Patent Number: 059149957
Section: claims

1. A nuclear reactor fuel assembly, comprising: a fuel assembly base;  a fuel assembly head;  mutually parallel fuel rods containing nuclear fuel and extending between said fuel assembly head and said fuel assembly base;  a water tube having first and second open ends and extending parallel to said fuel rods, said first end of said water tube being attached to and supported by said fuel assembly base;  an elongated extension body having first and second ends, said second end of said extension body gripping and being held at said fuel assembly head;  said second end of said water tube and said first end of said elongated extension body being attached to each other;  said elongated extension body having two mutually coaxially disposed partial bodies, one of said partial bodies having said second end of said extension body gripping said fuel assembly head and the other of said partial bodies having said first end of said extension body being attached to said water tube, one of said partial bodies being screwed into the other of said partial bodies; and  said second end of said extension body extending loosely through said fuel assembly head and said fuel assembly head being fixed on said second end of said extension body by a bayonet connection.  a fuel assembly base;  a fuel assembly head;  mutually parallel fuel rods containing nuclear fuel and extending between said fuel assembly head and said fuel assembly base;  a water tube having first and second open ends and extending parallel to said fuel rods, said first end of said water tube being attached to and supported by said fuel assembly base;  an elongated extension body having first and second ends, said second end of said extension body gripping and being held at said fuel assembly head;  said second of said water tube and said first end of said elongated extension body being screwed to each other;  said elongated extension body having two mutually coaxially disposed partial bodies, one of said partial bodies having said second end of said extension body gripping said fuel assembly head and the other of said partial bodies having said first end of said extension body being screwed to said water tube, one of said partial bodies being screwed into the other of said partial bodies;  said second end of said extension body extending loosely through said fuel assembly head and said fuel assembly head  being fixed on said second end of said extension body by a bayonet connection;  said bayonet connection being defined by first tongues radially formed on an outer jacket surface of said second end of said extension body, and a retaining sleeve being lockable with said fuel assembly head, said retaining sleeve being inserted between said second end of said extension body and said fuel assembly head, and second tongues radially formed on an inner jacket surface of said retaining sleeve for interlocking with said first tongues. 2. The nuclear reactor fuel assembly according to claim 1, further comprising a check nut seated on said one partial body being screwed into said other partial body, said check nut being braced against said other partial body. 3. The nuclear reactor fuel assembly according to claim 1, wherein said first end of said extension body is screwed into said second end of said water tube. 4. The nuclear reactor fuel assembly according to claim 1, wherein said second end of said water tube is screwed into said first end of said extension body. 5. The nuclear reactor fuel assembly according to claim 1, wherein said first end of said water tube is screwed into said fuel assembly base. 6. The nuclear reactor fuel assembly according to claim 2, further comprising a hollow weld with which said check nut is welded to said one partial body on which said check nut is seated. 7. The nuclear reactor fuel assembly according to claim 6, wherein said check nut and said one partial body have associated threads disposed at a distance from said hollow weld. 8. The nuclear reactor fuel assembly according to claim 2, wherein said check nut is welded to said partial body against which said check nut is braced with a lip or V-weld. 9. A nuclear reactor fuel assembly, comprising: 10. The nuclear fuel assembly according to claim 1, wherein the bayonet connection is defined by first tongues radially formed on an outer jacket surface of said second end of said extension body, and including a retaining sleeve being lockable with said fuel assembly head, said retaining sleeve being inserted between said second end of said extension body and said fuel assembly head, and second tongues radially formed on an inner jacket surface of said retaining sleeve for interlocking with said first tongues. 11. The nuclear fuel assembly according to claim 1, wherein said partial bodies have a fixed rotationally oriented position relative to one another .