Radiation protection -- Sealed sources -- Leakage test methods

This document specifies the different leakage test methods for sealed sources. It gives a comprehensive set of procedures using radioactive and non-radioactive means. This document applies to the following situations: — leakage testing of test sources following design classification testing in accordance with ISO 2919[1]; — production quality control testing of sealed sources; — periodic inspections of the sealed sources performed at regular intervals, during the working life. Annex A of this document gives guidance to the user in the choice of the most suitable method(s) according to situation and source type. It is recognized that there can be circumstances where special tests, not described in this document, are required. It is emphasized, however, that insofar as production, use, storage and transport of sealed radioactive sources are concerned, compliance with this document is no substitute for complying with the requirements of the relevant IAEA regulations[17] and other relevant national regulations. It is also recognized that countries can enact statutory regulations which specify exemptions for tests, according to sealed source type, design, working environment, and activity (e.g., for very low activity reference sources where the total activity is less than the leakage test limit).

Radioprotection -- Sources scellées -- Méthodes d’essai d’étanchéité

Le présent document spécifie les différentes méthodes d'essai d'étanchéité pour les sources scellées. Il propose un ensemble complet de modes opératoires utilisant des moyens radioactifs et non radioactifs. Le présent document s'applique aux situations suivantes: — essais d'étanchéité de sources d'essai suivant les essais de classification théorique selon l'ISO 2919[1]; — essais de contrôle de la qualité de production de sources scellées; — contrôles périodiques des sources scellées effectués ŕ intervalles réguliers pendant la durée de vie en service. L'Annexe A du présent document donne des recommandations ŕ l'utilisateur dans le choix de la ou des méthodes les plus appropriées en fonction de la situation et du type de source. Il est admis que, dans certaines circonstances, des essais spéciaux non décrits dans le présent document sont nécessaires. Il faut souligner cependant que, dans la mesure oů la production, l'utilisation, le stockage et le transport des sources radioactives scellées sont concernés, la conformité au présent document ne peut se substituer aux exigences des rčglementations de l'AIEA[17] et d'autres rčglementations nationales pertinentes. Il est reconnu également que les pays peuvent édicter des rčglementations qui spécifient des exemptions aux essais, en fonction du type de source scellée, de la conception, de l'environnement de travail et de l'activité (par exemple, pour les sources étalons de trčs faible activité dont l'activité totale est inférieure ŕ la limite de l'essai d'étanchéité).

General Information

Status
Published
Publication Date
02-Jul-2020
Current Stage
5060 - Close of voting Proof returned by Secretariat
Start Date
04-Jun-2020
Completion Date
03-Jun-2020
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INTERNATIONAL ISO
STANDARD 9978
Second edition
2020-07
Radiation protection — Sealed sources
— Leakage test methods
Radioprotection — Sources scellées — Méthodes d’essai d’étanchéité
Reference number
ISO 9978:2020(E)
ISO 2020
---------------------- Page: 1 ----------------------
ISO 9978:2020(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2020

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 2020 – All rights reserved
---------------------- Page: 2 ----------------------
ISO 9978:2020(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction ................................................................................................................................................................................................................................vi

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Requirements .......................................................................................................................................................................................................... 3

5 Test methods by radioactive means ................................................................................................................................................. 5

5.1 Immersion tests ..................................................................................................................................................................................... 5

5.1.1 Immersion test (hot liquid) .................................................................................................................................... 5

5.1.2 Immersion test (boiling liquid) ........................................................................................................................... 5

5.1.3 Immersion test with a liquid scintillator .................................................................................................... 6

5.1.4 Immersion test at room temperature ............................................................................................................ 6

5.1.5 Acceptance criteria ........................................................................................................................................................ 6

5.2 Gaseous emanation tests ................................................................................................................................................................ 6

5.2.1 Gaseous emanation test by absorption (for radium-226 sealed sources) ..................... 6

5.2.2 Gaseous emanation test by immersion with a liquid scintillator (for

radium-226 sealed sources) .................................................................................................................................. 6

5.2.3 Gaseous emanation test (for krypton-85 sealed sources) ........................................................... 6

5.2.4 Other gaseous emanation tests ........................................................................................................................... 7

5.2.5 Acceptance criteria ........................................................................................................................................................ 7

5.3 Wipe tests .................................................................................................................................................................................................... 7

5.3.1 Wet wipe test .................. .................................................... ................................................................................................. 7

5.3.2 Dry wipe test ....................................................................................................................................................................... 7

5.3.3 Acceptance criteria ........................................................................................................................................................ 7

6 Test methods by volumetric means .................................................................................................................................................. 7

6.1 Helium mass spectrometer leakage tests ........................................................................................................................ 8

6.1.1 Helium test [equivalent to leak test type B6 in ISO 20485] ........................................................ 8

6.1.2 Helium pressurisation test [equivalent to leak test type B5 in ISO 20485] .................. 8

6.1.3 Acceptance criteria ........................................................................................................................................................ 9

6.2 Bubble leakage tests ........................................................................................................................................................................... 9

6.2.1 Vacuum bubble test [equivalent to immersion technique using vacuum in
[6] 9

EN 1593 ........................................................................................................................................... ...................................

6.2.2 Hot-liquid bubble test [equivalent to immersion technique using liquid at
[6]

elevated temperature in EN 1593 .............................................................................................................. 9

6.2.3 Gas pressurisation bubble test [equivalent to immersion technique using
[6]

pressurisation of the object in EN 1593 ............................................................................................... 9

6.2.4 Liquid nitrogen bubble test .................................................................................................................................10

6.2.5 Acceptance criteria .....................................................................................................................................................10

6.3 Water pressurisation test ...........................................................................................................................................................10

Annex A (informative) Guidance for the choice of the tests to be carried out according to

purpose and sealed source type ........................................................................................................................................................11

Bibliography .............................................................................................................................................................................................................................13

© ISO 2020 – All rights reserved iii
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ISO 9978:2020(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.

This second edition cancels and replaces the first edition (ISO 9978:1992), which has been technically

revised. The main changes compared to the previous edition are as follows:

— Clause 4: Revised to add text specifying factors to be considered in designing an effective leak

testing regime for a particular type of sealed source;

— Clause 4: Requirement added that personnel performing leak tests be appropriately trained and

qualified, informative reference to ISO 9712 added;

— Clause 4: Requirement added that measurement uncertainty shall be considered in sentencing non-

binary test results;

— Table 1 — “Threshold detection values and limiting values for different test methods” has been

revised for clarity;

— 5.1: Informative reference to suitable assay techniques for immersion test liquid samples added:

ISO 19361 and ISO 19581;
— 5.1.1, 5.1.2, 5.1.4: Composition of suitable immersion test liquids clarified;

— 5.3: Informative reference to suitable wipe testing techniques (ISO 7503-2) added and clarification

that acceptance criteria is absolute without correction for wiping efficiency required;

— 6.1: Normative reference to ISO 20485 added for methods of helium leak testing and calculation of

acceptance limits;

— 6.2: Cautionary text added to state that efficacy of tests assume ideal conditions for vision of bubbles;

— 6.2.1: Cautionary text added regarding bubble testing of self-heated sources;
iv © ISO 2020 – All rights reserved
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ISO 9978:2020(E)
— A.1: Text expanded to clarify which tests to use under given circumstances.
© ISO 2020 – All rights reserved v
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ISO 9978:2020(E)
Introduction

The use of sealed sources has become so widespread that standards to guide the user, manufacturer

and regulatory agencies are necessary. When establishing these standards, radiation protection is the

prime consideration.

The purpose of this document, in conjunction with ISO 2919, is to minimise the risk to the public caused

by leakage of radioactive material into the general environment.

Leakage test methods for sealed sources were standardised in the first edition of this document. The

experience acquired since this date has necessitated the revision of this document.

vi © ISO 2020 – All rights reserved
---------------------- Page: 6 ----------------------
INTERNATIONAL STANDARD ISO 9978:2020(E)
Radiation protection — Sealed sources — Leakage test
methods
1 Scope

This document specifies the different leakage test methods for sealed sources. It gives a comprehensive

set of procedures using radioactive and non-radioactive means.
This document applies to the following situations:
[1]

— leakage testing of test sources following design classification testing in accordance with ISO 2919 ;

— production quality control testing of sealed sources;

— periodic inspections of the sealed sources performed at regular intervals, during the working life.

Annex A of this document gives guidance to the user in the choice of the most suitable method(s)

according to situation and source type.

It is recognized that there can be circumstances where special tests, not described in this document,

are required.

