ISO INTERNATIONAL STANDARD 9006 First edition 1994-10-15 Uranium metal and uranium dioxide powder and pellets Determination of nitrogen content --- Method using ammonia-sensing electrode Uranium metal, et poudre et pastlles de dioxyde d'uranium - Dosage de I'azote - Methode utilisant I'électrode sensible a I'ammoniac ISO Referencenumber ISO9006:1994(E) Copyright Ilr No reproduction or networking permited without license from IHS Not for Resale IS0 9006:1994(E) Foreword federationofnationalstandardsbodies(lsOmemberbodies).Theworkof preparing international Standards is normally carried out through IsO 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 International Electrotechnical Commission (iEC)onallmattersofelectrotechnicalstandardization. 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 International Standard ISO 9006 was prepared by Technical Committee ISO/TC 85, Nuclear energy, Subcommittee SC 5, Nuclear fuel technology. AnnexAformsanintegralpartofthisinternationalStandard ISO1994 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 the publisher. international Organizationfor Standardization Case postale 56 . CH-1211 Geneve 20 . Switzerland Printed in Switzerland Copyight intematinal Organization for Standardizalion No reproduction or networking permited without license from IHS Not for Resale INTERNATIONAL STANDARD @ ISO ISO9006:1994(E) Uranium metal and uranium dioxide powder and pellets - Determination of nitrogen content - Method using ammonia-sensing electrode Scope 1 converts ammonium ion to ammonia gas and maintains uranium(Vl) in solution as a complex anion, This International Standard specifies an analytical UO2(CO3)34-. method for determining the nitrogen content in uranium metal and uranium dioxide powder and The quantity of ammonia present in the aikaline pellets. solution is determined by recording the potential indicated by the ammonia-sensing electrode when it It is applicable to the determination of nitrogen, pre- is inserted in the solution, adding a known amount of sent as nitride, in uranium metal and uranium dioxide ammonia and again recording the potential indicated powder and pellets. The concentration range within bythe electrode. which the method can be used is between 9 μg and 600 μg of nitrogen per gram. Interference can occur The difference between the two values enables the from metals which form complex ammines, but these ammoniacontent of the solution,andhencethe nitro- are not normally present in significant amounts. gen content of the sample, to be determined. The ammoniais added intheform of astandard solution of ammonium chloride, the ammonium ion being in- 2 Principle stantly converted to ammonia when it is added to the alkaline solution. 2.1 The sample is dissolved in a mixture of hydro- chloric acid and hydrogen peroxide, producing a sol- A blank test is carried out using the amounts of hy- ution of uranium(Vi) and converting any nitrogen, drochloric acid, hydrogen peroxide and water that are present as nitride, to the ammonium ion. Potassium used for dissolving the test portion, and following the carbonate is added to convert the ammonium ion to same procedure for measuring the ammonia content. ammonia and uranium(Vl) is retained in solution as the carbonate complex anion. Ethylene diaminetetraacetic acid (EDTA) is present to complex metals which form ammines. The ammonia content is measured using an 3 Reactions ammonia-sensing electrode and a standard addition U4+ + (OO)2- → UO,2+ procedure. UO22+ + 3CO3