IEC 61031:2020

IEC 61031 ®
Edition 2.0 2020-07
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Nuclear facilities – Instrumentation and control systems – Design, location and
application criteria for installed area gamma radiation dose rate monitoring
equipment for use during normal operation and anticipated operational
occurrences
Installations nucléaires – Systèmes d'instrumentation et de contrôle-commande –
Critères de conception, d'implantation et d'application pour les matériels de
surveillance du débit de dose de rayonnement gamma à poste fixe, utilisés
pendant le fonctionnement normal et lors d'incidents de fonctionnement prévus

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IEC 61031 ®
Edition 2.0 2020-07
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Nuclear facilities – Instrumentation and control systems – Design, location and

application criteria for installed area gamma radiation dose rate monitoring

equipment for use during normal operation and anticipated operational

occurrences
Installations nucléaires – Systèmes d'instrumentation et de contrôle-commande –

Critères de conception, d'implantation et d'application pour les matériels de

surveillance du débit de dose de rayonnement gamma à poste fixe, utilisés

pendant le fonctionnement normal et lors d'incidents de fonctionnement prévus

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 13.280; 27.120.10 ISBN 978-2-8322-2197-6

– 2 – IEC 61031:2020 © IEC 2020
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 9
2 Normative references . 9
3 Terms and definitions . 10
4 Abbreviated terms . 11
5 Design principles . 11
5.1 Function and application criteria . 11
5.2 General requirements . 12
5.2.1 General characteristics and lifecycle . 12
5.2.2 Safety classification and applicable standards . 12
5.3 Range of measurements . 13
5.4 Location criteria . 13
5.4.1 General . 13
5.4.2 Detector assembly . 14
5.4.3 Processing assembly . 14
5.4.4 Alarm assembly . 14
5.5 Energy response . 14
5.6 Signal processing and display . 15
5.7 Power supply . 15
6 Functional test . 15
7 Qualification . 15
7.1 General . 15
7.2 Environmental qualification . 15
7.3 Seismic qualification . 16
7.4 Electromagnetic interference. 16
8 Calibration . 16
8.1 General . 16
8.2 Calibration and functional check . 16
8.2.1 General . 16
8.2.2 Initial calibration . 16
8.2.3 Calibration check after installation . 16
8.2.4 Functional check. 16
8.2.5 Countermeasures to loss of monitoring during calibration or functional
check . 17
8.3 Radiation calibration . 17
Annex A (informative) Examples of locations and measuring ranges of area radiation
monitors. 18
Annex B (informative) "Foldback" of detector . 20
Bibliography . 21

Figure B.1 – Foldback illustration . 20
Figure B.2 – GM recovery times . 20

Table 1 – Overview of the standards covering the domain of radiation monitoring in
nuclear facilities . 7
Table A.1 – Light water cooled reactor plants . 18
Table A.2 – Gas cooled reactor plants . 18
Table A.3 – Sodium cooled fast reactor plants . 19

– 4 – IEC 61031:2020 © IEC 2020
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
NUCLEAR FACILITIES –
INSTRUMENTATION AND CONTROL SYSTEMS –
DESIGN, LOCATION AND APPLICATION CRITERIA FOR
INSTALLED AREA GAMMA RADIATION DOSE RATE MONITORING
EQUIPMENT FOR USE DURING NORMAL OPERATION AND ANTICIPATED
OPERATIONAL OCCURRENCES
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
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rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 61031 has been prepared by subcommittee 45A: Instrumentation,
control and electrical power systems of nuclear facilities, of IEC technical committee 45: Nuclear
instrumentation.
This document is to be used in conjunction with IEC 60532:2010.
This second edition cancels and replaces the first edition published in 1990. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) The scope of the standard is extended from nuclear power plants to nuclear facilities and
the title is accordingly aligned.
b) The relevant standards published by IEC SC 45A since the publication of the first edition
are taken into account and refered to when relevant.

