Overview
ISO 23655-1:2022 - Water quality - Nickel-59 and nickel-63 - Part 1: Test method using liquid scintillation counting specifies a laboratory method to determine the activity concentration of radionuclides nickel-59 (59Ni) and nickel-63 (63Ni) in all types of water using liquid scintillation counting (LSC). The standard defines performance expectations using currently available LSC systems - for example, with a 200 min count and 1.5 L sample volume, typical achievable detection limits are ≈50 mBq·L−1 for 59Ni and ≈20 mBq·L−1 for 63Ni. The document also stresses that actual limits depend on instrument background, detection efficiency, dissolved material in samples and the presence of other radionuclides.
Key topics and technical requirements
- Principle and scope: LSC-based quantification of 59Ni and 63Ni activity concentration in water samples.
- Reagents and standards: Preparation and use of radionuclide and stable nickel standards, quenching agents, carrier and purification reagents.
- Sample handling: Guidance on sampling, preservation and sample preparation in line with the ISO 5667 series.
- Chemical separation: Isolation and purification steps (Annex A normative) to remove interferences before LSC measurement.
- Instrument setup and calibration: LSC window settings, background determination, calibration procedures and sample vial requirements.
- Measurement procedure: Source preparation, counting protocols (recommended counting time and sample volume) and procedures for iron/nickel separation when needed.
- Quality control and reporting: Requirements for nickel recovery determination, activity calculation, uncertainty estimation and characteristic limits (decision threshold and detection limit).
- Safety and competence: Emphasis on trained personnel and appropriate laboratory safety practices.
Practical applications and users
ISO 23655-1:2022 is intended for:
- Environmental and water quality laboratories performing radionuclide monitoring.
- Nuclear facilities and effluent monitoring teams verifying discharges.
- Regulatory agencies and public health bodies assessing compliance with guidance levels (e.g., WHO recommendations).
- Emergency response laboratories conducting rapid assessments after radiological incidents.
Practical uses include routine monitoring of drinking water, surface/groundwater and liquid effluents, wastewater checks prior to discharge, and analytical support for compliance and incident response.
Related standards
- ISO 23655 series (other parts for complementary methods)
- ISO 5667 series (water sampling and handling)
- ISO/IEC Guide 98‑3 (GUM - uncertainty evaluation)
- ISO 5667-20 (sampling guidance for radionuclides)
Keywords: ISO 23655-1:2022, nickel-59, nickel-63, liquid scintillation counting, LSC, water quality, radionuclide measurement, activity concentration, detection limit, environmental monitoring.