Abstract: A telescoping guide for extraction and reinsertion support handling of in-core instrument thimble assemblies in the area above the upper support plate in the upper internals of a pressurized water reactor. The telescoping guides extend between the upper ends of the upper internals support columns and an axially movable instrumentation grid assembly which is operable to simultaneously raise the telescoping guides and extract the in-core instrument thimble assemblies from the reactor fuel assemblies.

Abstract: A telescoping guide for extraction and reinsertion support handling of in-core instrument thimble assemblies in the area above the upper support plate in the upper internals of a pressurized water reactor. The telescoping guides extend between the upper ends of the upper internals support columns and an axially movable instrumentation grid assembly which is operable to simultaneously raise the telescoping guides and extract the in-core instrument thimble assemblies from the reactor fuel assemblies.

Abstract: A telescoping guide for extraction and reinsertion support handling of in-core instrument thimble assemblies in the area above the upper support plate in the upper internals of a pressurized water reactor. The telescoping guides extend between the upper ends of the upper internals support columns and an axially movable instrumentation grid assembly which is operable to simultaneously raise the telescoping guides and extract the in-core instrument thimble assemblies from the reactor fuel assemblies.

Abstract: A telescoping guide for extraction and reinsertion support handling of in-core instrument thimble assemblies in the area above the upper support plate in the upper internals of a pressurized water reactor. The telescoping guides extend between the upper ends of the upper internals support columns and an axially movable instrumentation grid assembly which is operable to simultaneously raise the telescoping guides and extract the in-core instrument thimble assemblies from the reactor fuel assemblies.

Abstract: Disclosed is a method for reducing embrittlement of certain materials of pressurized water reactor vessels caused by neutron flux. According to this method, "shadow shielding" is placed within the core support barrel in areas having a more benign flow environment than that of the downcomer area. This shadow shielding provides an increased neutron scattering cross section. In one example, the shadow shielding replaces segments of the core shroud plate in a manner which does not interfere with coolant flow in the vessel. The segments of the shroud plate which are replaced are those near critical regions of the vessel, typically welds. The size and shape of the shielding is determined according to plant specific requirements.

Abstract: A method of remotely installing or removing and assembling and disassembling nozzle dams (10) from outside a steam generator manway (14) using a tool set. The tools are a bifurcated segment lifting (torquing and push-pull) tool 60 to unweight and faciltate the operation of sliding dam segments (30,32) edgewise along sliding brackets (40) and bars (44) in an assembly and disassembly operation; a cam-lock component (36) operating T-shaped tool (80) with a nozzle dam rib avoiding offset (88), transverse quick-connect body (50b) straddling tool (90) pull a sleeve (50c) in order to disassembly quick-connects; and, a gasket installing, tensioning and removing hook tool (102).

Abstract: A multisectioned nozzle dam (30) for use in a steam generator (24) with an integral bolt ring (32) has a body structure of general circular shape. Redundant seals including at least three separate inflatable peripheral seals (48, 50 and 52) with an alarm (A) for indicating a pressure increase between the second and third seals (50 and 52) is provided. Redundant supports including a plurality of independent bars (60, 62, 64 and 66) bolted to the integral bolt ring (36) secure the dam (30) within the nozzle (26) to the appropriate axial position.

Abstract: A system and method for installing a nozzle dam unit (26) in a nuclear steam generator having a head (12) including a head internal surface, a manway (14) penetrating the head, and a nozzle (16) penetrating the head. The system comprises a manipulator (76) adapted to be passed through the manway and having open end (82) adapted to be attached remotely to the head internal surface and a free end including a clamp member (104). A plurality of nozzle dam segments (54, 56, 58) are each sized to pass through the manway and carry means thereon (120) for engaging at least one other segment, the segments when fully engaged to each other forming a dam subassembly sized to pass into and seat against the nozzle. The manipulator is controlled so that the clamp member grasps and supports one of the dam segments within the head until the subassembly is formed within the head, and then is translated within the head until the dam subassembly seats within the nozzle.

Abstract: A system and method for installing a nozzle dam unit (26) in a nuclear steam generator having a head (12) including a head internal surface, a manway (14) penetrating the head, and a nozzle (16) penetrating the head. The system comprises a manipulator (76) adapted to be passed through the manway and having one end (82) adapted to be attached remotely to the head internal surface and a free end including a clamp member (104). A plurality of nozzle dam segments (54, 56, 58) are each sized to pass through the manway and carry means thereon (120) for engaging at least one other segment, the segments when fully engaged to each other forming a dam subassembly sized to pass into and seat against the nozzle. The manipulator is controlled so that the clamp member grasps and supports one of the dam segments within the head until the subassembly is formed within the head, and then is translated within the head until the dam subassembly seats within the nozzle.

Abstract: A nuclear steam supply steam generator primary nozzle 16 is sealed by a nozzle dam having segmented bulkhead portions 42 and 45 with peripheral flanges 46,50,52. A rubber diaphragm with a body 54 and peripheral strata form oppositely opening cavities 56 and 58. Hydraulic pressure from either side enters one of the cavities to create a radial sealing force against the inside surface of nozzle 16. A closed cell foam rubber sealing material 76 of 20 to 30 durometer can be interposed between the cavity defining strata and the surface 16 to improve sealing. A hinged retaining ring 70 is pinned to hold the nozzle dam against radial surface 68 machined in nozzle 16.

Abstract: A bolt and keeper secure nuclear steam generation isolation dam segments in assembled relation. The bolt is rotated into locked position with its handle in a slot as a transverse projection on the bolt end is moved along a ramp into a securing notch against the bias of a compressible rubber spring.