ISO 10703:2021 Water quality — Gamma-ray emitting radionuclides — Test method using high resolution gamma-ray spectrometry

标准简介

Water quality — Gamma-ray emitting radionuclides — Test method using high resolution gamma-ray spectrometry是于2021-06发布的ISO标准，适用于全球范围。

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标准部分原文

Water quality — Gamma-ray emitting radionuclides — Test method using high resolution gamma-ray spectrometry

WARNING — Persons using this document should be familiar with normal laboratory practice. This document does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user to establish appropriate safety and health practices and to determine the applicability of any other restrictions.

IMPORTANT — It is absolutely essential that tests conducted according to this document be carried out by suitably trained staff.

1 Scope

This document specifies a method for the physical pre-treatment and conditioning of water samples and the determination of the activity concentration of various radionuclides emitting gamma-rays with energies between 40 keV and 2 MeV, by gamma-ray spectrometry according to the generic test method described in ISO 20042.

The method is applicable to test samples of drinking water, rainwater, surface and ground water as well as cooling water, industrial water, domestic and industrial wastewater after proper sampling, sample handling, and test sample preparation (filtration when necessary and taking into account the amount of dissolved material in the water). This method is only applicable to homogeneous samples or samples which are homogeneous via timely filtration.

The lowest limit that can be measured without concentration of the sample or by using only passive -2 137 1)

shield of the detection system is about 5·10 Bq/l for e.g. Cs . The upper limit of the activity corresponds to a dead time of 10 %. Higher dead times may be used but evidence of the accuracy of the dead-time correction is required.

Depending on different factors, such as the energy of the gamma-rays, the emission probability per nuclear disintegration, the size and geometry of the sample and the detector, the shielding, the counting time and other experimental parameters, the sample may require to be concentrated by evaporation -2

if activities below 5·10 Bq/l need to be measured. However, volatile radionuclides (e.g. radon and radioiodine) can be lost during the source preparation.

This method is suitable for application in emergency situations.

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 3696, Water for analytical laboratory use — Specification and test methods

ISO 5667-1, Water quality — Sampling — Part 1: Guidance on the design of sampling programmes and sampling techniques

ISO 5667-3, Water quality — Sampling — Part 3: Preservation and handling of water samples

ISO 5667-10, Water quality — Sampling — Part 10: Guidance on sampling of waste water

ISO 5667-14, Water quality — Sampling — Part 14: Guidance on quality assurance and quality control of environmental water sampling and handling

1) The sample geometry: 3l Marinelli beaker; detector: GE HP N relative efficiency 55 % ; counting time: 18h.

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

ISO 80000-10, Quantities and units — Part 10: Atomic and nuclear physics

3 Terms a nd definiti ons

For the purposes of this document, the terms and definitions given in ISO 80000-10 and the following apply.

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

— ISO Online browsing platform: available at https:// www .iso .org/ obp

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

3.1

blank sample

container of an identical composition to the one used for the water test sample, filled with demineralized water

3.2

dead time

time during spectrum acquisition (real time) during which pulses are not recorded or processed

Note 1 to entry: Dead time is expressed in percent, calculated as follows: real time minus live time, all divided by real time then multiplied by 100

3.3

dead time correction

correction to be applied to the observed number of pulses to take into account the number of pulses lost during the dead time (3.2)

3.4

decay constant

λ

quotient of the rate at which a population of radioactive atoms decreases because of radioactive decay by the size of that population of radioactive atoms

Note 1 to entry: It can also be expressed as the quotient of dP by dt,

dP 1 dN

λ== −

dtN dt

where

dP is the probability of a given nucleus undergoing a spontaneous nuclear transition from that en-

ergy state in the time interval dt;

N is the number of nuclei of concern existing at time t.

Note 2 to entry: The time required for half of the original population of radioactive atoms to decay is called the half-life. The relationship between the half-life, T1/2, and the decay constant is given by T1/2 = ln(2)/λ.

3.5

ef f ic ienc y

ratio of the number of gamma photons detected in the full energy peak to the number of the same type emitted by the radiation source in the same time interval, under stated conditions of detection

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