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

IEC 61031:2020 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.

General Information

Status
Published
Publication Date
27-Jul-2020
Current Stage
PPUB - Publication issued
Completion Date
28-Jul-2020
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IEC 61031
Edition 2.0 2020-07
INTERNATIONAL
STANDARD
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
IEC 61031:2020-07(en)
---------------------- Page: 1 ----------------------
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---------------------- Page: 2 ----------------------
IEC 61031
Edition 2.0 2020-07
INTERNATIONAL
STANDARD
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
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 13.280; 27.120.10 ISBN 978-2-8322-8586-2

Warning! Make sure that you obtained this publication from an authorized distributor.

® Registered trademark of the International Electrotechnical Commission
---------------------- Page: 3 ----------------------
– 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

---------------------- Page: 4 ----------------------
IEC 61031:2020 © IEC 2020 – 3 –

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

---------------------- Page: 5 ----------------------
– 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

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

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any IEC Publication and the corresponding national or regional publication shall be clearly indicated in the latter.

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services carried out by independent certification bodies.

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

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other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and

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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 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.
---------------------- Page: 6 ----------------------
IEC 61031:2020 © IEC 2020 – 5 –
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.
---------------------- Page: 7 ----------------------
– 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.

---------------------- Page: 8 ----------------------
IEC 61031:2020 © IEC 2020 – 7 –
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.
---------------------- Page: 9 ----------------------
– 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.

---------------------- Page: 10 ----------------------
IEC 61031:2020 © IEC 2020 – 9 –
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

---------------------- Page: 11 ----------------------
– 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]
---------------------- Page: 12 ----------------------
IEC 61031:2020 © IEC 2020 – 11 –
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
...

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