Patent Number: 
Section: claims

1. A boiling water reactor assembly, comprising:a control rod guide tube having a base flange;a drive housing pipe having a longitudinal axis defining an axial direction; anda bayonet plate closure coaxially connecting said drive housing pipe to said control rod guide tube, said bayonet plate closure having a two-part bayonet plate including:a) a central bayonet ring mounted rotatably about said longitudinal axis and having bayonet grooves, an underside and a periphery, andb) an outer ring mounted on said periphery of said bayonet ring, said outer ring having a concentric annular step bearing and sliding on said periphery and on said underside of said bayonet ring and said outer ring:i) reaching inward underneath said periphery of said bayonet ring, andii) being supported on said base flange of said control rod guide tube with spring pressure acting permanently on said control rod guide tube in said axial direction; anda disk spring configured to spread apart an axial distance between said bayonet ring and said base flange and apply pressure to a surface of said annular step in direction of said control rod guide tube. 2. The boiling water reactor assembly according to claim 1, wherein said disk spring surrounds said drive housing pipe with a radial sliding fit. 3. The boiling water reactor assembly according to claim 1, wherein said drive housing pipe has a tube shell and a contact surface protruding radially outwardly beyond said tube shell and having a planar shape, a conical shape or a surface with a crowned shape. 4. The boiling water reactor assembly according to claim 1, wherein said bayonet ring is braced axially while fitted on said drive housing pipe by an active spring pressure in a locked state of said bayonet plate closure. 5. A boiling water reactor assembly, comprising:a control rod guide tube having a base flange;a drive housing pipe having a longitudinal axis defining an axial direction; anda bayonet plate closure coaxially connecting said drive housing pipe to said control rod guide tube, said bayonet plate closure having a two-part bayonet plate including:a) a central bayonet ring mounted rotatably about said longitudinal axis and having bayonet grooves and a periphery, andb) an outer ring mounted on said periphery of said bayonet ring, said outer ring:i) reaching inward underneath said periphery of said bayonet ring, andii) being supported on said base flange of said control rod guide tube with spring pressure acting permanently on said control rod guide tube in said axial direction; andradially outwardly protruding retaining protrusions integrally formed at a head of said drive housing pipe and configured to reach over said bayonet ring from inside in a locked state of said bayonet plate closure. 6. The boiling water reactor assembly according to claim 5, wherein said bayonet ring has an inner side, said bayonet grooves are recesses located on said inner side of said bayonet ring complementary to said retaining protrusions at said head of said drive housing pipe, and said recesses are configured to be aligned with said retaining protrusions in a unlocked state of said bayonet plate closure. 7. A boiling water reactor assembly, comprising:a control rod guide tube having a base flange;a drive housing pipe having a longitudinal axis defining an axial direction; anda bayonet plate closure coaxially connecting said drive housing pipe to said control rod guide tube, said bayonet plate closure having a two-part bayonet plate including:a) a central bayonet ring mounted rotatably about said longitudinal axis and having bayonet grooves and a periphery, andb) an outer ring mounted on said periphery of said bayonet ring, said outer ring:i) reaching inward underneath said periphery of said bayonet ring, andii) being supported on said base flange of said control rod guide tube with spring pressure acting permanently on said control rod guide tube in said axial direction; andsaid bayonet ring being mounted rotatably on said drive housing pipe with axial play in an unlocked state of said bayonet plate closure. 8. A boiling water reactor assembly, comprising:a control rod guide tube having a base flange;a drive housing pipe having a longitudinal axis defining an axial direction; anda bayonet plate closure coaxially connecting said drive housing pipe to said control rod guide tube, said bayonet plate closure having a two-part bayonet plate including:a) a central bayonet ring mounted rotatably about said longitudinal axis and having bayonet grooves and a periphery, andb) an outer ring mounted on said periphery of said bayonet ring, said outer ring:i) reaching inward underneath said periphery of said bayonet ring, andii) being supported on said base flange of said control rod guide tube with spring pressure acting permanently on said control rod guide tube in said axial direction; andfastening pins having locking heads, reaching through said bayonet ring and configured to prevent rotation of said bayonet ring in a locked state of said bayonet plate closure.