PRESTRESSED CONCRETE VESSEL THROUGH PORTION HAVING SHEATHING TUBE

A prestressed concrete pressure vessel esp. for a gas-cooled reactor, has a wall penetration lined with a metal tube. This tube (2) has, inside it, an additional lining (3) at a distance (4) from the metal tube. Pref. the main liner tube (2) bonded to the concrete is closed at its outer end with a closure cap (12), and at its inner end with a plug (8). The additional lining (3) is pref. of sheet metal. Used for a penetration in a nuclear reactor which may be required for such purposes as instrumentation and is normally closed at its outer end. With such an arrangement, if the outer closure should fail, the consequent flow of hot gas out through the tube at high pressure would lead to rapid heating up of the tube and consequent damage to the adjacent structural concrete, in spite of the cooling tubes (14) which are designed for normal operating conditions.