BS ISO 18589-4-2009 Measurement of radioactivity in the environment - Soil - Measurement of plutonium isotopes (plutonium 238 and Plutonium 239 + 240) by alpha spectrometry《环境中的放射性.pdf

1、BS ISO18589-4:2009ICS 13.080.01; 17.240NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBRITISH STANDARDMeasurement ofradioactivity in theenvironment SoilPart 4: Measurement of plutoniumisotopes (plutonium 238 and plutonium239 + 240) by alpha spectrometryThis British Standardwas

2、 published under theauthority of the StandardsPolicy and StrategyCommittee on 30 April2009. BSI 2009ISBN 978 0 580 53278 8Amendments/corrigenda issued since publicationDate CommentsBS ISO 18589-4:2009National forewordThis British Standard is the UK implementation of ISO 18589-4:2009.The UK participa

3、tion in its preparation was entrusted to TechnicalCommittee NCE/2, Radiation protection and measurement.A list of organizations represented on this committee can be obtained onrequest to its secretary.This publication does not purport to include all the necessary provisionsof a contract. Users are r

4、esponsible for its correct application.Compliance with a British Standard cannot confer immunityfrom legal obligations.BS ISO 18589-4:2009Reference numberISO 18589-4:2009(E)ISO 2009INTERNATIONAL STANDARD ISO18589-4First edition2009-03-01Measurement of radioactivity in the environment Soil Part 4: Me

5、asurement of plutonium isotopes (plutonium 238 and plutonium 239 + 240) by alpha spectrometry Mesurage de la radioactivit dans lenvironnement Sol Partie 4: Mesurage des isotopes du plutonium (plutonium 238 et plutonium 239 + 240) par spectromtrie alpha BS ISO 18589-4:2009ISO 18589-4:2009(E) PDF disc

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8、he file; the PDF-creation parameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below. COPYRIGHT PROT

9、ECTED DOCUMENT ISO 2009 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 mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISOs m

10、ember 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.iso.org Published in Switzerland ii ISO 2009 All rights reservedBS ISO 18589-4:2009ISO 18589-4:2009(E) ISO 2009 All rights r

11、eserved iiiContents Page Foreword iv Introduction v 1 Scope . 1 2 Normative references . 1 3 Terms, definitions and symbols 1 4 Principle. 2 5 Chemical reagents and equipment . 2 6 Procedure 3 7 Expression of results . 4 8 Test report . 6 Annex A (informative) Plutonium desorption 7 Annex B (informa

12、tive) Chemical separation of plutonium by an organic solvent. 11 Annex C (informative) Chemical separation of plutonium on anionic resin 13 Annex D (informative) Chemical separation of plutonium by specific resins 15 Annex E (informative) Preparation of the source by electro-deposition 18 Annex F (i

13、nformative) Preparation of the source by co-precipitation 21 Bibliography . 22 BS ISO 18589-4:2009ISO 18589-4:2009(E) iv ISO 2009 All rights reservedForeword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work

14、of preparing International Standards is normally carried out through 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-government

15、al, in liaison with ISO, also take part in the work. ISO collaborates 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 mai

16、n task of technical committees is to prepare International Standards. 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. Att

17、ention 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 or all such patent rights. ISO 18589-4 was prepared by Technical Committee ISO/TC 85, Nuclear energy, Subcommittee SC 2, Radiation

18、protection. ISO 18589 consists of the following parts, under the general title Measurement of radioactivity in the environment Soil: Part 1: General guidelines and definitions Part 2: Guidance for the selection of the sampling strategy, sampling and pre-treatment of samples Part 3: Measurements of g

19、amma-emitting radionuclides Part 4: Measurement of plutonium isotopes (plutonium 238 and plutonium 239 + 240) by alpha spectrometry Part 5: Measurement of strontium 90 Part 6: Measurement of gross alpha and gross beta activities BS ISO 18589-4:2009ISO 18589-4:2009(E) ISO 2009 All rights reserved vIn

