Iec 60951 1 2009

IEC 60880, Nuclear power plants – Instrumentation and control systems important to safety – Software aspects for computer-based systems performing category A functions IEC 60980, Recomm

Basic requirements related to functions

The primary function of continuous radioactivity monitoring equipment in accident or post-accident scenarios is to consistently measure radiation levels in designated areas and processes These measurements are displayed in real-time at local sites, control rooms, and incident control centers, ensuring that plant operators remain informed about current radiological conditions This critical information enables operators to evaluate plant status, implement necessary actions to mitigate the effects of an accident, and prevent unintended radiation releases Additionally, it supports site emergency personnel and national authorities in executing actions essential for protecting both the public and plant staff Consequently, this equipment is designed to trigger alarms and provide inputs to other plant systems, facilitating the isolation of processes when abnormal radiation levels are detected.

The design and selection of equipment for continuous radioactivity monitoring in accident or post-accident scenarios are tailored to specific plant requirements This process encompasses three main components: monitoring of effluents and ventilation, process radiation monitoring, and area radiation monitoring.

Effluent and ventilation radiation monitors play a crucial role in measuring the radioactivity of gases released into the environment during accident and post-accident scenarios These monitors ensure that radiation levels remain safe for public health and facilitate early warning systems and process isolations, including containment vent isolation and control room habitability Typically, effluent radiation monitors operate as off-line systems, measuring radioactivity from samples drawn from the effluent or ventilation systems.

Process radiation monitors are essential devices that measure radioactivity in various fluids, including gases, liquids, and steam They play a crucial role in plant processes by providing early warnings and facilitating process isolations, particularly in detecting leaks in reactor coolant pressure boundaries and other systems These monitors can be categorized into three fundamental types.

• In-line monitors: the detector is located directly in the process stream (pipe, stack, tank, duct, etc.)

• On-line monitors: the detector directly faces the process stream

• Off-line monitors: a sample is drawn from the process stream to the detector located at some distance

Area radiation monitors are strategically installed in buildings exposed to high dose rates during accident and post-accident scenarios, particularly in reactor buildings These monitors function as essential post-accident monitoring devices and are typically wall-mounted in the designated areas or tanks To accommodate varying radiation levels, the electronic components of the monitors may be positioned at a distance from the detectors.

For the purpose of critical data collection, these monitors are usually designed to withstand adverse environmental and seismic conditions, during and after an accident

Radiation monitoring requirements and radiation monitoring system design should be addressed early in Plant design to establish effective monitoring at the appropriate sensitivity

For optimal performance, both the purchaser and manufacturer should adhere to the specified procedures outlined for this licensed content, which is intended solely for internal use at the Ranchi/Bangalore location, as supplied by the Book Supply Bureau.

• Establish the required measurement characteristics (purchaser):

• Determine the scenarios of normal and accidental operations, and the corresponding source terms (main isotopes to be measured by the monitor), including their chemical composition

To ensure effective emergency actions, it is crucial to identify the key information needed by plant operators and control systems This includes defining the roles of equipment dedicated to continuous radiation monitoring and categorizing them in accordance with IEC 61226 standards.

• Determine the optimum points of measurement taking into account installation conditions (location, interfaces to plant protection features, ambient conditions and qualification requirements, electrical connections through safety barriers, etc.)

• Calculate the activity transfers (propagation through pipes or ducts and through the safety barriers), in order to determine the activity spectrums and the background at the point of measurement

To establish an effective monitoring system, it is essential to define the time profile for the anticipated release and identify the necessary measurement and response times for the entire channel This includes considering the sampling system, if applicable, as well as the duration required to transmit or display information to the plant operator or control system.

When assessing radiation detectors, it is essential to evaluate their fundamental characteristics, including the type of radiation they measure, their sensitivity, measurement range, energy response, and overload performance Additionally, the specifications of the sampling system, if present, should also be considered to ensure accurate and reliable measurements.

To establish an acceptable false alarm rate, it is essential to consider the specific conditions of the plant and the potential consequences of measurement errors, including sampling losses Additionally, it is crucial to define the required precision and accuracy to ensure that the false alarm rate remains within the established threshold.

