IEC 62705 Edition 1 0 2014 07 INTERNATIONAL STANDARD NORME INTERNATIONALE Nuclear power plants – Instrumentation and control important to safety – Radiation monitoring systems (RMS) Characteristics an[.]
Function categorization for RMS
RMS in nuclear power plants continuously monitors radiological conditions by measuring radiation levels in designated areas, process lines, and at release points for gases and liquids It triggers alarms and can automatically respond when radioactivity levels exceed predefined abnormal thresholds.
The plant safety design base classifies individual RMS functions critical to safety into three categories: A, B, or C, based on their interconnections with other systems The design requirements for these systems and equipment align with Clause 7 of IEC 61226:2009 This categorization is determined during the system requirement specification phase.
System classification for RMS
RMS 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 6.2.3 of IEC 61513:2011
Examples of the classification for RMS installed in PWR and BWR plants are shown in
According to the category of the function, the following standards shall be applied to each system and equipment a) System and equipment performing category A functions
Any software in RMS performing category A function shall be designed and maintained in accordance with IEC 60880 Any HDL-Programmed Device (HPD) in the equipment of
RMS performing category A function shall be designed and maintained in accordance with
IEC 62566 Any hardware in RMS 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
Software in RMS that performs category B or C functions must be designed and maintained according to IEC 62138 standards Additionally, any hardware in RMS that performs category B functions, along with its software, must also adhere to these design and maintenance requirements.
IEC 60987 Hardware performing category C function shall be designed, selected and maintained according to the supplier's requirements which can meet the application specific qualification requirements
6 RMS detailed design and implementation
General
RMS generally consists of a combination of following equipment:
The above equipment may have resident software
The RMS shall be designed and implemented in accordance with appropriate requirements shown in the following standards.
Radioactive noble gas off-line monitoring
RMS for radioactive noble gas off-line monitoring is used for the following purposes:
The monitor is designed to measure the volumetric activity of radioactive noble gases in gaseous effluents at the discharge point, as well as to track variations in volumetric activity Additionally, it can be utilized to determine the total discharge of radioactive noble gases over a specified time period.
To assess the volumetric activity in air or gas systems, including control room ventilation, reactor leakage collection, drywell ventilation exhaust, fuel handling building ventilation exhaust, and reactor building ventilation purge exhaust, it is essential to detect any significant increases in radioactivity.
For RMS designed only for normal operation condition, the design and testing of RMS shall be performed in accordance with IEC 60761-1 and IEC 60761-3 Instead of the set of
IEC 60761-1 and IEC 60761-3, IEC 62302 may be used alternatively
RMS intended for accident conditions must be designed and tested according to IEC 60951-1 and IEC 60951-2 standards Additionally, the sampling assembly utilized for monitoring RMS should adhere to the design and testing requirements outlined in ISO 2889.
Radioactive aerosol off-line monitoring
RMS for radioactive aerosol off-line monitoring is used for the following purposes:
The monitor is designed to measure the volumetric activity of radioactive aerosols in gaseous effluents at the discharge point, as well as to track variations in volumetric activity Additionally, it can be utilized to determine the total discharge of radioactive aerosols over a specified time period.
To assess the volumetric activity in air or gas systems, including control room ventilation, reactor leakage collection, drywell ventilation exhaust, fuel handling building ventilation exhaust, and reactor building ventilation purge exhaust, it is crucial to detect any significant increases in radioactivity.
RMS designed for normal operating conditions must adhere to IEC 60761-1 and IEC 60761-2 for design and testing In contrast, RMS intended for accident conditions should follow IEC 60951-1 and IEC 60951-2 standards Additionally, the sampling assembly for RMS utilized in monitoring must be designed and tested according to ISO 2889.
Radioactive iodine off-line monitoring
RMS for radioactive iodine off-line monitoring is used for the following purposes:
The measurement of volumetric activity of radioactive iodines in gaseous effluents at the discharge point is essential for monitoring environmental safety This process also tracks variations in volumetric activity, providing critical data Additionally, the monitor can determine the total discharge of radioactive iodine over a specified time period, ensuring comprehensive assessment and compliance with safety regulations.
To assess the volumetric activity in air or gas systems, it is essential to monitor areas such as control room ventilation, reactor leakage collection, drywell ventilation exhaust, fuel handling building ventilation exhaust, and reactor building ventilation purge exhaust This monitoring helps in detecting any significant increases in radioactivity.
