ISO 18589-5:2019

Overview

ISO 18589-5:2019 specifies laboratory test methods for the measurement of Strontium‑90 (90Sr) activity in soil using proportional counting (PC) or liquid scintillation counting (LSC). It covers principles for measuring 90Sr in equilibrium with its daughter 90Y (and in the presence of 89Sr when relevant), describes chemical separation routes to isolate strontium/yttrium, and gives measurement, calculation and reporting requirements for environmental monitoring. The standard also notes applicability to related matrices (sludge, sediment, construction materials, products) when appropriate sampling is followed.

Key topics and technical requirements

• Scope of measurement
  • 90Sr determination in soil; options to measure 90Sr via equilibrium with 90Y or by direct 90Y measurement.
  • Special treatment when 89Sr (shorter-lived) contributes to activity after recent fallout.
• Chemical separation methods
  • Procedures presented include precipitation, liquid–liquid extraction and chromatography (crown‑ether resins) to prepare strontium/yttrium sources for counting.
• Source preparation and detection
  • Guidance for preparing counting sources suitable for PC and LSC, and for background determination.
• Measurement and calculation
  • Instructions for counting efficiency, count times, activity calculations, expression of results, standard uncertainty, decision thresholds and detection limits.
• Performance guidance
  • Example detection limits: using 20 g samples and 1 000 min counting, achievable detection limits are ~0.1–0.5 Bq·kg‑1 for 90Sr when 89Sr is negligible; ~1–2 Bq·kg‑1 for 90Sr and 89Sr when both are present.
• Documentation
  • Requirements for test reporting and examples of evaluation models are provided.

Applications and who uses it

• Practical uses
  • Environmental soil monitoring after routine or accidental discharges (liquid or gaseous), post‑accident fallout assessment, routine surveillance, and legacy contamination surveys.
  • Measurement in sludge, sediment or construction materials with correct sampling.
• Users
  • Environmental radiation monitoring laboratories, nuclear facility monitoring teams, regulatory authorities, emergency response laboratories, research institutes and organizations assessing contamination from global fallout.

Related standards

• ISO 18589 series (other parts) covering radioactivity measurement in environmental media and complementary methods for sample collection, preparation and measurement. Users should consult related parts of ISO 18589 for sampling, gamma spectrometry and other radionuclide-specific methods.

Keywords: ISO 18589-5:2019, Strontium‑90, 90Sr measurement, liquid scintillation counting, proportional counting, soil radioactivity, chemical separation, environmental monitoring.