• Check the metrological characteristics of the chosen instrument (agreement between the purchaser and the manufacturer):

To determine the instrument's response time, it is essential to measure the time associated with a specified accuracy and the duration required for the apparatus to trigger an alarm Additionally, the overall response time of the channel must be calculated, which encompasses the response time of the sampling system.

• Calculate, at the point of measurement, geometric detection efficiency, decision threshold and minimum detectable activity (or limit of detection), taking into account the appropriate shielding

Manufacturers must detail the variations of each instrument characteristic based on the relevant influence quantities or variable parameters At a minimum, these influence quantities should include:

• activity spectrum and time profile of the activity spectrum (during transient operating conditions) of the source to be measured,

• activity spectrum and time profile of the activity spectrum (during transient operating conditions) of the background,

• number of standard deviations (in order to calculate the minimum detectable activity or limit of detection),

• flow rate of the effluent to be measured,

• precision and time profile of the precision (in order to calculate the measurement time during steady-state as well as transient operating conditions),

• measurement time and response time (during transient operating conditions)

• For the influence quantities depending on the process or the location, the purchaser should indicate their range of values Otherwise, the manufacturer should make any

This document is licensed to MECON Limited for internal use in Ranchi and Bangalore, as supplied by the Book Supply Bureau It emphasizes the importance of formulating a useful hypothesis to consider the likely conditions under which the instrument will be utilized.

NOTE The term "manufacturer" includes the designer and the seller of the equipment The term "purchaser" includes the user

Signals that trigger protective actions to reduce the impact of structural, system, or component failures indicate that the equipment is integral to safety-related or protection systems Consequently, it must comply with the standards set forth in IEC 61226.

If qualification is needed, the equipment shall be environmentally qualified in accordance with the requirements of IEC 60780 (and IEC 60980 for seismic testing).

Measurement range

The purchaser must define the necessary effective measurement range, ensuring it is appropriate for radiation levels during both accident and post-accident scenarios The lower limit of this range should overlap with the measurement capabilities of monitors used under normal plant conditions by at least one decade on a logarithmic scale Additionally, the maximum measurable activity or dose rate must exceed the highest expected levels during accidents and post-accident conditions by at least one decade.

Energy response

The detector can be chosen to measure either beta or gamma radiation, and it is essential for the purchaser to verify that the energy response of the detection assembly is appropriate for monitoring potential activity.

Minimum detectable activity (or limit of detection)

The minimum detectable activity, also known as the limit of detection, is defined as a specific number of standard deviations of the signal estimated by the instrument in the absence of any activity, aside from background noise, under defined conditions This measurement should only be evaluated during steady-state operating conditions While it can be calculated using a formula that incorporates measurement time, this approach does not provide a precise indication of the lower limit of the measurement range.

The minimum detectable activity, also known as the limit of detection, varies based on the specific application and is influenced by local regulations and plant design, as determined by the plant designer.

The manufacturer must define the minimum detectable activity (limit of detection) for relevant nuclides, considering the check sources or provisions that ensure an on-scale indication on the monitor Additionally, all necessary data to determine the start of the effective measurement range, even under transient operating conditions, should be included It is also essential to specify the influence quantities, their value ranges, and the variations they induce on the minimum detectable activity.

Precision (or repeatability)

Precision, also known as repeatability, quantifies the variability of measurements around their average value Manufacturers provide this metric as a percentage of the signal value within a specified measurement range and confidence interval When assuming a Gaussian distribution for the estimations, this probability is typically represented in terms of standard deviations.

The precision of measurements can vary, with a 20% accuracy within a specific segment of the effective measurement range at a 95% probability, indicating that all estimates fall within ± 2σ, where σ represents the standard deviation In another segment of the effective range, the precision may be 30% with a different probability.

LICENSED TO MECON Limited - RANCHI/BANGALORE FOR INTERNAL USE AT THIS LOCATION ONLY, SUPPLIED BY BOOK SUPPLY BUREAU.

Precision must align with the assumptions of accident analysis, the needs of operators, and the requirements of other systems utilizing radiation monitoring signals Additionally, it should be defined for signal values that fall below the effective measurement range The manufacturer is responsible for specifying the influencing quantities, their value ranges, and the variations they introduce to precision.

Typically, the precision should be within 20 % over the entire effective range of measurement, all influence quantities taken into account.

