1、BS ISO 18417:2017Iodine charcoal sorbents fornuclear facilities Methodfor defining sorption capacityindexBSI Standards PublicationWB11885_BSI_StandardCovs_2013_AW.indd 1 15/05/2013 15:06BS ISO 18417:2017 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of ISO 18417:201
2、7. The UK participation in its preparation was entrusted to TechnicalCommittee NCE/2, Radiation protection and measurement. 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
3、 contract. Users are responsible for its correct application. The British Standards Institution 2017.Published by BSI Standards Limited 2017ISBN 978 0 580 84337 2 ICS 13.280 Compliance with a British Standard cannot confer immunity from legal obligations.This British Standard was published under the
4、 authority of the Standards Policy and Strategy Committee on 31 March 2017.Amendments/corrigenda issued since publicationDate T e x t a f f e c t e dBS ISO 18417:2017 ISO 2017Iodine charcoal sorbents for nuclear facilities Method for defining sorption capacity indexPiges iode pour installations nucl
5、aires Mthode pour dfinir la capacit de rtentionINTERNATIONAL STANDARDISO18417First edition2017-03Reference numberISO 18417:2017(E)BS ISO 18417:2017ISO 18417:2017(E)ii ISO 2017 All rights reservedCOPYRIGHT PROTECTED DOCUMENT ISO 2017, Published in SwitzerlandAll rights reserved. Unless otherwise spec
6、ified, 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 an intranet, without prior written permission. Permission can be requested from either ISO at the address below or I
7、SOs member body in the country of the requester.ISO copyright officeCh. de Blandonnet 8 CP 401CH-1214 Vernier, Geneva, SwitzerlandTel. +41 22 749 01 11Fax +41 22 749 09 47copyrightiso.orgwww.iso.orgBS ISO 18417:2017ISO 18417:2017(E)Foreword ivIntroduction v1 Scope . 12 Normative references 13 Terms
8、and definitions . 14 Principles of the method 25 Preparation of the test 45.1 General . 45.2 Removal of air impurity and humidity into the installation 45.3 Radioactive methyl iodide used for sorbent testing . 55.4 Preparation of sorbent samples . 55.5 Measuring devices 65.6 Conditions for achieving
9、 equilibrium during the test . 65.7 Safe conditions for workers and members of the public 66 Test conditions . 77 Sorbent testing . 78 Test performance . 99 Determination of the sorption capacity index109.1 Sorption capacity index determination 109.2 Calculating sorption capacity index . 119.3 Uncer
10、tainties of measurements 1210 Documenting test results 13Annex A (normative) Format of test report (for the customer) 14Annex B (normative) Format of internal test report 15Annex C (normative) Measurements results.16Annex D (informative) Example of expected results for sorption capacity index 17Bibl
11、iography .19 ISO 2017 All rights reserved iiiContents PageBS ISO 18417:2017ISO 18417:2017(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 normally carried o
12、ut 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 the work. ISO c
13、ollaborates 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 the different app
14、roval 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 document may be t
15、he 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 .org/ patents)
16、.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 voluntary nature of standards, the meaning of ISO specific terms and expressions related to conformity assessment, as well as information about ISO
17、s adherence to the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following URL: www .iso .org/ iso/ foreword .html.This document was prepared by Technical Committee ISO/TC 85, Nuclear energy, nuclear technologies, and radiological protection, Subcommittee
18、 SC 2, Radiological protection.iv ISO 2017 All rights reservedBS ISO 18417:2017ISO 18417:2017(E)IntroductionIodine sorbents are extensively used in nuclear facilities to remove radioiodine from gases and air in off-gas cleaning systems and ventilation installations. The sorbents are very important f
19、or protection of the members of the public and environment from iodine radionuclides radiation.In the normal operation of nuclear installations, the main hazard comes from radioactive isotopes of iodine; as examples, for reactors 131I and a minor extent 133I, for fuel processing facilities 129I, etc
20、. Iodine is one of the main contributors of the radiation impact on the environment. Under abnormal and accident conditions, some other isotopes 132I, 134I and 135I have also some significant effects on the total iodine dose (thyroid dose)3.The volatile radioiodine forms can occur in the gaseous rad
