1、July 2016 English price group 8No part of this translation may be reproduced without prior permission ofDIN Deutsches Institut fr Normung e. V., Berlin. Beuth Verlag GmbH, 10772 Berlin, Germany,has the exclusive right of sale for German Standards (DIN-Normen).ICS 27.120.30!%Wj“2529871www.din.deDIN E
2、N ISO 15646www.beuth.deDocument comprises 12 pagesDTranslation by DIN-Sprachendienst.In case of doubt, the German-language original shall be considered authoritative.Re-sintering test for UO2, (U,Gd)O2 and (U,Pu)O2 pellets (ISO 15646:2014);English version EN ISO 15646:2016,English translation of DIN
3、 EN ISO 15646:2016-07Nachsintertest fr UO2 , (U,Gd)O2- und (U,Pu)O2-Pellets (ISO 15646:2014); Englische Fassung EN ISO 15646:2016,Englische bersetzung von DIN EN ISO 15646:2016-07Test de refrittage pour pastilles UO2, (U,Gd)O2 et (U,Pu)O2 (ISO 15646:2014); Version anglaise EN ISO 15646:2016,Traducti
4、on anglaise de DIN EN ISO 15646:2016-0707.16-DIN EN ISO 15646:2016-07 2 A comma is used as the decimal marker. National foreword International Standard ISO 15646:2014 has been prepared by Technical Committee ISO/TC 85 “Nuclear energy, nuclear technologies, and radiological protection” of the Interna
5、tional Organization for Standardization (ISO) and has been taken over as EN ISO 15646:2016 by Technical Committee CEN/TC 430 “Nuclear energy, nuclear technologies, and radiological protection” (Secretariat: AFNOR, France). The responsible German body involved in its preparation was DIN-Normenausschu
6、ss Materialprfung (DIN Standards Committee Materials Testing), Working Committee NA 062-07 FBR Fachbereichsbeirat Kerntechnik und Strahlenschutz. The DIN Standard corresponding to the International Standard referred to in this document is as follows: ISO 3369 DIN EN ISO 3369 National Annex NA (infor
7、mative) Bibliography DIN EN ISO 3369, Impermeable sintered metal materials and hardmetals Determination of density EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN ISO 15646 April 2016 ICS 27.120.30 English Version Re-sintering test for UO2, (U,Gd)O2and (U,Pu)O2pellets (ISO 15646:2014) Test de r
8、efrittage pour pastilles UO2, (U,Gd)O2 et (U,Pu)O2 (ISO 15646:2014) Nachsintertest fr UO2-, (U,Gd)O2- und (U,Pu)O2-Pellets (ISO 15646:2014) This European Standard was approved by CEN on 21 February 2016. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the co
9、nditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN member. This European Standard exi
10、sts in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management Centre has the same status as the official versions. CEN members are the national st
11、andards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia,
12、Slovenia, Spain, Sweden, Switzerland, Turkey andUnited Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels 2016 CEN All rights of exploitation in any form and by any means reser
13、ved worldwide for CEN national Members. Ref. No. EN ISO 15646:2016 EEN ISO 15646:2016 (E) 2 Contents Page European foreword . 3 Foreword 4 1 Scope 5 2 Brief description of procedure . 5 3 Incidents . 5 4 Apparatus . 5 4.1 Equipment for measuring density 5 4.2 Heat treatment furnace . 6 5 Reagents .