It is emphasized, however, that insofar as production, use, storage and transport of sealed radioactive

sources are concerned, compliance with this document is no substitute for complying with the

[17]

requirements of the relevant IAEA regulations and other relevant national regulations. It is also

recognized that countries can enact statutory regulations which specify exemptions for tests, according

to sealed source type, design, working environment, and activity (e.g., for very low activity reference

sources where the total activity is less than the leakage test limit).
2 Normative references

The following documents are referred to in the text in such a way that some or all of their content

constitutes 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 20485:2017, Non-destructive testing — Leak testing — Tracer gas method
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
capsule
protective envelope, used to prevent leakage of radioactive material
© ISO 2020 – All rights reserved 1
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ISO 9978:2020(E)
3.2
dummy sealed source

facsimile of a sealed source, the capsule of which has the same construction and is made with exactly the

same materials as those of the sealed source that it represents, but containing, in place of the radioactive

material, a substance resembling it as closely as is practical in physical and chemical properties

3.3
leachable

soluble in water, yielding quantities greater than 0,1 mg/g in 100 ml of still water maintained

at 50 °C for 4 h
3.4
leakage

transfer of contained radioactive material from the sealed source to the environment

3.5
leaktight

term applied to sealed sources which, after undergoing leakage testing, meet the acceptance criteria

Note 1 to entry: The acceptance criteria are given in Table 1.
3.6
model designation

manufacturer’s unique term (number, code or a combination of these) which is used to identify a specific

design of sealed source
3.7
non-destructive test

test used to detect internal, surface and concealed defects or imperfections in materials, using

techniques that do not damage or destroy the items being tested
3.8
non-leachable

insoluble in water, yielding quantities less than 0,1 mg/g in 100 ml of still water maintained at 50 °C for 4 h

3.9
sealed source

radioactive material sealed in a capsule or associated with a material to which it is closely bonded, this

capsule or bonding material being strong enough to maintain leaktightness of the sealed source under

the conditions of use and wear for which it was designed
3.10
simulated sealed source

facsimile of a sealed source, the capsule of which has the same construction and is made with exactly the

same materials as those of the sealed source that it represents but it contains, in place of the radioactive

material, a substance resembling it as closely as possible in physical and chemical properties and trace

quantities of radioactive material

Note 1 to entry: The tracer is in a form soluble in a solvent which does not attack the capsule and has the maximum

activity compatible with its use in a containment enclosure.
3.11
standard helium leakage rate
5 3 3

helium leakage rate at an upstream pressure of 10 Pa ± 5 × 10 Pa and a downstream pressure of 10 Pa

or less at a temperature of 296 K ± 7 K (23 °C ± 7 °C)

Note 1 to entry: In this document, the unit Pascal cubic meter per second is used .

−6 3 −l 3 −1 −5 3 −1 −5 −1 −3

1) [1 × 10 Pa·m · s = 1 µPa·m ·s ≈ 10 atm·cm ·s ≈ 1 × 10 mbar·l·s ≈ 7, 5 × 10 lusec.]

2 © ISO 2020 – All rights reserved
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ISO 9978:2020(E)
3.12
test source

sample used in the performance tests, having the same material and construction as sealed sources of

the model for which classification is being established

Note 1 to entry: A test source may be a simulated sealed source, a dummy sealed source or production source.

Note 2 to entry: The performance tests are described in ISO 2919.
4 Requirements

The tests described in this document are all designed to test and verify that the sealed source is

leaktight. However not all tests are applicable in all circumstances. Correct application and choice of

test method and testing media is critically important in designing an effective leak test programme.

Factors to be considered include:
— the chemical form of the active material if leak test is by radioactive means;
— the type of test liquid used in immersion tests;
— the number of encapsulations;
— the internal void volume when tests are carried out by volumetric means;
— the temperature of the sealed source;

— the suitability of the test method for the environment in which it is being performed;

— the reason for performing the test (integrity testing of a test source, production leakage tests,

routine in service testing);
— the required sensitivity and acceptance criteria.

The test programme for test and production sealed sources should be considered as part of the design

process and validated or justified as appropriate to demonstrate its effectiveness and sensitivity. This

process may include the analysis of historic data.

The tests described in this document shall be designed, validated and carried out by competent and

qualified persons who have demonstrable appropriate training in the applied test methods. For test

methods by radioactive means, the persons shall also have appropriate training in radiation protection

and measurement.

NOTE 1 Qualification and certification methods for non-destructive testing personnel can be found in

[2]
ISO 9712 .

An evaluation should be made of uncertainty in the case of non-binary test results (e.g. radiation

measurements on immersion test samples) and taken account of in sentencing the result.

Guidance for choosing suitable tests are specified in Annex A.

According to the test type and the sealed source type, at least one of each of the tests described

in Clauses 5 and 6 should be carried out [see Annex A for the choice of the test(s)].

It should be noted that it is best practice to carry out more than one type of leakage test and also to

perform a final wipe as a contamination check.

The tests described in this document do not form an exhaustive list, and other test methods may be

developed. However, in the case where a special test, which is not described in this document, is carried

out (see Clause 1), the organisation shall validate that the applied method is at least as effective as

the corresponding method(s) given in this document in order to be able to claim compliance with this

document.
© ISO 2020 – All rights reserved 3
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ISO 9978:2020(E)

At the conclusion of the performed test(s), the sealed source shall be considered to be leaktight if it

complies with the acceptance criteria specified in Table 1.

It has been asserted that there is correspondence between the acceptance criteria for volumetric and

radioactive leak tests. Whilst there is no universally accepted basis for this assertion, experience has

shown that sources meeting the acceptance criteria shown in Table 1 have not subsequently been found

to leak.
3 −1 3 −1

NOTE 2 A leakage rate of 10 µPa · m · s for non-leachable solid contents and a rate of 0,1 µPa · m · s for

leachable solids and liquids was historically considered to be equivalent to the activity release limit of 2 000 Bq

[18]
(≈50 nCi) .

NOTE 3 A further confirmation of the volumetric acceptance threshold is given by Reference [8]. A leakage

−7 3 −1

rate of 10 atm · cm · s or more based on dry air at 298 K (25 °C) and for a pressure difference of 1 atm against

a vacuum of 10 atm (equivalent to or less) is considered to represent a loss of leaktightness, irrespective of the

physical nature of the content.

Table 1 — Threshold detection values and limiting values for different test methods

Acceptance criteria
Test method Subclause Threshold of detection
Non-leachable Leachable or
content gaseous content
Radioactive methods
Immersion test (hot liquid) 5.1.1 (10 to 1) Bq <200 Bq <200 Bq
Immersion test (boiling
5.1.2 (10 to 1) Bq <200 Bq <200 Bq
liquid)
Immersion test with a
5.1.3 (10 to 1) Bq <200 Bq <200 Bq
liquid scintillator
Immersion test at room
5.1.4 (10 to 1) Bq <200 Bq <200 Bq
temperature
<200 Bq
Gaseous emanation test 5.2.1 (4 à 0,4) Bq Unsuitable
222
( Rn/12 h)
Emanation test with a <200 Bq
5.2.2 (0,4 to 0,004) Bq Unsuitable
222
liquid scintillator ( Rn/12 h)
Gaseous emanation test
<4 000 Bq
(for krypton-85 sealed 5.2.3 (10 to 1) Bq Unsuitable
( Kr/24 h)
sources)
Wet wipe test 5.3.1 (10 to 1) Bq <200 Bq <200 Bq
Dry wipe test 5.3.2 (10 to 1) Bq <200 Bq <200 Bq
Non-radioactive methods – Helium tests Standard helium leakage rate
−2 −4
Helium test (10 to 10 )
3 −1 3 −1
6.1.1 <1 µPa · m · s <0,01 µPa · m · s
3 −1
(He filling before sealing) µPa · m · s
Helium pressurisation test
−2 3 −1 3 −1 3 −1
6.1.2 (1 to 10 ) µPa · m · s <1 µPa · m · s <0,01 µPa · m · s
(He bombing after sealing)

Non-radioactive methods – Bubble tests Corresponding standard helium leakage rate

No bubbles
3 −1b
Vacuum bubble test 6.2.1 (10 to 1) µPa · m · s Not sensitive enough
observed
Not sensitive
3 −1b
Hot-liquid bubble test 6.2.2 (50 to 5) µPa · m · s Not sensitive enough
enough

The threshold of detection is expressed as a range; its upper end defines the smallest detectable leak under typical,

well controlled industrial leak testing conditions and its lower end indicates the smallest detectable leak under excellent

(ideal) industrial leak testing conditions. Smaller leaks than those indicated can be detected under laboratory conditions.

