Abstract: A modeling system that arranges the model in a hierarchical structure of communicating and independently executing object modules controlled by an overall supervisor. Each object represents a component or a system and includes an object controller which communicates with other object modules, an object error checker and an object model. The objects communicate through a database accessible by all objects. The structure of the object module and the hierarchical structure itself are standardized allowing new components or systems to be added by adding a standard object module which includes an object model that is unique to the object being modeled. The controller for an object causes subobjects upon which the object model depends for data to be executed prior to execution of the object model. Such bottom up model traversal insures that models do not execute until all needed data is available. The error check module checks the controller and model modules to make sure they are executing properly.

Abstract: An ultrasonic level measuring system includes a transducer mounted on the bottom of a pipe which launches acoustic pulses up through the pipe wall into the water. The pulses are reflected from the water surface and received by the transducer along with pulses reflected by the pipe wall and reverberations within the pipe wall. The system has a monitor mode in which a variable threshold for the reflected pulses is set by dividing the time after a trigger pulse into time bins and automatically establishing a threshold level for each time bin. In a signal search mode, the time bin containing the liquid level is identified from a histogram recording reflected pulses which exceed the threshold levels for the various time bins. In a normal operating mode, foreground calculations precisely calculating the liquid level in the identified bin alternate with background calculations which reassess the identification of the time bin containing the liquid level.

Abstract: A system for simulating human performance of a predefined procedure for operating equipment uses operator characteristics defining how human operator performance will be simulated. The operator characteristics include at least one among decision making rules, execution accuracy rules and rules defining operator response speed. The rules are weighted by a probability function having a randomized factor to produce a specified result a given percentage of the time when the simulation is repeated using the same operator characteristics. The results of the simulation are recorded and analyzed to evaluate performance of a human operator having the defined operator characteristics.

Abstract: An overwidth slitting method slits a metal strip into two lengthwise pieces while trimming the side edges from the strip. The metal strip is placed on parallel spaced apart conveyors adjacent a slitter for conveying the strip to the slitter. The conveyors are raised above a plurality of vacuum cups which are disposed between the conveyors and are spaced along the length of the strip. The raised metal strip is aligned with respect to the slitter and the raised conveyors are lowered to a position where the bottom surface of the aligned strip engages the vacuum cups between the conveyors. A vacuum is applied to the vacuum cups for holding the strip in alignment relative to the slitter and then the metal strip is advanced on the conveyors into the slitter while sequentially releasing the vacuum from each vacuum cup engaged with the bottom surface of the metal strip as it advances. The advancing metal strip is simultaneously slit into two lengthwise pieces while the side edges are trimmed therefrom.

Abstract: A modular fuel assembly for a nuclear thermal engine includes a plurality of fuel elements each having a fueled, truncated conical shell and an unfueled peripheral lip at the base of the shell with radial passages there-through. The fuel elements are nested with the lips seating one on top of another to form a stack of fuel elements with frusto-conical flow passages between the shells of adjacent fuel elements which are divided into channels by ribs on the conical shells. The stack of fuel elements is mounted in a cylindrical housing with the bases of the shells facing a central inlet opening at one end of the housing. Propellant enters the central inlet opening, is deflected radially outward by a deflector into an annular flow distribution channel from which it flows radially inward through the passages in the fuel element lips, through the flow channels of frusto-conical passages between the fueled shells where it is heated, and out through a central exhaust passage.

Abstract: An integrated information system is provided for a plant with interactive processes running in functional equipment subsets, such as a nuclear power generation plant. Sensors are operatively coupled to monitor processes and equipment in the plant, collecting sample data for assessing operational conditions and for predicting maintenance requirements based on loading of the equipment. One or more processors access the sample data and compares present conditions to diagnostic specifications, technical specifications and historical data stored in memory and indexed to equipment subsets and functional operating groups. The processor(s) generate prioritized reports to alert users to potential operational and/or maintenance problems. In addition to the prioritized reports, the processor accesses and outputs to the users reports of the diagnostic and technical specifications applicable to the process parameters exhibiting the potential problems.

Abstract: The effects of steam generator tube ruptures in a pressurized water reactor are mitigated by reducing the pressure in the primary loop by diverting reactor coolant through the heat exchanger of a passive heat removal system immersed in the in containment refueling water storage tank in response to a high feed water level in the steam generator. Reactor coolant inventory is maintained by also in response to high steam generator level introducing coolant into the primary loop from core make-up tanks at the pressure in the reactor coolant system pressurizer. The high steam generator level is also used to isolate the start-up feed water system and the chemical and volume control system to prevent flooding into the steam header.

Abstract: A zirconium sponge regulus from a Kroll reduction process is contaminated with zirconium chlorides, unreacted magnesium and magnesium chloride. The sponge regulus is vacuum distilled at a temperature of at least 800.degree. C. and then cooled. Before opening the distillation vessel and exposing the sponge regulus to the atmosphere, the vessel is backfilled with a gas comprising 25% to 75%, by volume, carbon dioxide, carbon monoxide or mixtures thereof, with the balance an inert gas and impurities associated therewith.The sponge regulus is less susceptible to fires when exposed to the air or crushing in downstream processing, and the metal surfaces of the sponge regulus are passivated whereby the overall contamination of the sponge is significantly reduced.

Abstract: Elongated coolant pumps suspended under steam generators within containment in a power plant with limited access space, are removed and replaced by an elongated maintenance cart with an elongated opening along one side in which the motor is received. Rollers support the cart for conveying the elongated motor in an upright position out from under the steam generator and onto an elevator. The elevator is lowered to transfer support of the cart and motor through trunnions to saddles straddling the elevator for rotation of the cart to a generally horizontal position. The elevator then raises the horizontally disposed cart carrying the motor to a higher floor where it is rolled off the elevator and out through the auxiliary equipment hatch.