21、ioactive wastes as elemental iodine, the simplest organic compound methyl iodide, and some others such as hydrogen iodide under reducing conditions.Radioactive iodine can create a serious danger to the members of the public and workers in abnormal and accident conditions at nuclear facilities as far
22、 as the exposure in these conditions could be much higher than the exposure due to the natural background radiation.The need to prevent widespread dispersal of gaseous radioiodine from nuclear facilities is a major purpose of iodine sorbents. It is universally recognized that radioactive methyl iodi
23、de is the less readily removable radioiodine form. The removal of radioactive iodine from gaseous radioactive wastes at nuclear facilities is almost always performed with the help of impregnated activated charcoals that have become often accepted as the preferred iodine sorbents used in these facili
24、ties. Impregnated charcoals require a high efficiency especially from humid gases containing iodine in order to trap all the iodine gaseous compounds.Two types of tests are considered24: laboratory and in situ tests. Laboratory tests are done to establish the performance characteristics of the charc
25、oal to be used in retention systems under specified operating conditions. In situ tests are done to obtain a measure of the performance of retention systems under appropriate operational conditions.This document concerns only the laboratory tests. Laboratory tests of representative samples of charco
26、al (e.g. new charcoal, aged charcoal from iodine absorbers, etc.) are performed to establish their efficiency for a given test agent under specified conditions.The quality of sorbents and its potential application at nuclear facilities can be estimated by means of a criterion that defines specifical
27、ly the sorption capacity of the sorbent. Such criterion is called in this document the sorption capacity index.The index is defined by the result of a laboratory test on the basis of radioiodine activity distribution inside the sorbent. This index characterizes the total kinetic sorption process for
28、 established test conditions and show whether the sorbent can be used as iodine filters for nuclear facilities. One example of criteria is given in Annex D.This document provides a method to determine the quantitative quality of a sorbent and also to compare the performance of different iodine sorbe
29、nts at the specified conditions. It is useful for users of iodine sorbents (filter or sorbent manufacturers as well as operators). ISO 2017 All rights reserved vBS ISO 18417:2017BS ISO 18417:2017Iodine charcoal sorbents for nuclear facilities Method for defining sorption capacity index1 ScopeThe sco
30、pe of this document covers iodine sorbents for nuclear power plants, nuclear facilities, research and other nuclear reactors, iodine sorbents for laboratories, including nuclear medicine, and iodine sorbents for sampling equipment on sample lines.This document applies to iodine sorbents manufacturer
31、s and operators in order to measure the actual performance of these sorbents and their sorption capacity for radioiodine.This document applies to granulated and crushed iodine sorbents based on activated charcoal (hereinafter referred to as “sorbents”) used for trapping gaseous radioiodine and its c
32、ompounds. This document establishes the method and conditions for defining sorption capacity index in a laboratory.2 Normative referencesThere are no normative references in this document.3 Terms and definitionsFor the purposes of this document, the following terms and definitions apply.ISO and IEC
33、maintain terminological databases for use in standardization at the following addresses: IEC Electropedia: available at h t t p :/ www .electropedia .org/ ISO Online browsing platform: available at h t t p :/ www .iso .org/ obp3.1gaseous radioactive wasteswastes that contain radioactive material in
34、gas form for which no further use is foreseen and have radionuclides at concentrations or activities greater than clearance levels as established by a regulatory body3.2dischargeplanned and controlled release of (gas or liquid) radioactive material to the environment3.3mass transfer zonedefined zone
35、 (range) of sorbent volume in which the phenomena of substance mass transfer from gas to solid phases takes place3.4iodine sorbentsorbent intended for trapping radioiodine in gaseous radioactive wastesINTERNATIONAL STANDARD ISO 18417:2017(E) ISO 2017 All rights reserved 1BS ISO 18417:2017ISO 18417:2
