How are calibration and drift addressed for core protection sensors?

• A. Calibration is optional
• B. Regular calibration, verification against reference signals, drift monitoring, and recalibration or replacement per schedule
• C. Drift is acceptable within tolerance
• D. Only sensor replacement without calibration

Answer: (B)

Regular calibration and ongoing drift management are essential to keep core protection sensors accurate and trustworthy. These sensors must faithfully reflect actual reactor conditions because protective actions depend on their readings; as sensors age or experience temperature and electrical stresses, their outputs can drift away from true values. Regular calibration aligns the sensor outputs with precise reference standards, and verification against reference signals checks that the sensor responds correctly to known inputs and retains its proper characteristics. Drift monitoring detects gradual changes so degradation is identified before it impacts protection, and recalibration or replacement per a defined schedule ensures the sensors stay within required tolerance. Without this disciplined approach, readings can become unreliable, leading to missed trips or nuisance trips.