EN ISO 21909-2:2023
(Main)Passive neutron dosimetry systems - Part 2: Methodology and criteria for the qualification of personal dosimetry systems in workplaces (ISO 21909-2:2021)
Passive neutron dosimetry systems - Part 2: Methodology and criteria for the qualification of personal dosimetry systems in workplaces (ISO 21909-2:2021)
This document provides methodology and criteria to qualify the dosimetry system at workplaces where it is used. The criteria in this document apply to dosimetry systems which do not meet the criteria with regard to energy and direction dependent responses described in ISO 21909-1.
The qualification of the dosimetry system at workplace aims to demonstrate that:
— either, the non-conformity of the dosimetry system to some of the requirements on the energy or direction dependent responses defined in ISO 21909-1 does not lead to significant discrepancies in the dose determination for a certain workplace field;
— or, that the correction factor or function used for this specific studied workplace enables the dosimetry system to accurately determine the conventional dose value with uncertainties similar to the ones given in ISO 21909-1.
NOTE This document is directed at all stakeholders who are involved: IMSs, accreditation or regulatory bodies, and users of the particular dosimetry (the user is meant as the entity which assigns the dosimetry system to the radiation worker and records the assigned dose.)
The methodologies to characterize the work place field in order to perform the qualification of the dosimetry system are given in Annex A. Annex B is complementary as it gives the practical methods to follow, once one methodology is chosen.
The provider of the dosimetry system shall provide the type test results corresponding to ISO 21909‑1. However, when the dosimetry system to be qualified does not comply with all the criteria of ISO 21909‑1 dealing with the energy and angle dependence of the response, some tests of the ISO 21909-1 can be not performed.
The links between ISO 21909-1 and ISO 21909-2 are described in Annex E.
This document only addresses neutron personal monitoring and not criticality accident conditions.
Passive Dosimetriesysteme für Neutronenstrahlung - Teil 2: Verfahren und Kriterien für die Qualifizierung von Personendosimetriesystemen an Arbeitsplätzen (ISO 21909-2:2021)
Dieses Dokument enthält Verfahren und Kriterien zur Qualifizierung des Dosimetriesystems an Arbeitsplätzen, an denen es eingesetzt wird. Die Kriterien in diesem Dokument gelten für Dosimetriesysteme, die die in ISO 21909-1 beschriebenen Kriterien hinsichtlich der Energie- und Richtungsabhängigkeit des Ansprechver¬mögens nicht erfüllen.
Die Qualifizierung des Dosimetriesystems am Arbeitsplatz zielt darauf ab, Folgendes nachzuweisen:
– entweder die Nichtübereinstimmung des Dosimetriesystems mit einigen der in ISO 21909-1 festgelegten Anforderungen an die Energie- oder Richtungsabhängigkeit des Ansprechvermögens führt nicht zu signi¬fikanten Diskrepanzen bei der Dosisbestimmung für ein bestimmtes Arbeitsfeld;
– oder der für diesen speziell untersuchten Arbeitsplatz verwendete Korrektionsfaktor bzw. die verwendete Korrektionsfunktion ermöglicht dem Dosimetriesystem, den richtigen Wert der Dosis genau zu bestimmen, mit ähnlichen Unsicherheiten, wie sie in ISO 21909-1 angegeben sind.
ANMERKUNG Dieses Dokument richtet sich an alle beteiligten Akteure: Personendosis-Messstellen (IMS, en: individual monitoring service), Akkreditierungs- oder Aufsichtsbehörden und Anwender der jeweiligen Dosimetrie (mit Anwender ist die Stelle gemeint, die das Dosimetriesystem der strahlenexponierten Arbeitskraft zuordnet und die zugeordnete Dosis aufzeichnet).
Die Verfahren zur Charakterisierung des Arbeitsplatzes im Hinblick auf die Qualifizierung des Dosimetriesys¬tems sind in Anhang A aufgeführt. Anhang B ist eine Ergänzung, da er die praktischen Verfahren enthält, die zu befolgen sind, sobald ein Verfahren gewählt wurde.
Der Anbieter des Dosimetriesystems muss die Ergebnisse der Bauartprüfung nach ISO 21909-1 vorlegen. Erfüllt das zu qualifizierende Dosimetriesystem nicht alle Kriterien der ISO 21909-1, die sich mit der Energie- und Winkelabhängigkeit des Ansprechvermögens befassen, können einige Prüfungen der ISO 21909-1 nicht durchgeführt werden.
Die Verknüpfungen zwischen ISO 21909-1 und ISO 21909-2 sind in Anhang E beschrieben.
Dieses Dokument bezieht sich ausschließlich auf die reguläre Personenüberwachung für Neutronenstrahlung und nicht auf die Bedingungen eines Kritikalitätsereignisses.
