ISO 18589-3:2023

Overview - ISO 18589-3:2023 (gamma-ray spectrometry for soil)

ISO 18589-3:2023 specifies a non-destructive test method for the identification and measurement of gamma-emitting radionuclides in soil using gamma‑ray spectrometry. The method is applicable to large-volume samples (up to about 3 L) and covers photon energies from 5 keV to 3 MeV, with most routine measurements targeting the common gamma emitters between 40 keV and 2 MeV. It supports the use of germanium or other detectors with a resolution better than 5 keV and is intended for routine environmental radioactivity analysis, emergency site inspection and radiation protection surveillance.

Key technical topics and requirements

• Principle and scope: Identification and quantification of a broad range of gamma‑emitters in soils, rocks, construction materials, sediments, sludge and NORM/TENORM materials.
• Sample handling: Packaging, large-volume sample preparation and optional crushing of coarse fractions (see ISO 18589‑2 for unsieved material).
• Equipment: Detector selection (high‑resolution germanium recommended), cryostat/cooler, shielding, preamplifier and analogue/digital acquisition electronics.
• Calibration:
  • Energy calibration and efficiency calibration using reference sources and numerical methods.
  • Use of appropriate reference sources for laboratory systems.
• Corrections and data processing:
  • Dead time, pile-up and decay corrections (see ISO 20042 for fundamentals).
  • Self-attenuation (self-absorption) and true coincidence summing corrections.
  • Background subtraction, contributions from other radionuclides and laboratory background assessment.
• Quality control and uncertainty:
  • Procedures for quality assurance, determination of decision thresholds, detection limits, and reporting standard uncertainty.
• Reporting: Expression of activity per unit mass and detailed test report requirements.

Practical applications and primary users

• Environmental monitoring and surveillance programs (soil, urban and agricultural land).
• Radiation protection and regulatory compliance assessments.
• Emergency response and rapid site inspection after radiological incidents.
• Industries handling NORM/TENORM: mining (mineral sands), phosphate fertilizer production, construction materials testing.
• Accredited testing laboratories, national metrology institutes, environmental agencies, and radiation safety officers.

Related standards

• ISO 20042 - generic test method and fundamentals for gamma‑ray spectrometry (referenced for dead time/pile‑up and measurement fundamentals).
• ISO 18589-2 - guidance on sample preparation and crushing of coarse or anthropogenic materials.

Keywords: ISO 18589-3:2023, gamma-ray spectrometry, gamma-emitting radionuclides, soil radioactivity, NORM, TENORM, environmental monitoring, germanium detector, detection limit, self-attenuation, true coincidence summing.