20、troduction ISO 18589 is published in several parts for use jointly or separately according to needs. Parts 1 to 6 concerning the measurements of radioactivity in the soil have been prepared simultaneously. These parts are complementary and are addressed to those responsible for determining the radio

21、activity present in soil. The first two parts are general in nature. Parts 3 to 5 deal with nuclide-specific measurements and Part 6 deals with non-specific measurements of gross alpha or gross beta activities. Additional parts can be added to ISO 18589 in the future if the standardization of the me

22、asurement of other radionuclides becomes necessary. BS ISO 18589-4:2009BS ISO 18589-4:2009INTERNATIONAL STANDARD ISO 18589-4:2009(E) ISO 2009 All rights reserved 1Measurement of radioactivity in the environment Soil Part 4: Measurement of plutonium isotopes (plutonium 238 and plutonium 239 + 240) by

23、 alpha spectrometry 1 Scope This part of ISO 18589 describes a method for measuring plutonium 238 and 239 + 240 isotopes in soil by alpha spectrometry samples using chemical separation techniques. The method can be used for any type of environmental study or monitoring. These techniques can also be

24、used for measurements of very low levels of activity, one or two orders of magnitude less than the level of natural alpha-emitting radionuclides. The mass of the test portion required depends on the assumed activity of the sample and the desired detection limit. In practice, it can range from 0,1 g

25、to 100 g of the test sample. 2 Normative references 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) applie

26、s. ISO 31-9, Quantities and units Part 9: Atomic and nuclear physics ISO 11074, Soil quality Vocabulary ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories ISO 18589-1, Measurement of radioactivity in the environment Soil Part 1: General guidelines and defi

27、nitions ISO 18589-2, Measurement of radioactivity in the environment Soil Part 2: Guidance for the selection of the sampling strategy, sampling and pre-treatment of samples 3 Terms, definitions and symbols For the purposes of this document, the terms, definitions and symbols given in ISO 18589-1, IS

28、O 11074 and ISO 31-9 together with the following symbols apply. m Mass of the test portion, expressed in kilograms a Activity per unit of mass, expressed in becquerel per kilogram A Activity of the tracer added, expressed in becquerel, at the time of measurement tgSample counting time, expressed in

29、seconds BS ISO 18589-4:2009ISO 18589-4:2009(E) 2 ISO 2009 All rights reservedt0Background counting time, expressed in seconds rg, rgtGross count rate per second from measured plutonium and tracer, respectively r0, r0tBackground count rate per second from measured plutonium and tracer, respectively R

30、 Total measurement yield u(a) Standard uncertainty associated with the measurement result, expressed in becquerel per kilogram U Expanded uncertainty, expressed in becquerel per kilogram, calculated by U = k u(a) with k = 1, 2, a* Decision threshold, expressed in becquerel per kilogram a#Detection l

31、imit, expressed in becquerel per kilogram ,aaLower and upper limits of the confidence interval, expressed in becquerel per kilogram 4 Principle The plutonium is deposited as a thin source for measurement by alpha spectrometry using a grid chamber or semi-conductor detector-type apparatus. The source

32、s are usually prepared by electro-deposition or co-precipitation after chemical separation and purification of the plutonium isotopes present in the test portion1, 2, 3, 4. Direct deposition on the planchette, such as electro-spraying, can also be used. Specific chemical separation and purification

33、procedures are required in order to avoid interference from the presence of natural or artificial -emitters and stable nuclides in the sample, in quantities that are often greater than those of the plutonium isotopes during their measurement. These procedures allow the removal of the main sources of

34、 interference, including the salt content of the leaching solutions, especially hydrolyzable elements, in order to prepare the thinnest deposited source, other -emitting radionuclides, such as 241Am and the thorium isotopes, whose emissions can interfere with those of plutonium isotopes. The total y

