Radiation Protection Dosimetry (2016), Vol. 170, No. 1–4, pp. 13–16 Advance Access publication 5 October 2015

doi:10.1093/rpd/ncv423

EVOLUTION OF THE IEC AND EN STANDARDS FOR INDIVIDUAL MONITORING OF IONISING RADIATION M. Voytchev1,*, R. Behrens2, P. Ambrosi2, R. Radev3 and P. Chiaro4 1 Institut de Radioprotection et de Suˆrete´ Nucle´aire (IRSN), PSN-RES, SCA, LPMA, Saclay, Gif-sur-Yvette 91192, France 2 Physikalisch-Technische Bundesanstalt (PTB), Bundesallee 100, Braunschweig D-38116, Germany 3 Lawrence Livermore National Laboratory, PO Box 808, L-186, Livermore, CA 94550, USA 4 Department of Homeland Security, Domestic Nuclear Detection Office (DNDO), 245 Murray Lane, Bldg 410, Washington, DC 20528, USA *Corresponding author: [email protected]

INTRODUCTION The International Electrotechnical Commission (IEC) and the activities of its Sub Committee (SC) 45B ‘Radiation protection instrumentation’ were described in detail before(1). The European Committee for Electrotechnical Standardization (CENELEC) was also introduced as well as its technical committee (TC) 45B ‘Radiation protection instrumentation’. CENELEC TC 45B transposes IEC/SC 45B standards to European standards (EN) in a case by case manner thus being able to include technical modifications if needed. This article presents the evolution for the last 5 y of the IEC and EN standards for individual monitoring of ionising radiation. At the IEC level, these standards were developed within working groups (WGs) 8 and 14 of SC 45B. Recently, both WGs were merged into one, WG 8 ‘Active pocket and portable dose (rate) meters and monitors and passive dosimetry systems’. The authors of this article in the order listed are: (1) the secretary of IEC and CENELEC 45B committees; (2) the convener of IEC/SC 45B/WG 8, the chairman of CENELEC/TC 45B and the project leader (PL) of IEC 62387 and IEC TR 62461 Ed.2; (3) the past convener of IEC/SC 45B/WG8, the past chairman of CENELEC/TC 45B and the PL of IEC 61526 Ed. 3, IEC 60846-1 and IEC/TS 62743; (4) the PL of IEC 61005 Ed.3; (5) the chairman of IEC/SC 45B.

PASSIVE INDIVIDUAL PHOTON AND BETA DOSIMETRY SYSTEMS: IEC/EN 62387 The international standard that covers passive individual photon and beta dosimetry systems is IEC 62387 ‘Radiation protection instrumentation— passive integrating dosimetry systems for personal and environmental monitoring of photon and beta radiation’(2). IEC/EN 62387 editions The first edition of IEC 62387-1 from 2007 had ‘21’ in its number indicating that more parts of this standard were planned in order to address the specific requirements concerning different techniques of passive dosemeters: thermoluminescence detectors (TLD), optically stimulated luminescence, radio photoluminescence, direct ion storage, film dosemeters, etc. However, experience showed that this standard can cover all passive photon and beta dosemeter types and additional parts were not needed. The first IEC edition was transposed to EN 62387-1 in February 2012. The passive dosimetry systems used for individual monitoring of workers’ exposure to ionising radiation have a particular legal status in many European countries; therefore, many technical modifications were included in order to ensure that (at least most of) the current systems can fulfil the requirements. In December 2012, all of these technical modifications together with new developments gave

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This article presents the evolution of the International Electrotechnical Commission (IEC) and the European standards for individual monitoring of ionising radiation issued, respectively, from the committees IEC/Sub Committee 45B and European Committee for Electro-technical Standardization/Technical Committee 45B ‘Radiation protection instrumentation’. Standards for passive individual photon and beta dosimetry systems as well as those for active individual monitors are discussed. A neutron ambient dose equivalent (rate) meter standard and a technical report concerning the determination of uncertainty in measurement are also covered.