RMS designed for normal operation must adhere to IEC 60761-1 and IEC 60761-4 for design and testing, while those intended for accident conditions should follow IEC 60951-1 and IEC 60951-2 Additionally, the sampling assembly for RMS utilized in monitoring is required to be designed and tested according to ISO 2889.
Liquid off-line monitoring
RMS for continuous liquid off-line monitoring is used for following purposes:
To assess the volumetric activity of liquids at discharge points or surface water, a monitor can be utilized to measure both the volumetric activity and its variations Additionally, this device is effective for determining the total discharge of radioactive materials in liquid over a specified timeframe.
The design and testing of RMS shall be performed in accordance with IEC 60861.
Tritium off-line monitoring
RMS for continuous radioactive tritium off-line monitoring is used for following purposes:
The monitor is designed to measure the volumetric activity of tritium in gaseous effluents at the discharge point, as well as track variations in this activity Additionally, it can be utilized to determine the total discharge of tritium over a specified time period.
The design and testing of RMS shall be performed in accordance with IEC 60761-1 and
IEC 60761-5 Instead of the set of IEC 60761-1 and IEC 60761-5, IEC 62303 can be used alternatively.
On-line or in-line monitoring
RMS for online or inline monitoring is essential for continuous measurement, typically accomplished by placing detectors within the process stream, such as in a pipe or tank When designing RMS specifically for normal operating conditions, it is crucial that the design and testing adhere to established standards.
IEC 60768 For RMS designed for accident conditions, the design and testing of RMS shall be performed in accordance with IEC 60951-1 and IEC 60951-4.
Area monitoring
RMS for area monitoring is essential for tracking gamma radiation levels in nuclear power plants (NPP) For systems intended solely for normal operational conditions, the design and testing must adhere to IEC 61031 alongside IEC 60532 In contrast, RMS designed for accident scenarios requires compliance with specific standards for design and testing.
Centralized system
The centralized system collects and processes radiation data from across the plant, delivering essential information to operations personnel while also handling data recording, validation, display, and system control Its design and testing adhere to IEC 61504 and the IEC 61559 series, which outline the necessary requirements for such systems Additionally, if the centralized system is integrated into the safety parameter display system, its design must comply with IEC 60960 standards.
Leak detection
In addition to the above requirements, RMS shall be designed and tested in accordance with
IEC 61250 if the RMS is intended to be used for the leak detection in NPPs
RMS integration
System integration is performed by assembling and interconnecting the equipment of RMS as designed.
RMS validation
Following system integration, it is essential to verify that the integrated system meets all functional, performance, and interface specifications This validation process includes conducting tests on the system in its final equipment configuration Additionally, during system validation, it is crucial to assess the interfaces with other systems, including not only instrumentation and control (I&C) systems but also piping and mechanical components.
Following the system integration and validation, the RMS equipment is installed at the designated location within the NPP It is essential to verify that the environmental, seismic, and electromagnetic interference conditions at the site fall within the established qualification envelope.
During and after installation, testing will be conducted to ensure compliance with requirements, including verification of interfaces with other systems, such as instrumentation and control (I&C) systems, as well as piping and mechanical components.
The installed location of the equipment of RMS shall be designed in accordance with appropriate specific RMS standards shown in Clause 6 or NPP location design
Prior to the commissioning of the RMS in a Nuclear Power Plant (NPP), it is essential to conduct calibration Calibration records, generated in line with the specific RMS standards outlined in Clause 6, may be deemed acceptable for certain calibration documentation The initial calibration can be carried out during the installation process.
Modifications to the RMS design may be necessary when new system requirements are identified or when design defects are discovered during the evaluation of operational records and reports Key activities for implementing these modifications include thorough analysis and assessment of the existing system.
– the implementation of a modification to a system shall be carried out in accordance with defined procedures;
– testing of the correct operation of the system shall be done after a modification in accordance with the applicable referenced documents identified in Clause 6;
– no hardware/software modification, other than those specified in the maintenance procedures, shall be allowed as a matter of routine;
– should replacement hardware be required, it shall be demonstrated/justified that the replacement meets the specification of the original hardware
General
The qualification envelope for RMS equipment must meet the environmental standards of the NPP installation site A justification is required to demonstrate this compliance Additionally, the qualification requirements outlined here take precedence over those specified in the radiation monitor standards mentioned in Clause 6, even though each individual standard may have its own qualification criteria.