The text of this International Standard is based on the following documents:
FDIS Report on voting
45A/1328/FDIS 45A/1341/RVD
Full information on the voting for the approval of this International Standard can be found in the
report on voting indicated in the above table.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to
the specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
– 6 – IEC 61031:2020 © IEC 2020
INTRODUCTION
a) Technical background, main issues and organisation of the standard
This IEC standard specifically focuses on radiation monitoring systems used for normal
operation and anticipated operational occurrences in nuclear facilities such as nuclear power
plants.
This document is intended for use by purchasers in developing specifications for their plant
specific radiation monitoring systems and by manufacturers to identify needed product
characteristics when developing systems for normal operation and anticipated operational
occurrences. Some specific instrument characteristics such as measurement range, required
energy response, and ambient environment requirements will depend upon the specific
application. In such cases guidance is provided on determining the specific requirements, but
specific requirements themselves are not stated.
This document is intended to be used in conjunction with IEC 60532:2010.
For area gamma radiation dose rate monitoring equipment for accident and post-accident
conditions refer to IEC 60951-1 and IEC 60951-3 (not within the scope of this document).
b) Situation of the current standard in the structure of the IEC SC 45A standard series
IEC 61031 is at the third level in the hierarchy of SC 45A standards.
This document provides requirements for equipment for area radiation monitoring in normal
conditions in conjunction with IEC 60532. Other standards developed by SC 45A and SC 45B
provide guidance on instruments used for monitoring radiation as part of normal operations.
The IEC 60761 series provides requirements for equipment for continuous off-line monitoring
of radioactivity in gaseous effluents in normal conditions. IEC 60861 provides requirements for
equipment for continuous off-line monitoring of radioactivity in liquid effluents in normal
conditions. IEC 60768 provides requirements for equipment for continuous in-line and on-line
monitoring of radioactivity in process stream in normal and incident conditions. Finally,
ISO 2889 gives guidance on gas and particulate sampling. In addition, IEC 62705 was issued
on July 2014. IEC 62705 provides guidance on the application of existing IEC/ISO standards
covering design and qualification of system and equipment for RMS, and the overviews of the
standards covering the radiation monitoring in nuclear facilities are listed in Table 1 below.

Table 1 – Overview of the standards covering
the domain of radiation monitoring in nuclear facilities
IEC
Developer ISO
SC 45A SC 45B
Accident and
Scope Sampling Calibration post accident Normal conditions
conditions
IEC 62302,
ISO 4037-1, IEC 60951-1,
Radioactive noble gas
ISO 2889 N/A IEC 60761-1,
off-line monitoring
ISO 4037-3 IEC 60951-2
IEC 60761-3
ISO 4037-1, IEC 60951-1, IEC 60761-1,
Radioactive aerosol off-
ISO 2889 N/A
line monitoring
ISO 4037-3 IEC 60951-2 IEC 60761-2
ISO 4037-1, IEC 60951-1, IEC 60761-1,
Radioactive iodine off-
ISO 2889 N/A
line monitoring
ISO 4037-3 IEC 60951-2 IEC 60761-4
Liquid off-line
N/A N/A N/A N/A IEC 60861
monitoring
IEC 62303 /
Tritium off-line
N/A N/A N/A N/A IEC 60761-1,
monitoring
IEC 60761-5
ISO 4037-1, IEC 60951-1,
On-line or in-line
N/A IEC 60768 N/A
monitoring
ISO 4037-3 IEC 60951-4
ISO 4037-1, IEC 60951-1,
Area monitoring N/A IEC 61031 IEC 60532
ISO 4037-3 IEC 60951-3
Centralized system N/A N/A IEC 61504, IEC 60960 IEC 61559-1
IEC 61513, IEC 60880,
IEC 60987, IEC 61226,
Classification/basic
N/A N/A IEC 62138, IEC 62566, N/A
requirements
IEC 62645, IEC 61250
IEC 61500, IEC 61504
IEC 60980, IEC 62003,
Qualification N/A N/A IEC 62706
IEC/IEEE 60780-323
For more details on the structure of the IEC SC 45A standard series, see item d) of this
introduction.
c) Recommendations and limitations regarding the application of this Standard
It is important to note that this document establishes no additional functional requirements for
safety systems.
d) Description of the structure of the IEC SC 45A standard series and relationships with
other IEC documents and other bodies’ documents (IAEA, ISO)
The top-level documents of the IEC SC 45A standard series are IEC 61513 and IEC 63046.
IEC 61513 provides general requirements for I&C systems and equipment that are used to
perform functions important to safety in NPPs. IEC 63046 provides general requirements for
electrical power systems of NPPs; it covers power supply systems including the supply systems
of the I&C systems. IEC 61513 and IEC 63046 are to be considered in conjunction and at the
same level. IEC 61513 and IEC 63046 structure the IEC SC 45A standard series and shape a
complete framework establishing general requirements for instrumentation, control and
electrical systems for nuclear power plants.

