Patent Number: 046844929
Section: claims

1. In a water-cooled nuclear reactor including an openable reactor pressure vessel having a wall, feedwater distributors passing through the pressure vessel wall for flooding the pressure vessel, and a core barrel for fuel elements disposed below the feedwater distributors in the reactor pressure vessel, a repair fixture comprising a sealing box enclosing the feedwater distributors in the opened, flooded pressure vessel, means connected to said sealing box for pressing said sealing box liquid-tightly against the reactor pressure vessel wall enclosing at least some of the feedwater distributors, and evacuating means connected to said sealing box for emptying the feedwater distributors enclosed by said sealing box. 2. Apparatus according to claim 1, wherein the feedwater distributors having conduit connections leading to primary shutdown controls of the pressure vessel. 3. Apparatus according to claim 1, including a support ring lowerable into the pressure vessel, said sealing box being mounted on said support ring. 4. Apparatus according to claim 3, including a core barrel disposed in the pressure vessel below the feedwater distributor, said support ring including props engaging the core barrel when said support ring is lowered. 5. Apparatus according to claim 3, wherein said support ring has an outer periphery including lateral props engaging the inner surface of the pressure vessel wall for absorbing radial compressive forces of said sealing box. 6. Apparatus according to claim 5, including setting cylinders displacing said lateral props against the inner surface of the pressure vessel wall. 7. Apparatus according to claim 3, including means connected to said sealing box for displacing said sealing box in radial direction of said support ring. 8. Apparatus according to claim 3, including means connected to said sealing box for displacing said sealing box in circumferential direction of said support ring. 9. Apparatus according to claim 3, wherein said support ring has an axis of symmetry, and including a guide connected to said support ring in which said sealing box is displaceable vertically and parallel to said axis of symmetry. 10. Apparatus according to claim 3, including hydraulic cylinders connected to said sealing box for controlling displacements of said sealing box relative to said support ring. 11. Apparatus according to claim 10, wherein said hydraulic cylinders are operated by pure water preventing contamination of the water of the flooded pressure vessel. 12. Apparatus according to claim 3, including guide cams connected to said sealing box and adapted to a given reactor type for correctly displacing said sealing box in radial direction relative to said support ring. 13. Apparatus according to claim 3, wherein said support ring is divided into sections. 14. Apparatus according to claim 3, wherein said feedwater distributors are in the form of four feedwater distributors connected to the pressure vessel, and including guides being screwed to said support ring and movable along the periphery of said support ring toward said feedwater distributors. PG,24 15. Apparatus according to claim 1, wherein the pressure vessel has an axis of symmetry and contains fuel elements including outer fuel elements disposed at a given distance from said axis of symmetry, and the feedwater distributors protrude into the pressure vessel, and including a support ring on which said sealing box is mounted, said sealing box having a depth in radial direction of the pressure vessel being only great enough to cover the protrusion of said feedwater distributors, and said support ring and said sealing box leaving an unobstructed inside diameter of the pressure vessel being more than twice said given distance when said sealing box is pressed against the pressure vessel wall. 16. Apparatus according to claim 1, wherein said sealing box has rims to be pressed against the pressure vessel wall, and gaskets disposed on said rims. 17. Apparatus according to claim 16, wherein each of said gaskets is substantially L-shaped and has a longer and a shorter leg, said longer leg being pressed against the pressure vessel wall and having a narrow sealing edge and a wide sealing lip, and a shallow fillet disposed between said sealing lip and sealing edge. 18. Apparatus according to claim 1, wherein said evacuating means include a pump. 19. Apparatus according to claim 18, including a float switch disposed in said sealing box and connected to said pump for controlling said pump. 20. Apparatus according to claim 1, wherein the pressure vessel has a given water level, and including an air venting hose connected to said sealing box and leading above the water level. 21. Apparatus according to claim 1, wherein said sealing box is at least partly transparent. 22. Apparatus according to claim 21, including transparent windows disposed in said sealing box.