Abstract: An advanced control room complex for a nuclear power plant, including a discrete indicator and alarm system (72) which is nuclear qualified for rapid response to changes in plant parameters and a component control system (64) which together provide a discrete monitoring and control capability at a panel (14-22, 26, 28) in the control room (10). A separate data processing system (70), which need not be nuclear qualified, provides integrated and overview information to the control room and to each panel, through CRTs (84) and a large, overhead integrated process status overview board (24). The discrete indicator and alarm system (72) and the data processing system (70) receive inputs from common plant sensors and validate the sensor outputs to arrive at a representative value of the parameter for use by the operator during both normal and accident conditions, thereby avoiding the need for him to assimilate data from each sensor individually.

Abstract: An advanced control room complex for a nuclear power plant, including a discrete indicator and alarm system (72) which is nuclear qualified for rapid response to changes in plant parameters and a component control system (64) which together provide a discrete monitoring and control capability at a panel (14-22, 26, 28) in the control room (10). A separate data processing system (70), which need not be nuclear qualified, provides integrated and overview information to the control room and to each panel, through CRTs (84) and a large, overhead integrated process status overview board (24). The discrete indicator and alarm system (72) and the data processing system (70) receive inputs from common plant sensors and validate the sensor outputs to arrive at a representative value of the parameter for use by the operator during both normal and accident conditions, thereby avoiding the need for him to assimilate data from each sensor individually.

Abstract: An advanced control room complex for a nuclear power plant, including a discrete indicator and alarm system (72) which is nuclear qualified for rapid response to changes in plant parameters and a component control system (64) which together provide a discrete monitoring and control capability at a panel (14-22, 26, 28) in the control room (10). A separate data processing system (70), which need not be nuclear qualified, provides integrated and overview information to the control room and to each panel, through CRTs (84) and a large, overhead integrated process status overview board (24). The discrete indicator and alarm system (72) and the data processing system (70) receive inputs from common plant sensors and validate the sensor outputs to arrive at a representative value of the parameter for use by the operator during both normal and accident conditions, thereby avoiding the need for him to assimilate data from each sensor individually.

Abstract: An advanced control room complex for a nuclear power plant, including a discrete indicator and alarm system (72) which is nuclear qualified for rapid response to changes in plant parameters and a component control system (64) which together provide a discrete monitoring and control capability at a panel (14-22, 26, 28) in the control room (10). A separate data processing system (70), which need not be nuclear qualified, provides integrated and overview information to the control room and to each panel, through CRTs (84) and a large, overhead integrated process status overview board (24). The discrete indicator and alarm system (72) and the data processing system (70) receive inputs from common plant sensors and validate the sensor outputs to arrive at a representative value of the parameter for use by the operator during both normal and accident conditions, thereby avoiding the need for him to assimilate data from each sensor individually.

Abstract: An advanced control room complex for a nuclear power plant, including a discrete indicator and alarm system (72) which is nuclear qualified for rapid response to changes in plant parameters and a component control system (64) which together provide a discrete monitoring and control capability at a panel (14-22, 26, 28) in the control room (10). A separate data processing system (70), which need not be nuclear qualified, provides integrated and overview information to the control room and to each panel, through CRTs (84) and a large, overhead integrated process status overview board (24). The discrete indicator and alarm system (72) and the data processing system (70) receive inputs from common plant sensors and validate the sensor outputs to arrive at a representative value of the parameter for use by the operator during both normal and accident conditions, thereby avoiding the need for him to assimilate data from each sensor individually.

Abstract: The present invention is a system which determines nuclear reactor control rod axial position using a deviation signature database generated from a current or reference signal pattern produced by one or more strings of axially dispersed fixed incore detector sections in the reactor core. The deviation signature database is produced by assuming deviant axial positions for the control rods in the core, calculating expected detector signals for the assumed positions and storing the deviation of expected signals from a calibration reference along with corresponding assumed rod positions. The signature database is periodically updated to take into account changed core conditions. When a change in detector responses is detected the system performs a signature analysis of the deviations in the signature database using the current deviation from the reference to search for the closest match.

