Strålningsmätning

Kommittébeteckning: SIS/TK 405 (Kärnenergi)
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Svarsdatum: den 12 aug 2019
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This document specifies a procedure, in the field of ionizing radiation metrology, for the calculation of

the “decision threshold”, the “detection limit” and the “limits of the coverage interval” for a nonnegative

ionizing radiation measurand when counting measurements with preselection of time or

counts are carried out. The measurand results from a gross count rate and a background count rate as

well as from further quantities on the basis of a model of the evaluation. In particular, the measurand

can be the net count rate as the difference of the gross count rate and the background count rate, or the

net activity of a sample. It can also be influenced by calibration of the measuring system, by sample

treatment and by other factors.

ISO 11929 has been divided into four parts covering elementary applications in Part 1, advanced

applications on the basis of the ISO/IEC Guide 98-3-1 in Part 2, applications to unfolding methods in

Part 3, and guidance to the application in Part 4.

ISO 11929-1 covers basic applications of counting measurements frequently used in the field of ionizing

radiation metrology. It is restricted to applications for which the uncertainties can be evaluated on the

basis of the ISO/IEC Guide 98-3 (JCGM 2008). In Annex B of ISO 11929-1, the special case of repeated

counting measurements with random influences and in Annex C of ISO 11929-1, measurements with

linear analogous ratemeters are covered.

ISO 11929-2 extends ISO 11929-1 to the evaluation of measurement uncertainties according to the

ISO/IEC Guide 98-3-1. ISO 11929-2 also presents some explanatory notes regarding general aspects of

counting measurements and Bayesian statistics in measurements.

ISO 11929-3 deals with the evaluation of measurements using unfolding methods and counting

spectrometric multi-channel measurements if evaluated by unfolding methods, in particular, alpha- and

gamma-spectrometric measurements. Further, it provides some advice how to deal with correlations

and covariances.

ISO 11929-4 gives guidance to the application of ISO 11929, summarizing shortly the general procedure

and then presenting a wide range of numerical examples. The examples cover elementary applications

according to ISO 11929-1 and ISO 11929-2.

ISO 11929 also applies analogously to other measurements of any kind if a similar model of the

evaluation is involved. Further practical examples can be found in other International Standards, for

example [1-21].

Kommittébeteckning: SIS/TK 424 (Kemiska vattenundersökningar)
Källa: CEN
Svarsdatum: den 25 aug 2019
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This part of ISO 13164 describes a test method for the determination of radon-222 (222Rn) activity

concentration in non-saline waters by extraction and liquid scintillation counting.

The radon-222 activity concentrations, which can be measured by this test method utilizing currently

available instruments, are at least above 0,5 Bq l−1 for a 10 ml test sample and a measuring time of 1 h.

This test method can be used successfully with drinking water samples and it is the responsibility of the

laboratory to ensure the validity of this test method for water samples of untested matrices.

Annex A gives indication on the necessary counting conditions to meet the required detection limits for

drinking water monitoring.

Kommittébeteckning: SIS/TK 424 (Kemiska vattenundersökningar)
Källa: CEN
Svarsdatum: den 25 aug 2019
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This part of ISO 13165 specifies the determination of radium-226 (226Ra) activity concentration in nonsaline

water samples by extraction of its daughter radon-222 (222Rn) and its measurement using liquid

scintillation counting.

Radium-226 activity concentrations which can be measured by this test method utilizing currently

available liquid scintillation counters goes down to 50 mBq l−1. This method is not applicable to the

measurement of other radium isotopes.

Kommittébeteckning: SIS/TK 424 (Kemiska vattenundersökningar)
Källa: CEN
Svarsdatum: den 25 aug 2019
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This part of ISO 13165 specifies the determination of radium-226 (226Ra) activity concentration in all

types of water by emanometry.

The method specified is suitable for the determination of the soluble, suspended, and total 226Ra activity

concentration in all types of water with soluble 226Ra activity concentrations greater than 0,02 Bq l−1.

In water containing high activity concentrations of 228Th, interference from 220Rn decay products can

lead to overestimation of measured levels (see Figure A.2).

Kommittébeteckning: SIS/TK 424 (Kemiska vattenundersökningar)
Källa: CEN
Svarsdatum: den 25 aug 2019
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This part of ISO 13165 specifies the determination of radium-226 (226Ra) activity concentration in all types of water by coprecipitation followed by gamma-spectrometry (see ISO 18589‑3).

The method described is suitable for determination of soluble 226Ra activity concentrations greater than 0,02 Bq l−1 using a sample volume of 1 l to 100 l of any water type.

For water samples smaller than a volume of 1 l, direct gamma-spectrometry can be performed following ISO 10703 with a higher detection limit.

NOTE This test method also allows other isotopes of radium, 223Ra, 224Ra, and 228Ra, to be determined.

Kommittébeteckning: SIS/TK 424 (Kemiska vattenundersökningar)
Källa: CEN
Svarsdatum: den 20 sep 2019
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This document provides guidelines to enable testing laboratory using rapid test methods on all types of water samples that may be contaminated following a nuclear or radiological emergency situation:

— taking into account the specific context for the tests to be performed, e.g. an unknown and potentially unusual high level of contamination;

— using or adjusting, when possible, radioactivity test method implemented during routine situation to obtain a result rapidly or applying specific rapid test methods previously validated by the laboratory, e.g. for 89Sr determination;

— preparing the test laboratory to measure a large number of potentially contaminated samples.

The aim of this document is to ensure decision makers have reliable results needed to take actions on time and minimize the dose to the public.

Measurements are performed in order to minimize the risk for the public in checking the water quality of water supplies. For emergency situations, test results are compared to operational intervention levels.

Note Operational intervention levels (OILs) are derived from IAEA Safety Standards[13] or national authorities[5].

A key can be to use the usual and routine methods in a faster manner. The goal of these rapid measurements is often to check an unusual radioactivity level in the test sample, to identify the radionuclides and their activity concentration levels and to establish compliance of the sampled water with intervention levels[21]. It should be noted that in such circumstances validation parameters are not always valid (impossible use of standard measuring geometries for gamma spectrometry…) and thus uncertainties associated with the test results may increase.

The first steps of the analytical approach is usually based on gross alpha and gross beta test methods considered as screening methods (adaptation of ISO 10704 and ISO 11704) and gamma spectrometry (adaptation of ISO 20042, ISO 10703 and ISO 19581). Then, when necessary[3], test method standards for specific radionuclides are adapted and applied (for example, 90Sr measurement following ISO 13160) as proposed in Annex A.

This document refers to a set of already published ISO standards. When appropriate, this document also refers to national standards or other publically available documents.

Screening techniques that can be carried out directly in the field are not part of this document.