Systèmes dosimétriques passifs pour les neutrons - Partie 2: Méthodologie et critères de qualification des systèmes dosimétriques individuels aux postes de travail (ISO 21909-2:2021)
Le présent document donne des méthodologies et des critères afin de qualifier le système dosimétrique aux postes de travail auxquels il est utilisé. Les critères fournis dans ce document s’appliquent à des systèmes dosimétriques non conformes aux critères décrits à l’ISO 21909-1 concernant la dépendance des réponses par rapport aux distributions énergétiques et directionnelles de la fluence neutronique.
La qualification du système dosimétrique au poste de travail vise à démontrer que:
— soit la non-conformité du système dosimétrique vis-à-vis de certaines des exigences concernant les réponses dépendantes de l’énergie ou de la direction définies dans l’ISO 21909-1 n’entraîne pas d’écarts importants dans la détermination de la dose pour un certain champ de poste de travail;
— soit le facteur ou la fonction de correction utilisé pour ce poste de travail spécifiquement étudié permet au système dosimétrique de déterminer avec précision la valeur de dose conventionnelle avec des incertitudes semblables à celles indiquées dans l’ISO 21909-1.
NOTE Le présent document s’adresse à toutes les parties concernées: laboratoires de dosimétrie, organismes d’accréditation ou réglementaires et utilisateurs des systèmes dosimétriques particuliers (l’utilisateur est l’entité qui attribue le système dosimétrique au travailleur sous rayonnements et qui enregistre la dose attribuée).
Les méthodologies de caractérisation du champ d’un poste de travail pour procéder à la qualification du système dosimétrique sont décrites dans l’Annexe A. L’Annexe B est complémentaire car elle spécifie les méthodes pratiques à suivre, une fois la méthodologie choisie.
Le fournisseur du système dosimétrique doit communiquer les résultats des essais de type correspondant à l’ISO 21909-1. Toutefois, si le système dosimétrique à qualifier ne répond pas à tous les critères de l’ISO 21909-1 traitant de la dépendance énergétique et angulaire de la réponse, certains essais de l’ISO 21909-1 peuvent ne pas être réalisés.
Les liens entre l’ISO 21909-1 et l’ISO 21909-2 sont décrits à l’Annexe E.
Le présent document traite uniquement de la surveillance de la dose individuelle neutron, et non des conditions d’accident de criticité.
Sistemi pasivne nevtronske dozimetrije - 2. del: Metodologija in merila za kvalifikacijo osebnih dozimetričnih sistemov na delovnih mestih (ISO 21909-2:2021)
Ta dokument podaja metodologijo in merila za kvalifikacijo dozimetričnega sistema na delovnih mestih, kjer se uporablja. Merila iz tega dokumenta se uporabljajo za dozimetrične sisteme, ki ne izpolnjujejo meril glede odzivov, ki so opisani v standardu ISO 21909-1.
Cilj kvalifikacije dozimetričnega sistema na delovnem mestu je pokazati, da:
– dozimetrični sistem ni skladen z nekaterimi zahtevami glede odzivov, odvisnih od energije ali
smeri, ki so določeni v standardu ISO 21909-1, kar ne povzroča bistvenih neskladij pri
določanju doze za delovno mesto na določenem področju;
– ali pa lahko s korekcijskim faktorjem ali funkcijo, ki se uporablja za to določeno proučevano delovno mesto,
dozimetrični sistem natančno določi vrednost običajne doze z negotovostmi, ki so podobne
tistim iz standarda ISO 21909-1.
Metodologije za karakterizacijo področja delovnega mesta za izvedbo kvalifikacije
dozimetričnega sistema so podane v dodatku A. Dodatek B je dopolnilo, saj podaja praktične metode, ki jih je treba upoštevati ob izbiri katere od metodologij.
Ponudnik dozimetričnega sistema mora zagotoviti rezultate tipskega preskusa, ki ustrezajo standardu ISO 21909-1.
Kadar dozimetrični sistem za kvalifikacijo ne izpolnjuje vseh meril iz standarda ISO 21909-1, ki obravnava odvisnost odziva od energije in kota, nekateri preskusi iz standarda ISO 21909-1 niso mogoči.
