Abstract: A hydro-ball in-core instrumentation system employs detector strings each comprising a wire having radiation sensitive balls affixed diametrically at spaced positions therealong and opposite tip ends of which are transportable by fluid drag through interior passageways. In the passageways primary coolant is caused to flow selectively in first and second opposite directions for transporting the detector strings from stored positions in an exterior chamber to inserted positions within the instrumentation thimbles of the fuel rod assemblies of a pressure vessel, and for return. The coolant pressure within the detector passageways is the same as that within the vessel; face contact, disconnectable joints between sections of the interior passageways within the vessel facilitate assembly and disassembly of the vessel for refueling and routine maintenance operations.

Abstract: A reactor coolant pump has an outer casing with an internal cavity holding a coolant and a rotor rotatably mounted in the cavity within the coolant. An assembly for permitting inservice inspection of the pump rotor without first draining the coolant from the casing cavity is attached to an end of the pump. A cylindrical bore is defined through the casing in axial alignment with an end of pump rotor and opening into the internal cavity. An extension attached on the rotor end and rotatable therewith has a cylindrical coupler member extending into the bore. An outer end of the coupler member has an element configured to receive a tool for performance of inservice rotor inspection. A hollow cylindrical member is disposed in the bore and surrounds the coupler member.

Abstract: A nuclear reactor coolant pump utilizes a pivoted pad bearing assembly to rotatably mount its shaft through the pump housing. The bearing assembly includes a plurality of arcuate bearing segments disposed end-to-end in circumferentially spaced relation for encompassing the shaft and providing bearing contact therewith, and a plurality of pivot pins each extending radially between an outer annular split ring attached to the pump housing and one of bearing segments. The pivot pins are mounted for universal pivotal movement at their inner ends with the respective bearing segments. The pivot pins at their outer ends are mounted to the annular ring for adjustable radial movement for changing the radial position of the pivot pins relative to annular ring and thereby of the bearing segments relative to the shaft. A plurality of locking cups are provided for coupling the pivot pins in locked relation the annular ring to fix the pivot pins in desired adjusted positions relative thereto.

Abstract: A control rod support for mounting within a rod guide of a pressure vessel has plural, parallel axial extending passageway openings therein for receiving corresponding control rods of a control rod cluster. A channel extends from the passageway opening and through the support for accommodating each vane of a spider which supports the control rods and provides for telescoping movement of the control rod cluster relative to the rod guide and associated guide rod supports. Spaced interior side walls of the support defining the channel form junctures with the interior side wall defining the passageway opening; and planar wear surfaces extend from the respective junctures of the channel-defining interior side walls a sufficient lateral distance to provide planar-to-convex wear surface interfaces with the corresponding, contiguous surface segments of a generally cylindrical control rod which is received through the passageway opening and urged against the junctures.

Abstract: A canned pump is described which includes a motor, impeller, shaft, and high inertia flywheel mounted within a hermetically sealed casing. The flywheel comprises a heavy metal disk made preferably of a uranium alloy with a stainless steel shell sealably enclosing the heavy metal. The outside surfaces of the stainless steel comprise thrust runners and a journal for mating with, respectively, thrust bearing shoes and radial bearing segments. The bearings prevent vibration of the pump and, simultaneously, minimize power losses normally associated with the flywheel resulting from frictionally pumping surrounding fluid.

Abstract: A pressurized water reactor of an advanced design comprises, in vertically spaced relationship, a lower barrel assembly having lower and upper core plates, an inner barrel assembly and an axially removable calandria assembly having a lower calandria plate. A plurality of rod guides are cantilever-mounted in parallel axial relationship within the inner barrel assembly and, specifically, are rigidly mounted at the lower ends thereof to the upper core plate. Axially extending sleeves are affixed to the upper ends of the rod guides and telescopingly receive therein generally cylindrical supports which are affixed to and depend downwardly from the lower calandria plate and define alignment axes for the respectively associated rod guides.