Abstract: An advanced control room complex for a nuclear power plant, including a discrete indicator and alarm system (72) which is nuclear qualified for rapid response to changes in plant parameters and a component control system (64) which together provide a discrete monitoring and control capability at a panel (14-22, 26, 28) in the control room (10). A separate data processing system (70), which need not be nuclear qualified, provides integrated and overview information to the control room and to each panel, through CRTs (84) and a large, overhead integrated process status overview board (24). The discrete indicator and alarm system (72) and the data processing system (70) receive inputs from common plant sensors and validate the sensor outputs to arrive at a representative value of the parameter for use by the operator during both normal and accident conditions, thereby avoiding the need for him to assimilate data from each sensor individually.

Abstract: An advanced control room complex for a nuclear power plant, including a discrete indicator and alarm system (72) which is nuclear qualified for rapid response to changes in plant parameters and a component control system (64) which together provide a discrete monitoring and control capability at a panel (14-22, 26, 28) in the control room (10). A separate data processing system (70), which need not be nuclear qualified, provides integrated and overview information to the control room and to each panel, through CRTs (84) and a large, overhead integrated process status overview board (24). The discrete indicator and alarm system (72) and the data processing system (70) receive inputs from common plant sensors and validate the sensor outputs to arrive at a representative value of the parameter for use by the operator during both normal and accident conditions, thereby avoiding the need for him to assimilate data from each sensor individually.

Abstract: A plurality of neutron flux sensors (44,46,48,50) and a corresponding plurality of gamma flux sensors (62,64,66,68) are distributed throughout axial zones (24,26,28,30) of the core (14) at the same or closely proximate locations. A steady state comparison, or bias, between the signals of a given neutron/gamma sensor pair are monitored (314, 316), and a divergence (or convergence) can readily be detected through simple signal filtering, to detect a shift in the bias. The pattern of significant convergence and divergence throughout the core, is indicative of the thermal hydraulic stability of the core.

Abstract: In an electrical safety system primarily for controlling the insertion of absorber rods into a nuclear reactor core in response to a trip signal, two groups of switches are connected between a power supply and the rod magnets. One group of switches is controlled by signal converters which receive input signals from respective guardlines. The other group of switches is controlled by opto-isolator/photo-detector links which also receive the input signals from the guardlines. If fault conditions in the reactor are sensed by more than one of a group of fault sensors, the feeding of the input signals to the signal converters and the optical links is inhibited, and the switches open, thereby deenergizing the magnets.

Abstract: There is disclosed an inspection apparatus for peripheral surfaces of nuclear fuel pellets which includes a handling unit, an image pick-up device, a judging device and a sorting unit. The handling unit holds a prescribed number of nuclear fuel pellets in a line and rotates the same on their axes. The image pick-up device is disposed adjacent to the handling unit, and picks up image data as to the peripheral surfaces of the nuclear fuel pellets. The judging device is operably connected to the image pick-up device, and analyzes the image data outputted from the image pick-up device to output judging signals. The sorting unit is operably connected to the judging device and separates defective pellets from non-defective pellets based on the judging signals. The sorting unit includes a plurality of sorting members and actuators. The sorting members are disposed adjacent to the handling unit so as to correspond to the nuclear fuel pellets, respectively.

Abstract: Disclosed is a device for measuring dimensional characteristics of an elongate component which comprises:(a) an elongate rigid support that bears (i) an upper platform upon which is mounted a drive; (ii) a clamp mechanism for securing said component about its proximal end in a reference position; (iii) a lower platform which supports a pedestal for securing said component about its distal end in a reference position; and(b) a sensor carriage movably mounted to said rigid support and operatively connected to said drive for movement along the elongate extent of said support and having an opening penetrating therethrough for receiving said elongate component when it is secured by and substantially parallel to said rigid support, said carrier bearing a plurality of pivotally-mounted bell cranks spaced about said opening, each bell crank having a wheel for riding on said component during movement of the carrier and being in contact with a sensor capable of providing a signal correlative to displacement of the bell

Abstract: A control rod drop monitoring method and apparatus for use in a nuclear reactor including dedicated timers and displays to measure and display the drop time for each control rod when a reactor system trip occurs. The timers and displays may be made from CMOS technology, and may have millisecond resolution, if desired. The timers are initiated upon receipt of one or more reactor trip signals and are halted at the closure of switches for detecting the fully inserted or other preselected position of the control rods in the reactor core. The monitor system is designed for continuous operation. Reactor trip signals and limit switch signals are fed to latch circuits following a trip event or limit switch activation and are unaffected by subsequent changes in the state of the limit switches or trip signals. A manual reset is required to clear rod drop times. Also, a test mode is provided wherein all of the timers can be started and stopped, thereby providing a functional test of 100% of the monitor circuitry.

