1、BSI Standards PublicationBS ISO 12799:2015Nuclear energy Determination of nitrogen content in UO2, (U,Gd)O2and (U,Pu)O2sintered pellets Inert gas extraction and conductivity detection methodBS ISO 12799:2015 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of ISO 12799
2、:2015. The UK participation in its preparation was entrusted to TechnicalCommittee NCE/9, Nuclear fuel cycle technology.A list of organizations represented on this committee can be obtained on request to its secretary.This publication does not purport to include all the necessary provisions of a con
3、tract. Users are responsible for its correct application. The British Standards Institution 2015.Published by BSI Standards Limited 2015ISBN 978 0 580 75463 0ICS 27.120.30Compliance with a British Standard cannot confer immunity from legal obligations.This British Standard was published under the au
4、thority of the Standards Policy and Strategy Committee on 31 March 2015.Amendments/corrigenda issued since publicationDate T e x t a f f e c t e dBS ISO 12799:2015 ISO 2015Nuclear energy Determination of nitrogen content in UO2, (U,Gd)O2and (U,Pu)O2sintered pellets Inert gas extraction and conductiv
5、ity detection methodnergie nuclaire Dosage de la teneur en azote des pastilles frittes dUO2, (U,Gd)O2et (U,Pu)O2 Mthode dextraction par gaz inerte et mthode de mesurage de la conductivitINTERNATIONAL STANDARDISO12799First edition2015-03-15Reference numberISO 12799:2015(E)BS ISO 12799:2015ISO 12799:2
6、015(E)ii ISO 2015 All rights reservedCOPYRIGHT PROTECTED DOCUMENT ISO 2015All 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
7、an intranet, without prior written permission. Permission can be requested from either ISO at the address below or ISOs member 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.orgPu
8、blished in SwitzerlandBS ISO 12799:2015ISO 12799:2015(E)Foreword iv1 Scope . 12 Principle 13 Interferences 14 Reagents and materials . 15 Apparatus . 26 Sampling 26.1 Sampling procedure . 26.2 Sample preparation 27 Procedure. 27.1 Calibration 37.1.1 Blank test 37.1.2 Calibration of the analyser 37.1
9、.3 Check of the calibration using metal standard 37.2 Determination . 38 Calculation 49 Precision . 410 Test report . 4Bibliography 5 ISO 2015 All rights reserved iiiContents PageBS ISO 12799:2015ISO 12799:2015(E)ForewordISO (the International Organization for Standardization) is a worldwide federat
10、ion 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 subject for which a technical committee has been established has the right to be represented on that committe
11、e. International organizations, governmental and non-governmental, 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.The procedures used to develop this document and th
12、ose 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 noted. This document was drafted in accordance with the editorial rules of the ISO/IEC Directives, Part 2
13、(see www.iso.org/directives). Attention 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. Details of any patent rights identified during the development of the d
14、ocument will be in the Introduction and/or on the ISO list of patent declarations received (see www.iso.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
15、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 informationThe committee responsible for this document is ISO/TC 85, Nuclear Energy, Subcommitt
16、ee SC 5, Fuel Technology.iv ISO 2015 All rights reservedBS ISO 12799:2015Nuclear energy Determination of nitrogen content in UO2, (U,Gd)O2and (U,Pu)O2sintered pellets Inert gas extraction and conductivity detection method1 ScopeThis International Standard describes a procedure for measuring the nitr
17、ogen content of UO2, (U,Gd)O2, and (U,Pu)O2pellets. Nitrogen in nuclear fuel may be present either as elemental nitrogen or chemically combined in the form of nitrogenous compounds. The technique described herein serves to determine the total content of nitrogen excluding those compounds whose decom
18、position temperature is above 2 200 C (most notably Pu and U nitrides).2 PrincipleFor determining the nitrogen content of UO2, (U,Gd)O2, or (U,Pu)O2pellets, an analyser is employed which operates according to the carrier gas principle, using helium as the carrier gas, the nitrogen content being dete
19、rmined in a thermal conductivity cell.The weighed samples to be analysed are heated in a degassed high purity graphite crucible at a temperature of more than 1 770 C in a helium atmosphere. This high temperature destroys the majority of the nitrogen bearing compounds and causes nitrogen to be releas
20、ed along with other gaseous components like CO, CO2,and H2. The released gases are then swept by the carrier gas through oxidation and absorption columns to trap interfering species. The nitrogen passes through without being retained, and its quantity is subsequently measured in the thermal conducti
21、vity cell.3 InterferencesThe samples will not be heated to temperatures above 2 200 C since this would cause a reaction to take place between the UO2, (U,Pu)O2, or (U,Gd)O2pellet and the graphite, resulting in large quantities of CO2gas being released. These large quantities of gas can be not comple
22、tely trapped and would lead to errors in conductivity measurement.4 Reagents and materialsDuring the analysis, unless otherwise stated, use only reagents of recognized analytical grade. The reagents and materials below serve as examples to be used according to manufacturers recommendation.4.1 Helium
23、.Use helium as carrier gas with a purity of a volume fraction 99,995 %.4.2 Nitrogen.If nitrogen is used as calibration gas it will be of a purity 99,998 % in volume fraction.INTERNATIONAL STANDARD ISO 12799:2015(E) ISO 2015 All rights reserved 1BS ISO 12799:2015ISO 12799:2015(E)4.3 Reference materia
24、lA certified reference material (CRM) can be used as calibration media with certified nitrogen content (e.g. metal standards).NOTE Reference materials are available for example from National Institute of Standard and Technology (NIST) or Commission dtablissement des Mthodes dAnalyse (CETAMA).4.4 Cop
25、per(II) oxide.CuO purifies He/N2; converting H2to H2O and CO to CO2.4.5 Absorption media for CO2.Ascarite (sodium hydroxide over clay) or equivalent absorbs the CO2.4.6 Absorption media for H2O.Anhydrone Mg(ClO4)2 traps any H2O formed. A molecular sieve can also be used.4.7 Flux/melting accelerator.
