1、BSI Standards PublicationBS ISO 13168:2015Water quality Simultaneousdetermination of tritiumand carbon 14 activities Test method using liquidscintillation countingBS ISO 13168:2015 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of ISO 13168:2015.The UK participation
2、in its preparation was entrusted to TechnicalCommittee EH/3/8, Radioactivity measurements methods.A list of organizations represented on this committee can beobtained on request to its secretary.This publication does not purport to include all the necessaryprovisions of a contract. Users are respons
3、ible for its correctapplication. The British Standards Institution 2015. Published by BSI StandardsLimited 2015ISBN 978 0 580 81173 9ICS 13.060.60; 13.280Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was published under the authority of theStan
4、dards Policy and Strategy Committee on 31 July 2015.Amendments issued since publicationDate Text affectedBS ISO 13168:2015 ISO 2015Water quality Simultaneous determination of tritium and carbon 14 activities Test method using liquid scintillation countingQualit de leau Dtermination simultane des act
5、ivits volumiques du tritium et du carbone 14 Mthode par comptage des scintillations en milieu liquideINTERNATIONAL STANDARDISO13168First edition2015-07-01Reference numberISO 13168:2015(E)BS ISO 13168:2015ISO 13168:2015(E)ii ISO 2015 All rights reservedCOPYRIGHT PROTECTED DOCUMENT ISO 2015, Published
6、 in SwitzerlandAll rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior written permission. Permission c
7、an be requested from either ISO at the address below or ISOs member body in the country of the requester.ISO copyright officeCh. de Blandonnet 8 CP 401CH-1214 Vernier, Geneva, SwitzerlandTel. +41 22 749 01 11Fax +41 22 749 09 47copyrightiso.orgwww.iso.orgBS ISO 13168:2015ISO 13168:2015(E)Foreword iv
8、Introduction v1 Scope . 12 Normative references 13 Symbols, definitions and units . 24 Principle 35 Reagents and equipment . 35.1 Reagents 45.1.1 Water for the blank 45.1.2 Calibration source solutions 45.1.3 Scintillation solution. 45.1.4 Quenching agent. 55.2 Equipment . 55.2.1 Liquid scintillatio
9、n counter 55.2.2 Counting vials . 56 Sampling and samples 66.1 Sampling . 66.2 Sample storage 67 Procedure. 67.1 Sample preparation 67.2 Preparation of the sources to be measured . 67.3 Counting procedure 67.3.1 General 67.3.2 Control and calibration. 77.3.3 Measurement conditions 87.3.4 Interferenc
10、e control 88 Expression of results 88.1 General . 88.2 Activity concentration of tritium . 98.3 Activity concentration of carbon 14 . 98.4 Combined standard uncertainty for tritium . 108.5 Combined standard uncertainty for carbon 14 . 118.6 Decision threshold for tritium 118.7 Decision threshold for
11、 carbon 14 118.8 Detection limit for tritium 128.9 Detection limit for carbon 14 128.10 Confidence interval limits. 128.11 Calculations using the activity per unit of mass 139 Test report 13Annex A (informative) Example 14Bibliography .16 ISO 2015 All rights reserved iiiContents PageBS ISO 13168:201
12、5ISO 13168:2015(E)ForewordISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subj
13、ect for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IE
14、C) on all matters of electrotechnical standardization.The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the different types of ISO documents should be n
15、oted. This document was drafted in accordance with the editorial rules of the ISO/IEC Directives, Part 2. www.iso.org/directivesAttention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any
16、or all such patent rights. Details of any patent rights identified during the development of the document will be in the Introduction and/or on the ISO list of patent declarations received. www.iso.org/patentsAny trade name used in this document is information given for the convenience of users and
17、does not constitute an endorsement.For an explanation on the meaning of ISO specific terms and expressions related to conformity assessment, as well as information about ISOs adherence to the WTO principles in the Technical Barriers to Trade (TBT) see the following URL: Foreword - Supplementary info
18、rmationThe committee responsible for this document is ISO/TC 147, Water quality, Subcommittee SC3 Radioactivity measurements.iv ISO 2015 All rights reservedBS ISO 13168:2015ISO 13168:2015(E)IntroductionRadioactivity from several naturally-occurring and anthropogenic sources is present throughout the
