Determination of Polyacrylic Acid in Nuclear Power Plant Pressurized Water Reactor Secondary Feed Water

Significance of the Topic

Corrosion in secondary systems of pressurized water reactors (PWRs) leads to fouling, heat-transfer losses and reduced plant efficiency. Polyacrylic acid (PAA) has been adopted as a polymeric dispersant to mitigate metal oxide deposition and enhance corrosion resistance. Accurate monitoring of low‐level PAA in feed water is critical to maintain optimal dosing within administrative limits and to prevent adverse effects from other water treatment additives.

Objectives and Study Overview

This study aimed to develop a straightforward size‐exclusion chromatography (SEC) method to quantify PAA at concentrations below 20 µg/L in secondary feed water containing ethanolamine (ETA) and hydrazine. The method was validated using both simulated matrices and real plant samples to ensure selectivity, sensitivity and reproducibility.

Methodology and Used Instrumentation

The separation employed a Thermo Scientific Acclaim SEC‐1000 column (7.8 × 300 mm) with deionized water as eluent at 1.0 mL/min and 30 °C. A Dionex ICS‐5000+ system equipped with a single‐pump DC detector compartment, a VWD‐IC variable‐wavelength detector set at 200 nm and an AS‐AP autosampler with 5 mL syringe was used. Sample injection volume was 300 µL, chosen to enhance detection of trace PAA. Water blanks were maintained under helium blanket to minimize CO₂ intrusion, and glass vials were used to avoid PAA adsorption on polymers.

Main Results and Discussion

• The method achieved a limit of detection of ~2.6 µg/L in real secondary feed water matrices.
• Linearity over 5–200 µg/L gave a quadratic calibration curve with r² > 0.999.
• No interference from ETA (2.5–5 mg/L) or hydrazine (0.075–0.1 mg/L) was observed in simulated or real samples.
• Recovery studies at spiking levels of 6, 10 and 20 µg/L yielded 99.5–109% with RSD ≤ 4.8%.
• Precision for seven injections of 10 µg/L PAA showed retention‐time RSD ≤ 0.7% and peak‐area RSD ≤ 6.6%.

Benefits and Practical Applications

The proposed SEC method requires only water as eluent, eliminating buffer preparation and reducing consumable costs. It provides reliable, selective quantitation of trace PAA in PWR feed water, facilitating real‐time monitoring of dispersant dosing and helping operators maintain corrosion control while avoiding excessive polymer accumulation.

Future Trends and Applications

Advancements may include on‐line coupling of SEC with process sampling for continuous PAA monitoring, integration with multi‐detector systems (e.g., refractive index or conductivity) for molecular‐weight profiling and extension to other polymeric inhibitors. Automation and miniaturization of SEC devices could further enhance field deployability in nuclear plant water chemistry control.

Conclusion

This study delivers a robust, sensitive and cost‐effective SEC method for determining low‐level PAA in nuclear plant secondary feed water. Its high selectivity against common water‐treatment additives and strong analytical performance support its adoption for routine quality control and corrosion management in PWR systems.

References

1. Turner CW. Implications of Steam Generator Fouling on Material Degradation and Thermal Performance. Proc. 15th Int. Conf. Environ. Degradation of Materials in Nuclear Power Systems. 2011;2287–2299.
2. Fruzzetti K. Effect of Polymer Dispersant on Flow-Accelerated Corrosion of Steam Generator Materials. EPRI TR, 2005.
3. Lepine L, Gilbert R. Thermal Degradation of Polyacrylic Acid in Dilute Aqueous Solution. Polym. Degrad. Stabil. 2002;75(2):337–345.
4. Fruzzetti K. Reducing Deposits in Steam Generators. Nucl. Plant J. 2009;27:42–44.
5. Keeling DL, Polidoroff CT, Cortese S, Cushner MC. Ethanolamine Properties and Use for Feed Water pH Control. Proc. 7th Int. Symp. Environ. Degradation of Materials in Nuclear Power Systems. 1995;675–685.
6. Pein K, Molander A, Sawicki JA, Stutzmann A. Distribution of Iron Redox States for Different Hydrazine Concentrations and Potentials. Proc. 8th Int. Symp. Environ. Degradation of Materials in Nuclear Power Systems. 1997;113–119.
7. Liu A, Honma I, Ichihara M, Zhou H. Poly(acrylic Acid)-Wrapped Carbon Nanotubes Composite Solubilization in Water. Nanotechnology. 2006;17:2845–2849.
8. Jorand F, Sergent AS, Remy PP, et al. Contribution of Anionic vs Neutral Polymers to Green Rust Formation. Geomicrobiol. J. 2012;30:600–615.