1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationBS ISO 16424:2012Nuclear energy Evaluationof homogeneity of Gd distribution within gadoliniumfuel blends and determinationof Gd2O3content in gadolinium fuel pellets bymeasurement
2、s of uranium andgadolinium elementsBS ISO 16424:2012 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of ISO 16424:2012.The UK participation in its preparation was entrusted to TechnicalCommittee NCE/9, Nuclear fuel cycle technology.A list of organizations represented
3、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 responsible for its correctapplication. The British Standards Institution 2012. Published by BSI StandardsLimited 2012ISBN 978 0 580 73017 7I
4、CS 27.120.30Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was published under the authority of theStandards Policy and Strategy Committee on 31 December 2012.Amendments issued since publicationDate Text affectedBS ISO 16424:2012 ISO 2012Nuclear
5、 energy Evaluation of homogeneity of Gd distribution within gadolinium fuel blends and determination of Gd2O3content in gadolinium fuel pellets by measurements of uranium and gadolinium elementsnergie nuclaire valuation de lhomognit de la distribution du Gd dans les mlanges de combustibles au gadoli
6、nium et dtermination de la teneur en Gd2O3dans les pastilles combustibles au gadolinium par mesurage des lments uranium et gadoliniumINTERNATIONAL STANDARDISO16424First edition2012-12-01Reference numberISO 16424:2012(E)BS ISO 16424:2012ISO 16424:2012(E)ii ISO 2012 All rights reservedCOPYRIGHT PROTEC
7、TED DOCUMENT ISO 2012All 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 memb
8、er body in the country of the requester.ISO copyright officeCase postale 56 CH-1211 Geneva 20Tel. + 41 22 749 01 11Fax + 41 22 749 09 47E-mail copyrightiso.orgWeb www.iso.orgPublished in SwitzerlandBS ISO 16424:2012ISO 16424:2012(E) ISO 2012 All rights reserved iiiContents PageForeword iv1 Scope . 1
9、2 Normative references 13 Principle 14 Apparatus . 24.1 High dispersion direct reading ICP-AES 24.2 Analytical balance. 24.3 Small stainless steel spoon . 25 Reagents 26 Reference solutions . 26.1 Gadolinium element reference solutions . 26.2 Uranium element reference solutions 37 Sample preparation
10、 . 37.1 Sample preparation for evaluation of Gd homogeneity in gadolinium fuel blend 37.2 Sample preparation for determining the Gd2O3content of Gd fuel pellets 38 Calibration and analysis of the samples . 38.1 Calibration of Gd peak line intensity 38.2 Calibration of U peak line intensity . 38.3 Ev
11、aluation of Gd homogeneity in gadolinium fuel blend . 38.4 Determination of Gd2O3content in gadolinium fuel pellet 49 Precision . 610 Test report . 6Annex A (informative) Calibration and Gd and U measurement uncertainties . 7Annex B (informative) Derivation of O/M and O/U ratio formulas .10Annex C (
12、informative) Evaluation of Gd2O3measurement precision .12Bibliography .15BS ISO 16424:2012ISO 16424:2012(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 nor
13、mally 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-governmental, in liaison with ISO, also take part in
14、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 main task of technical committees is to prepare
15、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.Attention is drawn to the possibility that some o
16、f 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 16424 was prepared by Technical Committee ISO/TC 85, Nuclear Energy, Nuclear Technologies, and Radiological Protection, Subcommittee SC 5, Nuclear
17、Fuel Cycle.iv ISO 2012 All rights reservedBS ISO 16424:2012INTERNATIONAL STANDARD ISO 16424:2012(E)Nuclear energy Evaluation of homogeneity of Gd distribution within gadolinium fuel blends and determination of Gd2O3content in gadolinium fuel pellets by measurements of uranium and gadolinium elements
18、1 ScopeThis International Standard is applicable to the evaluation of the homogeneity of Gd distribution within gadolinium fuel blends, and the determination of the Gd2O3content in sintered fuel pellets of Gd2O3+UO2from 1 % to 10 %, by measurements of gadolinium (Gd) and uranium (U) elements using I
19、CP-AES.After performing measurements of Gd and U elements using ICP-AES, if statistical methodology is additionally applied, homogeneity of Gd distribution within a Gd fuel pellet lot can also be evaluated. However, this International Standard covers the statistical methodology only on a limited bas
