IEC 62401:2007

Radiation protection instrumentation - Alarming personal radiation devices (PRD) for detection of illicit trafficking of radioactive material

Describes design and functioning criteria along with testing methods for evaluating the performance of instruments for detection of illicit trafficking of radioactive material (for example, for border radiation monitoring). These instruments may be used in extreme environmental conditions, they are pocket-sized, carried on the body and used to detect and indicate the presence and general magnitude of penetrating ionizing radiation, including photons and/or neutrons.

Instrumentation pour la radioprotection - Dispositifs individuels d'alarme aux rayonnements pour la détection du trafic illicite des matières radioactives

Décrit les critères de conception et de fonctionnement ainsi que des méthodes d'essai pour évaluer la performance des instruments de détection de trafic illicite de matières radioactives (par exemple à la surveillance des frontières). Ces instruments peuvent être utilisés dans des conditions environnementales extrêmes; ils sont portables en poche, ou sur l'individu et ui sont utilisés pour détecter et signaler la présence et l'ordre de grandeur des rayonnements ionisants pénétrant, incluant les photons et/ou les neutrons.

General Information

• Status: Published
• Publication Date: 24-Jul-2007
• ICS: 13.280 - Radiation protection
• Technical Committee: SC 45B - Radiation protection instrumentation
• Drafting Committee: WG 15 - TC 45/SC 45B/WG 15
• Current Stage: DELPUB - Deleted Publication
• Start Date: 15-Dec-2017
• Completion Date: 26-Oct-2025

Relations

• Revised: IEC 62401:2017 - Radiation protection instrumentation - Alarming personal radiation devices (PRDs) for the detection of illicit trafficking of radioactive material
• Effective Date: 05-Sep-2023

Standards Content (Sample)

INTERNATIONAL IEC
STANDARD
CEI
NORME
First edition
INTERNATIONALE
Première édition
2007-07
Radiation protection instrumentation –
Alarming personal radiation devices (PRD)
for detection of illicit trafficking
of radioactive material
Instrumentation pour la radioprotection –
Dispositifs individuels d’alarme aux
rayonnements pour la détection du trafic
illicite des matières radioactives

Reference number
Numéro de référence
IEC/CEI 62401:2007
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INTERNATIONAL IEC
STANDARD
CEI
NORME
First edition
INTERNATIONALE
Première édition
2007-07
Radiation protection instrumentation –
Alarming personal radiation devices (PRD)
for detection of illicit trafficking
of radioactive material
Instrumentation pour la radioprotection –
Dispositifs individuels d’alarme aux
rayonnements pour la détection du trafic
illicite des matières radioactives

PRICE CODE
T
CODE PRIX
Commission Electrotechnique Internationale
International Electrotechnical Commission
МеждународнаяЭлектротехническаяКомиссия
For price, see current catalogue
Pour prix, voir catalogue en vigueur

– 2 – 62401 © IEC:2007
CONTENTS
FOREWORD.4

1 Scope and object.6

2 Normative references .6

3 Terms, definitions, quantities and units.7

3.1 Terms and definitions .7

3.2 Quantities and units .10

4 Design requirements .10
4.1 General requirements.10
4.2 Mechanical requirements.11
4.2.1 Size.11
4.2.2 Mass .11
4.2.3 Alarm characteristics .11
4.2.4 Case construction.11
4.2.5 Reference point marking.11
4.2.6 Switches.11
4.3 Electromagnetic requirements .12
5 Performance tests .12
5.1 General test conditions.12
5.1.1 Nature of tests.12
5.1.2 Reference conditions and standard test conditions .12
5.1.3 Tests performed under standard test conditions .12
5.1.4 Tests performed with variation of influence quantities.12
5.1.5 Statistical fluctuations.13
5.2 Radiation tests .13
5.2.1 General test information .13
5.2.2 Instrument setup.13
5.2.3 Gamma response .13
5.2.4 Rate of false alarms .14
5.2.5 Detection of gradually increasing radiation levels .14
5.2.6 Over-range .14
5.2.7 Detection of neutrons (if provided).15

