ISO 23468:2021

Overview

ISO 23468:2021 specifies an analytical method for determining heavy water isotopic purity using Fourier transform infrared spectroscopy (FTIR). The standard covers the full range of heavy water (D2O) concentration and is intended for process control and quality assurance in heavy water reactor power plants, research reactors, heavy water production facilities and related areas. The method relies on characteristic infrared absorption of O–H and O–D bonds and provides procedures for preparing reference standards, sampling, instrument setup, calibration and result reporting.

Key topics and technical requirements

• Principle: Measurement is based on FTIR absorption differences for HDO, H2O and D2O; key absorption regions include ~3400 cm−1 (O–H) and ~2500 cm−1 (O–D).
• Applicability: Valid across the whole D2O concentration range; subdivides mid-ranges into different spectral regions as needed.
• Reagents & gases: Demineralized light water (ISO 3696 grade 1), certified high-isotopic-purity D2O reference standards, acetone or absolute ethanol, helium (99.999 %) and dry nitrogen/compressed air (dew point < −30 °C).
• Instrumentation:
  • FTIR spectrometer with resolution ~4 cm−1 and spectral range 1000–6000 cm−1.
  • Super-sealed infrared liquid cells with Luer‑Lock fittings and reproducible path lengths (examples: 0.05–0.5 mm).
  • Syringes, syringe filters (0.45 μm), desiccator, oven and balance for sample handling.
• Reference standards & storage: Use certified high-purity D2O; prepare lower-concentration standards by mixing with light water; store standards in sealed ampoules or specially designed stainless-steel containers (annex guidance provided).
• Procedure essentials: Sampling methods (syringes or bottles), sample temperature adjustment, filtration, background spectrum acquisition, preparation of calibration curves for different concentration ranges, spectral scanning and post-measurement handling.
• Quality factors: Precision, uncertainty estimation, and common interferences (contaminants, air bubbles, cell-window contamination) are addressed.

Practical applications

• On-line and laboratory process control in heavy water reactor operation and maintenance.
• Quality control in heavy water production factories and certification laboratories.
• Routine isotopic purity verification for D2O handling, storage and transfers.
• Support for research and development involving deuterium-labeled water or reactor materials testing.

Who should use this standard

• Nuclear reactor analytical laboratories and plant process engineers
• Heavy water production QC teams and certified reference laboratories
• Regulatory bodies and inspection agencies responsible for reactor materials
• Researchers requiring reliable D2O isotopic-purity measurements

Related standards

• ISO 3696 - Water for analytical laboratory use (referenced for reagent water)
• ISO/TS 80004-6 - Nanotechnology terminology (FTIR definition source)
• ISO 6107, ISO 3534-2 - (terminology and precision definitions referenced)

Keywords: ISO 23468, heavy water, D2O, isotopic purity, FTIR, deuterium oxide, reactor technology, calibration, liquid cell, sampling, heavy water quality.