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
01-september-2023
Sistemi pasivne nevtronske dozimetrije - 2. del: Metodologija in merila za
kvalifikacijo osebnih dozimetričnih sistemov na delovnih mestih (ISO 21909-
2:2021)
Passive neutron dosimetry systems - Part 2: Methodology and criteria for the
qualification of personal dosimetry systems in workplaces (ISO 21909-2:2021)
Systèmes dosimétriques passifs pour les neutrons - Partie 2: Méthodologie et critères de
qualification des systèmes dosimétriques individuels aux postes de travail (ISO 21909-
2:2021)
Ta slovenski standard je istoveten z: EN ISO 21909-2:2023
ICS:
13.280 Varstvo pred sevanjem Radiation protection
17.240 Merjenje sevanja Radiation measurements
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
EN ISO 21909-2
EUROPEAN STANDARD
NORME EUROPÉENNE
July 2023
EUROPÄISCHE NORM
ICS 13.280
English Version
Passive neutron dosimetry systems - Part 2: Methodology
and criteria for the qualification of personal dosimetry
systems in workplaces (ISO 21909-2:2021)
Systèmes dosimétriques passifs pour les neutrons -
Partie 2: Méthodologie et critères de qualification des
systèmes dosimétriques individuels aux postes de
travail (ISO 21909-2:2021)
This European Standard was approved by CEN on 16 July 2023.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2023 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 21909-2:2023 E
worldwide for CEN national Members.
Contents Page
European foreword . 3
European foreword
The text of ISO 21909-2:2021 has been prepared by Technical Committee ISO/TC 85 "Nuclear energy,
nuclear technologies, and radiological protection” of the International Organization for Standardization
(ISO) and has been taken over as EN ISO 21909-2:2023 by Technical Committee CEN/TC 430 “Nuclear
energy, nuclear technologies, and radiological protection” the secretariat of which is held by AFNOR.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by January 2024, and conflicting national standards shall
be withdrawn at the latest by January 2024.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
Any feedback and questions on this document should be directed to the users’ national standards body.
A complete listing of these bodies can be found on the CEN website.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and the
United Kingdom.
Endorsement notice
The text of ISO 21909-2:2021 has been approved by CEN as EN ISO 21909-2:2023 without any
modification.
INTERNATIONAL ISO
STANDARD 21909-2
First edition
2021-12
Passive neutron dosimetry systems —
Part 2:
Methodology and criteria for the
qualification of personal dosimetry
systems in workplaces
Systèmes dosimétriques passifs pour les neutrons —
Partie 2: Méthodologie et critères de qualification des systèmes
dosimétriques individuels aux postes de travail
Reference number
ISO 21909-2:2021(E)
ISO 21909-2:2021(E)
© ISO 2021
All rights reserved. Unless otherwise specified, or required in the context of its implementation, 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 ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii
ISO 21909-2:2021(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms, definitions and symbols . 2
3.1 General terms and definitions . 2
3.2 Quantities . 3
3.3 Calibration and evaluation . . 4
3.4 Symbols . 6
4 Documentation and communication to the users . 7
5 Recommendations about the workplace to consider . 7
6 Methodologies and criteria to qualify the personal dosimetry system at a certain
workplace . 8
6.1 Choice of the methods to be used for the qualification at workplaces . 8
6.2 Quantification of the impact of the non-correct behaviour in terms of energy and
angle responses of the dosimetry system . 9
6.2.1 General . 9
6.2.2 Computational approach . 10
6.2.3 Experimental approach . 10
6.3 Qualification based on experimental tests of the dosimetry systems at the
workplace . 10
6.3.1 General method . 10
6.3.2 Performance test criteria . 11
6.3.3 First solution: tests at three levels of dose at the workplace .12
6.3.4 Second solution: tests at one level of dose at the workplace .13
6.3.5 Complementary tests based on ISO 21909-1 . 14
6.3.6 Unique correction for several workplaces . 15
Annex A (normative) Methodologies to characterize the workplace field .16
Annex B (normative) Determination of the neutron personal dose equivalent Hp(10) –
Practical methods .19
Annex C (informative) Example of a complete characterization of the workplace field .26
Annex D (informative) Determination of field-specific correction factors or functions –
Practical example: use of information from literature .28
Annex E (informative) Links between ISO 21909-1 and ISO 21909-2 .29
Bibliography .31
iii
ISO 21909-2:2021(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 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 collaborates 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 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 (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 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
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'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 SC 2, Radiological protection.
A list of all the parts in the ISO 21909 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
iv
ISO 21909-2:2021(E)
Introduction
ISO 21909-1 provides laboratory-based type tests, and performance requirements for passive neutron
dosimetry systems to be used for measurement of personal dose equivalent, H (10), for neutrons
p
[1]
ranging from thermal energy to approximately 20 MeV . No distinction between the different
techniques available in the marketplace is made in the description of the tests. ISO 21909 (series) aims
at covering all passive neutron detectors that can be used as a personal dosemeter in parts of, or in the
complete above-mentioned neutron energy range.
The main objective of ISO 21909 series is to achieve correspondence between performance tests and
conditions of use at the workplaces. Dosimetry systems complying totally with ISO 21909-1 should
give consistent dosimetry results in workplace environments without the requirement of precise
information on the characteristics of the radiation fields (neutron energy and direction distributions).
