1、BSI Standards Publication BS ISO 8425:2013 Nuclear fuel technology Determination of plutonium in pure plutonium nitrate solutions Gravimetric methodBS ISO 8425:2013 BRITISH STANDARD National foreword This British Standard is the UK implementation of ISO 8425:2013. The UK participation in its prepara
2、tion was entrusted to Technical Committee 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 contract. Users are responsible for its co
3、rrect application. The British Standards Institution 2013. Published by BSI Standards Limited 2013 ISBN 978 0 580 75791 4 ICS 27.120.30 Compliance with a British Standard cannot confer immunity from legal obligations. This British Standard was published under the authority of the Standards Policy an
4、d Strategy Committee on 31 December 2013. Amendments issued since publication Date Text affectedBS ISO 8425:2013 ISO 2013 Nuclear fuel technology Determination of plutonium in pure plutonium nitrate solutions Gravimetric method Technologie du combustible nuclaire Dtermination du plutonium dans les s
5、olutions de nitrate de plutonium pur Mthode gravimtrique INTERNATIONAL STANDARD ISO 8425 Second edition 2013-12-01 Reference number ISO 8425:2013(E)BS ISO 8425:2013ISO 8425:2013(E)ii ISO 2013 All rights reserved COPYRIGHT PROTECTED DOCUMENT ISO 2013 All rights reserved. Unless otherwise specified, n
6、o 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 an intranet, without prior written permission. Permission can be requested from either ISO at the address below or ISOs memb
7、er 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 SwitzerlandBS ISO 8425:2013ISO 8425:2013(E) ISO 2013 All rights reserved iii Contents Page Foreword iv Int
8、roduction v 1 Scope . 1 2 Normative references 1 3 Principle 1 4 Interferences 1 5 Reagents 1 6 Apparatus . 2 7 Procedure. 2 8 Expression of results 3 8.1 Method of calculation 3 8.2 Repeatability . 4 8.3 Systematic errors 4 9 Test report . 5 Annex A (informative) Gravimetric conversion factors for
9、the non-volatile impurities 6BS ISO 8425:2013ISO 8425:2013(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 through ISO technical comm
10、ittees. 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 collaborates closely with the
11、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 the different approval criteria needed for th
12、e 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 document may be the subject of patent rights. I
13、SO 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.org/patents). Any trade name used in this doc
14、ument 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 principles in the Technical Barriers to Tra
15、de (TBT) see the following URL: Foreword - Supplementary information The committee responsible for this document is ISO/TC 85, Nuclear energy, nuclear technologies, and radiological protection, Subcommittee SC 5, Nuclear fuel cycle. This second edition cancels and replaces the first edition (ISO 842
16、5:1987).iv ISO 2013 All rights reservedBS ISO 8425:2013ISO 8425:2013(E) Introduction This International Standard specifies a precise and accurate method for determining the concentration of plutonium in pure plutonium nitrate solutions and reference solutions. This method is based on an oxidation of
17、 the plutonium followed by weighing. Respecting certain conditions, the overall standard deviation on a single determination (gravimetric determination and impurities correction) can be below 0,1 %. ISO 2013 All rights reserved vBS ISO 8425:2013BS ISO 8425:2013Nuclear fuel technology Determination o
18、f plutonium in pure plutonium nitrate solutions Gravimetric method 1 Scope This International Standard specifies a precise and accurate gravimetric method for determining the concentration of plutonium in pure plutonium nitrate solutions and reference solutions, containing between 100 g and 300 g of
19、 plutonium per litre, in a nitric acid medium. 2 Normative references The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition
20、of the referenced document (including any amendments) applies. ISO 3696, Water for analytical laboratory use Specification and test methods 3 Principle The principle is as follows: a) treatment of a weighed portion of the plutonium nitrate solution with sulphuric acid and evaporation to dryness; b)
21、decomposition of the plutonium sulfate which is converted to oxide by heating in air; c) heating in air of the oxide at 1 200 C to 1250 C and weighing as stoichiometric plutonium dioxide, which is stable and non-hygroscopic; d) calculation of the plutonium content using a gravimetric conversion fact
22、or which depends slightly on the isotopic composition of the plutonium. If the latter is not known, it shall be measured, usually by mass spectrometry. 4 Interferences All non-volatile impurities interfere. If the mass fraction of the impurities is greater than 0,05 %, a correction shall be applied.
