ISO 11665-4:2021 Measurement of radioactivity in the environment — Air: radon-222 —Part 4: Integrated measurement method for determining average activity concentration using passive sampling and delayed analysis

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Measurement of radioactivity in the environment — Air: radon-222 —Part 4: Integrated measurement method for determining average activity concentration using passive sampling and delayed analysis是于2021-03发布的ISO标准，适用于全球。

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INTERNATIONAL STANDARD ISO 11665-4:2021(E)

Measurement of radioactivity in the environment — Air: radon-222 —

Part 4: Integrated measurement method for determining average activity concentration using passive sampling and delayed analysis

1 Scope

This document describes radon-222 integrated measurement techniques with passive sampling. It gives indications for determining the average activity concentration of the radon-222 in the air from measurements based on easy-to-use and low-cost passive sampling, and the conditions of use for the sensors.

This document covers samples taken without interruption over periods varying from a few days to one year.

This measurement method is applicable to air samples with radon activity concentrations greater 3

than 5 Bq/m .

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.

ISO 11665-1, Measurement of radioactivity in the environment — Air: radon-222 — Part 1: Origins of radon and its short-lived decay products and associated measurement methods

ISO 11929 (all parts), Determination of the characteristic limits (decision threshold, detection limit and limits of the coverage interval) for measurements of ionizing radiation — Fundamentals and application

ISO/IEC Guide 98-3, Uncertainty of measurement — Part 3: Guide to the expression of uncertainty in me a s ur ement (GUM:1 995)

ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories

IEC 61577-1, Radiation protection instrumentation — Radon and radon decay product measuring instruments — Part 1: General principles

3 Terms, d efinitions and symbols

3.1 Terms and definiti ons

For the purposes of this document, the terms and definitions given in ISO 11665-1 apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https://w ww .iso. org/o bp

— IEC Electropedia: available at http:// www .electropedia. org/

ISO 11665-4:2021(E)

3.2 Symbols

For the purposes of this document, the symbols given in ISO 11665-1 and the following apply.

average activity concentration, in becquerels per cubic metre

C

∗

decision threshold of the average activity concentration, in becquerels per cubic metre

C

#

detection limit of the average activity concentration, in becquerels per cubic metre

C



lower limit of the confidence interval of the average activity concentration, in becquerels C

per cubic metre



upper limit of the confidence interval of the average activity concentration, in becquerels C

per cubic metre

t sampling duration, in hours

U expanded uncertainty calculated by Uk=⋅u() with k = 2

u() standard uncertainty associated with the measurement result

u relative standard uncertainty

()

rel

μ quantity to be measured

μ background level

0

ω correction factor linked to the calibration factor and the sampling duration

4 Principle

Integrated measurement of the average radon activity concentration is based on the following elements:

a) continuous, passive sampling of an air sample representative of the atmosphere under investigation, by free convection and natural diffusion for a sensor in an open configuration (open to the air) or by natural diffusion for a sensor in a closed configuration (with an accumulation chamber);

b) simultaneous accumulation of a measurable physical quantity (etched tracks, electrostatic potential drop, radioactive atoms, etc.) on a suitable sensor;

c) measurement of the accumulated physical quantity with a direct link to the average radon activity concentration over the sampling period in question.

Several measurement methods meet the requirements of this document. They are basically distinguished by the type of accumulated physical quantity and how it is measured. The physical quantity and its related measurement may be as follows, for example:

— “latent tracks” produced in a polymer [solid-state nuclear track detector (SSNTD)] by ionization from alpha particles of the radon and its decay products; these latent tracks are detected and counted (see Annex A);

— charges produced in a solid [semi-conductor medium (silicon)] by ionisation from alpha particles of the radon and its decay products; they are detected by related electronics;

— discharge of an electret (non-rechargeable, positively charged element) by ionisation of the air due to the radioactive disintegration of radon and its decay products; the voltage variation relating to this discharge is measured (see Annex B);

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