Dynamic Reactor Trip Algorithm for Fast Shutdown and Spurious Trip Immunity
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Solution Overview
Problem
Modern nuclear reactor safety systems face challenges in quickly shutting down reactors during high-power events like loss of coolant accidents or uncontrolled power excursions while avoiding spurious trips that do not require shutdown, necessitating a balance between rapid response and immunity to false triggers.
Innovation Solution
A method involving sensors to detect fission rates, signal processing to determine flux signals, and derivative calculations to generate rate signals compared to setpoints, with additional biasing and amplification to produce trip signals for neutron absorption in the reactor core, ensuring timely and accurate shutdowns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the trip sensitivity is increased to enable faster shutdown during high-power events, then the response speed improves, but the system becomes more susceptible to spurious trips during normal operations
Solution Approach 1:
The trip setpoint is made dynamic by applying a gain factor to the rate signal that varies with reactor power level. At high power levels, the gain is increased to lower the effective trip threshold, enabling faster response to power excursions. At low power levels, the gain is reduced to maintain immunity to spurious trips. This dynamic adjustment resolves the contradiction by adapting the sensitivity to the operational context.
Solution Approach 2:
The system changes the parameter of trip sensitivity by multiplying the rate signal by a power-dependent gain factor. This parameter transformation allows the same hardware to achieve both high sensitivity at high power (for fast shutdown) and low sensitivity at low power (for spurious trip immunity), effectively resolving the contradiction through parameter modulation.
2Measurement precision
If the trip setpoint is lowered to detect smaller power excursions, then the measurement precision improves, but the system becomes more prone to false triggers from noise
Solution Approach 1:
The system uses feedback from the measured power level to dynamically adjust the trip threshold. The gain factor is determined by the current power level, creating a feedback loop that automatically adapts the sensitivity. This feedback mechanism allows the system to maintain high measurement precision when needed while automatically reducing sensitivity when noise susceptibility becomes a problem.
Solution Approach 2:
The trip threshold is made dynamic rather than fixed, allowing it to adapt to changing operational conditions. By linking the effective threshold to the current power level through the gain factor, the system achieves high precision detection capability when power levels warrant it, while automatically reducing sensitivity under conditions where noise is more problematic.
Data Source
AI summary
A controller for producing a nuclear reactor shutdown system trip signal in response to at least one detector signal. The controller includes a signal conditioning module receiving the at least one detector signal and outputting a measured flux signal. A rate module generates a rate signal from the measured flux signal. A comparator circuit compares the rate signal to a trip setpoint and generates a first trip signal.