– 8 – IEC 61031:2020 © IEC 2020
IEC 61513 and IEC 63046 refer directly to other IEC SC 45A standards for general topics
related to categorization of functions and classification of systems, qualification, separation,
defence against common cause failure, control room design, electromagnetic compatibility,
cybersecurity, software and hardware aspects for programmable digital systems, coordination
of safety and security requirements and management of ageing. The standards referenced
directly at this second level should be considered together with IEC 61513 and IEC 63046 as a
consistent document set.
At a third level, IEC SC 45A standards not directly referenced by IEC 61513 or by IEC 63046
are standards related to specific equipment, technical methods, or specific activities. Usually
these documents, which make reference to second-level documents for general topics, can be
used on their own.
A fourth level extending the IEC SC 45A standard series, corresponds to the technical reports
which are not normative.
The IEC SC 45A standards series consistently implements and details the safety and security
principles and basic aspects provided in the relevant IAEA safety standards and in the relevant
documents of the IAEA nuclear security series (NSS). In particular this includes the IAEA
requirements SSR-2/1, establishing safety requirements related to the design of nuclear power
plants (NPPs), the IAEA safety guide SSG-30 dealing with the safety classification of structures,
systems and components in NPPs, the IAEA safety guide SSG-39 dealing with the design of
instrumentation and control systems for NPPs, the IAEA safety guide SSG-34 dealing with the
design of electrical power systems for NPPs and the implementing guide NSS17 for computer
security at nuclear facilities. The safety and security terminology and definitions used by
SC 45A standards are consistent with those used by the IAEA.
IEC 61513 and IEC 63046 have adopted a presentation format similar to the basic safety
publication IEC 61508 with an overall life-cycle framework and a system life-cycle framework.
Regarding nuclear safety, IEC 61513 and IEC 63046 provide the interpretation of the general
requirements of IEC 61508-1, IEC 61508-2 and IEC 61508-4, for the nuclear application sector.
In this framework IEC 60880, IEC 62138 and IEC 62566 correspond to IEC 61508-3 for the
nuclear application sector. IEC 61513 and IEC 63046 refer to ISO as well as to IAEA GS-R-3
and IAEA GS-G-3.1 and IAEA GS-G-3.5 for topics related to quality assurance (QA). At level 2,
regarding nuclear security, IEC 62645 is the entry document for the IEC/SC 45A security
standards. It builds upon the valid high level principles and main concepts of the generic
security standards, in particular ISO/IEC 27001 and ISO/IEC 27002; it adapts them and
completes them to fit the nuclear context and coordinates with the IEC 62443 series. At level 2,
regarding control rooms, IEC 60964 is the entry document for the IEC/SC 45A control rooms
standards and IEC 62342 is the entry document for the IEC/SC 45A ageing management
standards.
NOTE 1 It is assumed that for the design of I&C systems in NPPs that implement conventional safety functions (e.g.
to address worker safety, asset protection, chemical hazards, process energy hazards) international or national
standards would be applied.
NOTE 2 The IEC/SC 45A domain was extended in 2013 to cover electrical systems. In 2014 and 2015 discussions
were held in IEC/SC 45A to decide how and where general requirements for the design of electrical systems were to
be considered. IEC/SC 45A experts recommended that an independent standard be developed at the same level as
IEC 61513 to establish general requirements for electrical systems. Project IEC 63046 is now launched to cover this
objective. When IEC 63046 is published this NOTE 2 of the introduction of IEC/SC 45A standards will be suppressed.

