Abstract: An apparatus for repairing a shroud in which one or more seam welds are cracked. The repair involves the attachment of a splice bracket to the shroud so that the bracket bridges the cracked weld seam and is applicable to both vertical and horizontal weld seams. The bracket is intended to structurally replace the shroud seam weld which is cracked. Multiple splice brackets can be placed along the length of a crack. Each splice bracket is attached to the shroud by a plurality of tapered fastener assemblies.

Abstract: A method for stabilizing direct current generated by neutron activation of a plurality of interconnected .beta.-emitter (nuclear decay electron) cells, which are placed in a specific position in the out-of-core region of a light water nuclear reactor. The method entails a synergistic combination of neutron-absorbing isotopes, in specific relationship to each other, the amount of each absorber and their respective locations in the neutron flux field being chosen to render the total current-time characteristic substantially constant over a significant number of reactor full-power-years. The method enhances the current output and lifetime of the current generator by greatly deferring burn-up of the neutron absorbers. If configured as a DC voltage source for powering radiation-hardened, high-temperature integrated circuitry contained in the reactor pressure vessel, voltage regulation circuitry is not necessary.

Abstract: A welding process and an apparatus used therein for providing a significant improvement in the detrimental tensile residual stress condition on the root side of welds, especially on the inside wall of piping welds. The method combines an extremely thin weld joint design with a non-circular cylindrical, thin welding electrode having an elongated cross-sectional shape. During welding, the elongated dimension is aligned parallel with the length of the weld joint. This combination enables joining of piping and other residual stress-sensitive components with both the initial weld joint preparation and the completed weld having a uniquely thin width and with a high aspect ratio of depth to width. Use of this high-aspect-ratio weld joint process substantially mitigates welding-induced residual stresses, without the normally required internal water cooling.

Abstract: A reference block for determining the characteristics of individual ultrasonic transducers contained within right circular cylinder type ultrasonic probes. Right circular cylinder type ultrasonic probes are designed for performing ultrasonic inspections of components that can only be examined from within a center line access hole. The reference block is made from the same material as that of the right circular cylinder type components which will be examined using the ultrasonic probe being characterized and is designed with curved contact surfaces that specifically duplicate the surfaces of those components. This reference block can be used to calibrate instruments prior to contact inspection using angle-beam search units. The reference block is also useful for checking the performance of both angle-beam and straight-beam search units and for evaluating instrument performance.

Abstract: A welding electrode for providing a significant improvement in the detrimental tensile residual stress condition on the root side of welds, especially on the inside wall of piping welds. The electrode has a tungsten alloy blade. The blade is made from sheets of tungsten alloy by cutting or stamping. The preferred shape of the blade is an isosceles triangle. The base of the flat triangular blade is secured in a slot formed in an electrode holder. The electrode holder is preferably T-shaped, with the shank of the holder being connected to a conventional welding torch. The holder is made of electrically conductive material, whereby the blade is coupled to the torch for producing an electric arc at the blade tip for welding. The blade is optionally covered with a ceramic coating to prevent arcing to the side walls of the groove formed between the parts being welded. A further option is to incorporate insulating stand-offs which protrude from both flat sides of the electrode blade.

Abstract: A textual database system in which concepts, i.e. blocks of text which are related or rely upon one another, are linked together by a database engine. Numerical variables can be embedded in text, which text is automatically updated as those variables change. As a textual document is being written, the system enables authors to record their thoughts, attaching them to the relevant sections of the document. It electronically captures and stores references to other reports or databases. As references are made, the system automatically establishes bi-directional links between the pieces of information. Also the genealogy of first and later versions of a textual block is recorded automatically.

Abstract: A tool for protecting a boiling water reactor component against damage by a shroud repair assembly suspended from a cable and lowered into the downcomer annulus. The tool has a roller with an outer surface made of a material which will not scratch the surface of a tie rod of the shroud repair assembly as the latter is lowered relative to the roller. The tool has sets of opposing grippers made of aluminum alloy which are pressed against opposing surfaces of the shroud and the reactor pressure vessel with sufficient force to clamp the tool in the annulus. The pressing force is generated by air-actuated cylinders which are actuated remotely. In one embodiment, the roller is fixed and acts as a stop to limit tangential travel of the suspended assembly. In another embodiment, the roller is displaceable in a tangential direction in response to remote actuation of a pair of air-actuated positioning cylinders.