5.2.8 Gamma response of neutron detector .15
5.3 Environmental tests.15
5.3.1 Temperature tests .15
5.3.2 Humidity tests.16
5.3.3 Dust and moisture resistance tests .17
5.4 Mechanical tests .18
5.4.1 General .18
5.4.2 Drop test .18
5.4.3 Vibration test .19
5.5 Electrical tests.19
5.5.1 General .19
5.5.2 Battery requirements .19
5.5.3 Electromagnetic and electrostatic interference tests .19
6 Documentation .20

62401 © IEC:2007 – 3 –
6.1 General .20

6.2 Type test report.20

6.3 Certificate .21

6.4 Operation and maintenance manuals.21

Bibliography.25

Table 1 – Reference conditions and standard test conditions .22

Table 2 – Summary of performance requirements .23

– 4 – 62401 © IEC:2007
INTERNATIONAL ELECTROTECHNICAL COMMISSION

____________
RADIATION PROTECTION INSTRUMENTATION –

ALARMING PERSONAL RADIATION DEVICES (PRD) FOR DETECTION

OF ILLICIT TRAFFICKING OF RADIOACTIVE MATERIAL

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with an IEC Publication.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 62401 has been prepared by subcommittee 45B: Radiation
protection instrumentation, of IEC technical committee 45: Nuclear instrumentation.

The text of this standard is based on the following documents:
FDIS Report on voting
45B/540/FDIS 45B/545/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.

62401 © IEC:2007 – 5 –
The committee has decided that the contents of this publication will remain unchanged until
the maintenance result date indicated on the IEC web site under "http://webstore.iec.ch" in

the data related to the specific publication. At this date, the publication will be

• reconfirmed,
• withdrawn,
• replaced by a revised edition, or

• amended.
– 6 – 62401 © IEC:2007
RADIATION PROTECTION INSTRUMENTATION –

ALARMING PERSONAL RADIATION DEVICES (PRD) FOR DETECTION

OF ILLICIT TRAFFICKING OF RADIOACTIVE MATERIAL

1 Scope and object
This International Standard applies to alarming radiation detection instruments that are

pocket-sized, carried on the body and used to detect and indicate the presence and general
magnitude of penetrating ionizing radiation, including photons and/or neutrons.
Personal Radiation Devices (PRD) alert the user to the presence of a source of radiation that
is distinctly above the measured average local background radiation level. They are not
intended to provide a measurement of dose equivalent rate.
The object of this standard is to describe design and functioning criteria along with testing
methods for evaluating the performance of instruments for detection of illicit trafficking of
radioactive material (for example, for border radiation monitoring). These instruments may be
used in extreme environmental conditions.
This standard does not apply to the performance of radiation protection instrumentation
covered in IEC 60846, IEC 61526, and IEC 62327.
The performances of the PRD with respect to neutrons may be degraded and not warranted
when they are used in other conditions than on the body.
2 Normative references
The following referenced documents are indispensable for the application 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.
IEC 60050-393:2003, International Electrotechnical Vocabulary (IEV) – Part 393: Nuclear
instrumentation – Physical phenomena and basic concepts
IEC 60050-394:1995, International Electrotechnical Vocabulary (IEV) – Chapter 394: Nuclear
instrumentation – Instrument
IEC 60529:1989, Degrees of protection provided by enclosures (IP Code)
Amendment 1 (1999)
IEC 61000-4-2:1995, Electromagnetic compatibility (EMC) – Part 4-2: Testing and measure-
ment techniques – Electrostatic discharge immunity test
Amendment 1 (1998)
Amendment 2 (2000)
—————————
There exists a consolidated edition 2.1 (2001) that includes edition 2.0 and its amendment.
There exists a consolidated edition 1.2 (2001) that includes edition 1.0 and its amendments.

62401 © IEC:2007 – 7 –
IEC 61000-4-3:2006, Electromagnetic compatibility (EMC) – Part 4-3: Testing and measure-
ment techniques – Radiated, radio-frequency, electromagnetic field immunity test

ISO 4037-1:1996, X and gamma reference radiation for calibrating dosemeters and doserate
meters and for determining their response as a function of photon energy – Part 1: Radiation

characteristics and production methods

ISO 4037-2:1997, X and gamma reference radiation for calibrating dosemeters and doserate

meters and for determining their response as a function of photon energy – Part 2: Dosimetry

for radiation protection over the energy ranges from 8 keV to 1,3 MeV and 4 MeV to 9 MeV