19、 environment. Thus, water bodies (e.g. surface waters, ground waters, sea waters) can contain radionuclides of natural, human-made, or both origins: natural radionuclides, including potassium 40, tritium, carbon 14, and those originating from the thorium and uranium decay series, in particular radiu
20、m 226, radium 228, uranium 234, uranium 238, lead 210, can be found in water for natural reasons (e.g. desorption from the soil and wash-off by rain water) or can be released from technological processes involving naturally occurring radioactive materials (e.g. the mining and processing of mineral s
21、ands or phosphate fertilizer production and use); human-made radionuclides, such as transuranium elements (americium, plutonium, neptunium, curium), tritium, carbon 14, strontium 90 and gamma emitting radionuclides can also be found in natural waters as a result of authorized routine releases into t
22、he environment in small quantities in the effluent discharged from nuclear fuel cycle facilities. They are also released into the environment following their use in unsealed form for medical and industrial applications. They are also found in the water as a result of past fallout contamination resul
23、ting from the explosion in the atmosphere of nuclear devices and accidents such as those that occurred in Chernobyl and Fukushima.Drinking-water may thus contain radionuclides at activity concentrations which could present a risk to human health. In order to assess the quality of drinking-water (inc
24、luding mineral waters and spring waters) with respect to its radionuclide content and to provide guidance on reducing health risks by taking measures to decrease radionuclide activity concentrations, water resources (groundwater, river, lake, sea, etc.) and drinking water are monitored for their rad
25、ioactivity content as recommended by the World Health Organization WHO and may be required by some national authorities.An international standard on a test method of simultaneous measurement of tritium and carbon 14 concentrations in water samples is justified for test laboratory carrying out these
26、measurements, required sometimes by national authorities, as laboratories may have to obtain a specific accreditation for radionuclide measurement in drinking water samples. Such standard is to be used as a screening method, until the interference of other beta emitters in the test portion is consid
27、ered negligible.Tritium and carbon 14 natural activity concentration can vary according to local geological and climatic characteristics, at a level below 5 Bq/l and below 0,1 Bq/l respectively. These radioactivity levels can be locally enhanced by nuclear installation authorized discharges of low l
28、evel radioactive effluent into the environment. The guidance level for tritium and carbon 14 in drinking water as recommended by WHO is 10 000 and 100 Bq/l respectively.4NOTE The guidance level is the activity concentration with an intake of 2 l/day of drinking water for 1 year, that results in an e
29、ffective dose of 0,1 mSv/year for members of the Public, an effective dose that represents a very low level of risk that is not expected to give rise to any detectable adverse health effect.This International Standard is one of a set of International Standards on test methods dealing with the measur
30、ement of the activity concentration of radionuclides in water samples. ISO 2015 All rights reserved vBS ISO 13168:2015BS ISO 13168:2015Water quality Simultaneous determination of tritium and carbon 14 activities Test method using liquid scintillation countingWARNING Persons using this International
31、Standard should be familiar with normal laboratory practice. This standard does not purport to address all of the safety issues, if any, associated with its use. It is the responsibility of the user to establish appropriate safety and health practices and to ensure compliance with any national regul
32、atory conditions.IMPORTANT It is absolutely essential that tests conducted according to this International Standard be carried out by suitably trained staff.1 ScopeThis International Standard describes a test method for the simultaneous measurement of tritium and carbon-14 in water samples by liquid
33、 scintillation counting of a source obtained by mixing the water sample with a hydrophilic scintillation cocktail.This is considered a screening method because of the potential presence of interfering nuclides in the test sample.The method can be used for any type of environmental study or monitorin
34、g.This International Standard is applicable to all types of waters having an activity concentration ranging from 5 Bq/l to 106Bq/l (upper limit of the liquid scintillation counters for direct counting). For higher activity concentrations, the sample can be diluted to obtain a test sample within this