Abstract: The present invention is a component monitoring system which includes all sensor and plant component monitoring at distributed plant locations close to the sensors which are the source of the signals to be analyzed. Minimally preconditioned analog sensor signals are multiplexed and further conditioned by a sensor signal preprocessor that adjusts the gain and filters the sensor signals before being applied to an analog-to-digital converter controlled by a data acquisition computer. The analog sensor signals are converted into digital samples and stored in a data memory of a digital signal processor using a direct memory access technique. The data acquisition computer also controls the selection of sensors, gain, etc., based on commands from a controller. The digital signal processor, once sufficient sensor data has been collected, performs appropriate processing using known digital signal processing techniques.

Abstract: Protection against the consequences of a cluster of control rods falling accidentally is provided by four chains, each of which includes two neutron flux detectors (D1A, D1B), two primary treatment circuits (R1A, S1A and R1B, S1B) associated with said two detectors such that each provides a primary fall signal in the event of the flux measured by the corresponding detector decreasing rapidly, and an OR gate (P1) for providing an output fall signal from the chain in the event of at least one of said primary signals being present. The detectors (D1A, D4B, D3A, D1B, D2A, D3B, D4A and D2B) are angularly distributed around the vertical axis (A) of the core (2). A secondary treatment circuit (6) causes an emergency reactor stop to take place in the event that it receives fall signals at the outputs from at least two chains.

Abstract: An electrical ground fault detection and limitation system for employment with a nuclear reactor utilizing a liquid metal coolant. Elongate electromagnetic pumps submerged within the liquid metal coolant and electrical support equipment experiencing an insulation breakdown occasion the development of electrical ground fault current. Without some form of detection and control, these currents may build to damaging power levels to expose the pump drive components to liquid metal coolant such as sodium with resultant undesirable secondary effects. Such electrical ground fault currents are detected and controlled through the employment of an isolated power input to the pumps and with the use of a ground fault control conductor providing a direct return path from the affected components to the power source.

Abstract: The present invention obtains enthalpy rise deviations in core power distribution using core exit thermocouples 18 and an inlet temperature detector 20. The enthalpy rise deviations are used to determine control rod position change relative a rod reference position. Because rod position change is linear with respect to enthalpy deviation, the change can be determined from the slope using the deviation. By adding the change to a reference rod position the actual rod position can be determined.

Abstract: A display, a display method and an apparatus are disclosed which produce a summary display depicting function states using discrete state bars centered in one window of a two-window display. The status bars represent the states of functions in a process as determined by status decision trees. The discrete states are emphasized by reference lines which indicate the state of each function. Priority among functions is indicated by vertically ranking the bars with the most important function bar appearing at the top. Each bar includes the name of the function, the state of the function and a procedure name for a procedure which can be used to solve the problem identified. The discrete function state is also indicated by the width of the bar and the bar color. On both sides of each bar, a data quality indicator can appear when the quality of the data is less than the best.

Abstract: A method and apparatus for monitoring the neutron flux in the core of a nuclear reactor by means of a neutron detector which is composed of two electrodes between which a d.c. bias voltage is applied and which has a greater neutron sensitivity when the d.c. bias voltage is applied with one polarity than with the opposite polarity, which involves operating the nuclear reactor at a power level in the vicinity of zero, and applying a d.c. bias level with the one polarity between the detector electrodes and measuring the neutron-induced current flowing through the detector electrodes.To permit reversal of the bias voltage polarity, a safety interlock is provided to permit this to occur only if the bias voltage has been brought below a selected level.