Environmental qualification
RMS is committed to ensuring specified accuracy and performance across a range of environmental conditions during normal plant operations In the event of an accident, RMS will also uphold these standards for accuracy and performance The environmental qualification for RMS will be conducted in accordance with IEC 60780 for equipment performing category A or B functions.
Equipment designated for category C functions, which necessitate specific environmental qualifications such as seismic resistance or operation under particular conditions, may be certified to industrial standards Any claims regarding performance in abnormal environmental conditions or seismic qualifications must be supported by documented evidence In cases where significant aging factors are present and qualified life cannot be established per IEC 60780, an ongoing qualification program must be proposed and justified in accordance with IEC 60780.
Seismic qualification
RMS must be engineered to endure seismic events while ensuring that its accuracy and performance remain intact during and after such occurrences The seismic qualification process should adhere to IEC 60980 standards for equipment classified under category A.
Electromagnetic interference
To mitigate the effects of electromagnetic interference (EMI) from equipment, necessary precautions must be implemented Unless a different agreement is established between the purchaser and the manufacturer, the evaluation of electromagnetic interference should adhere to the standards set by IEC 62003.
General
Calibration of the RMS is conducted as part of maintenance activities outlined in this Clause Any operation and maintenance tasks for the RMS not specified here will follow the guidelines set by IEC 61513.
Periodical calibration and functional check
General
RMS shall maintain the specified accuracy and performance features during operating period
For this purpose, calibration checks and functional checks shall be performed periodically.
Calibration check after installation
After installation, it is essential to conduct periodic calibration checks If the RMS equipment, particularly the detector assembly, cannot be relocated during the calibration period, alternative measures must be implemented to perform the calibration checks without removing the RMS equipment from its installed position.
Functional check
Periodic checks of RMS functions are essential The functional check procedure should align with the equipment standards outlined in Clause 6 or follow the manufacturer's instruction manual.
Countermeasures to loss of monitoring during calibration or functional
If the loss of monitoring functions during calibration or functional check period is not permitted, additional measures, such as alternative monitoring, shall be provided.
Radiation calibration
Radiation calibration shall be performed in accordance with equipment standards shown in
Clause 6 ISO 4037-1 and ISO 4037-3 are also referenced in the specific RMS standards as appropriate The quantity of radiation or radioactivity should be traceable to the National
The National Standardizing Laboratory for Radioactivity Measurements (NSLR) in the country where the Radiological Measurement System (RMS) is installed will ensure that calibration results are documented in compliance with the equipment standards outlined in Clause 6 and ISO 4037-3.
Calibration for other quantity
Other instruments such as flow meter, pressure gauge, etc., shall be calibrated according to the manufacturers’ instruction.
Traceability
When the calibration country of RMS equipment differs from the installation country, traceability of the calibration is acceptable if both countries are accredited under a Multi Recognition Agreement (MRA) for the calibrated quantity.
Example of safety classification for RMS important to safety
This annex presents an example of safety classification for Radiation Monitoring Systems (RMS) that are crucial for safety, as shown in Table A.1 It is important to emphasize that the actual classification of radiation monitors must be determined based on a safety analysis that adheres to national and/or international regulations applicable to the Nuclear Power Plant (NPP) where the RMS is implemented.