Abstract: Instrumentation for nuclear reactor head-mounted incore instrumentation systems fabricated of low nuclear cross section materials (i.e., zirconium or titanium). The instrumentation emits less radiation than that fabricated of conventional materials.

Abstract: High velocity reactor coolant water in a boiling water reactor or a pressurized water reactor transports radioactive ions and particles from a nuclear reactor vessel to the balance of the reactor coolant system where they deposit on chromium (III) oxide-containing surfaces. These radioactive deposits are removed in a dilute chemical decontamination process wherein permanganate ion-containing reactor coolant water is circulated throughout a reactor coolant system to oxidize chromium (III) oxide surfaces of the system to chromium (IV) oxide. Formic acid is added to the permanganate ion-containing reactor coolant water and then the formic acid-containing water is circulated throughout the reactor coolant system to reduce unreacted permanganate ions in the reactor coolant water to manganous ions.

Abstract: A safety system grade dropped rod detection system for a pressurized water reactor (PWR) utilizes core exit thermocouples arranged in multiple trains and hot and cold leg RTDs to generate a safety system grade rod stop signal. The system generates from the temperature signals a relative power deviation (RD) and a curvature index (CI), which is the spatial second derivative of RD for each fuel assembly. The CI signatures not only provide rapid, reliable detection of dropped control rods, but also clearly identify failed and failing thermocouples.

Abstract: Surfactants in an aqueous solution is recovered from polychlorinated biphenyls and other aromatic organic compounds contaminating the solution. An electrical current is passed through a surfactant-containing aqueous solution contaminated with a colloidal dispersion of organic compounds at a voltage sufficient to electrochemically breakup the dispersion without polymerizing the surfactant. The contaminating aromatic organic compounds are then separated from the surfactant-containing aqueous solution. The separated surfactant-containing aqueous solution may be recirculated to a waste treatment process for cleaning additional organic compounds from contaminated equipment.

Abstract: There is provided a hermetically sealed dry-coupled transducer apparatus and system adapted for improved measuring of liquid level in a pipe or vessel, or for other instrumentation applications. The transducer system is characterized by having a hermetic seal at the junction of an acoustic window 33' and an outer shell 31' (thereby hermetically sealing a forward aperture of the outer shell), and a thin, compliant, threaded cap 46 enclosing a rearward aperture of the outer shell. The cap provides means for repetitively assembling and disassembling the transducer module, if necessary, prior to welding. In addition, a push rod applies acoustic coupling force to a piezoelectric transducer element to effect dry coupling to a surface, while the compliant cap prevents significant force transmission to the shell. The system exhibits limited reverberation and, moreover, is suitable for use in high-temperature environments.

Abstract: A nuclear reactor has a passive system for adjusting the pH of post accident water in the containment vessel. A basic liquid is stored in the containment vessel at an elevation above the maximum post accident water level. When radiation levels in the containment vessel exceed a predetermined, normal level the basic liquid is gravitationally drained into sumps located in the containment vessel below the maximum post accident water level where it mixes with emergency core cooling system water, raising the pH of the water to about 7.

Abstract: A crack propagation test specimen has a base metal and a clad metal. The base metal has an upper surface and a bottom surface with a hole extending from the bottom surface toward the upper surface. The cladding metal is supported on the upper surface of the base metal and has a first slot cut therethrough which is in fluid flow communication with the hole in the base metal. A second slot is cut in the cladding metal adjacent to the first slot for receiving a wedge. The first slot and the second slot define a wall which closes over the first slot when a wedge is forced into the second slot to simulate a hairline crack. A mechanically deformed metal sample is disposed in the hole in the base metal to simulate a stressed base metal supporting a cladding metal subject to hairline cracking.

Abstract: A fluid valve has a valve body with a valve seat for receiving a valve disc to close the valve. The valve seat is iron or steel. The valve disc is made of zirconium and has a zirconium oxide layer on disc surface which seats against the valve seat when the valve is closed. The valve has remained in a corrosive service for over six months where the original iron valves not having an oxide coated zirconium disc only lasted a few days.

Abstract: A passive containment cooling system for a nuclear reactor containment vessel. Disclosed is a cooling water distribution system for introducing cooling water by gravity uniformly over the outer surface of a steel containment vessel using an interconnected series of radial guide elements, a plurality of circumferential collector elements and collector boxes to collect and feed the cooling water into distribution channels extending along the curved surface of the steel containment vessel. The cooling water is uniformly distributed over the curved surface by a plurality of weirs in the distribution channels.

Abstract: A nuclear reactor plant is provided in which the reactor coolant system contains a dissolved solution of enriched boric acid. The boron-10 to boron-11 atomic isotope ratio of the enriched boric acid solution is greater than 19.8:80.2 at the start of the reactor core cycle. The nuclear reactor plant design provides for minimal mixing between the reactor coolant solution containing the enriched boric acid solution and the natural boric acid solution used during refueling operations.

Abstract: A pressurizer tank in a pressurized water nuclear reactor is mounted between structural walls of the reactor on a substructure of the reactor, the tank extending upwardly from the substructure. For bearing lateral loads such as seismic shocks, a girder substantially encircles the pressurizer tank at a space above the substructure and is coupled to the structural walls via opposed sway struts. Each sway strut is attached at one end to the girder and at an opposite end to one of the structural walls, and the sway struts are oriented substantially horizontally in pairs aligned substantially along tangents to the wall of the circular tank. Preferably, eight sway struts attach to the girder at 90.degree. intervals. A compartment encloses the pressurizer tank and forms the structural wall. The sway struts attach to corners of the compartment for maximum stiffness and load bearing capacity.