1、BSI Standards PublicationBS ISO 16966:2013Nuclear energy Nuclearfuel technology Theoreticalactivation calculation methodto evaluate the radioactivity ofactivated waste generated atnuclear reactorsBS ISO 16966:2013 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of ISO
2、 16966:2013.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 beobtained on request to its secretary.This publication does not purport to include all the necessaryprovisions of a
3、contract. Users are responsible for its correctapplication. The British Standards Institution 2013. Published by BSI StandardsLimited 2013ISBN 978 0 580 75887 4ICS 27.120.30Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was published under the a
4、uthority of theStandards Policy and Strategy Committee on 31 December 2013.Amendments issued since publicationDate Text affectedBS ISO 16966:2013 ISO 2013Nuclear energy Nuclear fuel technology Theoretical activation calculation method to evaluate the radioactivity of activated waste generated at nuc
5、lear reactorsEnergie nuclaire Technologie du combustible nuclaire Mthode thorique de calcul de lactivation pour valuer la radioactivit des dchets activs produits par les centrales nuclairesINTERNATIONAL STANDARDISO16966First edition2013-12-01Reference numberISO 16966:2013(E)BS ISO 16966:2013ISO 1696
6、6:2013(E)ii ISO 2013 All rights reservedCOPYRIGHT PROTECTED DOCUMENT ISO 2013All 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
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8、gPublished in SwitzerlandBS ISO 16966:2013ISO 16966:2013(E) ISO 2013 All rights reserved iiiContents PageForeword ivIntroduction v1 Scope . 12 Terms and definitions . 13 Theoretical evaluation method . 23.1 General methodology 23.2 Point method 23.3 Range method 24 Calculations 44.1 General . 44.2 S
9、election and determination of input parameters and conditions 44.3 Activation calculations . 64.4 Validation and uncertainties . 74.5 Records 8Annex A (informative) Application and example of the theoretical activation calculation method 9Annex B (informative) Suggested procedure for the point metho
10、d for activation calculation .15Annex C (informative) Suggested procedure for range method for setting input data for activation calculations .21Annex D (informative) Dealing with uncertainties 39Annex E (informative) Reporting of results43Bibliography .45BS ISO 16966:2013ISO 16966:2013(E)ForewordIS
11、O (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 committees. Each member body interested in a subject for which a technical co
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15、ghts. 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 document is information given for the convenience of users and does not const
16、itute 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 Trade (TBT) see the following URL: Foreword - Supplementary informationThe com
17、mittee responsible for this document is ISO/TC 85, Nuclear energy, nuclear technologies, and radiological protection, Subcommittee SC 5, Nuclear fuel cycle.iv ISO 2013 All rights reservedBS ISO 16966:2013ISO 16966:2013(E)IntroductionThis International Standard presents guidelines on activation calcu
18、lation methods for evaluating the radionuclide content of activated waste generated at nuclear reactors.This International Standard addresses the basic process of planning, executing, and reporting of results for itemized component characterizations (point method) based on neutron source estimation
19、and component elemental compositions and physical parameters and usage in the reactor. This International Standard also introduces the range method that extends the point method to define a radionuclide distribution applicable to a collection of components of similar types and exposure histories tha
20、t take into account stochastic variations of the input parameters for material composition, neutron fluence rates, and exposure histories applicable to the ranges of these parameters found in the collection. ISO 2013 All rights reserved vBS ISO 16966:2013BS ISO 16966:2013Nuclear energy Nuclear fuel
21、technology Theoretical activation calculation method to evaluate the radioactivity of activated waste generated at nuclear reactors1 ScopeThis International Standard gives guidelines for a common basic theoretical methodology to evaluate the activity of radionuclides in activated waste generated at
22、nuclear reactors using neutron activation calculations.The evaluation of any additional activity contributed by deposited contamination is not addressed in this International Standard.2 Terms and definitionsFor the purposes of this document, the following terms and definitions apply.2.1activation ca
23、lculationmethod of theoretical calculation for determining the radioactivity induced by neutron irradiation2.2activated wasteradioactive waste which contains radioactivity induced by irradiationEXAMPLE Control rod, channel box, burnable poison, core support structures, reactor internal structures, a
24、nd materials in close proximity to the reactor core, etc.Note 1 to entry: It can also contain additional radioactivity in the form of surface contamination.2.3difficult-to-measure nuclidenuclide whose radioactivity is difficult to measure directly from the outside of the waste packages by non-destru
25、ctive assay meansSOURCE: ISO 21238:2007, modifiedEXAMPLE Alpha-emitting nuclides, pure beta-emitting nuclides, and characteristic X-ray-emitting nuclides.2.4control indexindex which has a constant relationship with the irradiation conditions affecting the activity concentration of the nuclide contai
26、ned in the activated waste and enables the calculation of the activity concentration of the target radionuclide by the use of a conversion factorEXAMPLE Fuel burnup.2.5key nuclidegamma-emitting nuclide whose radioactivity is correlated with that of difficult-to-measure nuclides and can be readily me
27、asured directly by non-destructive assay meansSOURCE: ISO 21238:2007, modifiedEXAMPLE 60Co.INTERNATIONAL STANDARD ISO 16966:2013(E) ISO 2013 All rights reserved 1BS ISO 16966:2013ISO 16966:2013(E)2.6parent elementchemical element which produces a target radionuclide via neutron irradiation2.7target
28、radionuclideradionuclide of which the activity and/or concentration has to be declared for disposal or transportation of waste packages2.8neutron fluence rateat a given point in space, the number of neutrons incident on a small sphere in a small time interval, divided by the cross-sectional area of
