Overview
ISO 9696:2017 - Water quality - Gross alpha activity - Test method using thick source - specifies a laboratory method for measuring gross alpha activity in non-saline waters (raw and potable). The method targets alpha-emitting radionuclides that are not volatile up to 350 °C and uses a thick source preparation for radiometric counting. Applicability depends on the water’s total soluble salts and the counter’s background count rate and counting efficiency; it is the laboratory’s responsibility to verify suitability for each sample.
Key Topics and Requirements
- Scope and limits: Applicable to raw and drinking waters but not to saline waters; radionuclides must be non-volatile up to 350 °C.
- Sampling and handling: References ISO 5667 series for correct sampling, preservation and chain-of-custody practices.
- Sample preparation stages: Detailed stages include pretreatment, concentration, sulfation, ignition, and source (planchet) preparation to produce a thick source suitable for alpha counting.
- Measurement and calibration: Procedures for measurement, background determination, and preparation of a calibration source are specified to derive activity concentrations.
- Performance metrics: Guidance on counting efficiency, background count rate, sensitivity and bias, and optimization of the determination for reliable results.
- Quality checks: Contamination checks, including consideration of radon isotope and polonium losses during sample processing.
- Data treatment: Methods for expressing results including calculation of activity concentration, standard uncertainty, decision threshold, detection limit, and confidence intervals (aligned with ISO 11929 and GUM principles).
- Laboratory competence: Conformance with accreditation and quality system requirements (e.g., ISO/IEC 17025) and proper training/safety for staff.
Applications and Who Uses It
ISO 9696:2017 is used by:
- Environmental and public health laboratories monitoring drinking water and raw water for radiological safety.
- Wastewater and liquid effluent monitoring programs to verify compliance with national limits.
- Water utilities and plant operators performing routine surveillance or emergency screening.
- Regulatory agencies and accredited testing bodies assessing compliance with guidance levels (e.g., WHO screening levels such as 0.5 Bq·L⁻¹ for gross alpha).
- Laboratories preparing for accreditation in radionuclide measurement.
Practical benefits include standardized gross alpha screening, reproducible results for regulatory compliance, and a clear framework for uncertainty and detection capability reporting.
Related Standards
Keywords: ISO 9696:2017, gross alpha activity, water quality, thick source, test method, non-saline waters, potable waters, radionuclide measurement, detection limit, decision threshold.