For the case that a dosimetry system does not comply with the full range of requirements in ISO 21909-1
with regard to the dependence of the response on the energy and direction distributions of the neutron
fluence, it remains necessary to evaluate the performance of the dosimetry system for the conditions
of the workplace. That means that this document is systematically used to qualify at workplaces a
dosimetry system that does not fulfil the criteria of ISO 21909-1 on the dependence of the response on
neutron energy and direction of incidence.
This document aims to address dosimetry systems with responses that show energy and directional
dependencies that do not comply with the test requirements in ISO 21909-1, but that are able to give
consistent and reliable dosimetry results at selected workplaces. In this case, a specific study of the
workplace where the dosimetry systems are used is necessary to demonstrate that the dosimetry
systems are suited for the workplace of application and, if needed, to determine the appropriate
corrections to be applied. This document gives requirements for the qualification of the dosimetry
system as well as methods for evaluating its performance and qualifying it for use in the workplace.
In cases where the dosimetry system meets the requirements of ISO 21909-1, it may still be desirable
to perform a similar study at the workplace to improve the performance of the neutron dosemeters. It
is also recommended that this document may be implemented, not only for passive dosimetry systems,
but for active dosimetry systems as well.
No qualification or correction of the dosimetry system at a workplace is required if the dosimetry
system fulfils the criteria of ISO 21909-1.
All the estimations of the uncertainties in this document have to be considered in accordance with the
[2]
GUM . Uncertainties quoted in this document are provided using a coverage factor k=2.
v
INTERNATIONAL STANDARD ISO 21909-2:2021(E)
Passive neutron dosimetry systems —
Part 2:
Methodology and criteria for the qualification of personal
dosimetry systems in workplaces
1 Scope
This document provides methodology and criteria to qualify the dosimetry system at workplaces where
it is used. The criteria in this document apply to dosimetry systems which do not meet the criteria with
regard to energy and direction dependent responses described in ISO 21909-1.
The qualification of the dosimetry system at workplace aims to demonstrate that:
— either, the non-conformity of the dosimetry system to some of the requirements on the energy or
direction dependent responses defined in ISO 21909-1 does not lead to significant discrepancies in
the dose determination for a certain workplace field;
— or, that the correction factor or function used for this specific studied workplace enables the
dosimetry system to accurately determine the conventional dose value with uncertainties similar
to the ones given in ISO 21909-1.
NOTE This document is directed at all stakeholders who are involved: IMSs, accreditation or regulatory
bodies, and users of the particular dosimetry (the user is meant as the entity which assigns the dosimetry system
to the radiation worker and records the assigned dose.)
The methodologies to characterize the work place field in order to perform the qualification of the
dosimetry system are given in Annex A. Annex B is complementary as it gives the practical methods to
follow, once one methodology is chosen.
The provider of the dosimetry system shall provide the type test results corresponding to ISO 21909-1.
However, when the dosimetry system to be qualified does not comply with all the criteria of ISO 21909-1
dealing with the energy and angle dependence of the response, some tests of the ISO 21909-1 can be not
performed.
The links between ISO 21909-1 and ISO 21909-2 are described in Annex E.
This document only addresses neutron personal monitoring and not criticality accident conditions.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitute requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 21909-1:2021, Passive neutron dosimetry systems — Part 1: Performance and test requirements for
personal dosimetry
ISO 8529-2:2000, Reference neutron radiations — Part 2: Calibration fundamentals of radiation protection
devices related to the basic quantities characterizing the radiation field
ISO 8529-3:1998, Reference neutron radiations — Part 3: Calibration of area and personal dosimeters and
determination of response as a function of energy and angle of incidence
ISO 21909-2:2021(E)
3 Terms, definitions and symbols
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at http:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1 General terms and definitions
3.1.1
detector
radiation detector
apparatus or substance used to convert incident ionizing radiation energy into a signal suitable for
indication and/or measurement
[SOURCE: IEC 60050-394:2007, 394-24-01, modified — the term “detector” has been added as the first
preferred term]
3.1.2
dosemeter
dosimeter
device having a reproducible, measurable response to radiation that can be used to measure the
absorbed dose or dose equivalent quantities in a given system
[SOURCE: ISO 12749-2:2013, 5.5]
3.1.3
personal dosemeter
meter designed to measure the personal dose equivalent (rate)
Note 1 to entry: A personal dosemeter can be worn on the trunk (whole-body personal dosemeter), at the
extremities (extremity personal dosemeter) or close to the eye lens (eye lens dosemeter).
[SOURCE: ISO 29661:2012, 3.1.21]
3.1.4
individual monitoring service
IMS
organization that operates a personal-dosimetry system which includes the evaluation of the reading of
dosemeters after their use and may include:
— providing the user with dosemeters;
— recording the results;
— reporting the results to the user
3.1.5
dosimetry system
system used for measuring absorbed dose or dose equivalent, consisting of dosemeters, measurement
instruments and their associated reference standards, and procedures for the system’s use
[SOURCE: ISO 12749-4:2015, 3.1.3, modified — the wording of the definition was slightly modified.]