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birth to the current IEC 62387. The EN transposition of this edition has just been finalised, and its publication is expected by the end of 2015. Changes in IEC 62387 (2012) The major changes included in this edition are listed below:

There were also several improvements, corrections and clarifications in different subsections: (1) concerning the non-linearity, for consistency with other standards and for better clarification, measurements are needed for at least three dose values in each order of magnitude (20, 40 and 80 %). There is a new interpretation for the coefficient of variation, and the requirement to use 10 dosemeters for the 3 lowest doses was removed; (2) concerning the energy and angular dependence, the old standard was found relatively tight for the lower energies. Thus, a progressive step increase of the performance requirements for the lower energies (E , 65 keV) was included. For example, the accepted variation of the Hp(10) relative response for photon energies E  65 keV is 229 to þ67 %, whereas that for E , 33 keV is 233 to þ100 %; (3) for Hp(0.07) whole-body dosemeters that cannot meet the angular dependence requirement at +458 for beta radiation, a new clause ‘Indication of the presence of beta dose’ was included. For the angles of incidence of +458, the response values shall be only measured and stated. Thus, such a dosemeter will be able either to measure the beta radiation or just to indicate its presence; (4) concerning the environmental and electromagnetic compatibility (EMC) tests on the reader, the following clause was added ‘In case, it can be made sure by physical reasons that temperature, light or EMC does not have a significant effect on the indicated value then this test can be omitted’. Changes in EN 62387 (expected publication in 2015) During the EN transposition that took place in 2014 and 2015, a distinction between environmental and 14

ACTIVE INDIVIDUAL MONITORS The two major active individual monitor standards IEC 61526 Ed. 3 (2010)(6) concerning active individual dosemeters and IEC 60846-1 (2009)(7) concerning ambient and/or directional meters and monitors were presented earlier(1). They were transposed as EN standards with very few modifications, respectively, in 2013 and 2014. It is important to state that the goal is to keep IEC and EN standards in the radiation protection instrumentation field as equivalent as possible. IEC 60846-2 (2007)(8) concerning the high-range portable instruments for emergency radiation protection purposes is currently being revised with small editorial changes, i.e. mainly harmonisation with the

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(1) extension of the photon energy range for dosemeters to measure Hp(0.07) from the old range of 8– 250 keV to the new range of 8 keV–10 MeV; (2) addition of performance requirements for dosemeters to measure Hp(3) for both photon and beta radiation; (3) addition of performance requirements for dosemeters to measure H0 (0.07) for both photon and beta radiation; (4) alignment with the recommendations on accuracy stated in ICRP Publication 75(3); (5) the standard covers the scope of ISO 12794(4) from 2000 concerning TLD dosemeters for extremities and eyes.

workplace monitoring was introduced (area monitoring as generic term covers both) since only environmental monitoring for H*(10) was covered before. In practice, the difference can be seen for the angular dependence that for the workplace dosemeters, it is verified up to 608, and for the environmental—up to 1208. The standard title was consecutively updated: ‘Radiation protection instrumentation—passive integrating dosimetry systems for individual, workplace and environmental monitoring of photon and beta radiation’. The term ‘personal monitoring’ was also changed to ‘individual monitoring’ to harmonise it with ICRP publication 103(5) and the recently published IAEA and EU basic safety standards. In order to soften the standard and to approximate it to the standard for active individual monitors, IEC 61526 Ed.3 (2010)(6), there is a small increase for the non-linearity performance requirement for all quantities: from (–9 to þ11 %) initially it goes now to (– 13 to þ18 %). A new requirement for Hp(3) for beta radiation was added ‘the indicated value due to beta radiation with energies up to the energy equivalent of 85Kr shall be less than 0.1.Hp(0.07)’, i.e. those dosemeters shall be insensitive to low-energy beta radiation. The requirement for the response to natural background radiation has been removed since only radiation in addition to natural background is in the focus, i.e. the indication due to natural background always has to be subtracted from the measured dose. All EMC tests except those for radio frequency (RF) electromagnetic fields (MF) and for power frequency magnetic fields became mandatory. The omission of the RF and MF tests is only possible if the manufacturer supplies a physically sound declaration that RF and MF do not significantly affect the indicated value or the effect is recognised and accompanied by an error message. Finally, several corrections and clarifications have been introduced. All these changes will serve as input for the next revision of the corresponding IEC standard IEC 62387:2012.