ISO 4037-3:1999, X and gamma reference radiation for calibrating dosemeters and doserate
meters and for determining their response as a function of photon energy – Part 3: Calibration
of area and personal dosemeters and the measurement of their response as a function of
energy and angle of incidence
ISO 8529-1:2001, Reference neutron radiations – Part 1: Characteristics and methods of
production
ISO 8529-2:2000, Reference neutron radiations – Part 2: Calibration fundamentals of
radiation protection devices related to the basic quantities characterizing the radiation field
ISO 8529-3:1998, Reference neutron radiations – Part 3: Calibration of area and personal
dosimeters and determination of response as a function of neutron energy and angle of
incidence
International Bureau of Weights and Measures: The International System of Units (SI),
Seventh edition, 1998
3 Terms, definitions, quantities and units
3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60050-393 and
60050-394, as well as the following, apply.
3.1.1
A-weighted sound level
frequency weighting of an acoustic spectrum according to a standardized frequency response
curve based on the frequency response of the human ear

3.1.2
accuracy
closeness of the agreement between the result of a measurement and the conventionally true
value of the measurand
[IEV 394-20-39, modified]
3.1.3
alarm
audible, visual, or other signal activated when the instrument reading exceeds a preset value
or falls outside of a preset range
[IEV 393-18-03, modified]
– 8 – 62401 © IEC:2007
3.1.4
background level
radiation field in which the instrument is intended to operate

3.1.5
conventionally true value of a quantity

CTV
best estimate of the value of a quantity used for a given purpose

NOTE A conventionally true value is, in general, regarded as sufficiently close to the true value for the difference
to be insignificant for the given purpose. For example, a value determined from a primary or secondary standard or

by a reference instrument, may be taken as the conventionally true value.

[IEV 394-20-10]
3.1.6
device
radiation detector with its associated electronics
3.1.7
effective range of measurement
range of values of the quantity to be measured over which the performance of a device meets
the requirements of this standard
[IEV 394-20-16, modified]
3.1.8
false alarm
alarm not caused by an increase in radiation level over background conditions
3.1.9
influence quantity
quantity that may have a bearing on the result of a measurement without being the subject of
the measurement
3.1.10
point of measurement
place at which the conventionally true values are determined and at which the reference point
of the instrument is placed for test purposes
3.1.11
readout
value, with units, displayed and/or recorded by the instrument as a result of the instrument’s
response to some influence quantity
3.1.12
reference point of an assembly
physical mark on a piece of equipment or assembly to be used in order to position it at a point
where the conventionally true value of the quantity to be measured is known
[IEV 394-20-15]
62401 © IEC:2007 – 9 –
3.1.13
relative intrinsic error
ε
REL
difference between the instrument’s reading, M, and the conventionally true value, CTV, of the

quantity being measured divided by the conventionally true value multiplied by 100 % when

subjected to a specified reference quantity under specified reference conditions

M −CTV
ε = × 100 %
REL
CTV
[IEV 394-20-12, modified]
3.1.14
response
R
ratio of the instrument reading to the conventionally true value of the measured quantity
3.1.15
standard deviation
positive square root of the variance.
3.1.16
standard test conditions
prescribed range for influence quantities to be used during testing of a measuring instrument
[IEV 394-20-26, modified]
3.1.17
type test
conformity testing on the basis of one or more specimens of a product representative of the
production
[IEV 394-20-28]
3.1.18
routine test
test to which an individual device is subjected during or after manufacture to ascertain
whether it complies with certain criteria
[IEV 394-20-08]
3.1.19
acceptance test
contractual test to prove to the customer that the device meets certain conditions of its
specification
[IEV 394-20-09]
3.1.20
uncertainty (of measurement)
parameter, associated with the result of a measurement, that characterizes the dispersion of
the values that could reasonably be attributed to the measurand
[VIM 3.9]
NOTE 1 The parameter may be, for example, a standard deviation (or a given multiple of it), or the half-width of
an interval having a stated level of confidence.

– 10 – 62401 © IEC:2007
NOTE 2 Uncertainty of measurement comprises, in general, many components. Some of these components may

be evaluated from statistical distribution of the results of series of measurements and can be characterized by

experimental standard deviations. The other components, which can also be characterized by experimental
standard deviations, are evaluated from assumed probability distributions based on experience or other
information.
NOTE 3 It is understood that the result of the measurement is the best estimate of the value of the measurand
and that all components of uncertainty, including those arising from systematic effects, such as components
associated with corrections and reference standards, contribute to the dispersion.

