PWR Control Rod Setpoint Optimization for Load Following
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Solution Overview
Problem
Current methods for controlling pressurized water nuclear reactors during load following are inefficient, leading to excessive control rod movements and effluent volumes, as they do not adequately account for xenon effects and fuel aging, resulting in power imbalances and increased stress on control mechanisms.
Innovation Solution
A method that optimizes the setpoint position of control rods based on estimated power increase time and xenon concentration variations, minimizing displacements and effluent volumes by strategically managing boron concentration and control rod positions using software implementing neutron codes for precise power control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If control rod positions are adjusted frequently to maintain power distribution during load following, then power control precision is improved, but control rod mechanism stress and effluent volume increase
Solution Approach 1:
The system performs preliminary calculation of optimal control rod positions using xenon concentration predictions and power distribution requirements before actual load following operations. This advance planning reduces the need for frequent emergency adjustments, thereby decreasing mechanical stress while maintaining power control precision.
Solution Approach 2:
The system continuously monitors actual power distribution and xenon concentrations, comparing them with predicted values. This feedback mechanism allows for minimal, targeted control rod adjustments only when deviations exceed thresholds, reducing overall movement frequency and mechanical stress while maintaining precise power control.
2Stability of the object's composition
If boron concentration is increased to compensate for xenon effects, then power distribution stability is improved, but effluent volume increases
Solution Approach 1:
The system dynamically adjusts boron concentration based on real-time xenon concentration measurements and power distribution requirements. By optimizing the boron concentration parameter to match actual conditions rather than using fixed high levels, the system maintains power distribution stability while minimizing unnecessary boron injection and subsequent effluent generation.
Solution Approach 2:
The system uses predictive xenon concentration calculations to anticipate power distribution changes and pre-adjust boron concentration levels. This self-regulating approach maintains stability without requiring excessive boron additions, thereby reducing effluent volume from boron processing operations.
3Loss of time
If control rod positions are optimized without considering xenon effects, then control rod movements are reduced, but power imbalances occur
Solution Approach 1:
The system introduces xenon concentration predictions as an intermediary parameter that mediates between control rod positions and power distribution outcomes. By calculating expected xenon effects and incorporating them into the optimization algorithm, the system determines control rod positions that account for xenon-induced power changes, achieving both reduced movements and maintained power uniformity.
Solution Approach 2:
The system performs preliminary calculation of xenon concentration evolution and its impact on power distribution before determining optimal control rod positions. This advance consideration of xenon effects allows the system to plan control rod movements that preemptively compensate for anticipated xenon-induced power changes, reducing the need for corrective movements while maintaining power distribution uniformity.
4Manufacturing precision
If frequent boron injections are performed to correct power imbalances, then power distribution control is improved, but effluent volume and operational complexity increase
Solution Approach 1:
The system implements a feedback mechanism that monitors power distribution deviations and xenon concentrations, triggering boron injections only when deviations exceed predetermined thresholds. This threshold-based feedback control reduces the frequency of boron injections compared to continuous or frequent adjustments, thereby simplifying operations while maintaining adequate power distribution control.
Solution Approach 2:
The system uses predictive xenon concentration calculations to anticipate power distribution imbalances before they occur. By performing preliminary boron concentration adjustments based on these predictions, the system prevents the need for frequent corrective injections, reducing operational complexity while maintaining precise power distribution control.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces control rod movements and effluent volumes, optimizing power control and minimizing the stress on control mechanisms by accounting for xenon effects and fuel aging, thereby improving reactor performance during load following.
Implementation Method 1
control rods made up of neutrophage element at different insertion positions so as to absorb more or less the neutrons
Implementation Method 2
pressurized water circulates, along the path marked by the arrows. This water rises in particular towards the core 2 to be heated there by ensuring the refrigeration of the core 2
Implementation Method 3
The water in the primary circuit 8 also supplies the steam generators 3 where it is cooled by ensuring the vaporization of water circulating in a secondary circuit 12
Implementation Method 4
ensuring the vaporization of water circulating in a secondary circuit 12
Implementation Method 5
the condenser 6 where this steam is condensed by indirect heat exchange with cooling water circulating in the condenser 6
Implementation Method 6
a core 2 divided into an upper zone and a lower zone and producing power
Data Source
Figure 1
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Figure 3
AI summary
The present invention relates to a method for controlling a pressurized water reactor (100) comprising the steps that involve measuring the effective power (Pe) of the nuclear reactor; acquiring a reference value for the desired power (Pc); acquiring an estimated duration (DURATION) for the increase in power in order to achieve said reference value of the target power (Pc) desired, said estimated duration (DURATION) corresponding to the time taken for the power to increase from said effective power (Pe) to said reference value for the target power (Pc); determining the reference position (Z) of at least one control rod cluster among said plurality of control rod clusters (40) in order to achieve said reference value for said target power (Pc) desired as a function of said estimated duration (DURATION), of said measured effective power (Pe) and of said reference value for said target power (Pc); monitoring the position of said at least one control rod cluster so as to position it in its reference position (Z).