ISO 21909-2:2021(E)
3.2 Quantities
3.2.1
dose equivalent
H
product of the absorbed dose D to tissue at the point of interest and the quality factor Q at that point:
HD= Q
−1
Note 1 to entry: The unit of dose equivalent is joule per kilogram (J·kg ), and its special name is sievert (Sv).
[SOURCE: ISO 80000-10:2019, 10-83, modified — Note 1 to entry added.]
3.2.2
neutron fluence
Φ
differential quotient of N with respect to a, where N is the number of neutrons incident on a sphere of
cross-sectional area a:
dN
Φ =
da
−2 −2
Note 1 to entry: The unit of neutron fluence is m , a frequently unit used is cm .
[SOURCE: ISO 80000-10:2019, 10-43, modified — the wording of the definition was slightly modified.]
3.2.3
energy distribution of the neutron fluence
Φ
E
quotient of dΦ by dE, where dΦ is the fluence of neutrons with energy between E and E + dE
dΦ
Φ =
E
dE
−2 −1
Note 1 to entry: The SI unit of the energy distribution of the neutron fluence is (m ·J ); a widely-used unit is
−2 −1
(cm ·MeV ).
Note 2 to entry: The energy distribution of the neutron fluence rate ϕ is the quotient of dΦ by dt, where dΦ is
E E E
−2 −1 −1
the increment of the energy distribution of the fluence in time interval dt. The unit is (m ·J ·s ); a widely-used
−2 −1 −1
unit is (cm ·MeV ·s ).
3.2.4
energy and direction distribution of the neutron fluence
Φ
E,Ω
quotient of dΦ by dE and dΩ, where dΦ is the fluence of neutrons with energy between E and E + dE and
propagating within a solid angle dΩ around a specified direction, Ω, expressed as
d Φ
Φ =
E,Ω
dEΩ
−2 −1 −1
Note 1 to entry: The SI unit of the energy and direction distribution of the neutron fluence is m ·J ·sr ; a widely-
−2 −1 −1
used unit is (cm ·MeV ·sr ).
Note 2 to entry: The energy and direction distribution of the neutron fluence rate Φ is the quotient of dΦ
E ,Ω E,Ω
by dt, where dΦ is the increment of the energy and direction distribution of the fluence in time interval dt. The
E,Ω
−2 −1 −1 −1 −2 −1 −1 −1
unit is (m ·J ·sr ·s ); a widely-used unit is (cm ·MeV ·sr ·s ).
ISO 21909-2:2021(E)
3.2.5
personal dose equivalent
H (d)
p
dose equivalent in soft tissue at an appropriate depth, d, below a specified point on the human body
−1
Note 1 to entry: The unit of personal dose equivalent is joule per kilogram (J·kg ) and its special name is sievert
(Sv).
Note 2 to entry: The specified point is usually given by the position where the individual’s dosimeter is worn.
[SOURCE: ICRP 103:2007]
3.2.6
ambient dose equivalent
H*(10), H’(0,07) or H’(3)
dose equivalent that would be produced by the corresponding aligned and expanded field in the ICRU
sphere at a depth, d, on the radius opposing the direction of the aligned field
[SOURCE: IAEA – Radiation Protection and Safety of Radiation Sources: International Basic Safety
Standards - Interim Edition IAEA Safety Standards Series GSR Part 3, 2011]
3.2.7
conversion coefficient
h (10,E,α)
pΦ
quotient of the personal dose equivalent at 10 mm depth, H (10), and the neutron fluence, Φ, at a point in
p
the radiation field used to convert neutron fluence into the personal dose equivalent at 10 mm depth in
the ICRU tissue slab phantom, where E is the energy of the incident neutrons impinging on the phantom
at an angle α
Note 1 to entry: The unit of the conversion coefficient is Sv⋅m . A commonly used unit of the conversion coefficient
is pSv⋅cm .
3.3 Calibration and evaluation
3.3.1
conventional true value for the neutron personal dose equivalent
conv
H
quantity value attributed by agreement to a quantity for a given purpose
conv
Note 1 to entry: The conventional value H is the best estimate of the quantity to be measured, determined by a
primary standard or a secondary or working measurement standard which are traceable to a primary standard.
Note 2 to entry: in this document, the quantity is the neutron personal dose equivalent.
[SOURCE: ISO/IEC Guide 99:2007, 2.12, modified — the term was changed.]