[IEV 394-20-40]
3.1.21
variance
σ
measure of dispersion, which is the sum of the squared deviation of observations x from their
i
mean x divided by one less than the number of observations n
n
2 2
σ = (x − x)
∑
i
n − 1
i=1
3.2 Quantities and units
In the present standard, units of the International System (SI) are used . The definitions of
radiation quantities are given in IEC 60050-393 and IEC 60050-394. The corresponding old
units (non-SI) are indicated in brackets.
Nevertheless, the following units may also be used:
–19
– for energy: electron-volt (symbol: eV), 1 eV = 1,602 × 10 J;
– for time: years (symbol: y), days (symbol: d), hours (symbol: h), minutes (symbol: min).
Multiples and submultiples of SI units will be used, when practicable, according to the SI
system.
4 Design requirements
4.1 General requirements
Instruments tested using this standard are carried on the body and are used to detect and
indicate the presence and general magnitude of radiation fields. These devices are not
intended to provide a measurement of dose-equivalent rate. However, the manufacturer may
provide an optional display of the air kerma rate from photon radiation. Alternative quantities

such as ambient dose equivalent rate expressed in Sieverts per hour are acceptable, provided
corrections are made by the manufacturer.
The instruments to be tested using this standard shall quickly alert the user to small increases
of radiation levels with a low occurrence of false alarms.
The following features are considered essential or desirable for the proper usability of
personal radiation detectors:
a) the following features shall be provided:
– simple to use for non-expert users;
– separate photon and neutron radiation alarms (if neutron response is provided), with
visual and acoustical alerts;
—————————
International Bureau of Weights and Measures: The international System of Units (SI), Seventh edition, 1998.

62401 © IEC:2007 – 11 –
– audible and/or visual indication that corresponds to the magnitude of the radiation field

(for example, increasing frequency or pitch of beep tone with increasing radiation

signal);
– readable display in all lighting conditions including darkness;

– small, rugged packaging, shock-resistant and water-resistant;

– protection of the setting of all operational parameters, if available;

– diagnostic capabilities;
– indication of battery status;

b) the following features should be provided:

– separate indication of the type of radiation detected (photon and/or neutron);
– silent alarms for covert operation such as vibration alarm and/or earphone with user
adjustable earphone volume to cope with the large variations in human hearing
sensitivity and noise level;
– high air kerma rate alarm with pre-settable level.
4.2 Mechanical requirements
4.2.1 Size
The overall dimensions of the instrument, excluding any clip, retaining device or external
alarm, should not exceed 200 mm in length, 100 mm in width and 50 mm in thickness, unless
it is incorporated into another device.
4.2.2 Mass
The mass of the complete instrument should not exceed 400 g.
4.2.3 Alarm characteristics
a) Location – The device shall be worn on the body in such a manner that the alarm can
always alert the wearer.
b) Alarm type – The frequency of an audible alarm should be within the range of 1 000 to
4 000 Hz. Where an intermittent alarm is provided, the signal interval shall not exceed 2 s.
The alarm volume at a distance of 30 cm from the alarm source shall be at least 85 dB(A).
The A-weighted sound level shall not exceed 100 dB(A) at 30 cm from the alarm source.
Where ambient noise levels would make the alarm inaudible or when a silent alarm is
necessary, a visual, vibratory or other additional signal shall be provided.
4.2.4 Case construction
The instrument case should be smooth, rigid, resistant to mechanical shock, dust-resistant
and water-resistant. Means shall be provided to securely affix the instrument to the user (for
example, a clip or ring), with attention given to the necessary orientation of the detector,
alarm type and display.
4.2.5 Reference point marking
The instrument shall be clearly marked to indicate the position of the reference point for
calibration and test purposes.
4.2.6 Switches
Any external switches shall be adequately protected to prevent accidental or unauthorized
operation.
– 12 – 62401 © IEC:2007
4.3 Electromagnetic requirements

Special precautions shall be taken in the design of the instrument to ensure proper operation

in the presence of electromagnetic disturbances, particularly radiofrequency fields.