Threshold values shown for bubble tests are rough approximations of the corresponding standard helium leakage

rates and are applicable only to single leaks under favourable visual conditions.

4 © ISO 2020 – All rights reserved
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ISO 9978:2020(E)
Table 1 (continued)
Acceptance criteria
Test method Subclause Threshold of detection
Non-leachable Leachable or
content gaseous content
No bubbles
3 −1b
Gas pressurisation bubble test 6.2.3 (10 to 1) µPa · m · s Not sensitive enough
observed
−1 −2
(10 to 10 ) No bubbles No bubbles
Liquid nitrogen bubble test 6.2.4
3 −1b
µPa · m · s observed observed
Non-radioactive methods – Mass gain Mass gain of water [µg]
Water pressurisation test 6.3 10 Mass gain < 50 Not sensitive enough

The threshold of detection is expressed as a range; its upper end defines the smallest detectable leak under typical,

well controlled industrial leak testing conditions and its lower end indicates the smallest detectable leak under excellent

(ideal) industrial leak testing conditions. Smaller leaks than those indicated can be detected under laboratory conditions.

Threshold values shown for bubble tests are rough approximations of the corresponding standard helium leakage

rates and are applicable only to single leaks under favourable visual conditions.

Prior to undergoing the following leakage tests the source shall be subject to a thorough visual

examination. The source may have to be cleaned to facilitate this. Any cleaning method should avoid the

blocking of any potential leakage path for subsequent tests.
All equipment used for tests shall be suitably maintained and calibrated.

The wipe test should only be considered as a leakage test for some specific types of sources (e.g. sources

with very thin windows such as foils for smoke detectors), for periodic inspections and in cases where

no other test is more suitable.

Wipe tests or liquid immersion test samples should, wherever possible, be checked immediately on

basic contamination measuring equipment; for example, a Geiger counter to establish whether there is

any gross contamination prior to final measurement on more sophisticated calibrated equipment.

5 Test methods by radioactive means
5.1 Immersion tests

NOTE Suitable assay techniques for evaluation of the activity in the test liquids for all of these immersion

[3] [4]
tests may be found in ISO 19361 and ISO 19581 .
5.1.1 Immersion test (hot liquid)

Immerse the sealed source in a liquid which does not attack the material of the outer surfaces of the

source and which, under the conditions of this test, is considered effective for detection of a leak.

Examples of such liquids include distilled water, weak detergent solutions or chelation agents and

also slightly alkaline or acid solutions with concentrations of about 5 %. Heat the liquid to 323 K ± 5 K

(50 °C ± 5 °C) and maintain it at that temperature for at least 4 h. Remove the sealed source and

measure the activity of the liquid. If a group of more than one source is tested at the same time in the

liquid sample, the acceptance criteria for a single source shall be used for the group as all the activity in

the liquid sample could be originating from a single leaking source. Further testing shall be performed

in such cases on smaller groups, or individual sources, in order to identify the leaking source and

positively confirm leak tightness of other sources in the group.

An ultrasonic cleaning method can also be used. In this case, the immersion time in the liquid

at 343 K ± 5 K (70 °C ± 5 °C) can be reduced to approximately 30 min.
5.1.2 Immersion test (boiling liquid)

Immerse the sealed source in a liquid which does not attack the material of the outer surfaces of the

source and which, under the conditions of this test, is considered effective for detection of a leak.

© ISO 2020 – All rights reserved 5
---------------------- Page: 11 ----------------------
ISO 9978:2020(E)

Examples of such liquids include distilled water, weak detergent solutions or chelation agents and

also slightly alkaline or acid solutions with concentrations of about 5 %. Boil for 10 min, allow to cool,

then rinse the sealed source in a fresh batch of liquid. Repeat these operations twice, re-immersing the

source in the original liquid. Remove the sealed source and measure the activity of the original liquid. If

a group of more than one source is tested at the same time in the liquid sample, the acceptance criteria

for a single source shall be used for the group as all the activity in the liquid sample could be originating

from a single leaking source. Further testing shall be performed in such cases on smaller groups, or

individual sources, in order to identify the leaking source and positively confirm leak tightness of other

sources in the group.
5.1.3 Immersion test with a liquid scintillator

Immerse the sealed source for at least 3 h at room temperature in a liquid scintillator solution that

does not attack the material of the outer surface of the source. Store away from light to avoid

photoluminescence. Remove the sealed source and measure the activity of the liquid by a liquid

scintillation counting technique.
5.1.4 Immersion test at room temperature

Immerse the sealed source in a liquid which does not attack the material of the outer surfaces of the

source and which, under the conditions of this test, is considered effective for detection of a leak.

Examples of such liquids include distilled water, weak detergent solutions or chelation agents and

also slightly alkaline or acid solutions with concentrations of about 5 %. After a period of at least 24 h,

remove the sealed source and measure the activity of the liquid. If a group of more than one source is

tested at the same time in the liquid sample, the acceptance criteria for a single source shall be used

for the group as all the activity in the liquid sample could be originating from a single leaking source.

Further testing shall be performed in such cases on smaller groups, or individual sources, in order to

identify the leaking source and positively confirm leak tightness of other sources in the group.

...

NORME ISO
INTERNATIONALE 9978
Deuxième édition
2020-07
Radioprotection — Sources scellées —
Méthodes d’essai d’étanchéité
Radiation protection — Sealed sources — Leakage test methods
Numéro de référence
ISO 9978:2020(F)
ISO 2020
---------------------- Page: 1 ----------------------
ISO 9978:2020(F)
DOCUMENT PROTÉGÉ PAR COPYRIGHT
© ISO 2020

Tous droits réservés. Sauf prescription différente ou nécessité dans le contexte de sa mise en œuvre, aucune partie de cette

publication ne peut être reproduite ni utilisée sous quelque forme que ce soit et par aucun procédé, électronique ou mécanique,

y compris la photocopie, ou la diffusion sur l’internet ou sur un intranet, sans autorisation écrite préalable. Une autorisation peut

être demandée à l’ISO à l’adresse ci-après ou au comité membre de l’ISO dans le pays du demandeur.

ISO copyright office
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Publié en Suisse
ii © ISO 2020 – Tous droits réservés
---------------------- Page: 2 ----------------------
ISO 9978:2020(F)
Sommaire Page

Avant-propos ..............................................................................................................................................................................................................................iv

Introduction ................................................................................................................................................................................................................................vi

1 Domaine d’application ................................................................................................................................................................................... 1

2 Références normatives ................................................................................................................................................................................... 1

3 Termes et définitions ....................................................................................................................................................................................... 1

4 Exigences ...................................................................................................................................................................................................................... 3

5 Méthodes d’essai par des moyens radioactifs ........................................................................................................................ 6

5.1 Essais par immersion ........................................................................................................................................................................ 6

5.1.1 Essai par immersion (liquide chaud) ............................................................................................................. 6

5.1.2 Essai par immersion (liquide bouillant) ..................................................................................................... 6

5.1.3 Essai par immersion avec scintillateur liquide ...................................................................................... 6

5.1.4 Essai par immersion à température ambiante ...................................................................................... 6

5.1.5 Critères d’acceptation ........................................................................................................................................... ....... 7

5.2 Essais d’émanation gazeuse ........................................................................................................................................................ 7

5.2.1 Essai d’émanation gazeuse par absorption (pour sources scellées de

radium-226) .................. ......................................................................................................................... .............................. 7

5.2.2 Essai d’émanation gazeuse par immersion dans un scintillateur liquide

(pour sources scellées de radium-226) ....................................................................................................... 7

5.2.3 Essai d’émanation gazeuse (pour sources scellées de krypton-85) .................................... 7

5.2.4 Autres essais d’émanation gazeuse ................................................................................................................. 7

5.2.5 Critères d’acceptation ........................................................................................................................................... ....... 7

5.3 Essais par frottis .................................................................................................................................................................................... 7

5.3.1 Essai par frottis humide ............................................................................................................................................ 7

5.3.2 Essai par frottis sec ........................................................................................................................................................ 8

5.3.3 Critères d’acceptation ........................................................................................................................................... ....... 8

6 Méthodes d’essai par des moyens volumétriques ............................................................................................................. 8

6.1 Essais d’étanchéité au spectromètre de masse à hélium .................................................................................... 8

6.1.1 Essai à l’hélium [équivalent au type d’essai d’étanchéité B6 de l’ISO 20485] ............ 9

6.1.2 Essai de pressurisation à l’hélium [équivalent au type d’essai d’étanchéité

B5 de l’ISO 20485] .......................................................................................................................................................... 9

6.1.3 Critères d’acceptation ........................................................................................................................................... ....... 9