35、ield for each analysis (chemical separation yield, thin-layer deposit and measurement) is determined by adding a standard solution of 236Pu or 242Pu considered as tracer. As a result, the procedure shall include a valence cycle, adjusting the tracer and the plutonium isotopes being measured to the s

36、ame oxidation state, in order to achieve identical chemical behaviour for all of them. 5 Chemical reagents and equipment The chemical reagents and equipment are described in Annex A for plutonium desorption, in Annexes B, C and D for chemical treatment and in Annexes E and F for the preparation of t

37、he deposited source. All the chemical reagents required to carry out this procedure shall be of analytical grade. BS ISO 18589-4:2009ISO 18589-4:2009(E) ISO 2009 All rights reserved 36 Procedure 6.1 Plutonium desorption It is necessary to desorb the plutonium from the soil test portion and into solu

38、tion. When the plutonium is absorbed onto soil particles from an aqueous solution or onto global fallout particles directly deposited on the soil, it is readily desorbed by direct acid treatment. Plutonium metabolized by animals or plants forms an organic complex that can be found in soil samples. I

39、t is released by the destruction of organic matter present in the soil by calcination of the test sample at 500 C to 600 C. In some cases, when heated, plutonium can form refractory compounds that require hydrofluoric acid treatment or fusion to make them soluble4. Two methods of plutonium desorptio

40、n are described in Annex A. In order to quantify the recovery yield, a tracer is added at the start of this step of the procedure; time is allowed, usually up to one day, to obtain equilibrium before starting the plutonium desorption. 6.2 Chemical separation There are three commonly used techniques

41、for the chemical separation of plutonium: liquid-liquid extraction, extraction on an ion-exchange resin or specific-extraction chromatographic resin. One method from each technique is presented in Annexes B to D: organic solvent5, separation by anionic resin6or by extraction chromatographic resin7,

42、8. 6.3 Preparation of the source to be measured The source can be prepared by deposition, either by electro-deposition on a planchette (a stainless steel disk), or by co-precipitation. 6.3.1 Electro-deposition method Electro-deposition is carried out after the chemical separation of the plutonium fr

43、om interfering elements. It allows the electrochemical deposition of the radionuclides in an ultra-thin layer onto the planchette9, 10. The procedure described in Annex E applies to the three chemical separation methods described in Annexes B, C and D. NOTE Electro-deposition is not a selective meth

44、od because the metal cations likely to form insoluble hydroxides can be deposited at the same time as the plutonium. 6.3.2 Co-precipitation method Co-precipitation, using fluoride compounds, can be carried out after the chemical separation of the plutonium from other interfering elements. It allows

45、the precipitation of the radionuclide(s) in the form of a thin layer on a filter. The procedure described in Annex F can be applied to the three chemical separation methods described in Annexes B to D. 6.4 Background determination Measure the background using a blank prepared for the method chosen,

46、starting with a clean test portion (or directly distilled water). 6.5 Measurement The plutonium activity per unit of mass is calculated by counting the sample source for an appropriate time. The same equipment conditions should be used for the sample, the background and the calibration source measur

47、ements. BS ISO 18589-4:2009ISO 18589-4:2009(E) 4 ISO 2009 All rights reservedThe counting time required depends on the sample and background count rates and also the detection limit and decision threshold required. The spectra should be inspected to confirm good peak separation and no interfering pe

48、aks. 7 Expression of results 7.1 Calculation of the activity per unit of mass The plutonium activity is calculated by integrating the number of counts in the corresponding peaks of the radionuclide tracer, 238Pu and/or 239 + 240Pu, of the alpha emission spectrum of the sample, obtained by alpha spec

49、trometry. The results of these integrations, divided by the counting time, are the gross count rates, rgtand rg, for the tracer and the plutonium isotopes, respectively. rgtand rgare corrected for the background contribution and, if needed, for the contribution of the tailing of higher-energy peaks, which depends on the detector characteristics. Background count rates are calculated from the alpha-emission spectrum of a blank sample by integrating the number of counts in th