5 Performance tests
5.1 General test conditions
5.1.1 Nature of tests
The required standard test conditions for environmental quantities, such as temperature and
pressure, as well as those for other quantities that may influence the performance of
instruments, are given in Table 1. Acceptable testing ranges for these quantities shall be met,
except where the effect of the condition or quantity itself is being tested. Environmental
quantities, such as temperature and humidity are referred to as influence quantities.
Measurements or calibrations should be carried out under reference conditions. Since this is
not always achievable or convenient, a small interval around the reference values can be
used. In this case, corrections to the reference conditions shall be made.
The tests in this standard are to be considered as type tests (see Table 1) unless otherwise
stated. The specifications given are evaluated by the tests given in the appropriate
subclauses. All tests using this standard shall be performed using the same conditions with
any accessories included with the instruments. Where no test is specified, it is understood to
mean that the characteristic can be verified by observation or consultation of the
manufacturer’s specifications. The user may employ certain parts of the standard as
acceptance tests.
5.1.2 Reference conditions and standard test conditions
Reference and standard test conditions are given in Table 1. Reference conditions are those
conditions to which the performances of the instrument are valid and standard test conditions
indicate the necessary tolerances in practical testing. Except where otherwise specified, the
tests in this standard shall be performed under the standard test conditions given in the third
column of Table 1.
5.1.3 Tests performed under standard test conditions
Tests, which are performed under standard test conditions, are listed in Table 2 which
indicates, for each characteristic under test, the requirements according to the subclause
where the corresponding test method is described. For these tests, the value of temperature,
pressure and relative humidity at the time of the test shall be stated and the appropriate
corrections made to give the response under reference conditions.

5.1.4 Tests performed with variation of influence quantities
For those tests, intended to determine the effects of variations in the influence quantities
given in Table 2, all other influence quantities shall be maintained within the limits for the
standard test conditions given in Table 1 unless otherwise specified in the test procedure
concerned.
62401 © IEC:2007 – 13 –
5.1.5 Statistical fluctuations

For any test involving the use of radiation, if the magnitude of the statistical fluctuations of the

indication, arising from the random nature of radiation alone, is a significant fraction of the

variation of the indication permitted in the test, then sufficient readings shall be taken to

ensure that the mean value of such readings may be estimated with sufficient accuracy to

demonstrate compliance with the test in question.

The interval between such readings shall be sufficient to ensure that the readings are

statistically independent.
5.2 Radiation tests
5.2.1 General test information
The reference point of the instrument shall be placed at the point of measurement. The
instrument shall be oriented with respect to the direction of the radiation field as indicated by
the manufacturer.
241 137 60
The following radionuclides shall be used for gamma testing: Am, Cs and Co. For
neutron, the test source shall be Cf.
5.2.2 Instrument setup
The instrument to be tested shall be placed under standard test conditions, switched on, set
up following instructions from the manufacturer, and allowed a stabilization and background
detection period specified by the manufacturer’s recommendations. The entire process from
the time the detector is turned on should not exceed the stabilization time of 1 minute (see
Table 1). When the detector is moved for ambient air kerma rate background verifications and
adjustments, it should be allowed a similar setup and stabilization period if required.
5.2.3 Gamma response
5.2.3.1 Requirement
a) Relative intrinsic error
NOTE This only applies where the instrument has an air kerma rate display.
Under standard test conditions the relative intrinsic error in the response of the instrument to
the reference photon radiation from Cs shall not exceed ± 30 % for all air kerma rates over
the manufacturer’s stated indicated display range.
b) Photon alarm
The PRD shall trigger a gamma alarm within 2 s when the air kerma rate is increased by
–1
0,5 μGy·h (±20 %) in a period of no more than 0,5 s at the reference point of the detector.
This requirement should be fulfilled in the continuous gamma ray energy range from 60 keV to
1 330 keV. This requirement shall be fulfilled at the background air kerma rates of
–1 –1
approximately 0,1 μGy·h and 0,3 μGy·h .
The air kerma rate shall be measured at the reference point of the instrument. A Cs source
shall be used to increase the natural background radiation level to be within ±30 % of the
required background air kerma rate.
5.2.3.2 Method of test
a) Relative intrinsic error
NOTE This only applies where the instrument has an air kerma rate display.