35、 range.2 Normative referencesThe following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any
36、 amendments) applies.ISO 5667-1, Water quality Sampling Part 1: Guidance on the design of sampling programmes and sampling techniquesISO 5667-3, Water quality Sampling Part 3: Preservation and handling of water samplesISO 9698, Water quality Determination of tritium activity concentration Liquid sci
37、ntillation counting methodISO 80000-10, Quantities and units Part 10: Atomic and nuclear physicsISO 11929, Determination of the characteristic limits (decision threshold, detection limit and limits of the confidence interval) for measurements of ionizing radiation Fundamentals and applicationISO/IEC
38、 Guide 98-3:2008, Uncertainty of measurement Part 3: Guide to the expression of uncertainty in measurement (GUM:1995)ISO/IEC Guide 99:2007, International vocabulary of metrology Basic and general concepts and associated terms (VIM)INTERNATIONAL STANDARD ISO 13168:2015(E) ISO 2015 All rights reserved
39、 1BS ISO 13168:2015ISO 13168:2015(E)3 Symbols, definitions and unitsFor the purposes of this document, the definitions, symbols and abbreviations defined in ISO 80000-10, ISO/IEC Guide 98-3 and ISO/IEC Guide 99, and the following apply.max Maximum energy for the beta emission, in keVVVolume of test
40、sample, in litrem Mass of test sample, in kilogram Density of the sample, in kilogram per litrecAT, cACActivity concentration, in becquerel per litre, respectively for tritium and carbon 14a Activity per unit of mass, in becquerel per kilogramAT, ACActivity of the calibration source, in becquerel, r
41、espectively for tritium and carbon 14t0Background counting time, in secondtgSample counting time, in secondttsT sC,Calibration counting time, in second, respectively for tritium and carbon 14rr0T 0C,Mean background count rate, per second, respectively for tritium and carbon 14rrgT gC,Mean sample cou
42、nt rate, per second, respectively for tritium and carbon 14rrsT sC,Calibration count rate, per second, respectively for tritium and carbon 14rsC TCalibration count rate, per second, for the interfering carbon 14 in the chosen window of the trit-ium energy rangeqDetection efficiency for the quenching
43、 parameter q Detection efficiency for the lowest value of the quenching parameterT,CDetection efficiency, respectively for tritium and carbon 14CTDetection efficiency for carbon 14 in the chosen window of the tritium energy range Correcting factor, for the interfering carbon 14 in the chosen window
44、of the tritium energy rangeffqT qC,Quench factor, respectively for tritium and carbon 14fqC TQuench factor, for the interfering carbon 14 in the chosen window of the tritium energy rangeucAT()ucAC()Standard uncertainty associated with the measurement result, in becquerel per litre, respectively for
45、tritium and carbon 142 ISO 2015 All rights reservedBS ISO 13168:2015ISO 13168:2015(E)U Expanded uncertainty, calculated by U = k u(cA) with k = 1, 2, in becquerel per litrecAT*, cAC*Decision threshold, in becquerel per litre, respectively for tritium and carbon 14cAT#, cAC#Detection limit, in becque
46、rel per litre, respectively for tritium and carbon 14ccAAtrianglerighttriangleleft, ccAT ATtrianglerighttriangleleft, ccAC ACtrianglerighttriangleleft,Lower and upper limits of the confidence interval, in becquerel per litre, respectively for tritium and carbon 144 PrincipleThe test sample is mixed
47、with the scintillation cocktail in a counting vial to obtain a homogeneous medium. Electrons emitted by the radionuclide transfer their energy to the scintillation medium. Molecules excited by this process return to their ground state by emitting photons that are detected by photodetectors.The elect
48、ric pulses emitted by the photodetectors are amplified, sorted (in order to remove random events) and analysed by the electronic systems and the data analysis software. The count rate of these photons allows the determination of the test sample activity, after correcting for the background count rat
49、e and detection efficiency.In order to determine the background count rate, a blank sample is prepared in the same way as the test sample. The blank sample is prepared using a reference water of the lowest activity available, also sometimes called “dead water”.In order to determine the detection efficiencies, it is necessary to measure a water sample having known tritium and carbon 14 activities under conditions that are identical to those used for the test sample. This water shall be a mixture of ce