Abstract: A method of compactly storing digital data includes the steps of sequentially entering a plurality of digital data entries into a shift register having a plurality of stages and summing successive groups of data entries as they are outputted from the shift register to produce singly compressed data entries that are subsequently entered into a second shift register. Sets of singly compressed data entries which are outputted from the second shift register are again added to obtain doubly compressed data entries which are entered into a third shift register. This process continues until a sufficient number of shift registers have been employed to accommodate all of the expected data entries.

Abstract: Dynamic logic units utilize magnetic cores of rectangular hysteresis loop material wound with an input winding, a pair of output windings connected to a CMOS flip-flop, and a d-c control winding. With a d-c current on the control winding, the core experiences flux reversals in response to a square wave on the input winding to generate output pulses which alternately switch the flip-flop to produce a square wave output which matches the input. In a first embodiment, the output windings are in the form of a center-tapped winding with the center tap grounded to provide a low impedance discharge path for the capacitors in grounded R-C filters on the inputs to the flip-flop which suppress voltage spikes. In a second embodiment, output windings on separate magnetic cores which share an input windings but only one of which has a control winding, are connected in opposition to eliminate the switching spikes in the signal applied to the flip-flop.

Abstract: A test tool for a reactor vessel level instrumentation system which simulates and verifies the values of input signals applied to the instrumentation system. The test tool includes potentiometers for simulating the signals produced by resistance temperature detectors, switches for simulating pump status and isolator overrange limit signals, a power supply, resistors and potentiometers for simulating temperature hot sensors and a pressure wide range sensor, and potentiometers and resistors for simulating differential pressure cell signals. The invention also includes a switchable meter for verifying the values of the various input signals simulated.

Abstract: A hybrid parallel/serial alarm management system in which sensor signals are intelligently processed to produce abnormality indication signals. The abnormality indication signals are divided into groups defined by functions of the system being monitored and are used to generate abnormality messages according to goal violation, process disturbance and process unavailability requirements for each function. Within each goal, process and support category the messages are ranked according to a predetermined local priority and chronologically within the same priority. Each function includes a spatially dedicated parallel display location which displays the highest priority portion of each category of messages associated with each function. The messages not displayed on the parallel display are displayed on a serial display unit in ranked order by category within function.

Abstract: A method and apparatus for monitoring and generating on-line, real time displays of two and three dimensional nuclear reactor core power distributions and off-line, periodically updated summaries of three dimensional nuclear reactor core power and burnup distributions is disclosed. The method and apparatus makes use of information obtained from inlet sensors and core-exit thermocouples to produce enthalpy rise values. Flux measurements are combined with enthalpy to produce power values. In one aspect of the invention, deviations from reference values are classified and displayed on a two-dimensional color graphics terminal where the various classifications are displayed according to a color code which enables a rapid and convenient method of analysis of the dynamics of the reactor operation.

Abstract: A method and apparatus for generating core-average and radially peaked, pointwise core axial power distributions of a nuclear reactor core from monitored responses of reactor flux obtained exterior of the core, such as responses obtained from ex-core power range nuclear detectors, and from responses of temperature obtained from selected core-exit thermocouples.

Abstract: A self-testing contact closure test circuit and method in which invalid logic states are artificially created in order to simulate a switch malfunction, and thus to determine whether the testing circuitry correctly identifies the invalid state. The system is designed to be used with switches such as those incorporating form "C" arrangements having two pairs of contacts which under normal circumstances are in opposite states.

Abstract: The remote measurement device comprises a supporting structure (5) consisting of a plane annular base connected to the end of a handling pole of great length, and a movable measuring assembly carried by the base (5) and consisting of a stage (30) movable in all directions of the plane of the base coming to rest on the plate (3). The stage (30) is integral with a tubular sleeve (36) the axis of which is perpendicular to the plane of the stage (30), and the supporting structure (5) has a thrust assembly (18) abutting against the outer surface of the sleeve (36). A tracer (38) with a movable rod is mounted on the sleeve (36), with its rod (40) in a radial direction and pointed towards the interior of the sleeve (36). For measurement, the sleeve (36) is slipped onto the cylindrical element (4), and the thrust assembly (18) moves the sleeve (36) and the stage (30) forming the movable measuring assembly as a result of a radial thrust exerted on the sleeve (36) in a zone diametrically opposite the tracer (38).