NUCLEAR FACILITIES –
INSTRUMENTATION AND CONTROL SYSTEMS –
DESIGN, LOCATION AND APPLICATION CRITERIA FOR
INSTALLED AREA GAMMA RADIATION DOSE RATE MONITORING
EQUIPMENT FOR USE DURING NORMAL OPERATION AND ANTICIPATED
OPERATIONAL OCCURRENCES
1 Scope
This document applies to the design, location and application of installed equipment for
monitoring local gamma radiation dose rates within nuclear facilities during normal operation
and anticipated operational occurrences. High range area gamma radiation dose rate
monitoring equipment for accident conditions currently addressed by IEC 60951-1 and
IEC 60951-3 is not within the scope of this document.
This document does not apply to the measurement of neutron dose rate. Additional equipment
for neutron monitoring may be required, depending on the plant design, if the neutron dose
rate makes a substantial contribution to the total dose equivalent to personnel.
This document provides guidelines for the design principles, the location, the application,
the calibration, the operation, and the testing of installed equipment for continuously
monitoring local gamma radiation dose rates in nuclear facilities under normal operation
conditions and anticipated operational occurrences. These instruments are normally referred
to as area radiation monitors. Portable instruments are also used for this purpose but are not
covered by this document.
Radiation monitors utilized in area radiation monitoring equipment are addressed in
IEC 60532. As discussed in IEC 60532, measurement of gamma radiation may be expressed
by a number of alternative quantities depending on national regulations. However, for this
type of instrument, the most likely quantity to be measured is the air kerma (Gy), or the
ambient dose equivalent H*(10)(Sv).
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.
IEC 60050-395:2014, International Electrotechnical Vocabulary – Part 395: Nuclear
instrumentation: Physical phenomena, basic concepts, instruments, systems, equipment and
detectors
IEC 60532:2010, Radiation protection instrumentation – Installed dose rate meters, warning
assemblies and monitors – X and gamma radiation of energy between 50 keV and 7 MeV
IEC 60880:2006, Nuclear power plants – Instrumentation and control systems important to
safety – Software aspects for computer-based systems performing category A functions
IEC 60951-1:2009, Nuclear power plants – Instrumentation important to safety – Radiation
monitoring for accident and post-accident conditions – Part 1: General requirements

– 10 – IEC 61031:2020 © IEC 2020
IEC 60951-3:2009, Nuclear power plants – Instrumentation important to safety – Radiation
monitoring for accident and post-accident conditions – Part 3: Equipment for continuous high
range area gamma monitoring
IEC 60980:1989, Recommended practices for seismic qualification of electrical equipment of
the safety system for nuclear generating stations
IEC 60987:2007, Nuclear power plants – Instrumentation and control important to safety –
Hardware design requirements for computer-based systems
IEC 61226:2009, Nuclear power plants – Instrumentation and control important to safety –
Classification of instrumentation and control functions
IEC 61513:2011, Nuclear power plants – Instrumentation and control important to safety –
General requirements for systems
IEC 62003:2020, Nuclear power plants – Instrumentation, control and electrical power systems
– Requirements for electromagnetic compatibility testing
IEC 62138:2018, Nuclear power plants – Instrumentation and control systems important to
safety – Software aspects for computer-based systems performing category B or C functions
IEC 62566:2012, Nuclear power plants – Instrumentation and control important to safety –
Development of HDL-programmed integrated circuits for systems performing category A
functions
IEC 62705:2014, Nuclear power plants – Instrumentation and control important to safety –
Radiation monitoring systems (RMS): Characteristics and lifecycle
IEC/IEEE 60780-323:2016, Nuclear facilities – Electrical equipment important to safety –
Qualification
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60050-395 as well as
the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
NOTE Specific terminology for the radiation monitoring system is given in IEC 62705 and specific terminology for
the area radiation monitor is given in IEC 60532
3.1
anticipated operational occurrence
deviation of an operational process from normal operation that is expected to occur at least
once during the operating lifetime of a facility but which, in view of appropriate design provisions,
does not cause any significant damage to items important to safety or lead to accident
conditions
[SOURCE: IAEA Safety Glossary, 2018 edition]

3.2
area radiation monitor
equipment designed for continuously monitoring local gamma radiation dose rates in a fixed
position in a nuclear facility
Note 1 to entry: The equipment usually consists of a gamma radiation sensitive detector, a signal processing unit,
interconnecting cables for signal transmission and a power supply. It is used to measure and display, locally and/or
at some remote location, the radiation dose rate present at the detector location.
3.3
calibration check
calibration procedure which is followed periodically on each area radiation monitor to ensure
that the response of the equipment remains within specified limits
3.4
local dose rate
dose rate at the detector location measured in whatever radiation dose rate quantity approved
under national regulations and displayed on the instrument in appropriate units
Note 1 to entry: See also IEC 60532.
3.5
normal operation
operation within specified operational limits and conditions
[SOURCE: IAEA Safety Glossary, 2018 edition]
4 Abbreviated terms
EMC Electromagnetic Compatibility
HPD HDL (hardware description language) – Programmed Device
I&C Instrumentation and Control
IAEA International Atomic Energy Agency
IEC International Electrotechnical Commission
ISO International Organization for Standardization
KERMA Kinetic Energy Released per unit MAss
NPP Nuclear Power Plant
NSLR National Standardizing Laboratory of a country for Radioactivity measurement
RMS Radiation Monitoring System