6.2 Essais d’étanchéité par bullage ................................................................................................................................................. 9

6.2.1 Essai de bullage à vide (équivalent à la technique d’immersion utilisant
[6]

le vide de l’EN 1593 ) ...........................................................................................................................................10

6.2.2 Essai de bullage dans un liquide chaud (équivalent à la technique
[6]

d’immersion utilisant le liquide à haute température de l’EN 1593 ) .......................10

6.2.3 Essai de bullage sous gaz pressurisé (équivalent à la technique
[6]

d’immersion utilisant la pressurisation de l’objet de l’EN 1593 ) ................................10

6.2.4 Essai de bullage dans l’azote liquide ...........................................................................................................10

6.2.5 Critères d’acceptation ........................................................................................................................................... ....10

6.3 Essai de pressurisation à l’eau ...............................................................................................................................................11

Annexe A (informative) Recommandations pour le choix des essais à effectuer en fonction

de l’objectif et du type de source scellée ..................................................................................................................................12

Bibliographie ...........................................................................................................................................................................................................................14

© ISO 2020 – Tous droits réservés iii
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ISO 9978:2020(F)
Avant-propos

L’ISO (Organisation internationale de normalisation) est une fédération mondiale d’organismes

nationaux de normalisation (comités membres de l’ISO). L’élaboration des Normes internationales est

en général confiée aux comités techniques de l’ISO. Chaque comité membre intéressé par une étude

a le droit de faire partie du comité technique créé à cet effet. Les organisations internationales,

gouvernementales et non gouvernementales, en liaison avec l’ISO participent également aux travaux.

L’ISO collabore étroitement avec la Commission électrotechnique internationale (IEC) en ce qui

concerne la normalisation électrotechnique.

Les procédures utilisées pour élaborer le présent document et celles destinées à sa mise à jour sont

décrites dans les Directives ISO/IEC, Partie 1. Il convient, en particulier de prendre note des différents

critères d’approbation requis pour les différents types de documents ISO. Le présent document a été

rédigé conformément aux règles de rédaction données dans les Directives ISO/IEC, Partie 2 (voir www

.iso .org/ directives).

L’attention est attirée sur le fait que certains des éléments du présent document peuvent faire l’objet de

droits de propriété intellectuelle ou de droits analogues. L’ISO ne saurait être tenue pour responsable

de ne pas avoir identifié de tels droits de propriété et averti de leur existence. Les détails concernant

les références aux droits de propriété intellectuelle ou autres droits analogues identifiés lors de

l’élaboration du document sont indiqués dans l’Introduction et/ou dans la liste des déclarations de

brevets reçues par l’ISO (voir www .iso .org/ brevets).

Les appellations commerciales éventuellement mentionnées dans le présent document sont données

pour information, par souci de commodité, à l’intention des utilisateurs et ne sauraient constituer un

engagement.

Pour une explication de la nature volontaire des normes, la signification des termes et expressions

spécifiques de l’ISO liés à l’évaluation de la conformité, ou pour toute information au sujet de l’adhésion

de l’ISO aux principes de l’Organisation mondiale du commerce (OMC) concernant les obstacles

techniques au commerce (OTC), voir le lien suivant: www .iso .org/ iso/ fr/ avant -propos.

Le présent document a été élaboré par le comité technique ISO/TC 85, Énergie nucléaire, technologies

nucléaires, et radioprotection, sous-comité SC 2, Radioprotection.

Cette deuxième édition annule et remplace la première édition (ISO 9978:1992), qui a fait l’objet d’une

révision technique. Les principales modifications par rapport à l’édition précédente sont les suivantes:

— Article 4: révision pour ajouter un texte spécifiant les facteurs à prendre en compte dans la

conception d’un régime d’essai d’étanchéité efficace pour un type particulier de source scellée;

— Article 4: ajout d’une exigence imposant que le personnel procédant aux essais d’étanchéité soit

formé et qualifié de manière appropriée, ajout d’une référence informative à l’ISO 9712;

— Article 4: ajout d’une exigence stipulant que l’incertitude de mesure doit être prise en compte dans

l’expression des résultats d’essais non binaires;

— Tableau 1 — révision des «valeurs de seuil de détection et valeurs limites pour différentes méthodes

d’essai» pour plus de clarté;

— 5.1: ajout de références informatives relatives aux techniques d’analyse adaptées pour les

échantillons pour essais par immersion dans un liquide: ISO 19361 et ISO 19581;

— 5.1.1, 5.1.2, 5.1.4: clarification de la composition des liquides appropriés pour essai par immersion;

— 5.3: ajout d’une référence informative relative aux techniques d’essai par frottis adaptées

(ISO 7503-2) et exigence d’une clarification précisant que les critères d’acceptation sont absolus

sans nécessiter de correction pour l’efficacité du frottis;

— 6.1: ajout d’une référence normative à l’ISO 20485 relative aux méthodes d’essai d’étanchéité à

l’hélium et de calcul des limites d’acceptation;
iv © ISO 2020 – Tous droits réservés
---------------------- Page: 4 ----------------------
ISO 9978:2020(F)

— 6.2: ajout d’un texte d’avertissement indiquant que l’efficacité des essais présume des conditions

idéales de visibilité des bulles;

— 6.2.1: ajout d’un texte d’avertissement concernant les essais de bullage de sources autochauffantes;

— A.1: ajout d’informations au texte pour clarifier les essais à utiliser dans des circonstances données.

© ISO 2020 – Tous droits réservés v
---------------------- Page: 5 ----------------------
ISO 9978:2020(F)
Introduction

L’utilisation des sources scellées est devenue à ce point répandue qu’il a été nécessaire d’élaborer des

normes pour guider l’utilisateur, le fabricant et les autorités règlementaires. Dans l’élaboration de ces

normes, la radioprotection est considérée comme primordiale.

En conjonction avec l’ISO 2919, l’objet du présent document est de réduire le plus possible le risque pour

le public causé par une fuite de matière radioactive dans l’environnement général.

Les méthodes d’essai d’étanchéité pour les sources scellées ont été normalisées dans la première

édition du présent document. L’expérience acquise depuis cette date a nécessité la révision du présent

document.
vi © ISO 2020 – Tous droits réservés
---------------------- Page: 6 ----------------------
NORME INTERNATIONALE ISO 9978:2020(F)
Radioprotection — Sources scellées — Méthodes d’essai
d’étanchéité
1 Domaine d’application

Le présent document spécifie les différentes méthodes d’essai d’étanchéité pour les sources scellées.

Il propose un ensemble complet de modes opératoires utilisant des moyens radioactifs et non radioactifs.

Le présent document s’applique aux situations suivantes:
[1]

— essais d’étanchéité de sources d’essai suivant les essais de classification théorique selon l’ISO 2919 ;

— essais de contrôle de la qualité de production de sources scellées;

— contrôles périodiques des sources scellées effectués à intervalles réguliers pendant la durée de vie

en service.

L’Annexe A du présent document donne des recommandations à l’utilisateur dans le choix de la ou des

méthodes les plus appropriées en fonction de la situation et du type de source.

Il est admis que, dans certaines circonstances, des essais spéciaux non décrits dans le présent document

sont nécessaires.

Il faut souligner cependant que, dans la mesure où la production, l’utilisation, le stockage et le

transport des sources radioactives scellées sont concernés, la conformité au présent document ne peut

[17]

se substituer aux exigences des règlementations de l’AIEA et d’autres règlementations nationales

pertinentes. Il est reconnu également que les pays peuvent édicter des règlementations qui spécifient

des exemptions aux essais, en fonction du type de source scellée, de la conception, de l’environnement

de travail et de l’activité (par exemple, pour les sources étalons de très faible activité dont l’activité

totale est inférieure à la limite de l’essai d’étanchéité).
2 Références normatives

Les documents suivants sont cités dans le texte de sorte qu’ils constituent, pour tout ou partie de leur

contenu, des exigences du présent document. Pour les références datées, seule l’édition citée s’applique.

Pour les références non datées, la dernière édition du document de référence s’applique (y compris les

éventuels amendements).

ISO 20485:2017, Essais non destructifs — Contrôle d'étanchéité — Méthode par gaz traceur

3 Termes et définitions

Pour les besoins du présent document, les termes et définitions suivants s’appliquent.