23、 If the mass fraction of the total non-volatile impurities is up to 0,1 %, the overall uncertainty of the measurement will depend on the precision of the impurities determination. There is no interference from up to at least 1 000 gg 1of phosphorus (present as phosphate) which is lost during the sul
24、phuric acid treatment. The chloride and fluoride contents of the sample should not exceed 25 gg 1 . 5 Reagents 5.1 Deionised water, with at least grade 1, in accordance with ISO 3696. 5.2 Sulphuric acid, solution with volume fraction of 50 %. While stirring, cautiously add 500 ml of the analytical r
25、eagent quality sulphuric acid ( = 1,84 gml 1 ) to 500 ml of cold distilled or deionised water (5.1). Allow to cool. INTERNATIONAL ST ANDARD ISO 8425:2013(E) ISO 2013 All rights reserved 1BS ISO 8425:2013ISO 8425:2013(E) 6 Apparatus Normal laboratory equipment for a plutonium laboratory. 6.1 Platinum
26、 crucibles, approximately 8 ml in capacity. 6.2 Polythene weighing burettes. 6.3 Furnace, in an air atmosphere glove box, with a temperature range from 300 C to 1 250 C. 6.4 Semi-micro balance, in an air atmosphere glove box, to weigh 25 g with an accuracy of 0,1 mg; the balance and weights should b
27、e certified or calibrated to 0,05 mg. 6.5 Radiant heater, in a glove box. 6.6 Desiccators. 7 Procedure 7.1 Heat a clean crucible (6.1) for 1 h at 1 200 C to 1 250 C. Cool in a desiccator for 20 min and then in the balance (6.4) for 5 min. Weigh to within 0,1 mg, repeating the heating until the mass
28、remains constant to within 0,1 mg. 7.2 Weigh out 1 g to 2 g of the sample solution containing 0,2 g to 0,4 g of plutonium from a polythene weighing burette (6.2) into the crucible. Record the masses (before the sample delivery, m 2 , and after the sample delivery, m 3 ) to within 0,1 mg. In order to
29、 avoid errors due to thermal effects, the weighing burette shall be allowed to adjust to the balance temperature before each weighing. 7.3 Add 1,0 ml of the sulphuric acid solution (5.2) to the crucible and swirl gently to mix. 7.4 Evaporate the solution under a radiant heater (6.5), by heating gent
30、ly until sulphuric acid fumes evolve and then more strongly until a dry residue has been obtained and the fuming has practically ceased. NOTE Plutonium nitrate is converted to plutonium sulphate as the nitrate compound spatters during the evaporation to dryness. 7.5 Without delay, transfer the cruci
31、ble and dried plutonium sulfate to the furnace (6.3) set at about 300 C. Maintain this temperature for about 15 min. Then raise the temperature by 5 C to 10 C per minute to about 850 C at which temperature the plutonium sulfate will have decomposed. 7.6 Increase the temperature to 1 200 C to 1 250 C
32、 and ignite at this temperature for 1 h. NOTE Alternatively, the operations in 7.4, 7.5, and 7.6 can be done in a temperature-programmed furnace with controlled air flow. 7.7 Cool the crucible and oxide in a desiccator (6.6) for 15 min and then in the balance for 5 min. Weigh to within 0,1 mg. 7.8 H
33、eat again at 1 200 C to 1 250 C for periods of 1 h (7.6), cool and weigh as in 7.7 until the mass remains constant to within 0,05 mg. Record this mass as m 4 .2 ISO 2013 All rights reservedBS ISO 8425:2013ISO 8425:2013(E) 7.9 Perform an isotopic analysis of the plutonium in a separate portion of the
34、 sample to calculate its mean relative atomic mass, A r (Pu). 7.10 Perform an analysis of the impurities that are not volatile at 1 200 C, usually by an emission spectrometric method or a mass spectrometric method, calculating the results for each impurity element as micrograms per gram of the sampl
35、e solution. 8 Expression of results 8.1 Method of calculation 8.1.1 Calculate the mass of the sample solution taken, m s , in grams, using Formula (1). m s= m 2- m 3(1) where m 2 is the mass, in grams, of the weighing burette before the sample delivery; m 3 is the mass, in grams, of the weighing bur
36、ette after the sample delivery. 8.1.2 Calculate the mass of the oxide formed, m 0 , in grams, using Formula (2). m 0= m 4- m 1(2) where m 4 is the mass, in grams, of the crucible plus oxide; m 1 is the mass, in grams, of the empty crucible. Depending on the context in which the results are to be use