Abstract: Components and systems which impact technical specifications (tech specs) in a nuclear power plant are modeled in a set of cascading operability trees which represent the various combinations of component, system and parameter statuses which can result in non-compliance with the tech specs. Cutsets for the operability trees are entered into a cutset table in the data base of a digital computer which tracks the effect of a selected event up through the trees by repetitively searching the cutset table using the top event activated by the selected event as the selected event for the next search, until an activated top event is reached which is not entered in the cutset table as an event. A separate cutset evaluation table is used to assure that all the members of a multiple event cutset have been activated before the associated top event is activated.

Abstract: Apparatus and process for supervising and controlling the operations of loading and unloading of fuel of a nuclear reactor comprising an information processor 30 formed from several units. A treatment unit 31 receives control signals giving notably the position, the speed, the load of machines 7 and 16 operating the loadings and unloadings of groups in the core 2, the reactor pool 3, and the spent fuel pit 14. A programmable unit 34 furnishes command signals, previously recorded, representing the loading sequence.

Abstract: The responses of a nuclear reactor refueling machine to commands from a detachable control console are simulated to allow operation of the console for testing and operator training with the console removed from the machine. A simulator, which is connected to the console by the same input and output leads which normally connect the console to the refueling machine, includes a single pulse generator driven by a single three phase A-C motor to simulate movement of the refueling machine bridge, trolley and hoist. The motor drive signals generated on separate console output leads are all connected to the single simulator motor, while the brake release signals energize relays which switch the pulse signals generated by the single pulse generator to the console input leads corresponding to the selected refueling machine component drive motor.

Abstract: Apparatus and a method for use therein are disclosed for an analog signal processor, particularly one suited for use in nuclear power plant applications, which converts analog process signals to digital form and employs continuous on-line automatic calibration in order to accurately compensate for gain and bias errors occurring in its input analog circuitry.

Abstract: A nuclear reactor output power meter for measuring the output of a nuclear reactor from the concentration signal of radioisotope .sup.16 N in a primary coolant loop, having a transient response correction circuit. This correction circuit includes an approximated normal distribution response filter. This filter has a group delay time substantially corresponding to a single circulation time necessary for the primary coolant loop of the nuclear reactor. This filter also has a rise time in the step response substantially corresponding to a spread in the rise time of the .sup.16 N concentration signal due to agitation occurring during the single circulation time.

Abstract: In a protection system for a complex process control system which generates three independent actuation signals, the power circuit includes three pairs of switches arranged in three groups connected in series with each other and with a load device and a voltage source. Each group of switches includes two switches selected from different pairs of switches and connected in parallel. The same circuit topography is used for normally energized and normally deenergized loads with normally closed siwtches used with the former and normally open switches used with the latter. For testing the circuit, each group of switches is shunted by a resistor to form a leakage path through the configuration of switches. The impedance of each resistor is several times that of a closed switch such that the leakage current is insufficient to energize the load, but sufficient to be detected by a current detector which measures the current drawn from the voltage source.

Abstract: The present invention relates to a method and apparatus for testing analog process protection and control systems which are composed of a plurality of channels each serving to monitor a selected process parameter.

Abstract: A signal processor which applies non-linear dynamic compensation to an applied analog signal is tested by applying to a reference ramp signal compensation having a transfer function equal to the inverse of the transfer function of the signal processor. This test signal is applied to the signal processor in place of the sensor signal so that after the compensation of the processor is applied to it, the resultant signal should match the reference signal. When the signal processing is carried out digitally in a microcomputer and the response to the test signal is multiplexed back to the tester along with response signals from other microcomputers, variable time skewing of the returned test signal is eliminated by feeding the reference signal through a processing path parallel to that of the test signal and then comparing those two signals in the tester.

Abstract: Each of the either normally closed or normally open switches, in an n out of m voted power interface circuit having parallel connected groups of serially connected switches, is shunted by a high impedance resistor to form a leakage path through each group of switches. A detector associated with each group of switches, and responsive to the change of impedance produced by actuation of a resistor shunted switch in the group, generates an output signal, preferably a one bit digital signal, indicative of the state of the switches in the group in response to a sequence of test signals which selectively actuate fewer switches than are required to actuate the load controlled by the power interface. Compensation for large variations in supply voltage is provided by incorporating each group of switches into a resistance measuring bridge circuit in which the digital output signal is generated by a comparator connected across the bridge. Preferably, the bridge circuits share common reference voltage generating legs.