14、6 6 Sampling . 6 7 Procedure. 6 7.1 Density measurements before heat treatment 6 7.2 Heat treatment . 7 7.3 Density measurements after heat treatment 7 8 Evaluation 7 9 Precision of the procedure 8 10 Test report . 8 Annex A (informative) Relationship between pellet mass evolution and O/M ratio evol
15、ution 9 Bibliography . 10 DIN EN ISO 15646:2016-07 EN ISO 15646:2016 (E) 3 European foreword The text of ISO 15646:2014 has been prepared by Technical Committee ISO/TC 85 “Nuclear energy, nuclear technologies, and radiological protection” of the International Organization for Standardization (ISO) a
16、nd has been taken over as EN ISO 15646:2016 by Technical Committee CEN/TC 430 “Nuclear energy, nuclear technologies, and radiological protection” the secretariat of which is held by AFNOR. This European Standard shall be given the status of a national standard, either by publication of an identical
17、text or by endorsement, at the latest by October 2016, and conflicting national standards shall be withdrawn at the latest by October 2016. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN and/or CENELEC shall not be held respo
18、nsible for identifying any or all such patent rights. According to the CEN-CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finla
19、nd, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. Endorsement notice The text of IS
20、O 15646:2014 has been approved by CEN as EN ISO 15646:2016 without any modification. DIN EN ISO 15646:2016-07 ForewordISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is
21、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-governmental, in liaison with ISO, also take part
22、in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) 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
23、 the different approval criteria needed for the different types of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).Attention is drawn to the possibility that some of the elements of this do
24、cument may be the subject of patent rights. ISO shall not be held responsible for identifying any 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 (see www.iso.
25、org/patents).Any trade name used in this document is information given for the convenience of users and 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
26、principles in the Technical Barriers to Trade (TBT) see the following URL: Foreword - Supplementary informationThe committee responsible for this document is ISO/TC 85, Nuclear energy, nuclear technologies, and radiological protection, Subcommittee SC 5, Nuclear fuel cycle.4EN ISO 15646:2016 (E) DIN
27、 EN ISO 15646:2016-07 1 ScopeThis International Standard describes a procedure for measuring the densification of UO2, (U,Gd)O2, and (U,Pu)O2pellets, achieved by heat treatment under defined conditions.The densification of fuel in power operation is an important design feature. Essentially, it is de
28、pendent on structural parameters such as pore size, spatial pore distribution, grain size, and in the case of (U,Gd)O2and (U,Pu)O2, oxide phase structure. A thermal re-sintering test can be used to characterize the dimensional behaviour of the pellets under high temperature. The results of this test
29、 are used by the fuel designer to predict dimensional behaviour in the reactor, because thermal densification in the reactor is also dependent on these structural parameters, albeit in a differing manner in terms of quantity.On the assumption of the prediction, it is necessary to correlate the resul
30、ts of this test by some correlation rules, because the results of this test vastly depend on the re-sintering conditions (such as heat treatment temperature, treatment time, gas content, and partial oxygen pressure).2 Brief description of procedureThe density of nuclear fuel pellets is measured befo
31、re the re-sintering test. Afterwards, the pellets are subjected to heat treatment in a furnace under specified conditions with regard to temperature, time, and sintering atmosphere. After cooling, the density is remeasured.The oxygen/metal molar ratio should remain constant during the re-sintering t
32、est. The difference between the two density measurements shall be used to assess the thermal stability of the pellet lot.3 IncidentsMinor chipping can occur during pellet handling. Densities of visibly chipped pellets shall not be measured using the geometric method, as the results will be inaccurat
33、e.Densities of such chipped pellets can be measured using the buoyancy method.4 ApparatusSpecifically for (U,Pu)O2, all operations shall be performed in glove boxes.4.1 Equipment for measuring densityThe same method shall be used before and after the re-sintering of pellets.In 4.1.1 and 4.1.2, two d
34、ifferent measurement methods are mentioned as examples. Other methods can be used if they meet the customer uncertainty requirement.4.1.1 Geometric measurement of densityA dial test indicator or micrometer with precision of 1 m shall be used in order to measure the diameter and the height.Analytical