Accuracy (or relative error)

Accuracy, also known as relative intrinsic error, quantifies the difference between the true value and the average of estimations Manufacturers provide this measure as a percentage of the signal value within the effective measurement range, corresponding to a specific confidence interval When assuming a Gaussian distribution for the estimations, this probability is typically represented in terms of standard deviations.

The accuracy of the measurements can reach 20% of the signal value within a specific segment of the effective measurement range, with a confidence level of 95% This indicates that all estimations fall within ±2σ, where σ represents the standard deviation Additionally, in another segment of the effective measurement range, the accuracy may be 30% with a different probability.

Accuracy must align with accident analysis assumptions, operator requirements, and the needs of other systems utilizing radiation monitoring signals Additionally, it should be defined for signal values that fall below the effective measurement range The manufacturer is responsible for specifying the influencing quantities, their value ranges, and the variations they introduce to accuracy.

Typically, the accuracy should be within 30 % over the entire effective range of measurement, all influence quantities taken into account.

Measurement time

The measurement time refers to the average duration required to estimate a signal under specified conditions, applicable only in steady-state operating scenarios While it can be calculated using a formula, this method does not account for the processing algorithms integrated into the monitor.

The manufacturer must define the measurement time and provide essential data, such as standard deviation or precision, to assess the accuracy of estimations and the false alarm rate Additionally, it is crucial to specify the influencing factors, their value ranges, and the variations they introduce to the measurement time.

Response time

The response time is the time needed for the monitor, after a sudden variation of the measured signal (for example a step), for its output signal or indication to reach 90 %

(increasing transition) or 10 % (decreasing transition) of the variation for the first time

NOTE For integrating systems, it is a percentage of the equilibrium value of the first derivative of the output signal as a function of time that should be considered

The response time is to be considered only in transient operating conditions It shall take into account the processing algorithms of the monitor

The manufacturer must determine the relevant calculations through tests or numerical simulations, providing essential data to assess the relationship between estimation precision and false alarm rates Additionally, it is crucial to specify the influencing quantities, their value ranges, and the variations they induce on response time.

Overload performance

The measurement must not drop below the maximum range or reach zero during or after exposure It should consistently provide a full-scale or clear indication Once the exposure is back within the maximum range, the system is required to recover within the timeframe specified by the purchaser.

Ambient background shielding or compensation devices

Shielding or electronic compensation shall be provided as necessary to reduce the effects of background radiation on the measurement of process radiation

Manufacturers and purchasers may agree that significant background radiation is expected only from specific directions or sources, such as vessels and pipes, allowing for tailored shielding construction In the absence of such an agreement, shielding must provide uniform radiation attenuation in all directions from the detector's sensitive volume, considering the structural materials of the detection assembly and the detector's angular response.

For equipment that cannot be easily detached from its shielding, it is essential that the shielding itself is designed for easy removal Additionally, the maximum weight of the components and the suitable handling methods must be mutually agreed upon by both the manufacturer and the purchaser.

To effectively mitigate the impact of background radiation, it is essential to select and position additional detectors in electronic techniques for optimal compensation, considering the energy range and radiation direction.

Requirements related to accident conditions

The design of equipment must guarantee that it effectively supports essential system functions and remains reliable under various environmental conditions, including normal, accident, and post-accident scenarios.

The accident and post-accident time interval during which system operation is required shall be specified by the purchaser

The purchaser must specify the local environmental conditions for the system's operation, including normal, accident, and post-accident scenarios This specification should encompass temperature, pressure, and their rate of change, as well as factors such as vibration, humidity, and exposure to aggressive or corrosive substances Additionally, it should address seismic conditions, the electromagnetic environment, and other adverse physical factors, along with the normal and accident radiation dose rates and the integrated radiation dose at the monitoring equipment's location.

The manufacturer is responsible for supplying equipment that can function within the specified environmental conditions, unless an alternative agreement is made with the purchaser Additionally, if required, the equipment must be validated for the specific environmental conditions of its application, adhering to applicable standards.

Equipment must be designed to reduce the impact of specified environmental conditions, with detector placement carefully chosen to account for accident and post-accident radiation levels, as well as necessary shielding Additionally, locations should be selected to ease maintenance and calibration tasks, while also considering the potential requirement for electronic equipment to be situated in areas with lower dose rates.