Abstract: A pressurized water reactor of an advanced design comprises, in vertically spaced relationship, a lower barrel assembly having lower and upper core plates, an inner barrel assembly and an axially removable calandria assembly having a lower calandria plate. A plurality of rod guides are cantilever-mounted in parallel axial relationship within the inner barrel assembly by rigidly mounting the lower ends thereof to the upper core plate. Axially extending sleeves affixed to the upper ends of the rod guides and telescopingly receive therein generally cylindrical supports which are affixed to and depend downwardly from the lower calandria plate and define alignment axes for the respectively associated rod guides. Axially extending leaf springs in each sleeve are normally biased radially inwardly and, in the assembled relationship of the calandria and inner barrel assemblies, resiliently and frictionally engage the respective cylindrical supports to maintain alignment and react both lateral and axial loads.

Abstract: A nuclear reactor in which rupture by fatigue of the components of the control-rod assemblies is precluded. The fatigue is caused by the vibration of the components or cavitation under the action of the coolant flowing at a high velocity transversely to the control-rod assemblies. A perforated shroud is provided between the control rod assemblies and the outlet nozzles. The shroud distributes the transversely-flowing coolant over a large volume so that its velocity is substantially lower than the resonant velocity at which vibrations of substantial amplitude of the components or cavitation is produced.

Abstract: A calandria for use in conducting the hot coolant of a nuclear reactor transversely. The calandria includes an upper plate and a lower plate which support tubes. The plates and tubes are enclosed in a shell which extends above the upper plate and has a supporting flange. The lower plate has holes for transmitting coolant into the region between the plates. The shell has openings whose boundaries mate with the outlet nozzles of the reactor. The tubes are of stainless steel and are dimensioned so that they have mass, stiffness and strength such that they are not subject to failure by the transverse flow of the coolant even at a high velocity.

Abstract: Disclosed is a reactor internals hold down spring and upper head region cooling passage. The hold down spring utilizes a plurality of stacks of Belleville spring washers to provide spring load and deflection capability to hold down the reactor vessel internals. Each spring assembly includes a generally leak tight means for passing an adjustable coolant flow to the upper reactor vessel head region in order to maintain that region at inlet coolant temperature. The spring assemblies are angularly spaced about a core barrel support flange to cooperate with coolant flow passage formed therein.

Abstract: A nuclear reactor steam generating plant having a pressurized water reactor with a single discharge line to a steam generator, with the primary coolant passing through the steam generator tubes divided into two streams in the channel head outlet section that is divided into two subsections. Discharge nozzles on the outlet subsections direct the streams of coolant to hermetically sealed pumps directly attached to the discharge nozzles, with the pumps directing the cooled primary coolant back to the reactor vessel. A single removable closure is provided for access to both subsections of the outlet section of the channel head, with a removable portion provided on the divider plate that forms the subsections.

Abstract: A core support system for a core barrel of a nuclear reactor, which core barrel has a bottom core support plate wherein the core support plate has apertures therethrough about the periphery thereof which communicate with recesses in engagement means for the core support plate, and keys inserted into the core support plate apertures and secured thereto with the lower section of the key extending into the recess of the engagement means. The method of installation enables alignment and securement of the core barrel in the pressure vessel without need for an assembler to enter the area between the core barrel support plate and the bottom of the vessel.

Abstract: A pipe loop arrangement for the closed primary system of a nuclear reactor. The heated reactor coolant flows through a horizontally positioned hot leg pipe while the return flow cooled reactor coolant flows through a cold leg pipe concentrically mounted within the hot leg pipe. A bell-mounted suction port and the high pressure discharge port of the reactor coolant pump are located within an outlet chamber with the steam generator. A transition piece slip fitted to an opening within the reactor vessel outlet flange connects the cold leg pipe to the inlet to the nuclear core. A flow shroud surrounding the pump discharge connects the pump discharge to the cold leg pipe, forms a volute for the pump discharge and separates the outlet chamber from the inlet chamber of the steam generator.

