Patent Number: 041464230
Section: claims

1. Nuclear reactor having a water-cooled hearth (3), a pressure vessel (1) of pre-stressed concrete, and an inner containment vessel (7, 8) spaced from the pressure vessel (1) so that an insulating gap (11, 12) is formed between the pressure vessel (1) and the containment (7, 8), characterized in that the containment (7, 8) consists of an upper part (8) and a lower part (7), the adjacent parts of the upper part (8) and the lower part (7) being arranged to form a water-filled lock (16), having a U-shaped cross section, between the insulating gap and the inside of the reactor, and adjacent parts of the lower part (7) and the pressure vessel being arranged to form a gas-filled passage (15), having an inverted U-shaped cross section, between the insulating gap and the inside of the reactor. 2. Nuclear reactor according to claim 1, characterized in that means (22) are provided to introduce gas into the gas-filled passage (15), and that the outer part of the gas-filled passage has a smaller vertical dimension than the inner part, so that excess gas introduced penetrates into the insulating gap.