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Process Improvements in Control Rod Calibrations for Excess Reactivity Shutdown Margin

This document outlines the advancements in control rod calibration processes at Kansas State University, particularly focusing on improving excess reactivity shutdown margins. It details calibration methods such as Positive Period and Rod Drop, emphasizing their accuracy and effectiveness for varying reactivity limits. The process includes collecting data through Virtual Instrument (VI) systems, analyzing data in Excel, and addressing potential challenges such as data collection time and human factors. Key techniques for enhancing accuracy, including MATLAB solutions and sensitivity evaluations, are also discussed.

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Process Improvements in Control Rod Calibrations for Excess Reactivity Shutdown Margin

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  1. Process Improvements inControl Rod Calibrations P. M. Whaley Kansas State University

  2. Excess reactivity Shutdown margin (reactive rod out) React. Addition Rate Pulse rod worth $2.50 $1.10 $0.087/s $2.00 (nominal) Reactivity Limits

  3. Rod calibration

  4. Calibration methods • Positive Period • More accurate in differential worth • More likely to propagate in integral worth • Rod Drop • Accuracy satisfactory for additions < $2.00 • K-State uses either: • Both methods covering full scale, or • Verification of worth if rods > $2.00 full out

  5. Calibration PROCESS Critical START Program Drop Rod • DAC collection • Coordinate manually • Coordinate in a VI • 6-second buffer loop Collect Data Write data to file (3) VI Senses Rod Drop (4) Stores Buffer & Subsequent Data STOP VI

  6. Calibration PROCESS (2) Import to Excel Find Drop Normalize to pre-drop average Time Scale Select & plot points Average & Error analysis Extrapolate

  7. Calibration PROCESS (3)

  8. Calibration PROCESS (4a)

  9. Calibration PROCESS (4b)

  10. Issues & Problems • Time • Analysis • Days to collect data • Followed by days to analyze data • Identifying erroneous data • Anomalous data cannot be corrected real-time • Human factors not optimal in the process • Plotting • Extrapolating • It’s going to get worse

  11. 250 kW, 3-Rod Core

  12. Upgrade, 4-Rod Core

  13. Automation

  14. Virtual Inst.

  15. Data Collection Critical START VI Drop Rod VI notes stability VI records continuously Write data to file VI Collects Data STOP recording

  16. Pre-Analysis Specify File Find Drop Select Tolerance Normalize to pre-drop average Option Manual

  17. Analysis Specify Analysis Start & Stop Interpolate Data Calculate Mean & Standard Dev

  18. Matrix • Power fractions, ASCI II files Time Reactivity Fraction • Differential equations for inhour equation • Matlab solution • Parameters from Hazard Summary Report

  19. For the Future • Evaluate sensitivity of measurement • Current measurements are satisfactory • HSR method uses β vice β-effective • HSR method uses l for aluminum fuel vice SS • Any changes subject to 10CFR50.59 • Measure kinetics parameters • White noise experiments • Pile oscillator • Determine if adjustments can be made to improve accuracy for large reactivity additions

  20. Acknowledgement SMART Laboratory Personnel • Tyler Krehbiel (LabView Programming) • Mark Harrison (Calculations)

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