Patent Number: 
Section: claims

1. A nuclear reactor primary coolant system (10), comprising:a primary coolant pipe (30) which delimits an inner space (32) in which a primary cooling fluid of the nuclear reactor flows, the primary cooling fluid flowing from the upstream direction in a downstream direction of the primary coolant pipe (30), and the primary coolant pipe has a central axis substantially parallel to the primary cooling fluid flow direction;an additional pipe (26) which is tapped from the primary coolant pipe (30), the additional pipe (26) delimiting an inner space which communicates with the inner space (32) of the primary coolant pipe (30);a sleeve (36) which has a first end (50) which is connected to the additional pipe (26), and a second free end (52) which is located in the inner space (32) of the primary coolant pipe (30), the second end of the sleeve opening up toward said central axis;wherein the second end (52) of the sleeve (36) terminates in and is delimited by a free peripheral edge (53) which has at least upstream and downstream sectors (56, 58) which are directed in the upstream and downstream direction of the primary coolant pipe (30), respectively, the upstream sector (56) penetrating more deeply into the inner space (32) from the primary coolant pipe (30) than the downstream sector (58). 2. The system according to claim 1, characterised in that the upstream and downstream sectors (56, 58) penetrate into the inner space (32) over first and second mean penetration depths, respectively, the first depth being greater than the second by at least 10% of the largest dimension of the cross section of the additional pipe (26). 3. The system according to claim 2, characterised in that the first mean penetration depth is greater than 50% of the largest dimension of the cross section of the sleeve (36) in the region of the free end (52) thereof. 4. The system according to any one of claims 1 to 3, characterised in that the peripheral edge (53) has a bevelled profile. 5. The system according to any one of claims 1 to 3, characterised in that the peripheral edge (53) has a notched profile. 6. The system according to claim 1, characterised in that the upstream sector (56) extends over at least 30% of the peripheral edge (53). 7. The system according to claim 1, characterised in that the sleeve (36) comprises a contraction (62) which terminates at the free end (52), the contraction (62) having a smaller flow cross-section than that of the additional pipe (26). 8. The system according to claim 7, characterised in that the contraction (62) extends between a restriction (60) which is formed in the sleeve (36) and the second free end (52), the restriction (60) being arranged in a connection zone of the sleeve (36) to the additional pipe (26). 9. The system according to claim 7, characterised in that the largest dimension of the flow cross-section of the additional pipe (26) is between 1.7 and 3 times the largest dimension of the flow cross-section of the contraction (62). 10. The system according to claim 1, the second end of the sleeve being tubular, wherein the upstream and downstream sectors are part of the tubular end. 11. A nuclear reactor primary coolant system (10), comprising:a primary coolant pipe (30) which delimits an inner space (32) in which a primary cooling fluid of the nuclear reactor flows, the primary cooling fluid flowing from the upstream direction in a downstream direction of the primary coolant pipe (30);an additional pipe (26) which is tapped from the primary coolant pipe (30), the additional pipe (26) delimiting an inner space which communicates with the inner space (32) of the primary coolant pipe (30);a sleeve (36) which has a first end (50) which is connected to the additional pipe (26), and a second free end (52) which is located in the inner space (32) of the primary coolant pipe (30);wherein the second end (52) of the sleeve (36) is tubular and terminates in and is delimited by a free peripheral edge (53) which has at least upstream and downstream sectors (56, 58), the upstream and downstream sectors being part of the second end of the sleeve and being directed in the upstream and downstream direction of the primary coolant pipe (30), respectively, the upstream sector (56) penetrating more deeply into the inner space (32) from the primary coolant pipe (30) than the downstream sector (58). 12. The system according to claim 11, the second end of the sleeve being substantially cylindrical. 13. The system according to claim 11, wherein the free peripheral edge has a closed contour. 14. A nuclear reactor primary coolant system (10), comprising:a primary coolant pipe (30) which delimits an inner space (32) in which a primary cooling fluid of the nuclear reactor flows, the primary cooling fluid flowing from the upstream direction in a downstream direction of the primary coolant pipe (30);an additional pipe (26) which is tapped from the primary coolant pipe (30), the additional pipe (26) delimiting an inner space which communicates with the inner space (32) of the primary coolant pipe (30);a sleeve (36) which has a first end (50) which is connected to the additional pipe (26), and a second free end (52) which is located in the inner space (32) of the primary coolant pipe (30);wherein the second end (52) of the sleeve (36) terminates in an opening delimited by a free peripheral edge (53) having at least upstream and downstream sectors (56, 58) directed in the upstream and downstream direction of the primary coolant pipe (30), respectively, the upstream sector (56) penetrating more deeply into the inner space (32) from the primary coolant pipe (30) than the downstream sector (58).