Abstract: A combined makeup tank and passive residual heat removal system that places a tube and shell heat exchanger within the core makeup tank. An intake to the tube side of the heat exchanger is connected to the hot leg of the reactor core and the outlet of the tube side is connected to the cold leg of the reactor core. The shell side of the heat exchanger is connected to a separate heat sink through a second heat exchanger.

Abstract: A steam generator system for a pressurized water reactor which employs an external to containment steam drum and recirculation loop piping. The steam generator system changes the arrangement of a typical pressurized water reactor recirculation steam generator by relocating the functions of steam separation and feedwater preheating outside of the reactor coolant system. The steam generator system and thermal hydraulic conditions are selected in order to minimize the size of the steam generator heat exchanger component volume inside of the containment. The external steam drum component can be isolated in accident conditions when desired and is used as a source of secondary fluid inventory for improved decay heat removal capability and tolerance for loss of feedwater events. Thus, the steam generator component volume inside of the containment is reduced and the amount of maintenance required for the reactor coolant system components are similarly reduced.

Abstract: An integral pressurized water reactor that combines all of the components typically associated with a nuclear steam supply system, such as the steam generator, reactor coolant pumps, pressurizer and the reactor, into a single reactor pressure vessel. The reactor pressure vessel is itself enclosed in a containment pressure vessel that also houses a number of safety systems, such as the core make-up tanks, the primary side of residual heat removal heat exchangers, an automatic depressurization system and a recirculation system that enables continuous core cooling through natural circulation over an extended period of time. Actuation of the passive systems is done by single actuation of valves, powered from redundant batteries.

Abstract: A probe for transporting a nondestructive inspection sensor through a tube, that employs wheels to reduce friction. The radial travel of the wheels are mechanically linked through a cam and axially reciprocal plunger arrangement that centers the probe at tube diameter transitions. Internal wire bending is minimized and a dynamic seal is provided to facilitate an insertion force at the probe and reduce or eliminate compressive load buckling of the flexible cable carried by the probe. Like the wheel arrangement, radial travel of the seal segments are mechanically linked to provide probe centering.

Abstract: A core shroud is provided, which includes a number of planar members, a number of unitary corners, and a number of subassemblies each comprising a combination of the planar members and the unitary corners. Each unitary corner comprises a unitary extrusion including a first planar portion and a second planar portion disposed perpendicularly with respect to the first planar portion. At least one of the subassemblies comprises a plurality of the unitary corners disposed side-by-side in an alternating opposing relationship. A plurality of the subassemblies can be combined to form a quarter perimeter segment of the core shroud. Four quarter perimeter segments join together to form the core shroud.

Abstract: A captive screw assembly with a knurled end that rotates the captive screw in a hole in which it is mounted as the captive screw is pressed into the hole. The lower end of a ferrule of the captive screw assembly terminates within the hole and is flared against the side wall of the hole.

Abstract: A rod cluster control assembly having a control rod upper end plug formed in two parts and connected together with a flexible joint coupling located at or below a connecting finger on a spider vane. The upper portion of the upper control rod end plug is screwed into the connecting finger on the spider vane and lock welded between a lower portion of the finger and a shoulder on an abutting ledge of the upper portion of the end plug.

Abstract: An auxiliary wedge positioning apparatus/assembly 100 for use in a nuclear reactor pressure vessel 12 having riser piping 44 and 144 and a jet pump assembly 46 and 120, the apparatus 100 having a combination slide wedge 105 and spring 103 mounted on a restraint bracket body 102 having a transverse rail 110 with end gull-wing hooked protrusions 111 with sections 150, 152, 156 and wing stability attachment 155, the slide wedge used for placement between the riser piping 44 and 144 and jet pump assembly 46 and 120 to control vibrations during operation of the reactor vessel 12.

Abstract: An inspection vehicle structured to inspect a portion of the turbine disk, preferably the blade attachment hubs, while the turbine disk is disposed within a turbine housing assembly is provided. A turbine disk is generally planar but includes a inner hub and an outer blade attachment hub. The inner hub is coupled to a shaft and the blade attachment hub provides a surface to which removable blades are attached. The area between the inner hub and outer blade attachment hub is substantially planar. The inner and blade attachment hubs are the “inspection areas” that the inspection vehicle is structured to inspect. The inspection vehicle travels over, and is magnetically coupled to the planar surface between the two hubs.

Abstract: A telescoping rod control cluster assembly change tool for moving control rod assemblies among fuel assemblies in a nuclear facility. The operation of the tool is completely mechanical and the telescoping feature enables the tool to have a relatively low profile when it is being moved and stored without housing a control rod assembly. Rigidly supported alignment cards guide a gripper that attaches to the control rod assembly as the control rod assembly is withdrawn into the tool with the alignment cards preventing any lateral or rotational movement of the gripper.

