SIST EN ISO 19361:2025 PDF

Overview

EN ISO 19361:2025 - Measurement of radioactivity: Determination of beta emitters activities by liquid scintillation counting (LSC) - is a CEN-endorsed European adoption of ISO 19361:2025. The standard specifies conditions and procedural requirements for measuring the activity concentration of beta-emitting radionuclides in liquid and prepared solid scintillation sources. It applies to aqueous and organic liquids and to solids prepared as particles, filters or planchets, and covers activity concentrations from about 1 Bq·L−1 to 10^6 Bq·L−1. Sample-specific pre-treatments for some radionuclides (e.g. distillation for 3H, benzene synthesis for 14C) are outside the scope.

Key topics and technical requirements

• Principle and scope: Measurement by mixing test sample with a scintillation cocktail to form a scintillation source measured in a liquid scintillation counter.
• Sample types and preparation: Guidance for liquid samples and for preparing solid samples as scintillation sources (filters, planchets). Note: planchets are small pans/supports of metal, plastic or glass.
• Reagents and equipment: Requirements for blank materials, calibration source solutions, scintillation cocktails, quench agents, counting vials and LSC instrumentation.
• Measurement procedure:
  • Determination of background and counting efficiency
  • Quench correction and calibration (including use of internal standards)
  • Counting procedures and instrument control/calibration
  • Interference control when other beta, alpha or gamma emitters are present - separation/extraction may be required to isolate the radionuclide of interest
• Data treatment and reporting: Expression of results, calculation of activity concentration, decision threshold, detection limit, and coverage intervals (aligned with ISO 11929 series).
• Informative annexes: Internal standard method, TDCR LSC, and Cerenkov measurement options are provided for advanced counting techniques.

Applications and users

This standard is intended for laboratories performing radioanalytical measurements and for organizations needing reliable beta activity data, including:

• Environmental and water monitoring laboratories (surface water, effluent)
• Nuclear industry and decommissioning teams
• Radioactive waste characterization and NORM assessments
• Regulatory bodies, accreditation bodies and proficiency testing providers
• Research institutions using LSC for beta-emitter quantification

Practical benefits include standardized LSC workflows, consistent activity concentration reporting, improved interference control, and harmonized limits of detection and uncertainty estimation.

Related standards

• ISO 11929 series (methods for decision threshold, detection limit and coverage interval) - referenced for result expression.
• Specific ISO/CEN test methods for radionuclide-specific pre-treatments (e.g., tritium and carbon-14) are referenced but are outside the scope of EN ISO 19361:2025.

Keywords: EN ISO 19361:2025, liquid scintillation counting, beta emitters, measurement of radioactivity, activity concentration, quench correction, counting efficiency, TDCR, Cerenkov.