Abstract: A nuclear fuel assembly having a tube-in-tube control rod guide tube design that incorporates an end plug that extends axially upward to an elevation above the lower most grid where it is sealed at its tipper end to the lower end of the control rod guide tube. The guide tube lower end plug has a threaded recess in its upper surface that mates with a corresponding dashpot end plug threaded extension that is formed as an insert in the lower end of the guide tube. A hole formed through the outer wall of the guide tube end plug at the elevation of the lower portion of the recess provides a positive inspection port for assuring the proper seating of the dashpot. A method of manufacture of such a fuel assembly is also disclosed.

Abstract: An unirradiated nuclear fuel assembly component transport system that includes a clamshell-type inner liner that opens either along its axial dimension or from the top to load and unload the fuel assembly being transported. The exterior dimensions of the liner conform to a generic overpack tubular container that protects the liner from impact loads and fires.

Abstract: The present invention provides a method for removing niobium-rich second-phase-particle (SPP) deposits from zirconium-niobium alloy components. The method comprises washing a freshly pickled and rinsed zirconium-niobium alloy component with an acidified oxalic acid or ammonium oxalate washing solution. The method of the present invention results in a rapid, efficient and complete removal of surface SPP deposits from the zirconium-niobium alloy component without pitting, leaving behind a clean, shiny surface without the need to use water blasting or mechanical wiping operations.

Abstract: A solid state reversing AC motor starter that employs a DC power source and a power bridge employing insulated gate bipolar transistors that provide an ungrounded three phase AC output. The AC output is connected to the power input of the motor starter, which requires simultaneous RUN and Directional Commands to initiate valve actuation.

Abstract: A secure connection between the bottom nozzle of a nuclear fuel assembly and the control rod guide thimbles having two or four crimped pockets in the side wall of a bottom nozzle leg counterbore which are formed by drilling two or four blind holes through the top surface of the bottom nozzle. After attaching the bottom nozzle to the fuel assembly with a crimp bolt a pneumatic tool is then inserted into a flanged cup feature on the crimp bolt head and the flanged portion of the cup feature of the crimp bolt is deformed into the crimp pockets. The crimp pockets are contained within the leg counterbore and prevent the screw from rotating or falling out of the assembly in the event of preload loss or screw fracture.

Abstract: A loose parts collection weir that is a nearly cylindrical structure that is integrally attached to the lower deck plate or sludge collector top plate of a steam generator to retain loose parts along the feedwater and recirculation water transit path to the tube bundle. The weir is a near vertical structure built into the upper drum of the steam generator, near the periphery of the lower deck plate or sludge collector top plate in the vicinity of the downcomer annulus. The weir may contain a radially inwardly projecting lip which forms a pocket for loose parts to collect. As the feedwater flows toward the downcomer annulus, loose parts will tend to deposit onto the lower deck plate aided by gravity and be trapped by the loose parts collection weir.

Abstract: A current limiting DC motor starter employing a closed loop current measurement to provide precise current control that adapts to changing motor conditions, integrated with a solid state reversing motor starter. The motor starter further includes a calibrated overcurrent indication and a control system interface that reduces the likelihood that cable faults and other single failures will cause spurious actuation of the motor.

Abstract: An advanced gray rod control assembly (GRCA) is for a nuclear reactor. The reactor has a plurality of fuel assemblies each including numerous elongated fuel rods supported in an organized array by substantially transverse support grids, and a plurality of guide thimbles disposed through the support grids and along the fuel rods. The GRCA includes a spider assembly structured to provide controlled insertion of gray rod assemblies within the thimbles of the fuel assembly, thereby controlling the rate of power produced by the reactor. Each gray rod assembly includes an elongated tubular member, a first end plug, a second end plug, a substantially pure silver neutron-absorber disposed within the tubular member, and a support tube surrounding the neutron-absorber within the tubular member to resist silver-swelling. Delta-power of the reactor is improved by minimizing the exposed surface area of the absorber and distributing it among all of the rods of the GRCA.

Abstract: A solid state reversing DC motor starter that is testable on-line and satisfies the requirements for nuclear safety grade equipment. The motor starter employs a bridge of solid state switches which connect the polarity of the motor winding to conform to the desired direction of travel. The reversing switch bridge is in series with the main switch that is coupled in parallel with a reduced current by-pass flow path.

Abstract: A nuclear reactor plant protection system printed circuit card comprises a first logic device having a number of basic logic circuits, and a second logic device operatively connected with the first logic device for testing the number of basic logic circuits without taking the printed circuit card out of service. A nuclear reactor plant protection system printed circuit card comprises a first logic device producing a first output signal in response to a test signal, a second logic device producing a second output signal in response to the test signal, and a comparator for comparing the first output signal and the second output signal, wherein the test signal has a pulse duration that is less than a latching period associated with the printed circuit card. A method of testing and a nuclear reactor control system incorporating the nuclear reactor plant protection system printed circuit card is also provided.

Abstract: A manipulator for servicing tubes extending through a tube sheet having three major components: a base member, a block member, and a foot member. The base member has a holder for supporting tooling or inspection devices. The base member also has at least one gripper for releasably gripping a tube extending through the tube sheet. The block member is connected to the base member for linear movement and rotation relative to the base member. The foot member is connected to the block member for linear movement relative to the block member. The foot member has at least one, and preferably two grippers, for releasably gripping a tube extending through the tube sheet. The manipulator supports itself using the two sets of expandable and translatable grippers that anchor into the tube ends and can move from tube to tube by alternately engaging each set of grippers.

