ISO/DIS 20041-1:2020过渡

Discharges from nuclear installations are subject to regulatory requirements established by various regulatory bodies. Rigorous control of the discharges is implemented by the facility operations within the framework of water and air discharge permits. This control is carried out from commissioning of the installation and throughout its entire lifetime. In particular, this involves making measurements of the physical, chemical and radioactivity characteristics in the gaseous and liquid effluents. The decommissioning of these nuclear installations also generates liquid and gaseous effluents that should be characterized and quantified before their discharge. Tritium and carbon‑14 are usually present in the gaseous effluents of nuclear power plants and other types of nuclear installations. ISO 2889 presents the methods and provisions for sampling airborne substances from the exhaust stacks of nuclear facilities. The provisions defined therein cover all physical forms of the materials present in gaseous effluents: aerosol particles, vapours and gases. These provisions are more restrictive for radioactive aerosol measurements, given greater possibilities of losses in the transport lines. However, in the gaseous effluents of nuclear facilities, tritium and carbon‑14 are present in gas or vapour forms as multiple chemical compounds, which requires adapting the provisions of ISO 2889. Furthermore, ISO 2889 only deals with tritium and carbon‑14 sample collection in the informative Annexes H and K. Therefore, ISO 20041 goes further by addressing, in detail, the provisions specific to sampling methods, and sample preparation and calculations for determining the tritium and carbon‑14 emissions. ISO 20041-1 covers the sampling methods or techniques for tritium and carbon‑14. ISO 20041-2 covers activity analysis of tritium and carbon-14 sampled emissions by the bubbling technique. ISO 20041-3 covers the activity analysis of tritium and carbon-14 sampled emissions by molecular sieve. The titles of the different parts are: — Part 1: Sampling of tritium and carbon‑14 in gaseous effluents — Part 2: Determination of the tritium and carbon-14 activities by bubbling technique — Part 3: Determination of the tritium and carbon-14 activities by molecular sieve 1 Scope ISO 20041-1 presents the methods and provisions for sampling tritium and carbon‑14 in the gaseous effluents generated by nuclear facilities during operation and decommissioning. Specifically included are sample withdrawal location, extraction, transport flow measurement, and collection for later analysis. This document doesn’t address to real time measurements of tritium activity and carbon-14 activity in the effluent air of stacks and ducts. Information about real time measurements can be found in the informative annex H of ISO 2889. Sample processing, analysis and calculations of tritium and carbon‑14 emissions are addressed in ISO 20041-2 and ISO 20041-3 respectively. 2 Normative references The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. There are no normative references in this document. ISO 2889:2010, Sampling airborne radioactive materials from the stacks and ducts of nuclear facilities ISO 5667-3:2018, Water quality — Sampling — Part 3: Preservation and handling of water samples ISO 10780:1994, Stationary source emissions — Measurement of velocity and volume flowrate of gas streams in ducts ISO 11929:2010, Determination of the characteristic limits (decision threshold, detection limit and limits of the confidence interval) for measurements of ionizing radiation — Fundamentals and application