Crediting the Inner O-Ring of a Chalfant‑Style Containment Vessel

Type B Radioactive Material Packaging are required by federal regulation to provide containment of the radioactive materials being transported with an allowable release rate based upon the conditions and the material. Type B Packaging design incorporate a Containment Vessel (CV) which performs this function. CV designs typically have two separate seals, one that performs the content containment function and a second that is used to verify the installation and functionality of the containment seal. The Savannah River National Laboratory has designed the “Chalfant-style” Containment Vessel, used on a family of Type B radioactive material packages, which utilizes a conical plug with dual O-Rings which is held in contact by a threaded nut to a conical sealing surface on the vessel body. The “outer” O-Ring is credited in the safety basis documents for providing containment. This paper discusses the challenges and benefits of crediting the “inner” O-Ring of a Chalfant-Style CV.