L’ISO et l’IEC tiennent à jour des bases de données terminologiques destinées à être utilisées en

normalisation, consultables aux adresses suivantes:

— ISO Online browsing platform: disponible à l'adresse https:// www .iso .org/ obp;

— IEC Electropedia: disponible à l'adresse http:// www .electropedia .org/ .
3.1
enveloppe
capsule protectrice utilisée pour empêcher toute fuite de matière radioactive
© ISO 2020 – Tous droits réservés 1
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ISO 9978:2020(F)
3.2
source scellée fictive

source scellée factice dont l'enveloppe est construite de la même manière et avec exactement les mêmes

matériaux que la source scellée qu'elle représente mais contenant, à la place de la matière radioactive,

une substance dont les propriétés physiques et chimiques sont aussi proches que possible de celles de la

matière radioactive
3.3
soluble

soluble dans l’eau, relâchant des quantités supérieures à 0,1 mg/l dans 100 ml d’eau plate maintenue

à 50 °C pendant 4 h
3.4
fuite

transfert de la matière radioactive contenue dans la source scellée vers l’environnement

3.5
étanche

terme appliqué aux sources radioactives scellées qui, après avoir subi des essais d’étanchéité, satisfont

aux critères d’acceptation
Note 1 à l'article: Les critères d’acceptation sont donnés dans le Tableau 1.
3.6
référence modèle

terme unique (nombre, code ou une combinaison de ceux-ci) propre au fabricant, permettant d’identifier

une conception donnée de source scellée
3.7
essai non destructif

essai destiné à détecter les défauts ou imperfections internes, superficiels et masqués dans les matériaux,

en utilisant des techniques qui n'endommagent pas et ne détruisent pas les éléments soumis à essai

3.8
non soluble

insoluble dans l’eau, relâchant des quantités inférieures à 0,1 mg/l dans 100 ml d’eau plate maintenue

à 50 °C pendant 4 h
3.9
source scellée

matière radioactive enfermée dans une enveloppe ou associée à un matériau auquel elle est intimement

liée, cette enveloppe ou ce matériau étant suffisamment résistants pour assurer l'étanchéité de la

source scellée dans les conditions d'emploi et d'utilisation pour lesquelles elle a été conçue

3.10
source scellée simulée

source scellée factice dont l'enveloppe est construite de la même manière et avec exactement les mêmes

matériaux que la source scellée qu'elle représente mais contenant, à la place de la matière radioactive,

une substance dont les propriétés physiques et chimiques sont aussi proches que possible de celles de la

matière radioactive ainsi que des traces de matière radioactive

Note 1 à l'article: L’élément traceur se présente sous forme soluble dans un solvant qui n’attaque pas l’enveloppe

et dont l’activité maximale est compatible avec son utilisation dans une enceinte de confinement.

2 © ISO 2020 – Tous droits réservés
---------------------- Page: 8 ----------------------
ISO 9978:2020(F)
3.11
taux de fuite d’hélium normalisé
5 3 3

taux de fuite d’hélium à une pression amont de 10 Pa ± 5 × 10 Pa et une pression aval de 10 Pa ou

moins à une température de 296 K ± 7 K (23 °C ± 7 °C)

Note 1 à l'article: Dans le présent document, l’unité Pascal-mètre cube par seconde est utilisée .

3.12
source d'essai

échantillon utilisé dans les essais de qualification, de matériaux et construction identiques aux sources

scellées du modèle pour lequel la classification est établie

Note 1 à l'article: Il peut s'agir d'une source scellée simulée, d'une source scellée fictive ou d'une source de

production.
Note 2 à l'article: Les essais de performance sont décrits dans l’ISO 2919.
4 Exigences

Les essais décrits dans le présent document sont tous conçus pour soumettre à l’essai les sources

scellées et contrôler qu’elles sont étanches. Cependant, tous les essais ne s’appliquent pas à toutes les

circonstances. La bonne application et le choix correct de méthodes et de supports d’essai sont d'une

importance critique pour la conception d’un programme efficace d’essais d’étanchéité. Les facteurs

dont il faut tenir compte incluent:

— la forme chimique de la matière active si l’essai d’étanchéité a lieu à l’aide de moyens radioactifs;

— le type de liquide d’essai utilisé dans les essais d’immersion;
— le nombre d’enveloppes;

— le volume de vide intérieur lorsque les essais sont effectués à l’aide de moyens volumétriques;

— la température de la source scellée;

— l’adaptation de la méthode d’essai à l’environnement dans lequel il est effectué;

— la raison de l’essai (essai d’intégrité d’une source d’essai, essais d’étanchéité de production, contrôles

périodiques pendant l’utilisation);
— la sensibilité exigée et les critères d’acceptation.

Il convient de considérer le programme d’essais pour les sources scellées d’essai et de production

comme faisant partie du processus de conception et de le valider ou le justifier comme étant approprié

pour démontrer son efficacité et sa sensibilité. Ce processus peut comprendre l’analyse de l’historique

des données.

Les essais décrits dans le présent document doivent être conçus, validés et exécutés par des personnes

compétentes et qualifiées qui peuvent démontrer qu’elles ont suivi une formation appropriée aux

méthodes d’essais appliquées. Pour les méthodes d’essai à l’aide de moyens radioactifs, les personnes

doivent également avoir suivi une formation appropriée à la radioprotection et aux mesures du

rayonnement.

NOTE 1 Des méthodes de qualification et de certification pour le personnel d’essais non destructifs sont

[2]
présentées dans l’ISO 9712 .

Il convient de procéder à une évaluation de l’incertitude dans le cas de résultats d’essais non binaires

(par exemple, mesurages de rayonnement sur des échantillons pour essais par immersion) et de la

prendre en compte dans l’expression des résultats.
−6 3 −l 3 −1 −5 3 −1 −5 −1 −3

1) [1 × 10 Pa·m · s = 1 µPa·m ·s ≈ 10 atm·cm ·s ≈ 1 × 10 mbar·l·s ≈ 7,5 × 10 lusec.]

© ISO 2020 – Tous droits réservés 3
---------------------- Page: 9 ----------------------
ISO 9978:2020(F)
Des recommandations pour le choix d’essais adaptés sont spécifiées à l’Annexe A.

En fonction du type d’essai et du type de source scellée, il convient d’exécuter au moins l’un des essais

décrits aux Articles 5 et 6 [voir l’Annexe A pour le choix du ou des essai(s)].

Il convient de noter que les bonnes pratiques consistent à exécuter plusieurs types d’essais d’étanchéité

ainsi qu’à effectuer un frottis final pour contrôle de non-pollution.

Les essais décrits dans le présent document ne constituent pas une liste exhaustive et d’autres

méthodes d’essai peuvent être développées. Cependant, dans le cas où un essai spécial non décrit dans

le présent document est exécuté (voir l’Article 1), pour pouvoir revendiquer la conformité au présent

document, l’organisation doit valider le fait que la méthode appliquée est au moins aussi efficace que la

ou les méthodes correspondantes données dans le présent document.

À la fin du ou des essais exécutés, la source scellée doit être considérée comme étanche si elle satisfait

aux critères d’acceptation spécifiés dans le Tableau 1.

Il a été vérifié qu'il existe une correspondance entre les critères d’acceptation pour les essais d’étanchéité

volumétriques et radioactifs. Bien que cette affirmation ne soit pas fondée sur des bases universellement

acceptées, l’expérience a montré que les sources ayant satisfait aux critères d’acceptation représentés

dans le Tableau 1 n’ont révélé aucune fuite par la suite.
3 −1

NOTE 2 Un taux de fuite de 10 µPa · m · s pour des contenus solides non lixivables et un débit

3 −1

de 0,1 µPa · m · s pour des solides et liquides solubles était historiquement considéré comme étant équivalent à

[18]
la limite de rejet d’activité de 2 000 Bq (≈50 nCi) .

NOTE 3 Une autre confirmation du seuil d’acceptation volumétrique est donnée par la Référence [8]. Un taux

−7 3 −1

de fuite de 10 atm · cm · s ou plus basé sur de l’air sec à 298 K (25 °C) et pour une différence de pression

de 1 atm contre un vide de 10 atm (équivalent ou inférieur) est considéré comme représentant une perte

d’étanchéité, quelle que soit la nature physique du contenu.

