The invention relates to methods for protecting a nuclear reactor core, such as a boiling water reactor core, from fuel and cladding damage due to thermal hydraulic instability in extended operating power flow conditions and, in particular, when an extended power uprate is implemented. The methods employ existing licensed stability methodologies and incorporated minor changes, e.g., to the Average Power Range Monitor (APRM)-based trip system to preclude operation inside the stability vulnerable region of the power/flow map. The APRM-based trip system is modified to set down the APRM flow-biased scram line when core flow is less than a predetermined core flow to prevent the core from entering an unstable region of operation.

A fuel element has a ratio of area of fissionable nuclear fuel in a cross-section of the tubular fuel element perpendicular to the longitudinal axis to total area of the interior volume in the cross-section of the tubular fuel element that varies with position along the longitudinal axis. The ratio can vary with position along the longitudinal axis between a minimum of 0.30 and a maximum of 1.0. Increasing the ratio above and below the peak burn-up location associated with conventional systems reduces the peak burn-up and flattens and shifts the burn-up distribution, which is preferably Gaussian. The longitudinal variation can be implemented in fuel assemblies using fuel bodies, such as pellets, rods or annuli, or fuel in the form of metal sponge and meaningfully increases efficiency of fuel utilization.

In an apparatus for evaluating reliability of a nuclear power plant operator, an expected task finishing time for each task of the operator is calculated based on input data for reliability evaluation of the operator to determine a task completion time for each task of the operator based on the calculated expected task finishing time and the input data. An initial time for the tasks is determined based on the input data and the task completion time for a current task. A total execution time of the operator is calculated based on the determined task completion time and initial time. An available time allowed for the operator to complete the tasks is calculated based on a predetermined allowed time and the determined initial time. A task failure probability is obtained from the difference between the calculated total execution time and the calculated available time based on probability distribution information.

Illustrative embodiments provide for the operation and simulation of the operation of fission reactors, including the movement of materials within reactors. Illustrative embodiments and aspects include, without limitation, nuclear fission reactors and reactor modules, including modular nuclear fission reactors and reactor modules, nuclear fission deflagration wave reactors and reactor modules, modular nuclear fission deflagration wave reactors and modules, methods of operating nuclear reactors and modules including the aforementioned, methods of simulating operating nuclear reactors and modules including the aforementioned, and the like.

Systems and methods are described herein for real-time data processing and for emergency planning. Scenario test data may be collected in real-time based on monitoring local or regional data to ascertain any anomaly phenomenon that may indicate an imminent danger or of concern. A computer-implemented method may include filtering a plurality of different test scenarios to identify a sub-set of test scenarios from the plurality of different test scenarios that may have similar behavior characteristics. A sub-set of test scenarios is provided to a trained neural network to identify one or more sub-set of test scenarios. The one or more identified sub-set of test scenarios may correspond to one or more anomaly test scenarios from the sub-set of test scenarios that is most likely to lead to an undesirable outcome. The neural network may be one of: a conventional neural network and a modular neural network.

This abnormality diagnosis system for diagnosing abnormalities in a plant is provided with: an abnormality diagnosis control unit which, with respect to an instrument parameter measured in a plant determined to have an indication of abnormality, predicts the development of the instrument parameter by extrapolation, and which generates an abnormality manifestation pattern that is a pattern of behavior of the instrument parameter after prediction; and a data storage unit which stores a plurality of abnormality model patterns PA, PB that are patterns of behavior of the instrument parameters corresponding to causes CA1, CA2, CB1, CB2 of plant abnormality. The abnormality diagnosis control unit makes a matching determination between the abnormality manifestation pattern that has been generated and the plurality of abnormality model patterns PA, PB stored in the data storage unit, and identifies, as the cause of the abnormality in the abnormality manifestation pattern.

A process signal control and monitoring system, includes: a signal processing device which is installed on an outside of a nuclear reactor containment vessel, an internal electrical power source, an analog-digital conversion part, an internal communication part which transmits the digital signal to the signal processing device, an internal repeater, and an external repeater which transmits the received signal to a communication satellite. When electric power supply from the signal processing device is disconnected, the internal electrical power source supplies electric power which is charged in the rechargeable battery, to the analog-digital conversion part and the internal communication part; and the internal communication part judges whether communication with the signal processing device is continued or disconnected; and when the communication is judged to be continued, the internal communication part continues transmitting the digital signal to the signal processing device.

The invention relates to methods for protecting a nuclear reactor core, such as a boiling water reactor core, from fuel and cladding damage due to thermal hydraulic instability in extended operating power flow conditions and, in particular, when an extended power uprate is implemented. The methods employ existing licensed stability methodologies and incorporated minor changes, e.g., to the Average Power Range Monitor (APRM)-based trip system to preclude operation inside the stability vulnerable region of the power/flow map. The APRM-based trip system is modified to set down the APRM flow-biased scram line when core flow is less than a predetermined core flow to prevent the core from entering an unstable region of operation.

A method of determining a core design parameter of a nuclear reactor, includes: calibrating an isolated voltage output from a NIS cabinet associated with the nuclear reactor using a calibrated signal source as an input to the NIS cabinet; recording values of the calibrated signal source used in the calibrating and corresponding values of the output voltage from the calibrating in an as-left cabinet calibration data table; using a computing device connected to the isolated voltage output from the NIS cabinet, converting the voltage output signal to a converted detector signal using at least some of the values in the as-left cabinet calibration data table in an improved signal conversion equation; and using the computing device, employing the converted detector signal to determine the core design parameter.

A programmable logic circuit (10) for controlling an electrical facility, in particular a nuclear facility, includes an operating unit (14). The operating unit includes a plurality of types of functional blocks (FB.sub.1, FB.sub.i, FB.sub.N), two distinct types of functional blocks being suitable for executing at least one distinct function, at least one processing module suitable for receiving at least one sequence (46) of functional block(s) to be executed, and at least one internal memory (38) configured to store at least said sequence (46). The programmable logic circuit (10) includes a single functional block of each type, a given functional block being suitable for being called several times, and an execution module (22) configured to execute the called functional block(s) in series, according to said sequence (46).