– 14 – 62401 © IEC:2007
The test shall be performed using sources of Cs for at least 3 air kerma rates. One at

–1
approximately 0,1 μGy·h , one at approximately 90 % of the maximum stated range of

indication and one at approximately 50 % of the maximum stated range of indication.

b) Photon alarm
241 137 60
The test is performed using the following sources: Am, Cs and Co. The air kerma rate
produced at the point of measurement shall be known with an uncertainty less than 20 % (k =
2). The entire instrument shall be within the homogenous radiation field for the test.

An alarm shall be triggered within 2 s after the ambient air kerma rate is raised by
–1 –1 –1,
0,5 μGy·h from a background level of 0,1 μGy·h and 0,3 μGy·h respectively, and with
95 % confidence level.
5.2.4 Rate of false alarms
The mean time to false alarm shall be greater than 1 h in all ambient radiation levels stated in
5.2.3.
With any number of instruments of the same construction in the appropriate background air
kerma rate, the detectors shall be exposed to the background radiation levels specified in
5.2.3 and monitored for at least 30 instrument hours (for example, three instruments operating
for 10 h each). The number of alarms during this period shall not exceed 30.
5.2.5 Detection of gradually increasing radiation levels
5.2.5.1 Requirement
The instrument’s alarm threshold shall not be affected by slowly increasing radiation levels
that may be caused when a wearer is slowly approaching or is being approached by a
radiation source.
5.2.5.2 Method of test
The test point is located at 1 m (± 0,3 m) from a Cs source and the air kerma at this point
–1
is 0,5 μGy·h above the background at the reference point of the instrument. From a distance
–1
of 5 m away from the test point, move the instrument at the speed of about 0,1 m·s and stop
at the test point. The alarm shall activate within 2 s after the instrument reaches the test
point. Return the instrument to the original point, allow the instrument to stabilize, and repeat
the process 9 additional times. The test result is acceptable if the alarm occurs for 8 of 10
trials.
5.2.6 Over-range
5.2.6.1 Requirement
The instrument shall indicate that an over-range condition exists when the ambient air kerma
rate is greater than the manufacturer-stated maximum ambient air kerma rate up to 50 times
–1
the maximum air kerma rate or 1 mGy·h , whichever is greater. During the over-range
condition, the alarm indication shall stay activated.
5.2.6.2 Method of test
Expose the instrument for 5 min to a step change in the ambient air kerma from background
–1
to 50 times the manufacturer’s stated maximum air kerma rate or 1 mGy·h , whichever is
greater. The instrument shall stay in the alarm condition and indicate an over-range condition
within 5 s of the step change and shall remain in that condition for the entire exposure period.

62401 © IEC:2007 – 15 –
5.2.7 Detection of neutrons (if provided)

5.2.7.1 Requirement
The PRD shall trigger a neutron alarm when exposed to a Cf source with an emission rate
4 –1
of 2 × 10 s (±20 %) (0,01 μg) at 25 cm from the instrument's reference point and within 5 s
of the exposure time.
5.2.7.2 Method of test
Neutron tests should be made in a low scatter irradiation facility (see ISO 8529-1) or with the

instrument placed in an area where there is open space on all sides of at least 1 m.

