1、 ISO 2012 Water quality Strontium 90 and strontium 89 Test methods using liquid scintillation counting or proportional counting Qualit de leau Strontium 90 et strontium 89 Mthodes dessai par comptage des scintillations en milieu liquide ou par comptage proportionnel INTERNATIONAL STANDARD ISO 13160
2、First edition 2012-07-15 Reference number ISO 13160:2012(E) ISO 13160:2012(E) ii ISO 2012 All rights reserved COPYRIGHT PROTECTED DOCUMENT ISO 2012 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or me
3、chanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISOs member body in the country of the requester. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.
4、iso.org Published in Switzerland ISO 13160:2012(E) ISO 2012 All rights reserved iii Contents Page Foreword iv 1 Scope 1 2 Normative references . 1 3 Symbols, definitions, and units . 1 4 Principle . 2 4.1 General . 2 4.2 Chemical separation . 2 4.3 Detection 3 5 Chemical reagents and equipment . 3 6
5、 Procedure 3 6.1 Test sample preparation 3 6.2 Chemical separation . 3 6.3 Preparation of the source for test . 5 6.4 Measurement 6 7 Expression of results . 8 7.1 Determination of 90 Sr in equilibrium with 90 Y . 8 7.2 Determination of 90 Sr by ingrowth of 90 Y . 9 7.3 Determination of 90 Sr in pre
6、sence of 89 Sr when 90 Sr is in equilibrium with 90 Y 11 7.4 Confidence limits .14 8 Quality control 14 9 Test report .15 Annex A (informative) Determination of 89 Sr and 90 Sr by precipitation and proportional counting 16 Annex B (informative) Determination of 89 Sr and 90 Sr by precipitation and l
7、iquid scintillation counting 20 Annex C (informative) Determination of 90 Sr from its daughter product 90 Y at equilibrium by organic extraction and liquid scintillation counting24 Annex D (informative) Determination of 90 Sr after ionic exchange separation by proportional counting 26 Annex E (infor
8、mative) Determination of 90 Sr after separation on a crown ether specific resin and liquid scintillation counting 29 Annex F (informative) Determination of 90 Sr from its daughter product 90 Y at equilibrium by organic extraction by proportional counting 31 Annex G (informative) Correction factor fo
9、r purity control using proportional counting 35 Bibliography .38 ISO 13160:2012(E) Foreword ISO (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 throu
10、gh ISO technical committees. Each member body interested in a subject 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 collabora
11、tes closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standar
12、ds. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of th
13、is document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 13160 was prepared by Technical Committee ISO/TC 147, Water quality, Subcommittee SC 3, Radiological methods. iv ISO 2012 All rights reserved INTERNATIONAL STANDARD I
14、SO 13160:2012(E) Water quality Strontium 90 and strontium 89 Test methods using liquid scintillation counting or proportional counting WARNING Persons using this International Standard should be familiar with normal laboratory practice. This document does not purport to address all of the safety pro
15、blems, 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 regulatory conditions. IMPORTANT It is absolutely essential that tests conducted in accordance with this International St and a
16、 rd be c ar r ied ou t by su i t a b l y quali fied s t a f f. 1 Scope This International Standard specifies the test methods and their associated principles for the measurement of the activity of 90 Sr in equilibrium with 90 Y, and 89 Sr, pure beta-emitting radionuclides, in water samples. Differen
17、t chemical separation methods are presented to produce strontium and yttrium sources, the activity of which is determined using a proportional counter (PC) or liquid scintillation counter (LSC). The selection of the test method depends on the origin of the contamination, the characteristics of the w
18、ater to be analysed, the required accuracy of test results and the available resources of the laboratories. These test methods are used for water monitoring following, past or present, accidental or routine, liquid or gaseous discharges. It also covers the monitoring of contamination caused by globa
19、l fallout. When fallout occurs immediately following a nuclear accident, the contribution of 89 Sr to the total amount of strontium activity is not negligible. This International Standard provides the test methods to determine the activity concentration of 90 Sr in presence of 89 Sr. 2 Normative ref