Abstract: A power interface circuit for normally deenergized loads includes the capability to test the operation and connections thereof without any possibility of accidental activation of the load. Three input signals may be received by the power interface circuit which supplies power to a load if two out of three of the input signals indicates activation of the load. A normally closed switch which ordinarily provides power directly to the voter is opened during testing so that the voter is supplied with a reduced power that is insufficient to activate the load. The normally closed switch is closed if any of the input signals indicate activation of the load. Current sensors are included in the power interface circuit to detect all possible logic combinations for activating the load and to detect the operation of the normally closed switch.

Abstract: Installation for electric connection of devices placed inside the containment of a PWR, comprising a first cable associated with each electric device, extending from the device and connected to a fixed connector installed above the cover of the reactor vessel. A second cable is connected to the connector and to a connector fixed to a plate remote from the reactor vessel. Each second cable is formed from several sections including a first section for connection to the fixed connector above the cover and to a lead-in connector at the end of a leak tight conduit installed horizontally above the cover and a second section inside the conduit. A third section is adapted for connection to a lead-out connector from the conduit and to the connector fixed to the plate at a distance from the reactor.

Abstract: A monitored nuclear reactor parameter, such as a startup range neutron monitoring signal, is filtered at a filter having a preselected time constant and amplified with the output being passed to one channel of a two channel comparator. The level of the amplification and the filter time constant are chosen to discriminate between normally increasing startup neutron density including the prompt-jump effect and exponentially increasing neutron density due to the occurrence of reactor casualty in view of the design parameters of the reactor. This same startup range neutron monitoring signal is passed unprocessed to the other channel of the two channel comparator. Comparison of the two signals is made with the binary output of the comparator flagging excess of the unprocessed signal over the filtered and amplified signal. Presence of the appropriate reactor flag is typically used to cause rod withdrawal blockage and/or SCRAM.

Abstract: A nuclear reactor power monitor utilizes radiation sensors, and a microprocessor implementing alpha-beta tracker equations. The use of alpha-beta tracker equations results in good noise suppression and fast follow capability. Therefore, alignment of the reactor power monitor is simplified and transients in the power level of a nuclear reactor can be detected.

Abstract: In a protection system for a complex process control system which generates three independent actuation signals, the power interface circuit includes three pairs of switches arranged in three parallel groups of switches connected in series with the load and a voltage source. Each group of switches includes two switches selected from different pairs of switches and connected in series. Normally closed switches are used with normally energized loads and normally open switches with normally de-energized loads. Logic gates control actuation of each individual switch in response either to an associated actuation signal or a test signal generated by a microprocessor. The microprocessor generates a sequence of patterns of test signals which result in various combinations of switch actuations. The current through each group of switches resulting from each combination of switch actuations is compared by the microprocessor with expected values to evaluate circuit performance.

Abstract: The dynamic logic of each channel of a multichannel protection system for a nuclear power plant provides a trip logic path and a global bypass logic path by which pulse signals from a clock source may be transmitted to a dc-to-dc power converter which energizes the undervoltage coils for a pair of contactors in the reactor trip switchgear. Each of the logic paths is constructed of basic logic units which in turn, each include a toroidal core of rectangular hysteresis loop magnetic material having a control winding which must be energized by a dc current in order for pulses applied to an input winding to appear at an output winding. Blockage of pulses through any one of the serially connected basic logic units in a logic path terminates the flow of pulses to the converter through that logic path. The control windings of corresponding logic units of the trip logic path in each channel are energized by one of a set of redundant sensors which monitor one of a plurality of reactor trip parameters.

Abstract: A method of determining the operability of a source range detector located adjacent a nuclear reactor in which the source range detector generates a count corresponding to the neutrons emitted by the reactor when the reactor is operating within the source range and a predetermined voltage is applied across the electrodes of the detector, the detector being subject to destruction when the reactor power level is above the source range and the predetermined voltage is applied across its electrodes.

