Abstract: A dual mode electronic identification system using a tag which has a RF receiver and transmitter contained therein. In the first mode the tag responds to an interrogation signal by transmitting identification data to the interrogator. In the second mode the tag periodically transmits an identification beacon signal to a directional sensing antenna which uses the signal to compute the position of the tag. The power supply for the tag operates from an internal battery or from power received from a portal signal via a tag receiving antenna. The battery can be automatically turned off when the tag is in the portal area and the unit can be shifted into the battery operated beacon mode when the tag is removed from the portal area.

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: A method of counting a plurality of pulses representative of randomly occurring events includes the steps of counting the number of pulses, having an amplitude exceeding a first threshold amplitude, which occur during a predetermined sampling period to obtain a first count and counting the number of pulses, having an amplitude exceeding a second threshold amplitude, which occur during the sampling period to obtain a second count. The second count is compared to a predetermined number and the counts for that sampling period are rejected if the second count is too large. If the second count is not too large, the true count is calculated by subtracting the second count from the first count. This counting procedure is repeated for a preselected number of successive sampling periods. After the final sampling period, all of the true counts are added to obtain an accumulated count and the accumulated count is multiplied by a scaling factor to obtain an output count.

Abstract: Signals from redundant sensors located throughout a pressurized water reactor (PWR) nuclear power plant are processed in four independent channel sets each of which includes a plurality of independent microcomputers which calibrate, convert to engineering units and calculate partial trip signals and engineered safeguard actuation signals from the sensor signals for use in the conventional voting logic of a plant protection system. The primary and secondary partial trip and engineered safeguard actuation functions associated with various postulated abnormal events are allocated to different independent microcomputers in the channel set for reliability. A test unit common to the channel set automatically, rapidly bypasses and tests each protection function independently while the other protection functions in the channel set remain on-line and also continually tests each microcomputer through a dummy test function performed along with the assigned protection functions.

Abstract: A position indication system for detecting the position of an elongated, metallic member which is linearly movable between first and second positions along an axis corresponding to its longitudinal dimension. A sensor is operatively associated with the member for producing a first output signal which corresponds to the position of the member and which fluctuates with changes in the temperature of the member. A temperature monitoring device is operatively associated with the member for monitoring its temperature and for producing a second output signal which varies in direct response to changes in the temperature of the member. A combining circuit is connected to the sensor and to the temperature monitoring device for receiving the first and second output signals and for producing a third output signal which represents the position of the member compensated for changes in temperature of the member.

Abstract: A rod position indicating system for a pressurized water reactor generates within containment redundant sets of digital detector signals and applies both sets to each of two communications buses each controlled by a separate bus controller/serial output device located inside of containment. A pair of redundant serial data links transmits the redundant data from each bus controller/serial output device through containment to a dedicated CRT display and the plant computer each of which generates rod position displays from redundant information selected from one of the data links. The data for each rod is selected individually from the redundant signals received on the one data link. Rod position is presented in bargraph form on a multi-page display which includes overall status information along with the detailed presentations.

Abstract: Numerous signal conditioning circuits on a plurality of printed circuit boards are calibrated remotely by a signal processing unit which sends coded signals to each board, either sequentially or in parallel, to connect either on-board or off-board test signals to one of the conditioning circuits in place of its field generated input. The processing unit utilizes the actual and expected responses of each conditioning circuit to low and high test signals to generate a gain and an offset which are applied to the conditioned field signal to provide a calibrated signal. The time constant for each conditioning circuit is also measured periodically, or upon a selected temperature change, for use in generating a minimum waiting period for obtaining valid data following transfers between the field generated signals and the test signals.

Abstract: A method for temperature compensating a position indicator which includes a sensor for producing an output signal whose magnitude corresponds to the position of an element that is linearly movable between first and second positions and which is subject to changes in temperature within a given temperature range and wherein the output signal of the sensor contains a temperature variable offset component and the rate of increase of the output signal as the element moves from the first to the second position fluctuates with changes in temperature.

Abstract: Coils placed at spaced locations along the path of an axially movable magnetically permeable and/or electrically conductive rod, which changes the impedance of each coil as it passes through, are connected in sets with each set comprising two series connected groups of equal numbers of parallel connected, non-adjacent coils energized by an a-c source. The voltage at the common node of each set of coils, which fluctuates as equal and unequal numbers of coils in the two groups in a given set are penetrated by the end of the rod, is compared with the voltage at the common node of a pair of series connected resistors, also energized by the a-c source, to generate one digit of an unambiguous, multi-digit, digital rod position signal. Since only one signal wire to the remote electronics is required for each set of coils, and since they only carry a voltage signal, the required wiring is minimized.

Abstract: An inadvertent approach to criticality in a nuclear fueled electric power generating unit is detected and an alarm is generated through on-line monitoring of the neutron flux. The difficulties of accurately measuring the low levels of neutron flux in a subcritical reactor are overcome by the use of a microcomputer which continuously generates average flux count rate signals for incremental time periods from thousands of samples taken during each such period and which serially stores the average flux count rate signals for a preselected time interval. At the end of each incremental time period, the microcomputer compares the latest average flux count rate signal with the oldest, and preferably each of the intervening stored values, and if it exceeds any of them by at least a preselected multiplication factor, an alarm is generated.

Abstract: A method is described for electrically converting an analog signal into a digital representation in a manner that maximizes noise rejection. The digital representation is formed from a preselected number of discrete points corresponding to sampled approximations of the analog signal. In establishing the magnitudes of the respective points, digital samples of the analog signal are taken at a predetermined number of discrete coordinates along the analog signal on either side of the respective discrete points. The predetermined number of coordinates are averaged and employed as corresponding approximations for the respective discrete points in the digital representative reproduction of the analog signal. The effects of harmonics of power line frequencies associated with processing electrical equipment are minimized by sampling the discrete coordinates for a particular point over an integral number of cycles of the power line frequency.

Abstract: In a nuclear reactor flux mapping system consisting of two operationally independent electronic subsystems for controlling the positioning of separate groups of in-core detectors within core thimbles, a communications link is provided between the two subsystems to enable one subsystem and its associated group of detectors to assume the flux mapping responsibility of the other subsystem in the event of a subsystem malfunction.

Abstract: In an automatic flux mapping system utilizing a microprocessor for control and data information processing, signals from the in-core detectors providing the flux mapping operation are converted to a frequency link and are made available to the microprocessor via a programmable timer thus minimizing the participation of the microprocessor so that the microprocessor can be made more available to satisfy other tasks.

Abstract: A method is described for electrically converting an analog signal into a digital representation in a manner that maximizes noise rejection. The digital representation is formed from a preselected number of discrete points corresponding to sampled approximations of the analog signal. In establishing the magnitudes of the respective points, digital samples of the analog signal are taken at a predetermined number of discrete coordinates along the analog signal on either side of the respective discrete points. The predetermined number of coordinates are averaged and employed as corresponding approximations for the respective discrete points in the digital representative reproduction of the analog signal. The effects of harmonics of power line frequencies associated with processing electrical equipment are minimized by sampling the discrete coordinates for a particular point over an integral number of cycles of the power line frequency.