Determination of Trace Anions in Nuclear Power Plant Secondary Feed Water Containing Polyacrylic Acid

Significance of the Topic

Control of ionic impurities in nuclear power plant secondary feed water is critical to prevent corrosion of steam generator components. Polyacrylic acid (PAA) is used as a dispersant but complicates low-level anion analysis. A reliable analytical approach is needed to detect trace levels of fluoride, chloride, and sulfate in this matrix.

Objective and Study Overview

This work aimed to develop and validate an ion chromatography (IC) method capable of quantifying sub-µg/L concentrations of target anions in simulated pressurized water reactor secondary feed water containing ethanolamine, hydrazine, and PAA. The study evaluates chromatographic performance, sensitivity, and robustness.

Methodology and Instrumentation

• Anion separation was performed on a Dionex IonPac AS15 analytical column with AG15 guard column using isocratic elution with 35 mM KOH generated electrolytically by EGC III KOH cartridge.
• Preconcentration and matrix removal were achieved using a Dionex IonPac UTAC-ULP2 ultralow pressure concentrator column, allowing direct injection of PAA-containing samples.
• Detection was conducted via suppressed conductivity using a Dionex ASRS 300 self-regenerating suppressor in recycle mode at 22 mA.
• Sample introduction employed a Dionex AS-AP autosampler injecting 1 mL at 30 °C and 0.25 mL/min flow rate.

Key Results and Discussion

• Calibration was linear from 0.1–20 µg/L with r² >0.9989 for all anions.
• Limits of detection ranged from 3.8 ng/L (fluoride) to 15 ng/L (sulfate); limits of quantification were below 0.05 µg/L.
• Spike recoveries in simulated PAA matrix were 92–101%, demonstrating accuracy.
• Retention time and peak area reproducibility over 69 injections yielded RSDs <0.08% and <2%, confirming method robustness.
• Polyacrylic acid and matrix cations were diverted to waste, protecting analytical column longevity.

Benefits and Practical Applications

The method offers rapid (20 min) and sensitive monitoring of corrosive anions in nuclear power plant feed water with minimal sample preparation. Its robustness and low detection limits support routine quality assurance and early corrosion risk assessment.

Future Trends and Opportunities

• Integration of inline sample preparation and automated data evaluation for online monitoring.
• Development of compact IC systems for field applications and remote nuclear facility monitoring.
• Use of advanced suppressor technologies and alternative detectors (e.g., mass spectrometry) to enhance selectivity.
• Application of machine learning algorithms to predict corrosion trends based on multi-parameter water quality data.

Conclusion

A robust IC method using concentrator and electrolytic eluent generation effectively quantifies trace fluoride, chloride, and sulfate in PAA-containing nuclear feed water. The approach ensures high sensitivity, reproducibility, and protection of analytical components, fulfilling critical monitoring requirements.

References

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