Table A.1 – Example of safety classification for RMS important to safety
Corresponding I&C functions for RMS and
IEC 61226 safety category Radiation monitor
Initiate signals to actuate safety function
Post accident monitoring Main cooling system isolation
Communi- cation to warn of significant on- or offsite release of radioactive materials
A (B) (C) 1 Main control room supply air duct radiation monitor Containment high range radiation monitor
Main steam line tunnel area radiation monitor Drywell sumps discharge radiation monitor
Reactor building vent exhaust radiation monitor
Fuel handling area air vent exhaust radiation monitor
Control building air intake radiation monitor
Drywell fission product radioactive gas radiation monitor Drywell fission product radioactive aerosol radiation monitor
C 3 Plant vent radiation monitor Main steam line radiation monitor Turbine island vent discharge radiation monitor
Steam generator blowdown radiation monitor
Standby gas treatment system offgas radiation monitor
Plant stack discharge radiation monitor Turbine building vent exhaust radiation monitor
Turbine gland seal condenser offgas radiation monitor Area radiation monitor
Relation between IEC 61513 system lifecycle and IEC 62705 requirements
This annex provides the relation between IEC 61513 system lifecycle phase and IEC 62705
RMS lifecycle requirements (Table B.1) The IEC 62705 requirements are the supplements of
IEC 61513 and it is not intended that IEC 62705 limits the application of other IEC 61513 requirements to RMS lifecycle
Table B.1 – Relation between IEC 61513 system lifecycle and IEC 62705 requirements
IEC 61513 System lifecycle phase IEC 62705 RMS lifecycle requirements
6.2.2 System requirement specification 5.1 Function categorization for RMS
6.2.3 System Specification 5.2 System classification for RMS
6.2.4 System detailed design and implementation 6 RMS detailed design and implementation
6.2.8 System design modification 9 RMS design modification
8 Overall operation and maintenance 11.2 Periodical calibration and functional check
5 Catégorisation et classement des SSR 34
5.1 Catégorisation des fonctions du SSR 34
6 Conception détaillée et mise en œuvre du SSR 34
6.2 Surveillance hors ligne des gaz rares radioactifs 35
6.3 Surveillance hors ligne des aérosols radioactifs 35
6.4 Surveillance hors ligne de l'iode radioactif 35
6.5 Surveillance hors ligne des liquides 36
6.6 Surveillance hors ligne du tritium 36
7 Intégration et validation du SSR 37
11.2 Etalonnage périodique et vérification fonctionnelle 39
11.2.4 Contre-mesures à la perte de surveillance pendant la vérification d'étalonnage ou la vérification fonctionnelle 39 11.3 Etalonnage des rayonnements 39
Annexe A (informative) Exemple de classement de sûreté pour les SSR importants pour la sûreté 40
Annexe B (informative) Relation entre le cycle de vie du système de l’IEC 61513 et les exigences de l’IEC 62705 42
Tableau 1 – Présentation des normes couvrant le domaine de la surveillance des rayonnements dans les centrales nucléaires de puissance 27
Tableau A.1 – Exemple de classement de sûreté pour les SSR importants pour la sûreté 40
Tableau B.1 – Relation entre le cycle de vie du système de l’IEC 61513 et les exigences de l’IEC 62705 42
CENTRALES NUCLÉAIRES DE PUISSANCE – INSTRUMENTATION ET CONTRÔLE-COMMANDE IMPORTANTS
POUR LA SÛRETÉ – SYSTÈMES DE SURVEILLANCE DES
RAYONNEMENTS (SSR): CARACTÉRISTIQUES ET CYCLE DE VIE
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La Norme internationale IEC 62705 a été établie par le sous-comité 45A: Systèmes d’instrumentation, de contrôle-commande et électriques des installations nucléaires, du comité d'études 45 de l’IEC: Instrumentation nucléaire
Le texte de cette norme est issu des documents suivants:
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Cette publication a été rédigée selon les Directives ISO/IEC, Partie 2
The committee has determined that the content of this publication will remain unchanged until the stability date specified on the IEC website at "http://webstore.iec.ch" in relation to the sought publication On that date, the publication will be updated.
• remplacée par une édition révisée, ou
INTRODUCTION a) Contexte technique, questions importantes et structure de la présente Norme
The IEC standard outlines the lifecycle management requirements for radiation monitoring systems (RMS) installed in nuclear power plants (NPPs) It applies to RMS hardware and is intended for use during normal operations, as well as during anticipated operational incidents, and for certain monitoring systems under accidental conditions Additionally, this standard may be applicable to other nuclear facilities, such as nuclear fuel storage and processing sites, by assessing the differences from nuclear power plants.
The purpose of this standard is to be utilized by operators of nuclear power plants, system evaluators, and regulators Additionally, it outlines the position of this standard within the IEC SC 45A collection of standards.
IEC 62705 is the third level in the hierarchy of standards for SC 45A This standard offers recommendations for applying existing IEC/ISO standards related to the design and qualification of systems and equipment for Safety Systems for Nuclear Power Plants It serves as a complement to the application of IEC 61513.
Annexe B, et elle n’a pas pour objectif de limiter l’application des autres exigences au cycle de vie des SSR
The following standards outline the general requirements and recommendations for Safety System Requirements (SSR) IEC 61513 serves as the primary standard within the SC 45A framework, detailing the general requirements for instrumentation and control (I&C) systems and hardware essential for ensuring safety functions in nuclear power plants.