20、is.NOTE 1 ISO 16796 also provides a method for Gd2O3content determination by atomic emission spectrometry using an inductively coupled plasma source (ICP-AES). The methodology of ISO 16796 is different from the one of this International Standard.NOTE 2 In this International Standard, gadolinium fuel
21、 blend represents a mixture of uranium dioxide (UO2) powder and gadolinium oxide (Gd2O3) powder. The physically blended and homogenized powder may additionally contain in it rather large quantities of uranium oxide (U3O8) powder particles and/or the M3O8powder particles obtained by oxidation of Gd p
22、ellets. In this International Standard, the symbol “M” in the chemical formula “M3O8” and in the terminology “O/M ratio” represents metallic elements U and Gd.2 Normative referencesThe following documents, in whole or in part, are normatively referenced in this document and are indispensible for its
23、 application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including amendments) applies.ISO 3696:1987, Water for analytical laboratory use S pecification and test methods3 PrincipleIf the Gd and U element contents and t
24、he oxygen to metal atomic ratio (commonly referred to as O/M ratio) in a gadolinium fuel pellet are measured or determined, the Gd2O3content of that pellet can be determined by calculation based on the stoichiometry of the pellet. The stoichiometric compositions for Gd and U will depend upon pellet
25、manufacturing specification. If the specification requires that the Gd2O3content in the pellet be 6 % as mass fraction, after manufacturing, the ratio of total Gd mass to total U mass in that pellet will be close to 0,063.The Gd and U element content values measured from a powder blend can make it p
26、ossible to evaluate whether Gd distribution in the powder is sufficiently homogeneous. Moreover, the two values make it possible to estimate accurately the actual Gd2O3content of the pellet after sintering. The estimated Gd2O3content can be used to anticipate whether the Gd pellets to be produced wi
27、ll meet Gd2O3content specifications or not. ISO 2012 All rights reserved 1BS ISO 16424:2012ISO 16424:2012(E)Impurity interferences have not been observed for the usual samples of the nuclear grade material. Very small quantities of impurity elements which might be contained in the samples do not aff
28、ect the principle of this International Standard.NOTE Even in the case of M3O8powder or mixture of UO2powder and Gd2O3powder, if the Gd and U element contents and the O/M ratio are measured or determined, the Gd2O3content (or Gd content) of that powder can be determined by calculation based on the s
29、toichiometry of the powder. Using the Gd2O3content (or Gd content) thus obtained and the O/M ratio, the uranium concentration factor of the powder can also be calculated so as to obtain accurate uranium accounting data.4 Apparatus4.1 High dispersion direct reading ICP-AESThe measured values should b
30、e indicated down to at least two decimal places when element concentrations in the range from 1 mg/l to 100 mg/l are measured. For determination of Gd and U element concentrations, 354,580 nm and 398,579 nm peaks in atomic emission spectrum are used, respectively. However, instead of the two peaks,
31、other peaks are also available.4.2 Analytical balanceThe sensitivity of the balance is 0,1 mg.4.3 Small stainless steel spoonThe small spoon is able to accommodate powder in the range from 1 mg to 100 mg.4.4 Hot plate.4.5 Glass beakers or polytetrafluoroethylene (PTFE) beakers.4.6 Micropipettes.4.7
32、Volumetric flasks.4.8 Percussion mortar.5 Reagents5.1 Nitric acid, aqueous solution at a volume fraction of 50 %.5.2 Water, distilled water or water complying with grade 3 of ISO 3696:1987.6 Reference solutions6.1 Gadolinium element reference solutionsThree Gd reference solutions whose Gd concentrat
33、ions are 5 mg/l, 10 mg/l and 15 mg/l, respectively, are used for calibration. These Gd reference solutions1)are the ones that have been manufactured by diluting a reference material with the water specified in 5.2.1) A certified gadolinium reference material from NIST (National Institute of Standard
34、s and Technology, USA) is an example of a suitable product available commercially. This information is given for the convenience of users of this document and does not constitute an endorsement of this product by ISO.2 ISO 2012 All rights reservedBS ISO 16424:2012ISO 16424:2012(E)6.2 Uranium element
35、 reference solutionsThree U reference solutions whose U concentrations are 50 mg/l, 70 mg/l and 100 mg/l, respectively, are used for calibration. These U reference solutions2)are the ones that have been manufactured by diluting a reference material with the water specified in 5.2.7 Sample preparatio