3.3.2
calibration
operation that, under specified conditions, in a first step, establishes a relation between the quantity
values with measurement uncertainties provided by measurement standards and corresponding
readings with associated measurement uncertainties and, in a second step, uses this information to
establish a relation for obtaining a measurement result from an indication
Note 1 to entry: Calibration may be expressed by a statement, calibration function, calibration diagram,
calibration curve, or calibration table. In some cases, it may consist of an additive or multiplicative correction of
the indication with associated measurement uncertainty.
Note 2 to entry: Calibration should not be confused with adjustment of a measuring system, often mistakenly
called “self-calibration”, or with verification of calibration.
Note 3 to entry: Often, the first step alone in the above definition is perceived as being calibration.
ISO 21909-2:2021(E)
[SOURCE: ISO/IEC Guide 99:2007, 2.39]
3.3.3
calibration factor
N
conv
quotient of the conventional quantity value, H , (3.3.1) divided by the reading, M, derived under
standard test conditions, given by the formula:
conv
H
N=
M
Note 1 to entry: mathematical functions, in some cases families of functions, can be used to provide calibration
factors over a range of conditions. Several different calibration functions can be defined for the same dosimetry
system and possibly be used for different conditions of exposure.
3.3.4
correction factor or function
numerical value or function by which the indication is multiplied to compensate for the deviation of
measurement conditions from reference conditions or for a systematic effect
Note 1 to entry: In this document, it corresponds to the factor or function, noted k , defined for a specific
n,E,Ω
workplace field, that is applied to the value of the measured dose equivalent in order to take into account the
systematic effect induced by the dose response of the dosimetry system.
[SOURCE: ISO 29661:2012, 3.1.9, modified — the wording of the definition was slightly modified.]
3.3.5
measured dose equivalent
H
M
product of the reading, M, and the calibration factor, N:
HM=⋅N
M
Note 1 to entry: More elaborate algorithms may also be used.
Note 2 to entry: This definition is only valid for a calibration field. To extend it to any other field, the correction
factor of function k , needs to be added. In that case, the formula becomes:
n,E,Ω
H = M·N·k
M n,E,Ω
3.3.6
phantom
object constructed to simulate the scattering and absorption properties of the human body for a given
ionizing radiation
Note 1 to entry: For calibrations for whole body radiation protection considerations, the ISO water slab phantom
is employed. It is made with polymethyl metacrylate (PMMA) walls (front wall 2,5 mm thick, other walls 10 mm
thick), of outer dimensions 30 cm x 30 cm x 15 cm and filled with water.
Note 2 to entry: In the cases of very non-uniform irradiation conditions, an extremity cylinder, pillar or rod
phantom may be used as described in ICRU report 66.
[SOURCE: ISO 12749-2: 2013, 4.1.6.1 modified — Notes 1 and 2 to entry added]
3.3.7
reading
M
quantitative indication of a detector or dosemeter when it is read out, generally corrected for
background, ageing, fading and non-linearity of the process or the read out system
ISO 21909-2:2021(E)
3.3.8
dose equivalent response
response
R
conv
measured dose equivalent, H , divided by the conventional quantity value, H , (3.3.1) of the dose
M
equivalent, as given by the following formula:
H
M
R=
conv
H
Note 1 to entry: The reading, M, is converted into dose equivalent, H , by multiplying M by an appropriate
M
conversion coefficient or by using a more elaborate algorithm.
M
H ()10
p
Note 2 to entry: In this document, the quantity is personal dose equivalent: R =
conv
H 10
()
p
Note 3 to entry: In this document, for the sake of brevity, H = H is used.
M
Note 4 to entry: The reciprocal of the response at reference conditions is equal to the calibration coefficient.
Note 5 to entry: In radiation metrology, the term response, abbreviated for this application from “response
characteristic” (VIM), is defined as the ratio of the reading, M, of the instrument, to the value of the quantity to be
measured by the instrument, for a specified type, energy and direction distribution of radiation. It is necessary,
in order to avoid confusion, to state the quantity to be measured, e.g. the “fluence response” is the response with
respect to the fluence, the “dose equivalent response” is the response with respect to dose equivalent.
[SOURCE: ISO 8529-3:1998, 3.2.10, modified]
3.4 Symbols
The list of the symbols used in this document is given in Table 1.
Table 1 — List of symbols
Symbol Meaning Unit
α angle of incidence of the irradiation field degree
Depth in ICRU 4-element or soft tissue. Recommended depths are 0,07 mm, 3 mm,
d mm
and 10 mm.