20、erences The following referenced documents are indispensable for the application 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 11929, Determination of the character
21、istic limits (decision threshold, detection limit and limits of the confidence interval) for measurements of ionizing radiation Fundamentals and application ISO 80000-10, Quantities and units Part 10: Atomic and nuclear physics 3 Symbols, definition s, and units For the purposes of this document, th
22、e definitions, symbols, and abbreviated terms defined in ISO 11929 and ISO 80000-10 and the following apply. A i calibration source activity of radionuclide i, at the time of calibration Bq c A,i activity concentration of radionuclide i Bq l -1 c A,i * decision threshold of radionuclide i Bq l -1 c
23、A,i # detection limit of radionuclide i Bq l -1 c A,i , c A,i lower and upper limits of the confidence interval of radionuclide i Bq l -1 ISO 2012 All rights reserved 1 ISO 13160:2012(E) R c,i chemical yield of the extraction of radionuclide i 1 r 0 background count rate s -1 r 0j background count r
24、ate for measurement j s -1 r g gross count rate s -1 r gj gross count rate for measurement j s -1 r j net count rate for measurement j s -1 r s calibration source count rate s -1 t time elapsed between separation of 90 Sr/ 90 Y (t = 0) and counting s t 0 background counting time s t d , t f start an
25、d finish time respectively of the measurement, referred to t = 0 s t g sample counting time s t j start time of the measurement j, referred to t = 0 s t s calibration source counting time s U expanded uncertainty, calculated by U = ku(c A ) with k = 1, 2 . Bq l -1 u(c A ) standard uncertainty associ
26、ated with the measurement result Bq l -1 V volume of the test sample l i counting efficiency for radionuclide i 1 i decay constant of radionuclide i 1 4 Principle 4.1 General 90 Sr, 90 Y and 89 Sr are pure beta-emitter radionuclides. Their beta-emission energies and half-lives are given in Table 1.
27、Table 1 Half-lives, maximum energies, and average energies of 90 Sr, 90 Y, and 89 Sr Parameter 90 Sr 90 Y 89 Sr Maximum energy 546,0 keV 2 283,9 keV 1 491,0 keV Average energy 196,4 keV 935,3 keV 586,3 keV Half-life 28,79 a 2,67 d 50,5 d 90 Sr can be directly measured or estimated through the measur
28、ement of its daughter product 90 Y. All the test methods are based on a chemical separation step followed by beta-counting of the element using PC or LSC. See Table 2. 4.2 Chemical separation Strontium is isolated from the water using precipitation, ion chromatography or specific chromatographic sep
29、aration using crown ether resin. Yttrium can be isolated by precipitation or liquidliquid extraction. The separation step should maximize the extraction of the pure element. The method chosen shall be selective with a high chemical yield. When thorium, lead or bismuth radioisotopes are present at hi
30、gh activity levels, 2 ISO 2012 All rights reserved ISO 13160:2012(E) they may interfere with 90 Sr, 90 Y or 89 Sr emission during the detection step. Other matrix constituents such as alkaline earth metals and in particular calcium for strontium, or transuranic and lanthanide elements for yttrium, r
31、educe the chemical yield of the extraction. The radiochemical separation yield is calculated using a carrier such as stable strontium or yttrium, or a radioactive tracer such as 85 Sr. Techniques like atomic absorption spectroscopy (AAS), inductively coupled plasmaatomic emission spectroscopy (ICPAE
32、S) or inductively coupled plasmamass spectrometry (ICP MS) to measure the carrier, and gamma-spectrometry to measure 85 Sr, are recommended. A carrier can also be measured by gravimetric methods, but the presence of inactive elements, essentially alkaline earth elements, in the leaching solutions ca
33、n lead to an overestimation of the radiochemical separation yields, particularly for the measurement of strontium. When stable strontium is added as a carrier, the original strontium concentration in the test sample must be known to avoid the overestimation of the radiochemical separation yield. 4.3
34、 Detection The use of LSC, which provides spectra and permits the detection of interference from unwanted radionuclides, is recommended in preference to PC, which does not distinguish between emissions from different beta- emitters. When PC is used, it is recommended that the purity of the precipita
35、te be checked by following the change over an appropriate time of the 90 Y or 89 Sr activity, even though this method is time consuming. Six test methods are presented in Annexes A, B, C, D, E, and F. 5 Chemical reagents and equipment The necessary chemical reagents and equipment for each strontium