Abstract: A method of monitoring a condition of a nuclear reactor pressure vessel disposed in a radioactive environment is provided. The method includes the steps of sensing a condition of the reactor pressure vessel with an instrument, transmitting a signal indicative of the condition of the reactor pressure vessel from the instrument to a powered wireless transmitting modem disposed in the radioactive environment, wirelessly transmitting a signal indicative of the condition of the reactor pressure vessel from the transmitting modem to a receiving modem in the line of sight of the transmitting modem, transmitting a signal indicative of the condition of the reactor pressure vessel from the receiving modem to a signal processing unit, and determining the condition of the reactor pressure vessel from the wirelessly transmitted signal.

Abstract: The present invention relates generally to nuclear reactors, and more particularly, to nuclear reactors having fuel assemblies that employ support grids. A method of reducing friction and physical contact between a fuel rod and support grid in a nuclear fuel assembly is provided. The method includes applying a lubricant composition to the outer surface of the fuel rod during fuel assembly fabrication and removing the lubricant composition afterward.

Abstract: A method for securing a captive screw assembly within a hole in a panel cover with a press. The press is centered over a hole in the panel and clamped to the panel. A force arm on the press is lowered to drive the captive screw into the hole and then the press is released from the panel.

Abstract: The present invention provides novel fuel assemblies for use with PWR nuclear reactors and power plants, and in particular, VVER nuclear reactors. The fuel assemblies offer enhanced structural stability, skeletal rigidity, and distortion (bow and twist) resistance to support high burn-up fuel management. Each fuel assembly may include a plurality of fuel rods, a plurality of control rods and guide thimbles, at least one instrumentation tube, and a plurality of grids. At least one fuel rod is replaced with a structural support replacement rod made from zirconium (Zr) alloy, stainless steel, or any other suitable material. The structural support replacement rod may be hollow or solid. The structural support replacement rods are preferably disposed at or about the periphery, and in some cases, the corners of the geometric array, which is preferably a hexagon or square.

Abstract: An integral pressurized light water reactor having most of the components of a primary side of a pressurized water reactor nuclear steam supply system housed in a single pressure vessel with a pressurizer separated from the remaining reactor system by a surge separator having multiple layers of separated steel plates with a number of concentric baffles extending therebetween. A circuitous flow path is provided through and between the plates and concentric baffles and a relatively stagnant pool of coolant is maintained within an innermost zone between the plates to provide thermal isolation.

Abstract: A robotic tubesheet walker having two rails connected by a central hinge, wherein the central hinge can be opened or closed by an actuation device. Upon each rail is mounted a carriage, wherein each carriage can move along its respective rail toward or away from the central hinge by means of a drive mechanism. Each carriage further contains at least two “gripper” attachment mechanisms, such as camlocks, to grip the tubesheet. The grippers either insert into tube holes within the tubesheet to fasten the respective carriage to the tubesheet, or retract to disengage. Further attached to the central hinge is a tool support fixture, and attached to the tool support fixture is a coupler that holds maintenance or inspection tools.

Abstract: A tubesheet anchor for suspending a tool from the underside of a heat exchanger tubesheet that inserts one end of two fingers into corresponding openings in the tubesheet and leverages one finger off the other to apply a frictional force to the sides of the tubesheet openings in which the fingers are inserted to clamp the fingers to the tubesheet.

Abstract: A method of refueling a nuclear reactor that includes the steps of removing the reactor vessel head and upper internals to a storage location and installing a cylindrical tank having open upper and lower ends, on the reactor vessel flange. The cylindrical tank is sealed to the reactor vessel and a penetration on the side of the cylindrical tank is sealed to a refueling canal that is connected to a spent fuel pool. The level of reactor coolant within the reactor vessel is then raised to at least partially fill the cylindrical tank to a level equal to that of the spent fuel pool. The refueling canal is then opened and a refueling machine supported on the reactor vessel is employed to transfer fuel assemblies between the core and the spent fuel pool.

Abstract: A silicon carbide Schottky diode solid state radiation detector that has an electron donor layer such as platinum placed over and spaced above the Schottky contact to contribute high energy Compton and photoelectrical electrons from the platinum layer to the active region of the detector to enhance charged particle collection from incident gamma radiation.

Abstract: A nuclear reactor having a penetration seal ring interposed between the reactor vessel flange and a mating flange on the reactor vessel head. Radial ports through the flange provide passage into the interior of the reactor vessel for utility conduits that can be used to convey signal cables, power cables or hydraulic lines to the components within the interior of the pressure vessel. A double o-ring seal is provided on both sides of the penetration flange and partial J-welds on the inside diameter of the flange between the flange and the utility conduits secure the pressure boundary.