36、n7.1 Sample preparation for evaluation of Gd homogeneity in gadolinium fuel blendUsing a small spoon, take randomly at least five different powder samples from the blended powder, then dissolve each of the samples in the nitric acid solution of 5.1. Number each beaker individually. The U concentrati
37、ons of the sample solutions prepared should be somewhere in the range from 50 mg/l to 100 mg/l.To evaluate the homogeneity of the Gd distribution within a Gd fuel pellet lot, take at least five different pellet samples from the lot and then crush each of the pellets into small pellet fragments as de
38、scribed in 7.2.NOTE 1 If about 2 mg of the powder sample is dissolved in 20 ml of the nitric acid solution, the required uranium concentration range will be obtained. Alternatively, if about 100 mg of sample is dissolved and then diluted by proper pipetting and addition of distilled water, the conce
39、ntration range can also be obtained.7.2 Sample preparation for determining the Gd2O3content of Gd fuel pelletsAfter crushing a gadolinium fuel pellet using a percussion mortar, randomly take a small sample from the pellet fragments, and dissolve it in the nitric acid solution. The U concentration sh
40、ould be somewhere in the range from 50 mg/l to 100 mg/l.8 Calibration and analysis of the samples8.1 Calibration of Gd peak line intensityThe three Gd reference solutions of 6.1 are used to calibrate the intensity of the Gd peak line. The Gd peak line intensity is repeatedly measured to establish an
41、 intensity-versus-concentration curve (regression curve) needed for determination of Gd concentrations. See A.1.8.2 Calibration of U peak line intensityThe three U reference solutions of 6.2 are used to calibrate the intensity of the U peak line. The U peak line intensity is repeatedly measured to e
42、stablish an intensity-versus-concentration curve (regression curve) needed for determination of U concentrations. See A.2.8.3 Evaluation of Gd homogeneity in gadolinium fuel blend8.3.1 Estimated Gd2O3contentMeasure the concentrations of Gd and U elements contained in the sample solutions (at least f
43、ive different solutions) that were prepared according to 7.1. Each sample solution is repeatedly measured six times, and the six measurement values of Gd and U each are averaged. Each sample solution will be given a Gd 2) A certified uranium reference material from NIST (National Institute of Standa
44、rds and Technology, USA) is an example of a suitable product available commercially. This information is given for the convenience of users of this document and does not constitute an endorsement of this product by ISO. ISO 2012 All rights reserved 3BS ISO 16424:2012ISO 16424:2012(E)average and a U
45、average. After all of the Gd concentration average and U concentration average sets have been obtained, the estimated Gd2O3content for each sample is calculated by the following formula:wGd2O3,estGdU(122()2Gd=+)( )(, ),)()10015 999 43157 25 (, ),15 9994157 25 238 03Gd U +=+ +()(,)( )( ,)()() ,05 100
46、 2 305220101700672 GdGd UUGdwherewGd2O3,estis the estimated Gd2O3content, mass fraction (%) as given by Gd2O3/(Gd,U)O2;157,25 is the atomic mass of gadolinium (Gd);238,03 is the atomic mass of uranium (U);15,9994 is the atomic mass of oxygen (O);Gdis the Gd concentration average in mg/l, indicated d
47、own to two decimal places;Uis the U concentration average in mg/l, indicated down to two decimal places.If five different sample solutions have been prepared and measured, five estimated values of Gd2O3content will be obtained by this procedure.NOTE The estimated Gd2O3content represents the most pos
48、sible Gd2O3content of the expected Gd pellet to be manufactured from the powder blend. As a general rule, after the powder blend has been sintered, the O/M ratio of manufactured Gd pellet will be 2 or very close to 2. Therefore, the actual Gd2O3content of the pellet will be very close to this estima
49、ted Gd2O3content.8.3.2 Evaluation of homogeneity of Gd distributionEvaluate the homogeneity of Gd distribution within the blended powder by applying a statistical methodology to the estimated contents of Gd2O3obtained in Clause 8.3.1. The average and the standard deviation calculated from at least five estimated values of Gd2O3content will be used for the evaluation.EXAMPLE If the homogeneity specification of the blended powder requires that one standard deviation of estimated Gd2O3content values of five ble