5 Design principles
5.1 Function and application criteria
The primary purpose of area radiation monitors is to protect personnel by alerting them to
significant changes in radiation levels. To this end, the monitors measure continuously the
gamma radiation dose rate in defined areas of a nuclear facility, and inform plant personnel by
audible and/or visual alarms when predetermined dose rate levels are exceeded. Items such
as meters, displays and alarm indicators, etc., shall be designed so that plant personnel in the
vicinity of the local indication devices can quickly and easily determine the conditions in the areas
monitored.
Area radiation monitors serve to protect plant personnel against radiation hazards and to inform
them immediately when predetermined radiation levels are exceeded within the plant.

– 12 – IEC 61031:2020 © IEC 2020
NOTE Area radiation monitors are not normally used for personnel dosimetry purposes, except as a source of
backup information, nor are they normally used for the determination of the length of time which personnel are
permitted to remain within radiation fields. They complement rather than replace operational health physics
measurements and procedures including use of portable equipment. Nevertheless, they can also provide
information on the effectiveness of such procedures.
Because of their location, area radiation monitors may also be capable of indicating changes in
plant parameters which are of interest to the plant operator. Where this is the case, monitor
output functions shall be available at a remote location, usually the plant control room or an
associated area.
Area radiation monitors may also be used for interlocks and/or for initiating protective actions.
In some cases, they may even be considered as inputs to reactor safety systems, although this
would not normally be regarded as good practice.
Area radiation monitors may also be used under accident conditions if the range of
measurement is appropriate to the defined purpose and all sub-assemblies are qualified for
the accident environmental conditions at their locations. This application is covered in more
detail in IEC 60951-1 and IEC 60951-3.
5.2 General requirements
5.2.1 General characteristics and lifecycle
The design of the area radiation monitor shall meet the requirements of IEC 60532.
Furthermore, the additional specific requirements given in IEC 61031 shall be met.
If signals from area radiation monitors are used as inputs to interlock systems or plant and/or
reactor safety systems, the design of such monitors shall also meet the appropriate
requirements of such systems (for example, in respect to interface requirements, classification,
reliability, qualification, etc.).
In the selection of the area radiation monitor, consideration shall be given to the range of
measurement, temperature, pressure, humidity, electromagnetic interference, vibration,
expected total integrated dose and seismic qualification in the areas where the equipment and
in particular the detector will be located. Any requirements to extend the normal
environmental specifications shall be identified (see IEC 60532).
The area radiation monitor performing functions that are important to safety shall comply with
the requirements relating to the characteristics and lifecycle of RMSs defined in IEC 62705 and
the standards referenced in IEC 62705 (e.g. IEC 61226).
5.2.2 Safety classification and applicable standards
The area radiation monitor shall be classified according to its suitability to implement I&C
functions up to a defined category during the system specification phase as shown in
IEC 61513:2011, 6.2.3.
According to the category of the function implemented, the following standards shall be applied:
a) System and equipment performing category A functions
Any software in the area radiation monitor performing category A function shall be designed
and maintained in accordance with IEC 60880. Any HDL-Programmed Device (HPD) in the
equipment of the area radiation monitor performing category A function shall be designed
and maintained in accordance with IEC 62566. Any hardware in the area radiation monitor
performing category A function and including software or HPD shall be designed and
maintained in accordance with IEC 60987.

