ISO/TC 85/SC 2/WG 19 - Individual monitoring of external radiation

The objective of this document is to promote the harmonization of data and information reporting formats in order to provide the basis for the evaluation of occupational exposure with a view to allow for benchmarking capacity at the user level, technical review level, country level and global level (such as UNSCEAR) database or register on occupational exposure. Activity sectors and occupations (where employees are classified as occupationally exposed workers) that is included in this database or register as well as dose types and different values of interest concerning occupational exposure are described as follows. A typical national dose register (NDR): — contains personal, employment, and dosimetric data of occupational employment and wage statistics (OEWs) in the country. — assists national authorities in controlling and safekeeping of the occupational doses and to allow statistical evaluations (e.g., dose trends to answer requests from regulators and others). — assists in regulatory control by notifying regulatory authorities of overexposures within their jurisdiction and the licensee in their respective facility. — contributes to health research and to the scientific knowledge on risks from occupational exposure to ionizing radiation. — provides dose histories to individual workers and organizations for work planning and for compensation and litigation cases. All information provided by the NDR, including dose histories, may be subject to confidentiality requirements. This document is aimed at national dose registries but may be also applicable to dosimetry services that provide data to national dose registries. NOTE Such a database or register on occupational radiation dose for different sectors will, among other reasons, allow to prepare the data necessary for more global surveys, such as those undertaken by the UNSCEAR and other databases such as IAEA’s Information System on Occupational Exposure in Medicine, Industry and Research (ISEMIR), Information System on Occupational Exposure (ISOE) and the European Platform for Occupational Radiation Exposure (ESOREX‑Platform). Presently, as the formats are different, the international description of national statistics is often incomplete or inaccurate, and in the end, the comparison of data is not established yet in many countries. This standard defines a common and easily shared format to collect reliable, traceable and directly comparable data on individual and collective exposure in activity sectors and occupations as defined in a common way. This document addresses: a) a common list of activity sectors and occupations, and b) a common and easily shared format about dose types and different values of interest concerning occupational exposure in order to collect consistent and directly comparable data on individual and collective exposure.

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.

This document applies to all passive neutron detectors that can be used within a personal dosemeter in part or in all of the above-mentioned neutron energy range. No distinction between the different techniques available in the marketplace is made in the description of the tests. Only generic distinctions, for instance, as disposable or reusable dosemeters, are considered. This document describes type tests only. Type tests are made to assess the basic characteristics of the dosimetry systems and are often ensured by recognized national laboratories This document does not present performance tests for characterizing the degradation induced by the following: — intrinsic temporal variability of the quality of the dosemeter supplied by the manufacturer; — intrinsic temporal variability of preparation treatments (before irradiation and/or before reading), if existing; — intrinsic temporal variability of reading process; — degradation due to environmental effects on the preparation treatments, if existing; — degradation due to environmental effects on the reading process. This document gives information for extremity dosimetry in the Annex C, based on recommendations given by ICRU Report 66. This document addresses only neutron personal monitoring and not criticality accident conditions. The links between this document and ISO 21909-2 are given in Annex A.

ISO 15382:2015 provides procedures for monitoring the dose to the skin, the extremities, and the lens of the eye. It gives guidance on how to decide if such dosemeters are needed and to ensure that individual monitoring is appropriate to the nature of the exposure, taking practical considerations into account. National regulations, if they exist, provide requirements that need to be followed. ISO 15382:2015 specifies procedures for individual monitoring of radiation exposure of the skin, extremities (hands, fingers, wrists, forearms, feet and ankles), and lens of the eye in planned exposure situations. It covers practices which involve a risk of exposure to photons in the range of 8 keV to 10 MeV and electrons and positrons in the range of 60 keV to 10 MeV. ISO 15382:2015 gives guidance for the design of a monitoring program to ensure compliance with legal individual dose limits. It refers to the appropriate operational dose quantities, and it gives guidance on the type and frequency of individual monitoring and the type and positioning of the dosemeter. Finally, different approaches to assess and analyse skin, extremity, and lens of the eye doses are given. It is not in the scope of this International Standard to consider exposure due to alpha or neutron radiation fields.

The quality of a supplier of a dosimetry service depends on both the characteristics of the approved (type‑tested) dosimetry system[1] and the training and experience of the staff, together with the calibration procedures and quality assurance programmes. This document specifies the criteria and the test procedures to be used for the periodic verification of the performance of dosimetry services supplying personal and/or area dosemeters. An area dosemeter can be a workplace dosemeter or an environmental dosemeter. The performance evaluation can be carried out as a part of the approval procedure for a dosimetry system or as an independent check to verify that a dosimetry service fulfils specified national or international type test performance requirements under representative exposure conditions that are expected or mimic workplace fields from the radiological activities being monitored. This document applies to personal and area dosemeters for the assessment of external photon radiation with a (fluence weighted) mean energy between 8 keV and 10 MeV, beta radiation with a (fluence weighted) mean energy between 60 keV and 1,2 MeV, and neutron radiation with a (fluence weighted) mean energy between 25,3 meV (i.e. thermal neutrons with a Maxwellian energy distribution with kT = 25,3 meV) and 200 MeV. It covers all types of personal and area dosemeters needing laboratory processing (e.g. thermoluminescent, optically stimulated luminescence, radiophotoluminescent, track detectors or photographic-film dosemeters) and involving continuous measurements or measurements repeated regularly at fixed time intervals (e.g. several weeks, one month). Active dosemeters (for dose measurement) may also be treated according to this document. Then, they should be treated as if they were passive (i.e. the dosimetry service reads their indicated values and reports them to the evaluation organization). [1] If this document is applied to a dosimetry system for which no approval (pattern or type test) has been provided, then in the following text approval or type test should be read as the technical data sheet provided by the manufacturer or as the data sheet required by the regulatory authority.

ISO 21909-1:2015 provides performance and test requirements for determining the acceptability of neutron dosimetry systems to be used for the measurement of personal dose equivalent, Hp(10), for neutrons ranging in energy from thermal to 20 MeV[1]. No distinction between the different techniques available in the market place is made in the description of the tests. Only generic distinctions, as disposable or reusable dosemeters for instance, are considered. This part of ISO 21909 gives information for extremity dosimetry, based on recommendations given by ICRU Report 66 in Annex A. [1] This maximal limit of the energy range is only an order of magnitude. The reference radiation fields used for the performance tests are those defined in ISO 8529-1. This means that the maximal energies could only be 14,8 MeV or 19 MeV. The present standard gives performance requirements to 14,8 MeV which is the typical neutron energy encountered for fusion. For fission spectra, the highest energies are around 20 MeV but the contribution to dose equivalent coming from neutrons with energy higher than 14,8 MeV is negligible.

ISO 21909:2005 provides performance and test requirements for determining the acceptability of personal neutron dosemeters to be used for the measurement of personal dose equivalent, Hp(10) for neutrons ranging in energy from thermal to 20 MeV.