Abstract: A wide range monitor apparatus for the output from a nuclear reactor has a logarithmic count rate measuring circuit and a Campbel measuring circuit corresponding to different neutron flux density ranges of the neutron flux output from a neutron detector. The apparatus monitors the nuclear reactor output as a single output which has a linearity with the neutron flux density over a wide range thereof. A logic circuit combines two comparison discrimination signals obtained by comparing low and high comparison voltages corresponding to the hysteresis width in an overlap region of the outputs from the two measuring circuits with detection output voltages from the two measuring circuits. One of the outputs from the two measuring circuits is selected in accordance with the logical level signal obtained by combining the two comparison discrimination signals by the logic circuit.

Abstract: A portable, microprocessor-based test instrument for the calibration, check testing, and checkout of nuclear power reactor systems under simulated operating conditions. The instrument includes a master microprocessor bus having direct communication to interchangeable plug-in printed circuit boards. Applications to which the invention may be put include rod control simulation and analysis, neutron monitoring system analysis, and rod block monitoring system simulation and analysis. The test instrument electronically interconnects at any of a plurality of points within a reactor control and monitoring system. The electrical network from the point of interconnection to the core rods is disabled and the test instrument, receives serial control command signals as would the disabled portion of the network. The test instrument also generates appropriate acknowledgements and response signals. Alternatively, a test instrument can generate faulty response signals to simulate improper command responses.

Abstract: This device is intended to measure the thermal power released locally in an area of the core of a nuclear reactor and comprises a conduit in the core of the reactor from the outside which contains a body which absorbs gamma radiations located at the measuring area and associated with a measuring thermocouple. A first junction of the thermocouple is placed so that it is brought to a temperature essentially representative of that of the reactor coolant and slightly affected by the gamma flux, and a second junction is placed so that it is brought to a temperature representative of that of the body which absorbs the radiations. The device comprises a supplementary thermocouple which has a first junction located near that of the measuring thermocouple and a second junction brought to a reference temperature.

Abstract: An apparatus for monitoring and evaluating the degree of risk associated with continued operation of a nuclear power plant while one or more plant components has failed or is otherwise unavailable. The apparatus has several functional sections, including means for storing a plant-specific data base of component-level core damage logic paths and component level failure probabilities, means for selecting plant condition scenarios by modifying the component failure probabilities to represent plant components actually or potentially unavailable, means for associating a figure of merit with the change in risk of core damage resulting from the unavailable components, and means for displaying the figure of merit relative to a base or reference value. As an interactive tool in the plant, the apparatus PSES displays the probability or risk of core damage almost instantly for any given state of plant readiness.

Abstract: A circuit for biasing a solid state crystal used as a radiation detector in hich the passage of the initial gamma ray pulse from the explosion of a nearby tactical nuclear weapon is utilized to temporarily remove the bias from said crystal for a time sufficient to permit the fast neutron pulse from the same explosion to pass by without permanently damaging the counter crystal. The circuit comprises an RC circuit between the bias supply and the crystal with a reverse biased diode across the capacitor.

Abstract: A system for monitoring a limited number of operating conditions in a nuclear reactor and for graphically displaying same on a display device is disclosed. The system parameters selected are those which typically change as a result of a reactor trip. As long as these system parameters remain within a "post-trip window" on the graphic display, the power plant is operating normally. If, however, any of the foregoing system parameters falls outside this "window", this is an immediate indication to the power plant operator to institute the necessary procedures to remedy same. A sequential controller (26) is provided to continuously sequentially sample the foregoing operating parameters and to transmit data regarding same to the display device.

Abstract: Safety actuator release device incorporating a release means, whereof one output supplies an output signal which can have two logic states, one of these states corresponding to the release of the actuator and the other state corresponding to the absence of the release of the actuator, testing and control means of said release means, whereby said testing and control means have two control inputs receiving the control signals from the release means in order that the output signal has one of two logic states and a test input receiving a test signal in such a way that said output supplies an output signal, whose logic state corresponds to the release of the actuator, even if the control signals lead to the supply of an output signal corresponding to the absence of release, wherein the testing and control means are constituted by three primary windings of a magnetic amplifier, two of these primary windings receiving direct currents corresponding to the control signals, while another of these windings is a test win