29、that sphere and the time intervalSOURCE: ISO 31-10:1992, modified3 Theoretical evaluation method3.1 General methodologyThe following two methodologies can be applied for estimating the radioactivity of the activated waste: Point method, a technique applicable to calculate the radioactivity concentra
30、tion in a representative piece or specific point of an activated waste item; Range method, a technique that is an extension of the point method applicable to a class of activated component of similar property and exposure condition to calculate the average radioactivity of a set or collection of act
31、ivated wastes by evaluating the range of its radioactivity concentrations typical of that set.3.2 Point methodPoint method provides the basic structure for performing activation calculations. It is generally performed on an item by item basis using directly applicable or best estimate values for key
32、 parameters, including neutron flux and material specification along with specific information on history of usage.This method can be used for the evaluation of all kinds of activated wastes, including in-core hardware and reactor internals. This method, in general, offers more precision on specific
33、 items and can be necessary in the situation where activated wastes are close to the disposal limits. This method is most often applied with corroborative dose rate survey and normalization with dose-based key nuclide estimates.NOTE See Annex B.3.3 Range method3.3.1 GeneralThe neutron and irradiatio
34、n conditions of the target activated waste vary depending on the neutron fluence rate at its physical position in the reactor. The total radioactivity of the whole activated item(s) can be estimated by repeating the activation calculation to cover all the necessary conditions of the neutron irradiat
35、ion among the whole activated item of the specified type. This provides typical or average values and distribution.The radioactivity concentration of some types of activated waste has a close relationship with the fuel burnup (e.g. components associated with fuel elements). Once equilibrium has been
36、 reached, the radionuclides produced in the same part of the same activated waste have constant composition ratios because those parts have the same elemental composition and irradiation conditions.2 ISO 2013 All rights reservedBS ISO 16966:2013ISO 16966:2013(E)Where reactor components are installed
37、 at a fixed location in the reactor (e.g. reactor pressure vessel) with a specified elemental composition, only the neutron fluence rates differ depending on the axial and radial position of this location.The following three theoretical evaluation methods are applicable as typical range methods:1 Co
38、nversion method; Correlation method; Distribution evaluation method.NOTE See Annex C.3.3.2 Conversion methodIn activated waste such as channel boxes and burnable poison which are used as fuel assembly parts, the induced radioactivity can be closely correlated with some common reactor control paramet
39、ers such as fuel burnup, since the cases where the items are of similar design and material, remain in the reactor for the same length of time, and are subject to the same neutron fluence as the fuel.In this method, the relationship (conversion factor) between the control index (such as fuel burnup)
40、 and the radioactivity concentration of such fuel assembly parts can be calculated by a series of activation calculations which cover the possible range of burnup variations. The radioactivity concentration of the activated waste can then be estimated by multiplying the control index such as burnup
41、and the conversion factor within its valid range.NOTE See Annex C.3.3.3 Correlation methodThe correlation method can be used if a particular part or individual item of an activated group is observed to have composition ratios of radionuclides produced simultaneously by irradiation that are constant
42、once equilibrium has been reached within a specified range because the elemental composition, neutron, and irradiation conditions (times) of the particular part are very similar.Therefore, the correlation between the difficult-to-measure (DTM) nuclides in the whole of the activated waste and the key
43、 nuclides produced simultaneously is evaluated by a series of activation calculations which cover the elemental composition, neutron, and irradiation conditions of several specific parts of several activated wastes of the same kind. The ratios between the key nuclides and the DTM nuclides are calcul
44、ated by evaluating this correlation, and the radioactivity concentration of each nuclide in the activated waste can be calculated by multiplying the ratio between the key nuclides and the DTM nuclides by the radioactivity concentration of the key nuclide. Note that the post irradiation decay time sh
45、ould be considered in this method since the ratio between the key nuclides and the DTM nuclides changes over time due to the difference in decay half-life.NOTE See Annex C.3.3.4 Distribution evaluation methodFixed reactor components are activated by direct neutron irradiation in the reactor. In the
46、case of such activated wastes, the elemental composition and irradiation conditions (time) can be considered to be similar for all items of the group, and only the neutron fluence rate differs depending on their installation locations in the reactor.In this method, the radioactivity concentration di
47、stribution and range of each radionuclide in all activated wastes can be calculated by a series of activation calculations which completely cover the neutron fluence rate at the installation location of the activated waste. The average radioactivity ISO 2013 All rights reserved 3BS ISO 16966:2013ISO
48、 16966:2013(E)concentration of each nuclide in the waste can then be calculated based on the resulting radioactivity concentration distribution.NOTE See Annex C.4 Calculations4.1 GeneralThe basic process for performing activation calculations for the purpose of estimating radionuclide concentrations
49、 in activated wastes involves several steps.a) Establish the context. This defines the purpose of the calculation, the radionuclides of interest, the accuracy and precision required, the basic geometry, and the overall scope of the required calculations. This is an important first step for selecting an appropriate calculation methodology and input parameters (e.g. involved materials, quantity of items, similarity of items, target waste form, accessibility of sampling, etc.).b) Select the calculation methodology, e.g. point
