Abstract: A nuclear reactor includes guide tubes; and vessel head penetrations each comprising a tubular adapter fixed in one of the openings and defining an inner passage. Each vessel head penetration also includes a tubular sleeve engaged in the inner passage and axially extending in line with one of the guide tubes. Each sleeve is suspended by an upper axial sleeve end lying on an upper range on the corresponding adapter. A lower axial end of the sleeve projects axially into the vessel beyond the adapter and is separated from an upper axial end of the corresponding guide tube by an axial gap having an axial height of less than 50 millimeters.

Abstract: A nuclear reactor includes guide tubes (12); and vessel head penetrations (22) each comprising a tubular adapter (24) fixed in one of the openings (2a) and defining an inner passage (34). Each vessel head penetration (22) also includes a tubular sleeve (36) engaged in the inner passage (34) and axially extending in line with one of the guide tubes (12). Each sleeve (36) is suspended by an upper axial sleeve end (38) lying on an upper range (40) on the corresponding adapter (24). A lower axial end (48) of the sleeve (36) projects axially into the vessel (1) beyond the adapter (24) and is separated from an upper axial end (54) of the corresponding guide tube (12) by an axial gap having an axial height of less than 50 millimeters.

Abstract: A method for working on a defective heating element of a pressurizer comprising a tank lying flat along a longitudinal axis and elongate heating elements extending within the tank, and at least one spacer plate through which the heating elements pass and which is capable of maintaining a transverse spacing between the heating elements is provided. The method includes cutting at least one spacer plate around the heating element so as to detach said heating element from said spacer plate, and then extracting the heating element from the tank in one single piece.

Abstract: A method for working on a defective heating element of a pressuriser comprising a tank lying flat along a longitudinal axis and elongate heating elements extending within the tank, and at least one spacer plate through which the heating elements pass and which is capable of maintaining a transverse spacing between the heating elements is provided. The method includes cutting at least one spacer plate around the heating element so as to detach said heating element from said spacer plate, and then extracting the heating element from the tank in one single piece.