35、 balance with readability of +1 mg for weighing the pellets.5 EN ISO 15646:2016 (E) DIN EN ISO 15646:2016-07 4.1.2 Measurement of density using buoyancy methodSee ISO 3369.4.2 Heat treatment furnaceA programmable furnace able to reach temperatures of about 1 800 C under gas scavenging and to hold a
36、homogeneous temperature of the sintering area shall be used. It is advisable to use two different thermocouples for furnace control and monitoring.5 Reagents5.1 Gas.The furnace gas shall ensure a constant oxygen/heavy metal ratio. Usually, the re-sinter test employs a similar furnace atmosphere to t
37、hat used when the pellets were sintered during manufacture. The test furnace shall be qualified to prove that the oxygen/heavy metal ratio of the fuel tested does not change by more than 0,005. The following are examples of furnace atmospheres that can be used.NOTE Heavy metal = U, U+Pu, or U+Gd, de
38、pending on the concerned product. For UO2fuel: pure hydrogen (purification better than a volume fraction of 99,99 %); mixture of noble gas (purification better than a volume fraction of 99,99 %) with at least 3 % hydrogen. For (U,Pu)O2and (U,Gd)O2fuels: pure argon (purification better than a volume
39、fraction of 99,99 %); pure argon (purification better than a volume fraction of 99,99 %) with 7 % hydrogen, humidified as required to maintain fuel stoichiometry; argon with 4 % hydrogen and CO2as required to maintain fuel stoichiometry; dry cracked ammonia gas (75 % H2-25 % N2by volume) with gas mi
40、xture purity of at least 99,9 % by volume and a dew point less than 40 C.5.2 Degassed water, distilled and degassed (e.g. by boiling) water as buoyancy test fluid, or distilled water to which a wetting agent (soap) has been added to eliminate any microbubbles.6 SamplingIn case of using the geometric
41、 method for the density measurement, the selected pellets shall be free of any visible defects liable to bias the density measurements (e.g. chipping, cracking, thumbnail cracks, etc.). In case of using the buoyancy method for the density measurement, the pellets with these visible defects can be ke
42、pt.7 Procedure7.1 Density measurements before heat treatmentThe density of the fuel pellets has to be measured prior to the heat treatment. Of all the procedures available, geometric density measurements and the buoyancy method have been proven most satisfactory for routine quality control inspectio
43、n. The geometric method is preferable where the pellets have a large fraction of open pores (i.e. pores having a connection to the pellet surface). Pellets that have sustained 6EN ISO 15646:2016 (E) DIN EN ISO 15646:2016-07 chipping are better measured using the buoyancy method or the penetration im
44、mersion method as defined in ISO 9278.7.2 Heat treatmentFollowing the density measurement, the pellets, after position identification to ensure traceability, are subjected to heat treatment in the furnace using the following parameters. Heating rate: 15 C/min (at higher rates the pellets could burst
45、). A heating rate of 5 C/min is recommended in order to be sure not to burst the pellets. Heat treatment temperature: shall be specified jointly by the customer/fuel designer and the fuel vendor. As example, temperatures of the order of 1 700 C are generally applied. Treatment time: shall be specifi
46、ed jointly by the customer/fuel designer and the fuel vendor. As example, residence time of the order of 24 h is generally applied. Suitable treatment atmosphere (see Examples 1 to 3).EXAMPLE 1 For UO2pellets, pure hydrogen (5.1) or mixtures of noble gas with at least 3 % hydrogen (5.1) can be used.
47、EXAMPLE 2 For (U, Gd)O2and (U, Pu)O2pellets, a shift in stoichiometry of pellets occurs during treatment when using dry hydrogen or dry hydrogen/noble gas mixtures. This can be avoided by using a gas atmosphere with a suitable oxygen partial pressure which keeps the stoichiometry constant during re-
48、sintering. Adjusting the oxygen partial pressure can be done by admixing CO2in appropriate proportions to the re-sinter atmosphere or by using wet hydrogen or wet hydrogen/noble gas mixtures.EXAMPLE 3 A pure argon atmosphere can be used.NOTE For (U, Gd)O2pellets, if necessary, an adjustment of the i
49、nitial oxygen/heavy metal (U+Gd) ratio can be performed by heat treatment of the pellets at 150 C in air during a holding time of 5 h. The heat-up rate shall be low enough to avoid cracking especially at high Gd contents. The annealing step ensures the adjustment of the equilibrium stoichiometry for (U,Gd)O2fuel pellets with a Gd content up to 10 % by mass. Cool down rate: 15 C/min. Records: For each re-sintering run, the temperature profile is recorded. If the temperature profile satisfies the heat treatment condition specified above, the results o
