ISO 19461-1:2018

INTERNATIONAL ISO
STANDARD 19461-1
First edition
2018-07
Radiological protection —
Measurement for the clearance
of waste contaminated with
radioisotopes for medical
application —
Part 1:
Measurement of radioactivity
Radioprotection — Mesurage pour la libération des déchets
contaminés par des radioisotopes lors des applications médicales —
Partie 1: Mesurage de la radioactivité
Reference number
©
ISO 2018
© ISO 2018
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ii © ISO 2018 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Fundamentals . 2
4.1 Radioisotopes for medical application . 2
4.1.1 General. 2
4.1.2 Nuclear medicine . 3
4.1.3 Radiation therapy . . . 3
4.2 Application of clearance level . 4
4.3 Classification and characteristics of radioactive waste. 5
5 Measurement method and procedure . 5
5.1 General . 5
5.2 Procedure for I. 6
5.3 Procedure for other radionuclides. 6
6 Requirements . 7
6.1 Control of the radioactive waste to be stored for disposal. 7
6.2 Measurement before storage . 7
6.3 Storage of radioactive waste . 7
6.4 Disposal method . 7
7 Uncertainty . 8
8 Documentation of radioactivity measurement results . 8
9 Reporting of results . 8
10 Quality control . 9
Annex A (informative) Example of the procedure for the clearance of radioactive waste .10
Annex B (informative) Measurement result of the radioactivity of the radioactive waste .14
Bibliography .18
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
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electrotechnical standardization.
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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
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This document was prepared by Technical Committee ISO/TC 85, Nuclear energy nuclear technologies
and radiological protection, Subcommittee SC 2, Radiation protection.
A list of all the parts in the ISO 19461 series can be found on the ISO website.
iv © ISO 2018 – All rights reserved

Introduction
This document addresses the method for radioactivity measurement, the procedure for determining the
storage period, the condition for the clearance of waste contaminated with radioisotopes for medical
application based on the initial condition of each type of waste, and the equation to obtain radioactivity
from counting measurements using a detector. From the equation, the appropriate duration of storage
for the radioactive waste before final disposal can be evaluated.
The amounts of radioisotopes used in medical facilities that are disposed of as waste have been
increasing rapidly, due to the development of various technologies applied to diagnosis and radiation
treatment using nuclear medicine.
Most of the nuclear medicine applications employ radioisotopes with a short half-life, such as F being
99m
used in positron emission tomography/computed tomography (PET/CT) diagnosis and Tc being
used for a bone or thyroid scan. However, the quantities used in the medical facility can be so large that
the disposal of the consequent radioactive waste becomes a serious concern.
The International Atomic Energy Agency (IAEA) proposed criteria for the clearance level of radioactive
waste depending on the individual dose (10 μSv/y) and collective dose (1 man-Sv/y) (IAEA Safety Series
[10] [11]
No 111-P-1.1) , and concentration of each nuclide (IAEA RS-G-1.7) , and methods for determining
the clearance level from the criteria by evaluating the dose or concentration of the radioactive waste on
a case-by-case basis.
However, the practical application of the IAEA methods is so complicated that most countries use an
alternative method to determine the minimum storage time based on the measurement of radioactivity
and radioactive decay for the mainly short-lived radioactive wastes instead of the direct application of
IAEA criteria. Therefore, the measurement of radioactivity becomes more significant for obtaining an
accurate minimum storage time for each radioactive waste before its disposal.
By considering the current situation regarding the clearance level, this document proposes radioactivity
measurement methods useful for establishing the minimum storage duration necessary to attain the
applicable clearance level for radioactive wastes, and for verifying wastes have decayed to below the
applicable clearance level prior to disposal as non-radioactive waste.
The medical administration of radioactive material is carefully controlled. Therefore, in most cases
an estimate of initial activity in waste, sufficient for calculating the minimum storage time for decay
to clearance levels, can be derived from knowledge of the administration process, and no initial
measurement is necessary or warranted. In such cases the method described in 5.3 can be used to
estimate the appropriate storage time.
INTERNATIONAL STANDARD ISO 19461-1:2018(E)
Radiological protection — Measurement for the clearance
of waste contaminated with radioisotopes for medical
application —
Part 1:
Measurement of radioactivity
1 Scope
This document establishes a method for radioactivity measurement and determination of the storage
periods of the radioactive wastes produced as a result of the medical application of radioisotopes based
on counting measurements using a detector and decay correction of the initial activity concentration of
the radioisotopes contained in the waste stream.
It provides a set of controls and measurements for the self-clearance of the radioactive wastes by which
the medical facility can be assured of meeting the clearance level.
This document can also be used by testing laboratories or radioactive waste disposal operators.
This document can also be useful for the guidance of the regulatory body.
NOTE Due to the nature of the tests outlined, this document cannot be applied to pure beta emitting nuclides
nor to alpha emitting nuclides with low energy gamma rays.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
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 https: //www .iso .org/obp
— IEC Electropedia: available at http: //www .electropedia .org/
3.1
activity
number of spontaneous nuclear disintegrations per unit time.
Note 1 to entry: The activity is expressed in becquerels (Bq).
3.2
bulk
anything greater than the amount of moderate quantities
Note 1 to entry: The term of moderate quantities indicates quantities that “are at most on the order of a ton” of
material.
3.3
calibration
set of operations that establishes, under specific conditions, the relationship between values of a
quantity and the corresponding values traceable to primary standards
3.4
certified reference material
CRM
reference material characterized by a metrologically valid procedure for one or more specified
properties, accompanied by a certificate that provides the value of the specified property, its associated
uncertainty, and a statement of metrological traceability
3.5
clearance level
value established by the competent authority, expressed in terms of activity, activity concentration
or surface contamination (fixed and non-fixed) at or below which radioactive material or radioactive
objects within authorized practice may be removed from any further regulatory control by the
regulatory body
3.6
decay
spontaneous transformation of one radioisotope into one or more different isotopes (known as “decay
products” or “daughter products”), accompanied by a d
...