b) System and equipment performing category B or C functions
Any software in the area radiation monitor performing category B or C function shall be
designed and maintained in accordance with IEC 62138. Any hardware in the area radiation
monitor performing category B function and including software shall be designed and
maintained in accordance with IEC 60987. Hardware performing category C function in the
area radiation monitor shall be designed, selected and maintained according to the
supplier's requirements.
5.3 Range of measurements
The required area radiation monitoring range shall be specified as agreed between
manufacturer and purchaser. These ranges shall take into account the radiation environment
of the plant design on the basis of:
– the expected minimum gamma radiation dose rate and whether it is desirable to monitor that
rate,
– the expected dose rate in normal operating conditions, and
– the expected peak dose rate under anticipated operational occurrences.
The measuring range shall normally be high enough to assure an on-scale reading for radiation
dose rates up to the expected peak dose rate under anticipated operational occurrences.
However, when high transient dose rates occur in areas during periods when personnel access
is prevented, it may not be necessary to meet this requirement. In order to avoid false dose rate
indication in this situation, the radiation monitoring system shall comply with the overload
testing specified in IEC 60532.
In the event of a high transient dose rate, the instrument shall maintain on over-range indication
and alarm status. It is necessary to avoid "foldback" of the detector. "Foldback" is shown in
Annex B.
Unless otherwise specified, the area radiation monitor shall at least cover the measuring
−5 −2
range of 10 Gy/h or Sv/h to 10 Gy/h or Sv/h. It is expected that, in most applications, a
measuring range of four or five decades will be used (see Annex A). Six or more decades
may be required for some special applications.
Examples of ranges of measurement of area radiation monitors in boiling and pressurized light
water reactors, gas cooled reactors and sodium cooled fast reactors are given in Annex A.
5.4 Location criteria
5.4.1 General
Location criteria and safety requirements for area radiation monitors shall be appropriate to the
plant design.
Generally, they will be required at those locations which can be routinely entered by plant
personnel and where one or more of the following plant conditions are identified:
a) where the dose rates are significant and may increase rapidly and without other indication;
b) where the radiation dose rate can increase sufficiently to require evacuation of personnel;
c) where occasional high radiation dose rates might preclude access at certain times;
d) where the dose rate data is required prior to personnel access;
e) where the dose rate can rapidly increase due to external operation of the controls by others.
In addition, area radiation monitors may be required at locations such as access routes and plant
areas where access is essential under accident conditions.

– 14 – IEC 61031:2020 © IEC 2020
Examples of locations of area radiation monitors in different types of nuclear facilities are given
in Annex A.
Area radiation monitors will normally be required to monitor the local radiation dose rate inside a
containment building where personnel access is possible. The detector location will normally
be immediately inside all entrances (personnel and equipment locks) and other locations, where
regular access is required.
Because periodic calibration and maintenance of area radiation monitors generally require
access to the detector assembly in order to expose it to an appropriate radiation field, care
shall be taken in choosing the location of this assembly so as to facilitate introduction of a
suitable radiation source or field generator and to minimize radiation scatter as well as access
problems to the equipment to be calibrated.
The detector location shall be chosen, as far as is consistent with the required monitor
function, in order to avoid adverse environmental conditions and significant levels of
electromagnetic interference.
Depending on the technical solution chosen (i.e. ionization chamber detectors, scintillation
detector) one important location criteria should also be (to the extent possible) to minimize the
required cabling length between the detector assembly and the processing assembly.
5.4.2 Detector assembly
The radiation detector assembly shall be located so that the radiation dose rate which is
measured is representative of the radiation dose rate to personnel in the monitored area (e.g.
the location of the detector assembly shall be such that inadvertent shielding by structural
material is minimized). Mounting of the detector assembly shall be realized such, that the
preferential direction of the detector is oriented to the area to be monitored.
5.4.3 Processing assembly
The location of the processing assembly shall be chosen to be compatible with its maximum
withstand total integrated dose without failure.
5.4.4 Alarm assembly
The alarm assembly location shall be chosen to provide as far as possible warning to operators
before they enter a high radiation area (e.g. outside the entrance to the containment
building or enclosed areas). Audible and visible alarm assemblies shall be located to warn
personnel who may be in areas of high radiation dose rate and personnel who may be
approaching such areas.
In some circumstances, it may be appropriate to use either audible or visible alarms alone.
5.5 Energy response
The radiation area monitor shall measure the dose rate due to gamma rays of the energy range
of at least 80 keV to 1,5 MeV according to IEC 60532.
If more than 20 % of the local gamma radiation dose rate to be measured is due to gamma
radiation having an energy less than 80 keV or more than 1,5 MeV (e.g. gamma radiation of
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the isotopes N and/or Kr), the effective response of the monitor shall be extended to cover
the appropriate photon energy.

5.6 Signal processing and display
Area radiation monitors inform and warn personnel in working areas and in the control room or
other locations about the gamma radiation level (and its variation) within the plant. Therefore,
appropr
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