Abstract: A method and an apparatus for repairing a core plate having a cracked support structure. The method entails the step of providing a vertical compression load path between the core plate and one or more control rod guide tubes. This is accomplished by installing a plurality of load-bearing elements between the core plate and the flanges of the guide tubes. Each load-bearing element is placed between the core plate and a guide tube flange so that core plate pressure loads are reacted by the weight of the fuel rather than the core plate support structure. The load-bearing element may take the form of a solid ring, a C-shaped spring collar or a hinged collar.

Abstract: A strongback for lowering a tie rod into the downcomer annulus of a boiling water reactor during a shroud repair operation. The tie rod strongback is suspended from a cable via a cable adaptor at its upper end. The lower end of the strongback is coupled to a tie rod adaptor, which in turn couples to the top of the tie rod. The strongback is a welded assembly of square tubes, channels for reinforcing the joints of the welded tubes, and upper and lower couplings. In particular, the strongback has mutually parallel first and second rigid linear members which are disposed vertically when the strongback is suspended from a plumb cable. The second rigid linear member is connected to the first rigid linear member by a relatively obliquely disposed third rigid linear member.

Abstract: A support structure for clamping the inner coils and inner lamination rings of an inner stator column of an electromagnetic induction pump to prevent damaging vibration. A spine assembly, including a base plate, a center post and a plurality of ribs, serves as the structural frame for the inner stator. Stacked alignment rings provide structure to the lamination rings and locate them concentrically around the spine assembly central axis. The alignment rings are made of a material having a high thermal expansion coefficient to compensate for the lower expansion of the lamination rings and, overall, provide an approximate match to the expansion of the inner flow duct. The net result is that the radial clamping provided by the duct around the stator iron is maintained (approximately) over a range of temperatures and operating conditions.

Abstract: A telescoping mast with zero clearance which can be used in a fully automatic, relative positioning refueling machine. The telescoping mast consists of a series of nested tubes separated by spacers of unique design. Each spacer consists of an upper spacer assembly attached to the upper end of an inner tube segment nested in an outer tube segment and slidable inside the outer tube segment; and a lower spacer assembly attached to the lower end of the outer tube segment and slidable outside the inner tube segment. The spacer assemblies are preferably made of molded plastic, for example, polyethylene. Each spacer assembly is formed by a spacer ring and a plurality of corrugated members connected at one end to the spacer ring. The distal ends of the corrugated members of the upper spacer assembly contact the distal ends of respective ones of the corrugated members of the lower spacer assembly when the inner tube segment is in an extended position relative to the outer tube segment.

Abstract: A method for ensuring the distribution of noble metal in the reactor circuit during plant application without measuring the reactor water for noble metal content by chemical analysis. The method involves the measurement of electrochemical corrosion potential in an autoclave or a high-flow test section that is connected to the reactor water circuit through sample lines downstream of the injection port, preferably the point in the reactor circuit which is furthest from the injection port. If the noble metal flows into the autoclave or test section at these distant points in the reactor circuit, then the noble metal will deposit on the test specimens inside the autoclave or test section.

Abstract: A sensor system for mapping absolute acoustic noise intensity in a three-dimensional acoustic noise field. Localized noise sources within a vessel are extracted using a distant array of transducers mounted on the vessel wall. The absolute intensity can be measured even when totally masked by background noise at the transducer locations. The system includes an integrated transducer installation. Each transducer is an accelerometer which is mounted on the vessel wall using a rigid attachment rod which serves as an ultrasonic waveguide. The output of each transducer is split into low- and high-frequency components, the low-frequency component being a function of the vibrational displacement of the localized portion of the vessel wall and the high-frequency component being a function of the vibrational/ultrasonic waves propagating through the localized portion of the vessel wall.

Abstract: A pre-oxidation treatment for decreasing the amount of chromium deposited on out-of-core surfaces such as the internal surfaces of recirculation piping. Hydrogen peroxide is injected into the reactor coolant through the recirculation line during reactor shutdown after H.sub.2 addition has been terminated. A dilute acid solution (e.g., nitric acid) is also injected into the loop to serve as a catalyst to accelerate the oxidation reactions. An appropriate water pH (e.g., in the range of 5-6) is maintained by acid injection. The coolant temperature during shutdown is maintained at approximately 150.degree. C. or lower. The peroxide concentration in the recirculation piping is maintained at approximately 1 ppm or higher as needed. The oxidation process should be allowed to take effect in the proposed temperature range with the recirculation pump in operation for at least a few hours to 24 hours, depending on the temperature and the oxide film thickness.

