Overview
EN ISO 9696:2017 - "Water quality - Gross alpha activity - Test method using thick source (ISO 9696:2017)" is a standardized laboratory method adopted by CEN for measuring gross alpha activity in non-saline waters, including raw and potable waters. The method targets alpha‑emitting radionuclides that are non‑volatile up to 350 °C and uses a thick source (concentrated) sample preparation and counting approach. Laboratories must confirm the method’s suitability for their samples based on water chemistry and instrument performance.
Key topics and technical requirements
- Scope: Applicable to non‑saline waters; designed for alpha emitters not volatile to 350 °C; intended for raw and drinking water monitoring.
- Analytical principle: Preparation of a concentrated, thick source followed by alpha counting; includes background correction and calibration.
- Critical procedure stages (as specified in the standard):
- Sampling and pretreatment
- Concentration stage
- Sulfation and ignition of residues
- Thick source preparation
- Measurement and background determination
- Calibration and preparation of calibration sources
- Performance and quality:
- Sensitivity, bias, detection limit and decision threshold must be assessed.
- Performance depends on total soluble salts in the sample and on counter characteristics (background count rate, counting efficiency).
- Controls for contamination and specific radionuclide losses (e.g., radon, polonium) are required.
- Laboratory responsibility: Verify method suitability for the sample matrix and demonstrate performance characteristics and uncertainty.
Applications and users
Who uses EN ISO 9696:2017:
- Environmental and public health laboratories performing routine drinking water surveillance
- Water utilities monitoring gross alpha activity in supply sources
- Regulatory agencies and compliance testing bodies
- Emergency response teams requiring rapid screening of multiple water samples
Practical uses:
- Screening for elevated natural or anthropogenic alpha radioactivity in drinking and raw waters
- Supporting compliance with national limits and guidance (e.g., WHO screening guidance for gross alpha)
- Providing a rapid, standardized gross‑alpha screening result prior to more specific radionuclide analysis
Related standards and references
- ISO/IEC Guide 98‑3 (uncertainty of measurement)
- ISO 5667‑20 (sampling guidelines for radioactivity in water)
- WHO guidelines on drinking‑water quality (screening levels, context for gross alpha)
- Annex A (informative) in EN ISO 9696:2017 provides performance criteria and acceptance guidance
EN ISO 9696:2017 is an essential reference for laboratories performing gross alpha screening using thick‑source techniques, ensuring consistent, auditable results across environmental and drinking‑water monitoring programs.