Place the instrument at the centre of the front plexiglas face of a 30 cm × 30 cm × 15 cm
standard water slab phantom or alternative phantom, as defined in ISO 8529-3, facing the
radiation source. Gamma rays from the source shall be shielded with 1 cm of lead. Then
4 –1
increase the neutron field to the required level 2 × 10 s (±20 %) (0,01 μg) at 25 cm within a
period of not more than 2 s. The instrument shall indicate the presence of neutrons within a
period of 5 s after the field increase. Reduce the field and repeat the test 9 additional times.
The test result is acceptable if presence is indicated in 8 of 10 exposures.
4 –1
NOTE The emission rate of 2 × 10 s at 25 cm is approximately equivalent to a neutron fluence rate at the
–2 –1
point of measurement of 2,55 cm ·s .
5.2.8 Gamma response of neutron detector
5.2.8.1 Requirements
The instrument shall not trigger a neutron alarm when exposed to a Co gamma ray source
–1
producing an air kerma rate at the reference point of the instrument up to 100 μGy·h
(±20 %) for a duration of 100 s.
NOTE This air kerma rate has been chosen as the highest value permissible for law enforcement at a 1 m
distance according to the recommendations of IAEA for operational response. It is also the highest permissible air
kerma rate at 1 m distance (transport index 10) according to IAEA transport regulations.
5.2.8.2 Method of test
Response of instrument to gamma rays is tested by exposing the PRD for 100 s to a Co
–1
radiation source producing an air kerma rate of 100 μGy·h (±20 %) at the reference point of
the instrument. The distance between the source and the instrument shall be not less than
50 cm.
No neutron alarms should be observed during the test.
5.3 Environmental tests
5.3.1 Temperature tests
5.3.1.1 Requirements
Over the range of temperature from –20 °C to +50 °C, the instrument shall function correctly
–1
and alarm at an increase in ambient background of 0,5 μGy·h . As a result of the
temperature change, the indication of the magnitude of the radiation field or the indication of
the air kerma rate (if provided) shall not change by more than ±30 % or one unit of indication,
whichever is greater.
– 16 – 62401 © IEC:2007
There shall be no visible external damage to the instrument, and all control functions shall be
verified to be operating correctly.

If the manufacturer has stated a wider operational temperature range, the instrument’s ability
to perform correctly shall be tested over that range.

5.3.1.2 Method of test
Before starting each test, the instrument shall be placed in an environment with a temperature

of 20 °C ± 2 °C for a period of 30 min. The relative humidity of the environment should be less

than 65 % to prevent condensation during testing.

Shock and ramp temperature tests shall be performed once to the high temperature extreme
of +50 °C ± 5 °C and once to the low temperature extreme of –20 °C ± 3 °C applying the
following procedure.
a) Shock tests – room temperature to high and low temperature extreme
The instrument shall be either placed direct in an environmental chamber that has
equilibrated to the extreme temperature (high or low) or it shall be introduced in the
chamber at 20 °C, and then the temperature in the chamber shall be changed to the
extreme level within 5 min. Reading changes, as a function of time, shall be recorded for a
period of 30 min. At the end of this part of the test, the instrument shall be placed in the
same manner at a temperature of 20 °C ± 2 °C for a period of 30 min, and the reading of
the instrument at the end of interval shall be recorded. The reading (if provided) shall not
change by more than ±30 % or one unit of indication, whichever is greater.
The instrument shall then be exposed to a Cs source producing an air kerma rate of
–1
0,5 μGy·h over the ambient background level of radiation. The instrument shall function
correctly and shall alarm.
b) Temperature ramp tests – room temperature to high and low temperature extreme
The instrument shall be placed in a test chamber at a temperature of 20 °C ± 2 °C. The
temperature shall then be linearly changed to the extreme temperature (high or low) at a
–1
rate of approximately 10 °C·h . Reading changes occurring during this time period shall
be recorded. The temperature of the test chamber shall be maintained at the extreme
temperature level for 30 min and the reading of the instrument shall be recorded. The
reading (if provided) shall not change by more than ±30 % or one unit of indication,
whichever is greater.
The instrument shall then be exposed to a Cs source producing an air kerma rate of
–1
0,5 μGy·h over the ambient background level of radiation. The instrument shall function
correctly and shall alarm.
5.3.2 Humidity tests
5.3.2.1 Requirements
Over the range of relative humidity from 40 % to 93 % at 35 °C, the instrument shall function
–1
correctly and alarm at an increase in ambient background of 0,5 μGy·h . As a result of the
humidity change, the indication of the magnitude of the radiation field or the indication of the
air kerma rate (if provided) shall not change by more than ±30 % or one unit of indication,
whichever is greater.
There shall be no visible external damage to the instrument, and all control functions shall be
verified to be operating correctly.

62401 © IEC:2007 – 17 –
5.3.2.2 Method of test
The humidity tests may be performed along with the temperature tests, if the environmental

chamber can provide the appropriate settings for both tests.

The instrument shall be placed in an environmental chamber at a temperature of (20 ± 2) °C

and relative humidity of approximately 65 % and allowed to stabilize for 30 min. Any reading

changes occurring during this time period shall be recorded. The temperature and relative

humidity shall then be linearly increased to 35 °C and 93 %, respectively, at a rate of

approximately 10 % relative humidity per hour.
...