Abstract: The leakage of gases in gas cooled nuclear reactors is detected by an arrangement utilizing a flexible material to cover areas of potential leakage and create detection cavities inside the concrete vessel of a nuclear power plant. The detection cavities are connected to the gas collector housed within the concrete vessel by means of gas-tight connecting conduits or lines. A negative pressure is applied to the gas collection device connecting conduits and detection cavities to extract any gas leakage within the power plant. Gas measuring devices and display devices are included in the system to identify, quantify or locate gas leakage.

Abstract: Disclosed is a closure combination for pressure vessels comprising a carrier cover in contact with a sealing cover for covering and closing an opening in a pressure vessel by contact with a flange member of a liner element disposed within the opening in the pressure vessel and sealed by a sealing means in communication with the flange member and the sealing cover.