E Neutron energy eV
-2
Φ Neutron fluence m
H Dose equivalent Sv
H*(10) Ambient dose equivalent at 10 mm depth Sv
conv
H Conventional true value for the neutron personal dose equivalent Sv
Personal dose equivalent whose value is chosen in the range:
H Sv
HD
0,8 mSv < H < 2 mSv
HD
H Measured dose equivalent Sv
M
H (d) Personal dose equivalent at a depth d Sv
p
H (10) Personal dose equivalent at 10 mm depth Sv
p
conv
H Conventional true value for the neutron personal dose equivalent. Sv
p
h (d,E,α) Fluence-to-personal-dose-equivalent conversion factor Sv⋅m
p
R Dose-equivalent response -
U
Expanded uncertainty of the measured personal dose equivalent As quantity
H
M
Expanded uncertainty of the conventional true value for the personal dose equiva-
U
As quantity
conv
lent
H
ISO 21909-2:2021(E)
Table 1 (continued)
Symbol Meaning Unit
Expanded uncertainty of a combined quantity of conventional quantity values.
U This uncertainty is equivalent to the half-width of the confidence interval about As quantity
com
the combined quantity at a confidence level of 95 %
This document uses SI units. However, the following units of practical importance for time and energy
are used when necessary:
— days (d) and hours (h) for time;
–19
— electron-volt (eV) knowing that 1 eV = 1,602 × 10 J.
-1
The SI unit of dose equivalent is J∙kg but the dedicated name for the unit of dose equivalent is sievert
(Sv).
4 Documentation and communication to the users
The IMS (individual monitoring service) shall specify in its documentation whether the dosimetry
system complies or not with requirements in ISO 21909-1 in terms of its energy and angular dependence.
If the dosimetry system is not in compliance, the dosimetry system shall be qualified for the workplace
in which it is to be used. The IMS should inform the user (responsible for the workers monitoring, i.e.,
employer, RPO…) on the energy and angular range for which the dosimetry system does not fulfil the
criteria of ISO 21909-1 and that the dosimetry system shall be qualified for the workplace in which it is
used. The qualification of the dosimetry system at the workplace shall be done in accordance with this
document.
The IMS should also indicate the need to qualify the dosimetry system in the situation in which the
dosimetry system is deployed to different workplaces or even different worker’s locations, each
requiring a unique correction. A specific note shall be given to the users, explaining that a dosimetry
system for which the response is corrected for one specific workplace cannot be used at several
workplaces except if it is qualified globally for those several workplaces.
In the situation where the IMS is not in charge of performing the qualification, it shall give to the user
all the results of the characterisation in accordance with ISO 21909-1.
5 Recommendations about the workplace to consider
When characterizing a specific workplace, the variability in energy or directional distributions of
the neutron field shall be taken into account. To achieve this objective, the exposure situations that
show the highest differences in terms of neutron fluence rate or neutron dose rate, different shielding
materials and thicknesses, surfaces of scattering, have to be considered.
In case that the spectral neutron fluence can be significantly different for the possible locations of the
workers in one given workplace, the effect of these different exposure situations on the response of the
dosimetry system shall be considered. If needed, several workplaces can be defined taking the different
worker’s locations into account. The attention to this issue is essential to insure the robustness and
reliability of the dosimetry system at this workplace.
Moreover, in case that the workplace field varies with time, i.e., neutron sources and/or shielding and/or
locations of exposure change, the effect of the new exposure situation on the response of the dosimetry
system shall be considered. Only different exposure situations for which it was already shown that the
ISO 21909-2:2021(E)
dosimetry system fulfils the requirements with the same correction function (if needed) are acceptable
without a new study.
NOTE 1 The definition of the workplace is conceptually simple. In the case when a worker is working in front
of a glovebox, it is easy to define one specific workplace. However, in some situations, for example around a
transport container, the spectrum can be very different at the edge of the container compared to the middle of
the container.
The workplace conditions have a significant impact on the neutron fluence, energy and direction
distributions. The following shall be considered in any evaluation of the performance of the dosimetry
system in this environment: emission rate and energy distribution, mass, density, geometry, shielding,
materials present at the workplace, location of work, typical orientation of worker, etc.
NOTE 2 An example where the neutron fluence, energy and direction distributions can be significantly
modified at the same workplace is for storage facilities. Indeed the amount of neutron sources may vary, but also
the geometrical configuration and the composition of the neutron emitters and the surrounding materials. To
sum up, the type, the number and the locations of stored sources may vary. These modifications may induce high
variations in terms of fluence rate, energy and directional distributions of the neutron field in such a workplace.
6 Methodologies and criteria to qualify the personal dosimetry system at a
certain workplace
6.1 Choice of the methods to be used for the qualification at workplaces
Two methods a) and b) are described below to qualify the dosimetry system at a specific workplace.
