This poses significant challenges due to the flammability risk. IAEA regulations require that the H2 content stay below the lower flammability limit (LFL) to eliminate this risk. Additionally, in many packages containing radioactive material, continuous venting is not permitted. The combination of these two requirements complicates the design of packages, requiring shortened shipping windows, an inerting atmosphere within the package, or other mitigating actions. To address this, we propose a compact permeation system comprised of a continuous gas permeable membrane (e.g., silicone) supported by a porous metal filtration material. The design prevents the release of radioactive material while allowing for the rapid permeation of H2 through the membrane. It can be tailored to prevent H2 accumulation by aligning the permeation flow rate with the H2 generation rate. Analytical and experimental models show that the permeation flow rate through the membrane quickly matches the generation rate even at low H2 partial pressures, thereby removing the need for other more burdensome amelioration techniques. This novel approach provides a simple and costeffective solution to a longstanding problem within the radioactive materials packaging commu