Abstract: The invention is a film-riding seal for a pump shaft that is resistant to the deposition of iron oxides such as hematite and goethite on the confronting, spaced apart, seal surfaces. The seal generally comprises a ceramic runner mounted on the pump shaft and an adjacent ceramic stationary sealing ring. The runner has a sealing surface and the stationary sealing ring has sealing surface confronting the runner sealing surface. The ceramic sealing surfaces include a catalyst selected from the group consisting of rhenium, ruthenium, rhodium, palladium, silver, osmium, iridium, platinum, gold and mixtures thereof.

Abstract: The invention provides a method for a sulfur based hydrogen production cycle wherein the sulfur products are maintained in a gaseous state throughout the cycle. The cycle includes a decomposition of a gaseous phase sulfur trioxide to sulfur dioxide and water in a decomposition reactor and an oxidation of gaseous sulfur trioxide with H2O in an electrolyzer to form sulfur trioxide and hydrogen. Costs are reduced by elimination of energy costs previous necessary to convert the sulfuric products from liquid to gas and back again and by extending the lifespan of decomposition catalysts through the elimination of water in an SO2/SO3 stream.

Abstract: A vacuum arc remelt furnace system that automatically monitors for electrode to crucible arcing in a VAR furnace. The vacuum arc remelt furnace system includes a crucible, an electrode provided within the crucible, and a spectrometer operatively coupled to the gap between the electrode and the crucible. The spectrometer detects the presence of one or more copper-specific light wavelengths in light that is present in the gap, and preferably generates an alarm and/or shuts the furnace down depending upon what is detected. Also, a method of operating a vacuum arc remelt furnace to automatically monitor for electrode top crucible arcing. The method includes collecting light that is present in the gap between the crucible and said electrode, and determining whether one or more copper-specific light wavelengths are present in the light. An alarm is generated and/or the furnace is shut down depending upon what is detected.

Abstract: A method is for establishing a nuclear reactor core loading pattern (LP) for fuel assemblies and burnable absorbers (BAs). The method establishes an optimum LP through the steps of: a) providing nuclear data representing fuel assemblies and BAs in a nuclear reactor core; b) depleting the nuclear data to form a reference core depletion; c) incorporating the nuclear data into a system of linear equations of a nuclear design quality flux solution method; d) defining the system of linear equations to include constraints which accurately represent the neutron physics of the reactor; employing the equations as a constraint matrix for a MIP solver to find an optimum core pattern solution; f) repeating steps b) through e) updating the constraints and objective functions to satisfy specified engineering requirements and establish an optimum core loading pattern. An algorithm for deriving the system of equations is also disclosed.

Abstract: A pressure vessel penetration sidewall adjacent a tube installed in the penetration by a clearance fit is inspected by passing an eddy current probe having a pair of circumferential coils through the tube. Eddy currents are induced in the pressure vessel as the probe passes through the penetration tube and degradation of the pressure vessel adjacent the clearance is determined based upon the eddy currents induced in the pressure vessel by the probe.

Abstract: An ultrasonic testing assembly structured to examine a test object, wherein the test object has a surface, and the examination examines the structure of the test object under the surface as well as the profile of the surface.

Abstract: A head assembly for a reactor pressure vessel includes a removable closure head, an array of control rod drive mechanisms, a seismic support platform, a missile shield assembly and a cooling system for drawing atmospheric air across electromagnetic coil stack assemblies. The cooling system includes: a lower shroud surrounding the coil stack assemblies with an end open to the atmosphere around the CRDMs; a plurality of extending internal ducts disposed within the array of CRDMs upwardly to an upper plenum disposed above the seismic support platform and a plurality of fan assemblies disposed on the upper plenum. The missile shield is disposed within the upper plenum. The cooling system effectively cools the coil stack assemblies during fuel cycles and does not hinder access to the CRDMs during an outage. The head assembly has lift legs for transporting either the entire head assembly as an integral unit or the structure above the seismic support platform a subassembly.

Abstract: A method and associated apparatus for detecting concealed fissile, fissionable or special nuclear material in an article, such as a shipping container, is provided. The article is irradiated with a source of fast neutrons, and fast neutrons released by the fissile or fissionable material, if present, are detected between source neutron pulses. The method uses a neutron detector that can detect and discriminate fast neutrons in the presence of thermal neutrons and gamma radiation. The detector is able to process high count rates and is resistant to radiation damage, and is preferably a solid state neutron detector comprised of silicon carbide.

Abstract: A method of fabricating a fuel assembly grid that includes providing a plurality of interconnected straps that form a lattice pattern, wherein the lattice pattern of the straps defines a plurality of cells, providing a sleeve that has a cylindrical portion and a flared portion, and inserting the sleeve into at least one of the cells. When inserted, at least a portion of the cylindrical portion of the sleeve will reside inside the cell and the flared portion will extend above the top end of the cell and overhang the perimeter of the cell. The flared portion is melted and flows over and fuses to the straps that define the cell. The straps may include weld tabs over which the melted material flows and to which it fuses. The melting and fusing steps also preferably cause any loose straps surrounding the cell to become attached to the sleeve.