Nuclear Reactor In-Vessel Detector Signal Validation
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Solution Overview
Problem
Current nuclear reactor monitoring systems, such as the BEACON™ core monitoring system, lack a method to automatically detect and validate the validity of incore detector and core exit thermocouple signals, leading to potential inaccurate operating margins and unnecessary operation limitations due to invalid detector signals.
Innovation Solution
A method that involves running predictive calculations to generate anticipated outputs for detector elements, comparing actual signals to these predictions, and using Monte Carlo analysis to determine if signals fall within expected ranges under adverse conditions, with spline fitting to identify and remove invalid detectors from core calculations after verifying a sufficient number of valid detectors remain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fixed incore detectors and core exit thermocouples are used to monitor reactor power distribution, then continuous monitoring capability is improved, but the system becomes vulnerable to invalid signals that can cause inaccurate operating margins and unnecessary operation limitations
Solution Approach 1:
The system performs preliminary validation of detector signals before using them in power distribution calculations. By checking signal consistency with predicted values and comparing ratios of actual to anticipated outputs, the system identifies and removes invalid signals in advance, preventing them from causing inaccurate operating margins or unnecessary operation limitations.
Solution Approach 2:
The system continuously compares actual detector signals against predicted values generated from reactor operating state models. This feedback mechanism allows the system to detect when a signal deviates from expected behavior and automatically adjust by removing the invalid signal from calculations, thereby maintaining monitoring reliability.
2Measurement precision
If automatic signal validation is implemented to remove invalid detector outputs, then measurement accuracy is improved, but system complexity increases due to predictive calculations, ratio comparisons, and spline fitting procedures
Solution Approach 1:
The validation system uses the reactor's own operating state parameters (power level, control rod positions, coolant flow rates) to generate predicted detector outputs. This self-service approach allows the system to validate its own measurements using physically-based models rather than requiring external validation equipment or complex computational procedures.
Solution Approach 2:
The system transforms the validation problem into a parameter comparison problem by calculating ratios of actual to anticipated detector outputs. This parameter transformation simplifies the validation logic to a matter of comparing ratios against expected ranges, reducing computational complexity while maintaining measurement precision.
3Ease of operation
If invalid detector signals are not automatically removed, then operational simplicity is maintained, but false alarms and diagnostic time increase due to inaccurate operating margins
Solution Approach 1:
The system automatically performs signal validation and removal without requiring operator intervention. The validation process is self-executing, using the reactor's operating state to identify and remove invalid signals, thereby maintaining operational simplicity while eliminating the need for manual diagnostic procedures.
Data Source
AI summary
A method to perform signal validation for either reactor fixed incore detectors and/or core exit thermocouples to enhance core monitoring systems. The method uses a combination of both measured sensor signals and expected signal responses to develop a ratio of measured to expected signals. The ratios are evaluated by determining the expected ratios for each detector based on the behavior of the remaining collection of detectors, taking into account the geometry/location of the other detectors. The method also provides for automatic removal of invalid detectors from the core power distribution determination if sufficient detectors remain on line to adequately characterize the core's power distribution.