EVOLUTION OF THE IEC AND EN STANDARDS

IEC ‘Guide to the expression of uncertainty in measurement’ (GUM S1)(14) including guidance when to use a particular method. In addition, a simple method to judge whether a measurement result is significantly above zero or not, based on ISO 11929(15), was added. Finally, the technical report contains many examples for the uncertainty determination of dosemeters according to IEC 60846-1, IEC 62387, IEC 61005, etc.

NEUTRON AMBIENT DOSE EQUIVALENT (RATE) METERS: IEC 61005 ED. 3

ISO STANDARDS FOR INDIVIDUAL MONITORING OF IONISING RADIATION

Neutron ambient dose equivalent (rate) meters are covered by IEC 61005(10). The third edition was published in July 2014 and replaced the second edition from 2003. The major changes are as follows:

IEC/SC45B/WG14 and ISO/TC85/SC2/WG19 agreed in 2010 that the photon and beta passive individual monitoring will be covered by IEC whereas the neutron passive dosimetry will be considered within ISO as neutron measurements often require special procedures for precise measurements. The revised ISO 21909-1(16) treating the passive neutron dosimetry systems will soon replace ISO 21909(17) from 2005. Discussions on a second part of this standard have been recently started aiming to cover the characterisation of workplace neutron fields in order to qualify passive neutron dosimetry systems prepared for a specific workplace. Several other ISO standards have been published or are being prepared concerning recommendations for dealing with discrepancies between personal dosemeter systems(18), monitoring of the dose to the lens of the eye, the skin and the extremities(19), criteria and performance limits for the periodic evaluation of processors of personal dosemeters for X- and gamma-radiation(20) and characteristics of reference pulsed radiation for photon radiation(21). For the latter, a second part for pulsed neutrons radiation is foreseen.

(1) the upper neutron energy of instruments addressed by the standard was increased from 16 to 20 MeV as per requests of several countries. It was agreed that above that energy there are no convenient and reliable methods for calibration and verification of the instrument response for standardisation purposes; (2) the requirement for the variation of the relative response due to neutron energy was modified from the undefined ‘manufacturer shall specify the energy response. . .’ to defined minimum response requirements in three neutron energy sub-regions covering the entire range to 20 MeV; (3) the choice of test sources was modified to better suit the minimum response requirements; (4) a requirement for Monte Carlo calculations of the instrument response curve was introduced because suitable monoenergetic calibration sources are not readily available to cover the entire neutron energy range in sufficient detail; (5) the agreement between the Monte Carlo calculated and the measured instrument response from the test sources is to be within +20 %; (6) general requirements for instrument’s software design structure and data protection were added; (7) and a clause for additivity of the indicated value (neutron dose/dose rate) was included. Tests according to this standard were presented(11). The EN transposition of the standard started in 2015. DETERMINATION OF UNCERTAINTY IN MEASUREMENT: IEC TR 62461 ED. 2 The technical report IEC TR 62461 Ed. 2(12) concerning the determination of uncertainty in measurement according to the ISO/IEC ‘Guide to the expression of uncertainty in measurement’ (GUM)(13) was revised and published in 2015. This edition added the Monte Carlo method according to Supplement 1 to the ISO/ 15

CONCLUSIONS The standards discussed in this article provide manufacturers with internationally acceptable requirements (specifications) and provide device users with assurance of the rigorous quality and accuracy of the measurements. The above standards have been used for several years for conformity instrumentation evaluations, in intercomparison programmes and as references when drafting tenders and contracts. Experts from all countries are welcome to contribute to the IEC and CENELEC work. The national IEC or CENELEC committees should be contacted for registration. REFERENCES 1. Voytchev, M., Ambrosi, P., Behrens, R. and Chiaro, P. IEC standards for individual monitoring of ionizing radiation. Radiat. Prot. Dosim. 144(1– 4), 33–36 (2011).

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new edition of IEC 60846-1 as of 2009. IEC 60846-2 publication is expected in 2016. An IEC technical specification IEC/TS 62743(9) concerning electronic counting dosemeters for pulsed fields of ionising radiation was published in 2012. A new IEC standard project based on this technical specification is in preparation and should cover all dosemeters for pulsed fields of ionising radiation.