Tableau 1 — Valeurs de seuil de détection et valeurs limites pour différentes méthodes d’essai

Critères d’acceptation
Méthode d’essai Paragraphe Seuil de détection
Contenu Contenu soluble
non soluble ou gazeux
Méthodes radioactives
Essai par immersion
5.1.1 (10 à 1) Bq <200 Bq <200 Bq
(liquide chaud)
Essai par immersion
5.1.2 (10 à 1) Bq <200 Bq <200 Bq
(liquide bouillant)
Essai par immersion avec
5.1.3 (10 à 1) Bq <200 Bq <200 Bq
scintillateur liquide
Essai par immersion à
5.1.4 (10 à 1) Bq <200 Bq <200 Bq
température ambiante
<200 Bq
Essai d’émanation gazeuse 5.2.1 (4 à 0,4) Bq Inapproprié
222
( Rn/12 h)
Essai d’émanation avec <200 Bq
5.2.2 (0,4 à 0 004) Bq Inapproprié
222
scintillateur liquide ( Rn/12 h)
Essai d’émanation gazeuse
<4 000 Bq
(pour sources scellées de 5.2.3 (10 à 1) Bq Inapproprié
( Kr/24 h)
krypton-85)

Le seuil de détection est exprimé sous forme de plage, dont la limite supérieure définit la plus petite fuite détectable

dans des conditions d’essai d’étanchéité typiques, bien contrôlées et industrielles, et la limite inférieure indique la plus

petite fuite détectable dans des conditions d’essai d’étanchéité industrielles excellentes (idéales). Les fuites inférieures à

celles indiquées peuvent être détectées en conditions de laboratoire.

Les valeurs de seuil représentées pour les essais de bullage sont des approximations grossières des débits de fuite

d’hélium normalisés correspondants et sont applicables uniquement à des fuites uniques dans des conditions visuelles

favorables.
4 © ISO 2020 – Tous droits réservés
---------------------- Page: 10 ----------------------
ISO 9978:2020(F)
Tableau 1 (suite)
Critères d’acceptation
Méthode d’essai Paragraphe Seuil de détection
Contenu Contenu soluble
non soluble ou gazeux
Essai par frottis humide 5.3.1 (10 à 1) Bq <200 Bq <200 Bq
Essai par frottis sec 5.3.2 (10 à 1) Bq <200 Bq <200 Bq
Méthodes non radioactives – Essais à l’hélium Taux de fuite d’hélium normalisé
Essai à l’hélium
−2 −4
(10 à 10 )
3 −1 3 −1
(Remplissage en He avant 6.1.1 <1 µPa · m · s <0,01 µPa · m · s
3 −1
µPa · m · s
le scellement)
Essai de pressurisation
à l’hélium
−2 3 −1 3 −1 3 −1
6.1.2 (1 à 10 ) µPa · m · s <1 µPa · m · s <0,01 µPa · m · s
(Bombardement de He
après le scellement)

Méthodes non radioactives – Essais de bullage Taux de fuite d’hélium normalisé correspondant

Aucune bulle
3 −1b
Essai de bullage sous vide 6.2.1 (10 à 1) µPa · m · s Pas assez sensible
observée
Essai de bullage dans Pas assez
3 −1b
6.2.2 (50 à 5) µPa · m · s Pas assez sensible
un liquide chaud sensible
Essai de bullage sous gaz Aucune bulle
3 −1b
6.2.3 (10 à 1) µPa · m · s Pas assez sensible
pressurisé observée
−1 −2
Essai de bullage dans (10 à 10 ) Aucune bulle Aucune bulle
6.2.4
3 −1b
l’azote liquide µPa · m · s observée observée
Méthodes non radioactives – Gain de masse Gain de masse en eau [µg]
Essai de pressurisation Gain de
6.3 10 Pas assez sensible
à l’eau masse <50

Le seuil de détection est exprimé sous forme de plage, dont la limite supérieure définit la plus petite fuite détectable

dans des conditions d’essai d’étanchéité typiques, bien contrôlées et industrielles, et la limite inférieure indique la plus

petite fuite détectable dans des conditions d’essai d’étanchéité industrielles excellentes (idéales). Les fuites inférieures à

celles indiquées peuvent être détectées en conditions de laboratoire.

Les valeurs de seuil représentées pour les essais de bullage sont des approximations grossières des débits de fuite

d’hélium normalisés correspondants et sont applicables uniquement à des fuites uniques dans des conditions visuelles

favorables.

Avant de subir les essais d’étanchéité suivants, la source doit être soumise à un examen visuel

approfondi. Pour le faciliter, il peut être nécessaire de nettoyer la source. Il convient que la méthode de

nettoyage évite de bloquer toute voie de fuite potentielle pour les essais ultérieurs.

Tout l’appareillage utilisé pour les essais doit être correctement entretenu et étalonné.

Il convient que l’essai par frottis ne soit considéré comme un essai d’étanchéité que pour certains types

de sources spécifiques (par exemple, des sources avec des fenêtres très minces telles que des feuilles

pour les détecteurs de fumée), pour les contrôles périodiques et dans les cas où aucun autre essai n’est

plus adapté.

Il convient, dans la mesure du possible, que les échantillons pour essais par frottis ou pour essais par

immersion dans un liquide soient contrôlés immédiatement sur un appareillage de mesure de pollution

basique; par exemple un compteur Geiger, pour repérer l’existence d’une éventuelle pollution flagrante

avant le mesurage final sur un appareillage étalonné plus sophistiqué.
© ISO 2020 – Tous droits réservés 5
---------------------- Page: 11 ----------------------
ISO 9978:2020(F)
5 Méthodes d’essai par des moyens radioactifs
5.1 Essais par immersion

NOTE Des techniques d’analyse adaptées pour l’évaluation de l’activité dans les liquides d’essai pour tous ces

[3] [4]
essais d’immersion se trouvent dans l’ISO 19361 et l’ISO 19581 .
5.1.1 Essai par immersion (liquide chaud)

Immerger la source scellée dans un liquide n’attaquant pas le matériau des surfaces extérieures de

cette source et qui, dans les conditions de cet essai, est jugé efficace pour la détection d'une fuite. Des

exemples de tels liquides comprennent l’eau distillée, des solutions de détergents doux ou d’agents de

chélation et également des solutions légèrement basiques ou acides de concentration voisine de 5 %.

Chauffer le liquide à 323 K ± 5 K (50 °C ± 5 °C) et le maintenir à cette température pendant au moins

4 h. Retirer la source scellée et mesurer l’activité du liquide. Si plusieurs sources scellées sont soumises

à l’essai simultanément dans le même échantillon de liquide, le critère d’acceptation pour une source

unique doit être utilisé pour toutes les sources, car tou
...

FINAL
INTERNATIONAL ISO/FDIS
DRAFT
STANDARD 9978
ISO/TC 85/SC 2
Radiation protection — Sealed sources
Secretariat: AFNOR
— Leakage test methods
Voting begins on:
2020­04­08
Radioprotection — Sources scellées — Méthodes d’essai d’étanchéité
Voting terminates on:
2020­06­03
RECIPIENTS OF THIS DRAFT ARE INVITED TO
SUBMIT, WITH THEIR COMMENTS, NOTIFICATION
OF ANY RELEVANT PATENT RIGHTS OF WHICH
THEY ARE AWARE AND TO PROVIDE SUPPOR TING
DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
Reference number
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO­
ISO/FDIS 9978:2020(E)
LOGICAL, COMMERCIAL AND USER PURPOSES,
DRAFT INTERNATIONAL STANDARDS MAY ON
OCCASION HAVE TO BE CONSIDERED IN THE
LIGHT OF THEIR POTENTIAL TO BECOME STAN­
DARDS TO WHICH REFERENCE MAY BE MADE IN
NATIONAL REGULATIONS. ISO 2020
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ISO/FDIS 9978:2020(E)
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ii © ISO 2020 – All rights reserved
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ISO/FDIS 9978:2020(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction ................................................................................................................................................................................................................................vi

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Requirements .......................................................................................................................................................................................................... 3

5 Test methods by radioactive means ................................................................................................................................................. 5

5.1 Immersion tests ..................................................................................................................................................................................... 5

5.1.1 Immersion test (hot liquid) .................................................................................................................................... 5

5.1.2 Immersion test (boiling liquid) ........................................................................................................................... 5

5.1.3 Immersion test with a liquid scintillator .................................................................................................... 5

5.1.4 Immersion test at room temperature ............................................................................................................ 5

5.1.5 Acceptance criteria ........................................................................................................................................................ 6

5.2 Gaseous emanation tests ................................................................................................................................................................ 6

5.2.1 Gaseous emanation test by absorption (for radium-226 sealed sources) ..................... 6

5.2.2 Gaseous emanation test by immersion with a scintillator (for radium-226

sealed sources) .................................................................................................................................................................. 6

5.2.3 Gaseous emanation test (for krypton-85 sealed sources) ........................................................... 6

5.2.4 Other gaseous emanation tests ........................................................................................................................... 6

5.2.5 Acceptance criteria ........................................................................................................................................................ 6

5.3 Wipe tests .................................................................................................................................................................................................... 6

5.3.1 Wet wipe test .................. .................................................... ................................................................................................. 6

5.3.2 Dry wipe test ....................................................................................................................................................................... 7

5.3.3 Acceptance criteria ........................................................................................................................................................ 7

6 Test methods by volumetric means .................................................................................................................................................. 7

6.1 Helium mass spectrometer leakage tests ........................................................................................................................ 7

6.1.1 Helium test [equivalent to leak test type B6 in ISO 20485] ........................................................ 7

6.1.2 Helium pressurization test [equivalent to leak test type B5 in ISO 20485] ................. 8

6.1.3 Acceptance criteria ........................................................................................................................................................ 8

6.2 Bubble leakage tests ........................................................................................................................................................................... 8

6.2.1 Vacuum bubble test [equivalent to immersion technique using vacuum in
[6] 8

EN 1593 ........................................................................................................................................... ...................................