Choose and apply one of these two methods (see also Figure 1).
a) The first approach is based on a characterization in terms of the energy and direction distribution
of the neutron fluence encountered at the workplace. The method consists of evaluating the
impact of the non-compliance of the dosimetry system to the requirements of the dependence
of the response on energy or direction of incidence defined in ISO 21909-1. For such dosimetry
systems, specific correction at workplaces shall not be performed if it has been demonstrated that
the non-compliance does not lead to significant discrepancies in the dose determination for the
considered workplace field. The impact shall be quantified and the dosimetry system shall fulfil the
requirements of 6.2.
b) The second approach is based on a qualification of the dosimetry system itself performed directly
at the considered workplace. In that case, it should be demonstrated that the correction factor or
function used for the specific workplace enables to accurately determine the conventional dose
equivalent quantity with uncertainties similar to the ones required in ISO 21909-1. The required
tests and the performance limits are given in 6.3.
ISO 21909-2:2021(E)
Figure 1 — Decision diagram to determine the method to use to qualify the dosimetry system at
a workplace
6.2 Quantification of the impact of the non-correct behaviour in terms of energy and
angle responses of the dosimetry system
6.2.1 General
This approach is restricted to dosimetry systems that show under-responses in regard to the criteria of
ISO 21909-1:
— for the lower energies and/or the higher energies of the minimal rated energy range as defined in
ISO 21909-1;
— or, for the higher angles of the angle range as defined in ISO 21909-1.
To demonstrate in this specific case, the small impact on dose equivalent measurement, two methods
can be used: calculations (6.2.2) or experimental tools (6.2.3).
ISO 21909-2:2021(E)
The location(s) at which the dosimetry system is qualified in the workplace shall be, at minimum,
the one(s) representative for the usual locations of the workers in the room. In both approaches, it is
acceptable to consider to characterizing the workplace field in terms of the energy dependence of the
neutron fluence without taking into account the direction distribution of the neutron fluence (i.e., usual
neutron spectrometers allowing the determination of H*(10) can be used.)
6.2.2 Computational approach
The approach consists in using both:
— the information on the characteristics of the workplace in terms of energy and direction distributions
of the neutron fluence from calculations. Apply the numerical approach described in (A.2.2) to
determine this information.
— and all the results of the tests of performance of the dosimetry system obtained from the type tests
defined in ISO 21909-1, in order to qualify the dosimetry system at the workplace.
The dosemeters can be used at the workplace without corrections under the following conditions:
— a range of acceptable energy/angle responses against ISO 21909-1 shall be found by defining an
upper and or lower energy limit; only mono-energetic beams demanded in ISO 21909-1 shall be
considered for defining the limits;
— it shall be demonstrated by workplace calculations that H (10) neutron dose contribution due to
p
neutrons corresponding to energies/angles outside of the aforementioned defined range is lower
than 10 % of the total neutron dose.
The criteria given in ISO 21909-1 for the mono-energetic neutron fields shall be used to define the lower
or upper limit in useful energy response of the dosimetry system.
6.2.3 Experimental approach
The experimental approach is similar in concept to the computational approach but the dose
contribution due to neutrons with energies below a threshold for low energies and/or above a threshold
for high energies is assessed using experimental tool. Apply (A.2.1) to have the information on the
energy distribution.
As stated previously, the workplace(s) in which the dosimetry system is to be qualified shall be the
one(s) representative of the usual locations of the workers in the room.
6.3 Qualification based on experimental tests of the dosimetry systems at the
workplace
6.3.1 General method
This approach is based on the assessment of H (10) at the workplace. This personal dose equivalent
p
value determined by the dosimetry system is compared to a reference value obtained from a reference
measurement.
Firstly, the reference value H (10) shall be assessed. To do so, apply Annex A to define which methodology
p
to use, and apply the corresponding practical method in Annex B.
When a dosimetry system uses different correction functions or factors, choose the system that is the
most adapted to the specific workplace.
Secondly, for the measurement of H by the dosimetry system to be qualified, a minimum of four
M
dosemeters shall be placed on a phantom. Use the same phantom, and at the same position and at the
conv
same directional incidence, used to determine the reference value of H (10), denoted as H . The value
p
H to be considered in the calculation of the response is the average of the four measurements.
M
ISO 21909-2:2021(E)
The dosemeters shall be placed on the front face of the phantom. The phantom and irradiation geometry
used in the experimental irradiation shall be in accordance with ISO 8529-3:1998, 6.2.
The phantom shall be positioned in order that the 0° incidence corresponds to the orientation the most
representative of the worker’s position.
NOTE 1 The correction factor or function can be estimated using several methods. The experimental results
from this on-site qualification can be used, but supporting published information (see Annex D) or tests using
simulated workplace fields can also be used, to help determine the appropriate correction factor or function.
The response R, is defined as the quotient of the mean measured dose equivalent value H , of the
M
irradiated dosemeters with the correction factor or function applied if needed, and the reference value
conv
H :
H
M
R=
conv
H
The value of the response, R, shall meet the following criteria defined in 6.3.2.
conv
The tests shall be performed at either one (see 6.3.4) or three (see 6.3.3) levels of dose equivalent H .
NOTE 2 The choice between these tw
...
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