Abstract: A tool for lifting a tie rod off of the refueling floor and lowering the tie rod into the downcomer annulus of a boiling water reactor during a shroud repair operation. The tie rod lifting tool can be attached to the end of a strongback suspended from a hoisting cable or to the end of the cable itself. One embodiment of the tie rod lifting tool has redundant locking pins which interlock with corresponding holes formed in the end of the tie rod. The locking pins are moved out of locking engagement in response to actuation of respective pneumatic cylinders. The locking pins are latched so that the tie rod cannot be disengaged from the lifting tool unless the latches are first manually released by an operator using a handling pole.

Abstract: A reactor protection system having four divisions, with quad redundant sensors for each scram parameter providing input to four independent microprocessor-based electronic chassis. Each electronic chassis acquires the scram parameter data from its own sensor, digitizes the information, and then transmits the sensor reading to the other three electronic chassis via optical fibers. To increase system availability and reduce false scrams, the reactor protection system employs two levels of voting on a need for reactor scram. The electronic chassis perform software divisional data processing, vote 2/3 with spare based upon information from all four sensors, and send the divisional scram signals to the hardware logic panel, which performs a 2/4 division vote on whether or not to initiate a reactor scram. Each chassis makes a divisional scram decision based on data from all sensors. Each division performs independently of the others (asynchronous operation).

Abstract: A method and an apparatus for stabilizing a shroud against lateral deflection. The shroud restraint stabilizer has springs which exert radially inwardly directed forces that resist lateral deflection of the shroud relative to the reactor pressure vessel. Each stabilizer includes a stabilizer preload spring and a seismic restraint spring. Each spring has resilient arms integrally connected to opposing ends of a common main support span. The resilient arms of the stabilizer preload spring form a first leaf spring of relatively lower stiffness and the resilient arms of the seismic restraint spring form a second leaf spring of relatively higher stiffness. The different stiffnesses are achieved by providing the first leaf spring with a longer base than that of the second leaf spring. The pads on the seismic restraint spring are in contact with the reactor pressure vessel, but are not preloaded under operating conditions. The seismic restraint spring is loaded in response to lateral deflection of the shroud, e.g.

Abstract: A nuclear power generation complex constructed on a stratum of rock overlain by soil deposits. All major structures in the power generation complex (i.e., reactor, turbine, radwaste and control buildings) are located on a common mat foundation that houses elastomeric bearings or seismic isolators. The foundation includes a concrete slab supported by a plurality of pedestals. Each of the pedestals is embedded in the rock. Preferably, each pedestal is a circular metal shell filled with underwater-type concrete, and the concrete slab is reinforced with steel bars. For example, a reactor building is supported by one set of seismic isolators mounted on the concrete slab, and a turbine building is supported by another set of seismic isolators mounted on the concrete slab. The isolators filter out a great deal of the seismic vibratory inputs. The common mat foundation eliminates differential movements between the buildings.

Abstract: A device for generating direct current by neutron activation of a plurality of series-connected beta-emitter (nuclear decay electron) cells, located in the out-of-core region of a light water nuclear reactor. The device can be used as either a current source, or preferably configured as a DC voltage source, capable of powering low-power, radiation-hardened, high-temperature integrated circuitry contained in the reactor vessel. As such, the device acts like a DC battery that is activated by (n, .gamma.) reactions, both thermal and epithermal (by resonance capture). The device is not operable until exposed to a substantial neutron flux, so it has unlimited shelf-life and is not radioactive during manufacture In the preferred embodiment, an isotope of the metallic rare-earth element dysprosium is configured in a "sandwich" geometry to generate sufficient current that a useful steady voltage can be generated by means of a simple voltage regulation circuit.

Abstract: A tool for pushing a suspended shroud repair tie rod assembly radially inward in the downcomer annulus of a boiling water reactor. The tie rod pusher tool includes a pole adaptor for coupling to the end of a service pole, a pole adaptor extension having one end connected to the pole adaptor, a mounting channel connected to the other end of the pole adaptor extension, a hydraulic spreader mounted on the mounting channel, an adaptor bracket having a proximal end connected to the pivoting member of the hydraulic spreader, a rocker plate pivotably mounted on the distal end of the adaptor bracket, and a saddle mounted on the rocker plate. Using a service pole, the tool is lowered into a position whereat the saddle contacts the tie rod assembly when the hydraulic spreader is actuated. In the open position, the saddle bears against the tie rod assembly with sufficient force to displace the assembly radially inward until the clevis hook clears the clevis pin.