26、Tin, copper, or nickel granules are used to flux the melting of the sample.5 Apparatus5.1 Nitrogen analyser, apparatus fitted with an appropriate furnace with controllable temperature and with the analytical cell, suitably adapted for handling plutonium bearing samples where relevant.5.2 Graphite cr
27、ucibles, suitable for the appropriate sample types.The impurity content should not exceed 2 g/g.5.3 Balance, with an accuracy of 1 mg.6 Sampling6.1 Sampling procedureWhen sampling the fuel pellets, ensure that pellets are not contaminated; use metal forceps or pincers for sampling pellets.6.2 Sample
28、 preparationThe fuel pellets are crushed in a percussion mortar. The fragments used for the analysis should be larger than 1 mm. The desired fragment size could be obtained by passing the crushed pellet through an appropriate sieve. The size of the resulting sample should be 1,0 g to 1,5 g.7 Procedu
29、rePrior to use, the nitrogen analyser will be checked to ensure that it is leak tight. Checking involves visual inspection of key parts that are prone to leak such as furnace O-ring and gas supply tubes. The thermocouple will be regularly checked (calibration).2 ISO 2015 All rights reservedBS ISO 12
30、799:2015ISO 12799:2015(E)7.1 Calibration7.1.1 Blank testTo verify the functional capability of the analyser, blank values are determined to obtain information on the condition of the upstream gas purification columns and on the leak tightness of the analyser. Blank values exceeding the analyser dete
31、ction limit require adequate measures of correction.7.1.2 Calibration of the analyserThe nitrogen analyser shall be calibrated before sample measurement. There are two possibilities of calibration: calibration with gas; calibration with certified standards.In case of calibration with gas, depending
32、on the type of analyser, it can be performed by the analyser manufacturer or/and the final user. A well-defined volume of the calibration gas (4.2), which is corrected on standard conditions, is injected and analysed. This calibration is performed three times.In the case of calibration with certifie
33、d standards, they are weighed to the nearest 1mg accuracy.7.1.3 Check of the calibration using metal standardTo check the calibration of the equipment, standard (4.3) having certified nitrogen content is weighed to the nearest 1 mg and analysed. The quantity of the released nitrogen is measured. The
34、 result may differ from the certified values by not more than the total uncertainty of the analysis process.If it is not the case the calibration should be repeated.7.2 Determinationa) Prior to loading of the sample in the graphite crucible, heat the latter first to around 2 200 C for degassing.b) W
35、eigh the sample to the nearest 1 mg.c) Insert sample and flux/melting accelerator (4.7) into the analyser.d) Purge with carrier gas.e) Fill the crucible with the sample and heat it up to 1 770 C.f) Measure the nitrogen content. ISO 2015 All rights reserved 3BS ISO 12799:2015ISO 12799:2015(E)8 Calcul
36、ationCalculate the nitrogen mass fraction (g/g sample) from the following formula:wmmNN22=wherewN2is the nitrogen mass fraction in g/g sample;mN2is the nitrogen mass in g;m is the mass of sample in g;9 PrecisionFor samples containing one gram to two grams and having a nitrogen content of 10 g/g, a r
37、epeatability standard deviation of 20 % (relative) can be expected.For stainless steel standards having a nitrogen content of 10 g/g and 2 g/g, standard deviations of 15 % and 66 % (relative), respectively, have been achieved10 Test reportThe test report shall include the following information:a) id
38、entification of sample;b) the method used by reference to this International Standard (i.e. ISO 12799);c) the results and the form in which they are expressed;d) any deviations from the procedure;e) any unusual features observed;f) location and date of the test;g) detection limit.4 ISO 2015 All righ
39、ts reservedBS ISO 12799:2015ISO 12799:2015(E)Bibliography1 ISO/IEC Guide 98-3:2008, Uncertainty of measurement Part 3: Guide to the expression of uncertainty in measurement (GUM:1995) ISO 2015 All rights reserved 5BS ISO 12799:2015ISO 12799:2015(E) ISO 2015 All rights reservedICS 27.120.30Price base
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