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12. International Electrotechnical Commission. Radiation protection instrumentation—determination of uncertainty in measurement. IEC TR 62461 Ed.2. International Electrotechnical Commission (2015). 13. International Standardization Organization and International Electrotechnical Commission. Uncertainty of measurement—part 3: guide to the expression of uncertainty in measurement. ISO/IEC Guide 98-3. International Standardization Organization and International Electrotechnical Commission (2008). 14. International Standardization Organization and International Electrotechnical Commission. Uncertainty of measurement—part 3 supplement 1: propagation of distributions using a Monte Carlo method. ISO/IEC Guide 98-3/Suppl 1. International Standardization Organization and International Electrotechnical Commission (2008). 15. International Standardization Organization. Determination of the characteristic limits (decision threshold, detection limit and limits of the confidence interval) for measurements of ionizing radiation—fundamentals and application. ISO 11929. International Standardization Organization (2010). 16. International Standardization Organization. Passive neutron dosimetry systems—part 1: performance and test requirements for personal dosimetry. ISO/FDIS 21909-1. International Standardization Organization. 17. International Standardization Organization. Passive personal neutron dosemeters—performance and test requirements. ISO 21909 (2005). 18. International Standardization Organization. Radiological protection—recommendations for dealing with discrepancies between personal dosimeter systems used in parallel. ISO 15690. International Standardization Organization (2013). 19. International Standardization Organization. Radiological protection—procedures for monitoring the dose to the lens of the eye, the skin and the extremities. ISO/FDIS 15382. International Standardization Organization. 20. International Standardization Organization. Radiation protection—criteria and performance limits for the periodic evaluation of processors of personal dosemeters for X and gamma radiation. ISO 14146. International Standardization Organization (2000) to be revised. 21. International Standardization Organization. Radiological protection—characteristics of reference pulsed radiation— part 1: photon radiation. ISO/TS 18090-1. International Standardization Organization (2015).

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2. International Electrotechnical Commission. Radiation protection instrumentation—passive integrating dosimetry systems for personal and environmental monitoring of photon and beta radiation. IEC 62387. International Electrotechnical Commission (2012). 3. ICRP. General principles for the radiation protection of workers. ICRP Publication 75. ICRP (1997). 4. International Standardization Organization. Nuclear energy—radiation protection—individual thermoluminescence dosemeters for extremities and eyes. ISO 12794. International Standardization Organization (2000). 5. ICRP. The 2007 Recommendations of the International Commission on Radiological Protection. ICRP Publication 103. ICRP (2007). 6. International Electrotechnical Commission. Radiation protection instrumentation—measurement of personal dose equivalents Hp(10) and Hp(0.07) for X, gamma, neutron and beta radiations—direct reading personal dose equivalent meters. IEC 61526 Ed.3. International Electrotechnical Commission (2010). 7. International Electrotechnical Commission. Radiation protection instrumentation—ambient and/or directional dose equivalent (rate) meters and/or monitors for beta, X and gamma radiation—part 1 portable workplace and environmental meters and monitors. IEC 60846-1. International Electrotechnical Commission (2009). 8. International Electrotechnical Commission. Radiation protection instrumentation—ambient and/or directional dose equivalent (rate) meters and/or monitors for beta, X and gamma radiation—part 2: high range beta and photon dose and dose rate portable instruments for emergency radiation protection purposes. IEC 60846-2. International Electrotechnical Commission (2007). 9. International Electrotechnical Commission. Radiation protection instrumentation—electronic counting dosemeters for pulsed fields of ionizing radiation. IEC/TS 62743. International Electrotechnical Commission (2012). 10. International Electrotechnical Commission. Radiation protection instrumentation—neutron ambient dose equivalent (rate) meters. IEC 61005 Ed.3. International Electrotechnical Commission (2014). 11. Leake, J. W., Clements, J., Croydon, W. F., Lowe, T. and Mason, R. S. Improvements to the Leake neutron detector III: increased sensitivity and compliance with ANSI and IEC standards. Nucl. Instrum. Methods Phy. Res. A 783, 80– 84 (2015).