6.2.2 Hot-liquid bubble test [equivalent to immersion technique using liquid at
[6]

elevated temperature in EN 1593 .............................................................................................................. 9

6.2.3 Gas pressurization bubble test [equivalent to immersion technique using
[6]

pressurisation of the object in EN 1593 ............................................................................................... 9

6.2.4 Liquid nitrogen bubble test .................................................................................................................................... 9

6.2.5 Acceptance criteria ........................................................................................................................................................ 9

6.3 Water pressurization test .............................................................................................................................................................. 9

Annex A (informative) Guidance for the choice of the tests to be carried out according to

purpose and sealed source type ........................................................................................................................................................10

Bibliography .............................................................................................................................................................................................................................12

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ISO/FDIS 9978:2020(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 non­governmental, 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.

This second edition cancels and replaces the first edition (ISO 9978:1992), which has been technically

revised. The main changes compared to the previous edition are as follows:

— Clause 4: Revised to add text specifying factors to be considered in designing an effective leak

testing regime for a particular type of sealed source;

— Clause 4: Requirement added that personnel performing leak tests be appropriately trained and

qualified, informative reference to ISO 9712 added;

— Clause 4: Requirement added that measurement uncertainty shall be considered in sentencing non-

binary test results;

— Table 1 — “Threshold detection values and limiting values for different test methods” has been

revised for clarity;

— 5.1: Informative reference to suitable assay techniques for immersion test liquid samples added:

ISO 19361 and ISO 19581;
— 5.1.1, 5.1.2, 5.1.4: Composition of suitable immersion test liquids clarified;

— 5.3: Informative reference to suitable wipe testing techniques (ISO 7503-2) added and clarification

that acceptance criteria is absolute without correction for wiping efficiency required;

— 6.1: Normative reference to ISO 20485 added for methods of helium leak testing and calculation of

acceptance limits;

— 6.2: Cautionary text added to state that efficacy of tests assume ideal conditions for vision of bubbles;

— 6.2.1: Cautionary text added regarding bubble testing of self-heated sources;
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ISO/FDIS 9978:2020(E)
— A.1: Text expanded to clarify which tests to use under given circumstances.
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ISO/FDIS 9978:2020(E)
Introduction

The use of sealed sources has become so widespread that standards to guide the user, manufacturer

and regulatory agencies are necessary. When establishing these standards, radiation protection is the

prime consideration.

The purpose of this document, in conjunction with ISO 2919, is to minimise the risk to the public caused

by leakage of radioactive material into the general environment.

Leakage test methods for sealed sources were standardised in the first edition of this document. The

experience acquired since this date has necessitated the revision of this document.

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FINAL DRAFT INTERNATIONAL STANDARD ISO/FDIS 9978:2020(E)
Radiation protection — Sealed sources — Leakage test
methods
1 Scope

This document specifies the different leakage test methods for sealed sources. It gives a comprehensive

set of procedures using radioactive and non­radioactive means.
This document applies to the following situations:
[1]

— leakage testing of test sources following design classification testing in accordance with ISO 2919 ;

— production quality control testing of sealed sources;

— periodic inspections of the sealed sources performed at regular intervals, during the working life.

Annex A of this document gives guidance to the user in the choice of the most suitable method(s)

according to situation and source type.

It is recognized that there can be circumstances where special tests, not described in this document,

are required.

It is emphasized, however, that insofar as production, use, storage and transport of sealed radioactive

sources are concerned, compliance with this document is no substitute for complying with the

requirements of the relevant IAEA regulations and other relevant national regulations. It is also

recognized that countries can enact statutory regulations which specify exemptions for tests, according

to sealed source type, design, working environment, and activity (e.g., for very low activity reference

sources where the total activity is less than the leakage test limit).
2 Normative references

The following documents are referred to in the text in such a way that some or all of their content

constitutes 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 20485:2017, Non-destructive testing — Leak testing — Tracer gas method
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
capsule
protective envelope, used to prevent leakage of radioactive material
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ISO/FDIS 9978:2020(E)
3.2
dummy sealed source

facsimile of a sealed source, the capsule of which has the same construction and is made with exactly the

same materials as those of the sealed source that it represents, but containing, in place of the radioactive

material, a substance resembling it as closely as is practical in physical and chemical properties

3.3
leachable

soluble in water, yielding quantities greater than 0,1 mg/g in 100 ml of still water maintained

at 50 °C for 4 h
3.4
leakage

transfer of contained radioactive material from the sealed source to the environment

3.5
leaktight

term applied to sealed sources which, after undergoing leakage testing, meet the acceptance criteria

Note 1 to entry: The acceptance criteria are given in Table 1.
3.6
model designation

manufacturer’s unique term (number, code or a combination of these) which is used to identify a specific

design of sealed source
3.7
non-destructive test

test used to detect internal, surface and concealed defects or imperfections in materials, using

techniques that do not damage or destroy the items being tested
3.8
non-leachable

insoluble in water, yielding quantities less than 0,1 mg/g in 100 ml of still water maintained at 50 °C for 4 h

3.9
sealed source

radioactive material sealed in a capsule or associated with a material to which it is closely bonded, this

capsule or bonding material being strong enough to maintain leaktightness of the sealed source under

the conditions of use and wear for which it was designed
3.10
simulated sealed source

facsimile of a sealed source, the capsule of which has the same construction and is made with exactly the

same materials as those of the sealed source that it represents but it contains, in place of the radioactive

material, a substance resembling it as closely as possible in physical and chemical properties and trace

quantities of radioactive material

Note 1 to entry: The tracer is in a form soluble in a solvent which does not attack the capsule and has the maximum

activity compatible with its use in a containment enclosure.
3.11
standard helium leakage rate
5 3 3

helium leakage rate at an upstream pressure of 10 Pa ± 5 × 10 Pa and a downstream pressure of 10 Pa

or less at a temperature of 296 K ± 7 K (23 °C ± 7 °C)

Note 1 to entry: In this document, the unit Pascal cubic meter per second is used .

−6 3 −l 3 −1 −5 3 −1 −5 −1 −3

1) [1 × 10 Pa·m · s = 1 µPa·m ·s ≈ 10 atm·cm ·s ≈ 1 × 10 mbar·l·s ≈ 7, 5 × 10 lusec.]

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ISO/FDIS 9978:2020(E)
3.12
test source

sample used in the performance tests, having the same material and construction as sealed sources of

the model for which classification is being established

Note 1 to entry: A test source may be a simulated sealed source, a dummy sealed source or production source.

Note 2 to entry: The performance tests are described in ISO 2919.
4 Requirements

The tests described in this document are all designed to test and verify that the sealed source is

leaktight. However not all tests are applicable in all circumstances. Correct application and choice of

test method and testing media is critically important in designing an effective leak test programme.

Factors to be considered include:
— the chemical form of the active material if leak test is by radioactive means;
— the type of test liquid used in immersion tests;
— the number of encapsulations;
— the internal void volume when tests are carried out by volumetric means;
— the temperature of the sealed source;

— the suitability of the test method for the environment in which it is being performed;

— the reason for performing the test (integrity testing of a test source, production leakage tests,

routine in service testing);
— the required sensitivity and acceptance criteria.

The test programme for test and production sealed sources should be considered as part of the design

process and validated or justified as appropriate to demonstrate its effectiveness and sensitivity. This

process may include the analysis of historic data.

The tests described in this document shall be designed, validated and carried out by competent and

qualified persons who have demonstrable appropriate training in the applied test methods. For test

methods by radioactive means, the persons shall also have appropriate training in radiation protection

and measurement.

NOTE 1 Qualification and certification methods for non-destructive testing personnel can be found in

[2]
ISO 9712 .

An evaluation should be made of uncertainty in the case of non-binary test results (e.g. radiation

measurements on immersion test samples) and taken account of in sentencing the result.

