Trace-level determination of cations in the secondary circuit of a PWR-type nuclear power plant using ion chromatography after inline sample preparation

Importance of the Topic

Water chemistry control in nuclear power plants is critical for preventing corrosion and maintaining system integrity. Accurate measurement of trace cations such as lithium and sodium at parts‐per‐trillion levels in the presence of high concentrations of ethanolamine and other matrix components ensures reliable monitoring of the secondary circuit.

Objectives and Study Overview

This study introduces an automated inline sample preconcentration ion chromatography method to quantify trace cations in the secondary circuit of a PWR‐type nuclear power plant. The goal is to simplify sample preparation, achieve low detection limits, and maintain high precision and accuracy.

Methodology and Instrumentation

• Inline preconcentration using a Metrosep C PCC 1 HC column integrated with Metrohm Inline Sample Preparation (MISP).
• Isocratic ion chromatography without chemical suppression to detect inorganic cations and amines.
• Automated multi‐injection calibration via an 800 Dosino and peristaltic pump filling a 10 µL loop with concentrated standard.
• Sequential aspiration of air gaps and ultrapure water rinses to eliminate carryover and contamination.

Instrumentation Used

• Professional IC 850 Cation – Prep 2 system
• Professional Sample Processor 858 with pump and injector
• 800 Dosino dosing unit and 10 mL Dosing Unit
• Metrosep C PCC 1 HC preconcentration column
• Metrosep C2 – 250 analytical column with guard

Main Results and Discussion

• Calibration in the µg/L range enabled quantitation in the ng/L (ppt) range with correlation coefficients > 0.999.
• Relative standard deviations below 1.5 % for concentration and retention time stability in the upper ppt range.
• Recovery rates between 98.5 % and 99.9 % for lithium, sodium, ammonium, and ethanolamine at ppb levels.
• Carryover for metal cations below 0.3 % due to effective air gap and rinse procedures.

Benefits and Practical Applications

• Eliminates manual and time‐consuming sample preparation steps.
• Provides robust and reproducible trace cation quantitation in complex matrices.
• Enhances laboratory throughput for routine power plant water monitoring.
• Adaptable to other industrial water quality and QA/QC analyses.

Future Trends and Potential Applications

• Integration of inline preconcentration IC into online and real‐time monitoring systems.
• Extension to additional ionic species and organic contaminants.
• Coupling with advanced detectors such as ICP‐MS for comprehensive trace element analysis.
• Development of fully automated workflows for continuous process analytics.

Conclusion

The inline preconcentration ion chromatography method delivers a fast, accurate, and highly reproducible approach for trace‐level cation analysis in nuclear power plant secondary circuits. Its streamlined workflow, low detection limits, and minimal carryover support improved monitoring and preventive maintenance strategies.

Reference

• Hartmann T., Viehweger K. H., Wille A. Trace‐level determination of cations in the secondary circuit of a PWR‐type nuclear power plant using ion chromatography after inline sample preparation, Metrohm AG Application Note 8.000.6072EN.