Overview
ISO 20045:2023 - Measurement of the radioactivity in the environment - Air: tritium - Test method using bubbler sampling - defines a validated field sampling method to determine atmospheric tritium activity concentrations by trapping airborne tritium in a liquid via bubbler sampling. Results are reported in becquerel per cubic metre (Bq·m‑3). The standard provides formulas for a four‑bubbler sampling system (and guidance to apply them to a single trapping module with two bubblers when only tritiated water vapour (HTO) is present) and sets practical detection limits for typical monitoring campaigns.
Key technical topics and requirements
- Principle: Air is drawn through a water-based trapping solution by bubbling; tritiated species (HTO and some tritiated gases) are collected for laboratory analysis.
- Sampling system design: Specifications and formulae are given for systems with four bubblers; applicability to one-module/two-bubbler systems is described for HTO-only atmospheres.
- Sampling parameters: Guidance on sampling head location, air flow rate, sampling duration and sampled air volume to obtain representative and reproducible data.
- Trapping solution and efficiency: Requirements for the trapping water solution and methods to determine trapping efficiency (see informative Annex B).
- Performance metrics: Typical detection limit of the method is between 0.2 Bq·m‑3 and 0.5 Bq·m‑3 for about one week of sampling; decision threshold, coverage intervals and uncertainty estimation approaches are included.
- Quality and reporting: Procedures for sample collection, transport, conservation and reporting; the method is intended for use within quality systems such as ISO/IEC 17025.
- Laboratory analysis context: While ISO 20045 covers field sampling and calculation of air activity (Bq·m‑3), laboratory measurement of tritium in the trapping solution (Bq·L‑1) is handled by standards like ISO 9698 and ISO 13168 (liquid scintillation counting methods).
Practical applications and users
ISO 20045:2023 is intended for:
- Environmental and radiological monitoring laboratories conducting air tritium monitoring
- Nuclear power plants, fuel cycle facilities and research sites for routine emissions surveillance and compliance
- Regulatory bodies and public‑health authorities assessing atmospheric tritium concentrations
- Emergency response teams measuring tritium after incidents and researchers conducting environmental studies or long‑term trend analysis
Typical uses include routine environmental monitoring, compliance verification, impact assessment near tritium‑emitting facilities, and emergency or incident sampling.
Related standards
- ISO 9698 - Tritium in water: liquid scintillation counting
- ISO 13168 - Simultaneous determination of tritium and carbon‑14 by liquid scintillation
- ISO/IEC Guide 98‑3 (GUM) - Uncertainty of measurement
Keywords: ISO 20045:2023, tritium air monitoring, bubbler sampling, HTO, Bq·m‑3, environmental radioactivity, detection limit, trapping efficiency, liquid scintillation.
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