Guidance for choosing suitable tests are specified in Annex A.

According to the test type and the sealed source type, at least one of each of the tests described

in Clauses 5 and 6 should be carried out [see Annex A for the choice of the test(s)].

It should be noted that it is best practice to carry out more than one type of leakage test and also to

perform a final wipe as a contamination check.

The tests described in this document do not form an exhaustive list, and other test methods may be

developed. However, in the case where a special test, which is not described in this document, is carried

out (see Clause 1), the organisation shall validate that the applied method is at least as effective as

the corresponding method(s) given in this document in order to be able to claim compliance with this

document.
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ISO/FDIS 9978:2020(E)

At the conclusion of the performed test(s), the sealed source shall be considered to be leaktight if it

complies with the acceptance criteria specified in Table 1.

It has been asserted that there is correspondence between the acceptance criteria for volumetric and

radioactive leak tests. Whilst there is no universally accepted basis for this assertion, experience has

shown that sources meeting the acceptance criteria shown in Table 1 have not subsequently been found

to leak.
3 −1 3 −1

NOTE 2 A leakage rate of 10 µPa · m · s for non­leachable solid contents and a rate of 0,1 µPa · m · s for

leachable solids and liquids was historically considered to be equivalent to the activity release limit of 2 000 Bq

[18]
(≈50 nCi) .

NOTE 3 A further confirmation of the volumetric acceptance threshold is given by Reference [8]. A leakage

−7 3 −1

rate of 10 atm · cm · s or more based on dry air at 298 K (25 °C) and for a pressure difference of 1 atm against

a vacuum of 10 atm (equivalent to or less) is considered to represent a loss of leaktightness, irrespective of the

physical nature of the content.

Table 1 — Threshold detection values and limiting values for different test methods

Acceptance criteria
Test method Subclause Threshold of detection
Non-leachable Leachable or
content gaseous content
Radioactive methods
Immersion test (hot liquid) 5.1.1 (10 to 1) Bq <200 Bq <200 Bq
Immersion test (boiling
5.1.2 (10 to 1) Bq <200 Bq <200 Bq
liquid)
Immersion test with a
5.1.3 (10 to 1) Bq <200 Bq <200 Bq
liquid scintillator
<200 Bq
Gaseous emanation test 5.2.1 (4 to 0,4) Bq Unsuitable
222
( Rn/12h)
Emanation test with a <200 Bq
5.2.2 (0,4 to 0,004) Bq Unsuitable
222
liquid scintillator ( Rn/12h)
Wet wipe test 5.3.1 (10 to 1) Bq <200 Bq <200 Bq
Dry wipe test 5.3.2 (10 to 1) Bq <200 Bq <200 Bq
Non­radioactive methods – Helium tests Standard helium leakage rate
−2 −4
Helium test (10 to 10 )
3 −1 3 −1
6.1.1 <1 µPa · m · s <0,01 µPa · m · s
3 −1
(He filling before sealing) µPa · m · s
Helium pressurization test
−2 3 −1 3 −1 3 −1
6.1.2 (1 to 10 ) µPa · m · s <1 µPa · m · s <0,01 µPa · m · s
(He bombing after sealing)

Non­radioactive methods – Bubble tests Corresponding standard helium leakage rate

No bubbles
3 −1b
Vacuum bubble test 6.2.1 (10 to 1) µPa · m · s Not sensitive enough
observed
Not sensitive
3 −1b
Hot-liquid bubble test 6.2.2 (50 to 5) µPa · m · s Not sensitive enough
enough
No bubbles
3 −1b
Gas pressurization bubble test 6.2.3 (10 to 1) µPa · m · s Not sensitive enough
observed
−1 −2
(10 to 10 ) No bubbles No bubbles
Liquid nitrogen bubble test 6.2.4
3 −1b
µPa · m · s observed observed
Non­radioactive methods – Mass gain Mass gain of water [µg]
Water pressurization test 6.3 10 Mass gain < 50 Not sensitive enough

The threshold of detection is expressed as a range; its upper end defines the smallest detectable leak under typical,

well controlled industrial leak testing conditions and its lower end indicates the smallest detectable leak under excellent

(ideal) industrial leak testing conditions. Smaller leaks than those indicated can be detected under laboratory conditions.

Threshold values shown for bubble tests are rough approximations of the corresponding standard helium leakage

rates and are applicable only to single leaks under favourable visual conditions.

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ISO/FDIS 9978:2020(E)

Prior to undergoing the following leakage tests the source shall be subject to a thorough visual

examination. The source may have to be cleaned to facilitate this. Any cleaning method should avoid the

blocking of any potential leakage path for subsequent tests.
All equipment used for tests shall be suitably maintained and calibrated.

The wipe test should only be considered as a leakage test for some specific types of sources (e.g. sources

with very thin windows such as foils for smoke detectors), for periodic inspections and in cases where

no other test is more suitable.

Wipe tests or liquid immersion test samples should, wherever possible, be checked immediately on

basic contamination measuring equipment; for example, a Geiger counter to establish whether there is

any gross contamination prior to final measurement on more sophisticated calibrated equipment.

5 Test methods by radioactive means
5.1 Immersion tests

NOTE Suitable assay techniques for evaluation of the activity in the test liquids for all of these immersion

[3] [4]
tests may be found in ISO 19361 and ISO 19581 .
5.1.1 Immersion test (hot liquid)

Immerse the sealed source in a liquid which does not attack the material of the outer surfaces of the

source and which, under the conditions of this test, is considered effective for detection of a leak.

Examples of such liquids include distilled water, weak detergent solutions or chelation agents and

also slightly alkaline or acid solutions with concentrations of about 5 %. Heat the liquid to 323 K ± 5 K

(50 °C ± 5 °C) and maintain it at that temperature for at least 4 h. Remove the sealed source and measure

the activity of the liquid. If more than one sealed source is tested in the same liquid sample, all activity

shall be assumed to have originated from a single source.

An ultrasonic cleaning method can also be used. In this case, the immersion time in the liquid

at 343 K ± 5 K (70 °C ± 5 °C) can be reduced to approximately 30 min.
5.1.2 Immersion test (boiling liquid)

Immerse the sealed source in a liquid which does not attack the material of the outer surfaces of the

source and which, under the conditions of this test, is considered effective for detection of a leak.

Examples of such liquids include distilled water, weak detergent solutions or chelation agents and

also slightly alkaline or acid solutions with concentrations of about 5 %. Boil for 10 min, allow to cool,

then rinse the sealed source in a fresh batch of liquid. Repeat these operations twice, re-immersing the

source in the original liquid. Remove the sealed source and measure the activity of the original liquid.

If more than one sealed source is tested in the same liquid sample, all activity shall be assumed to have

originated from a single source.
5.1.3 Immersion test with a liquid scintillator

Immerse the sealed source for at least 3 h at room temperature in a liquid scintillator solution that

does not attack the material of the outer surface of the source. Store away from light to avoid

photoluminescence. Remove the sealed source and measure the activity of the liquid by a liquid

scintillation counting technique.
5.1.4 Immersion test at room temperature

Immerse the sealed source in a liquid which does not attack the material of the outer surfaces of the

source and which, under the conditions of this test, is considered effective for detection of a leak.

Examples of such liquids include distilled water, weak detergent solutions or chelation agents and

also slightly alkaline or acid solutions with concentrations of about 5 %. After a period of at least 24 h,

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ISO/FDIS 9978:2020(E)

remove the sealed source and measure the activity of the liquid. If more than one sealed source is tested

in the same liquid sample, all activity shall be assumed to have originated from a single source.

This test may be useful where hot liquid tests are not practical, however the hot liquid tests are

recommended whenever possible since their use has been widely recognized for many years and also

because they may be more effective.
5.1.5 Acceptance criteria

The sealed source is considered to be leaktight if the total activity detected in the liquid sample is less

than 200 Bq (≈5 nCi).
5.2 Gaseous emanation tests
5.2.1 Gaseous emanation test by absorption (for radium-226 sealed sources)

Place the sealed source in a small gas-tight container with a suitable absorbent, for example activated

carbon, cotton or polyethylene, and leave it for at least 3 h. Remove the source and close the container.

Immediately measure the activity of the absorbent.

5.2.2 Gaseous emanation test by immersion with a scintillator (for radium-226 sealed sources)

Follow the procedure described in 5.1.3.
5.2.3 Gaseous emanation test (for krypton-85 sealed sources)

Maintain the sealed source under reduced pressure for 24 h. Analyse the content of the chamber for

krypton-85 by a plastic scintillation counting technique. Repeat the test after
...

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