36、017(E)3.5free volumevoid between grains or crushed grains of the sorbent inside the whole volume containing the sorbentNote 1 to entry: The free volume can be expressed as in Formula (1):VVfr=sorb(1)whereVfrfree volume; fraction free volume in sorbent volume;Vsorbsorbent volume.3.6contact timegas fl
37、ow transit time through sorbent layerNote 1 to entry: Contact time is expressed using Formula (2): =VQfrcol(2)whereQcolthe volumetric gas flow rate in the inlet sectional column.Note 2 to entry: The contact time defined here does not consider the geometric volume of the sample, but only its free vol
38、ume.3.7bulk densitysorbratio between granulated or crushed grains sorbent mass (definite granulation) and the total volume containing the sorbent3.8sorption capacity indexcriterion indicating the degree of reduction of gaseous radioiodine in the gas flowing through the sorbent under specified test c
39、onditionsNote 1 to entry: The index is valid only for a specific chemical form of the radioactive gas. In this document, the index has been calculated for radioactive methyl iodide. The index can also be calculated with other gaseous species, such as radioactive iodine, but the results cannot be com
40、pared with the ones obtained with radioactive methyl iodide.4 Principles of the methodThe main rationale for the method defined in this document are the following: radioactive methyl iodide (CH3131I) is the most difficult form of radioiodine to trap in nuclear facilities discharges; the distribution
41、 of radioactive methyl iodide along sorbent layer is exponential; there is an active mass transfer zone in the sorbent layer;2 ISO 2017 All rights reservedBS ISO 18417:2017ISO 18417:2017(E) the amount of sorbed radioactive methyl iodide depends on the contact time between the gas and sorbent.The sor
42、ption capacity index indicates the degree by which radioactive methyl iodide concentration in gas phase is reduced during the contact of the gas flow with the sorbent.The principle of the method is the following: indoor laboratory air is used as carrier gas; air is transferred in the test plant by m
43、eans of extraction device (fan, vacuum pump, etc.); in order to remove indoor laboratory air pollutants, aerosols and humidity, air flow passes through an aerosol filter, an air conditioning system used for humidity (e.g. zeolite or dehumidifier) and volatile compounds removal (e.g. activated charco
44、al); the humidity level shall be maintained to a specified value and be controlled. One example for this humidity control is to split the total air flow and pass one of the flows through a second air condition system (e.g. humidifier); the air temperature and air flow are regulated and measured befo
45、re introduction in the sample to test (e.g. the air temperature is control by heat insulation of the sectional column or to place it in a vessel with controlled temperature); radioactive methyl iodide is injected into the carrier gas from a generator and then it is trapped in the sectional columns c
46、ontaining the sorbent to be tested; before discharging the test gas, the air is passed through a protection column for radiation protection issues and for control of the penetration radioiodine and to ensure a low level of iodine active species in discharged air; each section test column is monitore
47、d for radioiodine content via gamma monitors (0,364 MeV for 131I); the sorption capacity index is calculated using the formula given in Clause 9.Figure 1 presents the principle of an example scheme of the test plant used for the method presented in this document. ISO 2017 All rights reserved 3BS ISO
48、 18417:2017ISO 18417:2017(E)Key1 flowmeter2 aerosol filter3 dehumidifier4 charcoal5 injection of radioactive methyl iodide6 generator of radioactive methyl iodide7 humidifier8 temperature controlled chamber9 sectional column10 protection column11 vacuum pump12 room air13 controller humidity, tempera
49、ture, absolute pressure and pressure dropFigure 1 Schematic of principle equipment and a process diagram of the test plant5 Preparation of the test5.1 GeneralBased on the typical arrangement proposed in Clause 4, the test involves the following stages.5.2 Removal of air impurity and humidity into the installationRemoving air pollutant and controlling humidity and temperature are important for the tests because these parameters can have a significant impact on the results. In order to clean the installation