37、d, masses m sand m 0can require standard corrections for air buoyancy effects. 8.1.3 Calculate the total mass of impurities (in the heated state), I 0 , in grams, in the sample using Formula (3). I 0= 10 6 m s (3) where m s is the mass of the sample solution taken, in grams (see 8.1.1); I n is the q
38、uantity of the impurity element, n, in micrograms per gram of the sample solution (see 7.10); C n is the gravimetric conversion factor for the element n on heating at 1 200 C (see Annex A for the gravimetric conversion factors for common impurities). 8.1.4 Calculate the mass of pure PuO 2in the oxid
39、e, m c , in grams, using Formula (4). ISO 2013 All rights reserved 3BS ISO 8425:2013ISO 8425:2013(E) m c= m 0- I 0(4) where I 0 is the total mass of impurities, in grams (see 8.1.3). 8.1.5 Calculate the gravimetric conversion factor for this batch of plutonium, C Pu , using Formula (5). C Pu= A AA (
40、5) where A r (0) (= 15,999 4) is the relative atomic mass of oxygen; A r (Pu) is the mean relative atomic mass of plutonium calculated using Formula (6). A r (Pu) = mmm mm m (6) where m 238,m 239,etc. are the mass fractions of the plutonium isotopes 238 Pu, 239 Pu, etc. in the sample, determined by
41、mass spectrometry (see 7.9). 8.1.6 Calculate the plutonium content of the sample, Pu, in grams per kilogram of the sample solution, using Formula (7). Pu = (7) 8.2 Repeatability The standard deviation for a single gravimetric determination is about 0,05 %. In order that the standard deviation of the
42、 impurity correction factor stands below 0,1 %, the impurities shall be measured to the following: with a standard deviation of 50 % (detection limit), up to 1 000 gg 1of impurities; with a standard deviation of 25 % (semiquantitative analysis), up to 2 500 gg 1of impurities; with a standard deviati
43、on of 10 % (quantitative analysis), up to 6 500 gg 1of impurities. In these conditions, the overall standard deviation on a single determination (gravimetric determination and impurities correction) is below 0,1 %. 8.3 Systematic errors The systematic errors due to weighing have a coefficient of var
44、iation not greater than 0,014 %. Non-stoichiometry of the plutonium oxide is a potential source of bias. The coefficient of variation of this factor is expected to be less than 0,1 %. Non-volatile impurities are responsible for three further possible sources of bias: a) calibration errors in the imp
45、urity analysis; b) uncertainties in the impurity conversion factors;4 ISO 2013 All rights reservedBS ISO 8425:2013ISO 8425:2013(E) c) impurities that are not corrected for because they are neither measured nor detected (sources of positive bias). These sources can cause a systematic error of up to 2
46、0 % of the total impurity concentration. 9 Test report The test report shall include the following information: a) the identification of the sample; b) a reference to the method used; c) the results of the measurement and the associated overall uncertainties, impurities percentage, and method of exp
47、ression used; d) any unusual features noted during the test; e) any operations not included in this International Standard; f) a note of whether or not buoyancy corrections have been applied (see 8.1.2). ISO 2013 All rights reserved 5BS ISO 8425:2013ISO 8425:2013(E) Annex A (informative) Gravimetric
48、 conversion factors for the non-volatile impurities Impurity Probable shape of the impurity Conversion factor C n Ag Ag 1,00 Al Al 2 O 3 1,89 Am AmO 2 1,13 B B 2 O 3 3,22 Ba BaO 1,12 Be BeO 2,78 Bi Bi 2 O 3 1,11 Ca CaO 1,40 Cd Cd 1,00 Co CoO 1,27 Cr Cr 2 O 3 1,46 Cu Cu 1,00 Fe Fe 3 O 4 1,38 K K 2 O
49、1,21 Mg MgO 1,66 Mn Mn 3 O 4 1,39 Na Na 2 O 1,35 Ni Ni 2 O 3 1,40 P P 2 O 5 2,29 Pb PbO 1,07 Rare earths M 2 O 3 1,16 Sb Sb 2 O 3 1,20 Si SiO 2 2,14 Sn SnO 1,13 Ta Ta 2 O 5 1,22 Th ThO 2 1,14 Ti TiO 2 1,67 V V 2 O 5 1,78 W WO 3 1,26 Zn ZnO 1,24 Zr ZrO 2 1,35 NOTE This information is deduced from the most reliable available information,
