Patent Number: 
Section: claims

1. Pressuriser for a pressurised water nuclear power station, comprisingan outer casing which delimits an inner space;a duct which is located away from the casing and extends beneath the casing;a tap which places the inner space of the casing in communication with the duct, this tap having a lower end being welded to the duct by means of a weld seam and an upper end which opens into the inner space;a weld protecting sleeve arranged inside the tap and which has a lower peripheral edge which is engaged in the duct, an annular space selectively filled with a primary liquid being defined radially between the sleeve and the tap and the duct, the sleeve bounding the annular space on the inside, the tap and the duct bounding the annular space on the outside;wherein the duct has inside the lower peripheral edge of the sleeve an inner volume; andwherein the annular space has at least one opening along at least a portion of the lower peripheral edge of the sleeve and is in fluidic communication through the at least one opening with the inner volume of the duct. 2. Pressuriser according to claim 1, wherein the annular space is open along the entire lower peripheral edge of the sleeve. 3. Pressuriser according to claim 1, wherein the tap defines an inner channel which places the duct and the inner space of the casing in communication, the pressuriser comprising a crown which is rigidly fixed to an inner side of the casing around the inner channel, the sleeve having an upper end portion which is fixed to the crown. 4. Pressuriser according to claim 3, wherein the crown and/or the upper end portion of the sleeve comprise(s) circulation holes which place the annular space in communication with the inner space of the casing. 5. Pressuriser according to claim 4, wherein a passage cross-section of the circulation holes is calibrated in order to limit a flow rate of primary liquid through the annular space to a maximum predetermined value. 6. Pressuriser according to claim 5, wherein a total passage cross-section of the circulation holes is between 0.5% and 2% of the passage cross-section of the inner channel of the tap. 7. Pressuriser according to claim 3, wherein the annular space has, along the lower peripheral edge of the sleeve, a passage cross-section of between 2% and 10% of the passage cross-section of the inner channel of the tap. 8. Pressuriser according to claim 3, wherein the sleeve is removably mounted on the crown. 9. Pressuriser according to claim 3, wherein it comprises a strainer which covers the inner channel of the tap and which is removably mounted on the crown. 10. Pressuriser according to claim 9, wherein the upper end portion of the sleeve is engaged between the strainer and the crown.