A device is provided for use in securing a remnant of a tube through a wall of a pressure vessel. The device include an anti-ejection device for attachment to the remnant on an interior side of the pressure vessel and an end cap for attachment to the remnant on an exterior side of the pressure vessel for sealing an open end of the remnant. The anti-ejection device includes an anti-rotation member for constraining the remnant and the anti-ejection device against relative rotation therebetween. A bolt connects the anti-ejection device, the remnant, and the end cap.

The invention relates to a device for closing a pipe opening, opening upwards, of a drive casing pipe accommodating the control rod drive of a boiling water reactor, said device comprising a closure plug with a plug housing, opening downwards, a sealing element guided axially so as to be movable within the plug housing, which element has a sealing face providing a sealing contact with an annular counter face defining the pipe opening, a locking element provided to fix the plug housing on the drive casing pipe, and a spring, which is supported by the upper end thereof on the plug housing and by the lower end thereof on the sealing element and holds said element in a lower end position.

A method for retrofitting a nuclear power plant which include dismantling and removing all the components of the primary circuit apart from the LWR reactor vessel, which is essentially emptied of all material and neutralized, subsequently replacing a part of these components with subassemblies that are each made up of an integrated SMR reactor and a mixed concrete/metal structure, which mixed concrete/metal structure is also used as a reactor pit for the SMR reactor, which reactor pit is advantageously filled with water, anchoring the SMR to the inside of the reactor building and advantageously contributing to the third confinement barrier while ensuring minimal disruption to the infrastructure of the reactor building.