36、measurement method are specified in Annexes A, B, C, D, E, and F. During the analyses, unless otherwise stated, use only reagents of recognized analytical grade and laboratory water such as distilled or demineralized water or water of equivalent purity as specified in ISO 3696. 1 6 Procedure 6.1 Tes
37、t sample preparation Strontium is determined from the water test sample. If filtration is required, add the tracer or carrier after this step of the procedure and allow sufficient time to attain chemical equilibrium before starting the test sample preparation. If stable strontium is added as carrier
38、, the original concentration shall be determined in the test sample in this step of the procedure before the addition of the carrier. 6.2 Chemical separation 6.2.1 General There are several routine analyses of 89 Sr and 90 Sr involved in the separation and purification of strontium: precipitation, l
39、iquidliquid extraction or chromatographic techniques (ion exchange or chromatographic extraction). Annexes A, B, C, D, E, and F describe a test method for each of these techniques. ISO 2012 All rights reserved 3 ISO 13160:2012(E) Table 2 Determination procedures for strontium depending on its origin
40、 Origin Old contamination Fresh contamination Radionuclide 90 Sr+ 90 Y 90 Sr+ 90 Y 89 Sr Element Method Product Carrier or Tracer c Separation Sr Y a Sr Chromatography b Precipitation Extraction Precipitation Chromatography b Precipitation 90 Sr 90 Y 90 Sr+ 89 Sr 85 Sr or stable Sr Stable Y 85 Sr or
41、 stable Sr Equilibrium90 Sr+ 90 Y 20 d Yes (recommended) No No Yes No Number One One Two or more Emissions 90 Sr 90 Y 90 Y 90 Sr 90 Y 89 Sr Equipment PC or LSC (total) PC or LSC (total or Cherenkov) PC or LSC (total) Calibration sources 90 Sr+ 90 Y 90 Sr 90 Y 90 Y 90 Sr+ 90 Y 89 Sr 90 Sr 90 Y 89 Sr
42、a Y separation is performed following the 90 Sr 90 Y equilibrium in the test sample. b Liquid chromatography or specific chromatography using crown ether resin. Measurement(s) c Carrier or tracer element measurements can be taken using gamma-spectrometry for 85 Sr (tracer), by gravimetry, atomic abs
43、orption spectrometry (AAS), inductively coupled plasma (ICP) or mass spectrometry (MS) for Sr and Y (tracer and/or carrier). 6.2.2 Precipitation techniques The precipitation technique is suitable for the separation of all mineral elements, including strontium, in water samples with high mineral salt
44、 contents. This technique is very efficient, but not selective for strontium. The use of large quantities of nitric acid and the need to wait for the yttrium to reach equilibrium limit its use. The addition of nitric acid leads to a strontium precipitate with other interfering elements. Successive d
45、issolution precipitation cycles concentrate strontium in the precipitate, while yttrium and other elements remain in the supernatant fraction. The most usual procedures lead to a SrCO 3precipitate. For the test method with 90 Sr and 90 Y at equilibrium, either the global contribution of yttrium and
46、strontium is directly measured in the precipitate or the yttrium activity is measured after a last separation from the strontium. In this latter case, the chemical yield is estimated by the addition of an yttrium carrier to the source before the yttrium separation. The final product is an yttrium pr
47、ecipitate, usually in the form of an oxalate. In the absence of 89 Sr, 90 Sr is measured by counting the beta-emission of 90 Y or of 90 Y and 90 Sr in equilibrium. 4 ISO 2012 All rights reserved ISO 13160:2012(E) When 89 Sr in the water test sample cannot be neglected, the direct measurement method
48、of strontium at two different times shall be chosen. Two precipitation methods are described: Annex A employs PC for 89 Sr and 90 Sr; Annex B employs LSC for 89 Sr and 90 Sr. 6.2.3 Liquidliquid extraction technique This technique is based on the extraction using an organic solvent of 90 Y at equilib
49、rium with its radioactive parent 90 Sr. The chemical separation is fast and requires few technical resources. A provisional result may be achieved after 3 d (approximately one yttrium decay period). However, total selectivity of the extraction is not always possible. In the presence of high levels of natural radioactivity, interference may occur, making it difficult to determine very low levels of strontium activity. This test method is suitable for all samples with low activity of beta-emitting radionuclide. 9