Abstract: Failure of the control-rod assemblies, particularly the control-rod guides and the WDRC's, by transverse flow of coolant through these members is prevented by directing the flow through a calandria above the guides. To avoid a high pressure drop in the coolant between the calandria and the outlet nozzles, the outlet nozzles are at the same level as the calandria. The calandria has hollow tubes between upper and lower supports. The length of the portion of the tubes between the supports is greater than the diameter of the outlet nozzles.

Abstract: Apparatus comprising a seal connector is disclosed for sealingly connecting flow channels in the core support plate with flow channels in fuel assemblies for use in a spectral shift pressurized water nuclear reactor. Spectral shift is obtained by displacing a portion of the light water in the core with deuterium oxide or a combination of deuterium oxide and light water or various gases such as helium during the initial state of reactor operation to harden the nuclear spectrum and thereby reduce excess reactivity and increase the production of fissile materials. The seal connectors provide a sealed flow channel for introducing the deuterium oxide into the core during the early stages of reactor operation and for reintroducing the light water into the core during the later stages of reactor operation.

Abstract: A locking ring for preventing inadvertent unfastening of threaded fasteners comprises a substantially cylindrical ring having a slot extending the entire width of the ring for allowing the ring to be easily compressed to fit into a counterbore that is slightly smaller than the uncompressed ring. The locking ring also comprises at least one protrusion on the outer surface of the ring that is capable of being inserted into an indentation in the counterbore when the ring is inserted in the counterbore. The locking ring is capable of having a threaded member disposed therethrough when the locking ring is disposed in the counterbore. The locking ring may also be crimped so as to engage the threaded fastener disposed therein so that the interconnection of the locking ring with the counterbore and threaded fastener prevents inadvertent unfastening of the threaded fastener.

Abstract: A nuclear reactor including, in the upper internals, a guide structure capable of effectively accommodating and guiding without binding the large number of neutron-absorber rods included in modern reactors of improved efficiency. The neutron-absorber rods include control rods, gray rods, and water-displacement rods. All rods are suspended in clusters from spiders or vanes. The upper internals of the reactor includes cruciform guides for the control-rod and gray-rod clusters. Each of these guides is composed of a plurality of vertical guide sections of transverse cruciform cross section. Plates extending throughout the cross-section of the reactor are supported between each pair of successive guide sections. The plates are perforated, the perforations in each plate being patterned to pass the water-displacement rod clusters. The plates are oriented so that the patterned perforations are aligned to serve as guides for the water-displacement rod clusters.

Abstract: An apparatus for moving and positioning a tool for plugging a defective heat exchanger tube of a steam generator in a nuclear reactor includes a base, a plug magazine supported on the base, a guidance mechanism mounting the plugging tool and a positioning mechanism supported on the base and mounting the guidance mechanism. The guidance mechanism is operable to align and position the tool relative to the plug magazine and the defective heat exchanger tube to correspondingly effect, upon operation of the tool, plug loading when the tool is located in a plug dispensing position adjacent to the plug magazine and plug unloading when the tool is located in a plug applying position adjacent to the defective tube. The positioning mechanism is operable to assume folded and unfolded conditions to transfer the guidance mechanism and the plugging tool therewith respectively between the plug dispensing and applying positions.

Abstract: Apparatus is disclosed for introducing a low neutron moderating fluid into the reactor vessel of a spectral shift pressurized water nuclear reactor and for distributing the moderating fluid through the lower core support plate into the fuel assemblies in the core.

Abstract: The lower end of a nuclear reactor core barrel (16) is laterally stabilized within the reactor pressure vessel (10) by four auxiliary support structures (100) equiangularly disposed about the periphery of the reactor lower hemispherical shell (12). The core barrel lower support plate (18) has keys (122) secured thereto for disposition within recesses (114) defined within crossbeams (102) of the structures (100) through which horizontal radial and tangential forces, as well as severe vertical loads, are transmitted from the core barrel (16) to the reactor vessel (10). Shock absorbers (120) interconnect the keys (122) and the crossbeams (102), and divergent brackets (104) serve to radially space the crossbeam (102) from the shell wall (12) so as to define a vertical coolant flow channel (108) through each structure (100).