Consideration shall be given to the possibility that materials used in the construction of the monitors may release poisonous or corrosive substances under adverse environmental

MECON Limited is licensed for internal use at the Ranchi and Bangalore locations, with materials supplied by the Book Supply Bureau The design aims to minimize risks associated with conditions like fire, high temperatures, or high radiation through careful selection of materials and effective containment strategies.

Reliability

The required reliability of the functions shall be specified either quantitatively (mean time between failures) or qualitatively (compliance with the single failure criterion)

For any part of the equipment (including sampling assembly, if any), subject to appropriate planned maintenance, the following requirement shall be reached:

• MTBF (Mean Time Between Failure): > 20 000 h (with preventive maintenance):

A failure modes and effects analysis (FMEA) must be conducted alongside the MTBF calculation for equipment classified as safety-critical in category A, as per IEC 61226 standards.

• The manufacturer shall specify the frequency of routine maintenance, and fully describe each maintenance procedure (see 4.14.2) These maintenance requirements should be kept to a practical minimum.

User interface

General

The system will continuously display and record activity or dose rates, and it will also trigger an alarm when these levels surpass a predetermined threshold.

Display of measured value

The choice between logarithmic scales, linear scales, or numeric displays shall be appropriate to the purpose of the equipment Logarithmic scales or numeric displays are generally preferred

Assemblies equipped with linear scales must allow for range adjustments, ensuring that scaling factors remain within a maximum of 10 Additionally, there should be a clear indication of the active scale in use.

In situations where accident conditions lead to significant fluctuations in readings, manual range switching should only be employed if explicitly approved by the purchaser.

Alarms

The alarm and indication facilities shall be appropriate for the purpose of the equipment

Alarm circuits must be designed to either maintain an alarm condition until manually reset or to automatically reset once the alarm state is cleared The selection of alarm modes should be straightforward while ensuring strong administrative controls, which can be implemented through methods such as requiring a key, password, or minor equipment adjustments to change modes.

All alarm functions shall be provided with test facilities to allow checking of alarm operation

In the case of adjustable alarms, checking shall be possible over the range of adjustment with indication of the actual alarm operation point

Alarm functions shall be agreed upon between the supplier and the manufacturer As a minimum the following alarms shall be provided as applicable

At least one adjustable alarm setpoint shall be provided, adjustable over:

• at least 10 % to 90 % of scale reading (linear scales), from 50 % of the lowest decade to

90 % of the highest decade (logarithmic scales),

• or from 10 % of the second least significant decade to 90 % of the highest decade (digital display)

As many separate alarms as practicable should be provided for electronic or mechanical fault

At least, the following should be provided when appropriate:

• Loss of the sampling circuit

• Loss of the cooling system

• Loss of the heating system

Status indication

The following indications should be provided when appropriate:

• Gas stream cooling device On

• Gas stream heating device On

• Group fault alarms are indicated

• Occurrence of internal power supply changeover if internal supplies (e.g., batteries) are provided.

Local indications

Local indication and alarm units must be installed in easily accessible locations near the detector assembly This is essential for managing access to high radiation areas during accidents or for maintenance and calibration during regular plant operations.

Where provided, the local indication and alarm units shall be qualified for the conditions appropriate to their purpose and location, in accordance with IEC 60780 If the local indication

MECON Limited is licensed for internal use at the Ranchi and Bangalore locations, with supplies provided by the Book Supply Bureau It is essential to ensure that alarm units meet different qualifications than the detector, demonstrating that any failure of these units will not compromise the critical functions of the monitor.

System testing, maintenance facilities and ease of decontamination

System testing

Capability shall be provided to allow periodic checks of the satisfactory operation of the system from the detector to the measurement display, alarm functions, and system outputs

These checks should include operational checks, calibration, and verification of the measurement linearity

The system should allow for the evaluation of the detector's response at a designated point on the measurement scale without direct access, utilizing a remote-controlled check source Furthermore, it is essential to verify additional points, necessitating access to the detector and ensuring consistent check conditions, which can be achieved through a support structure for the detector during assessments with reference sources.

Maintenance facilities

The manufacturer must outline the routine maintenance frequency and provide detailed descriptions of each maintenance procedure, considering the failure rates of individual components to establish an effective preventive maintenance schedule.

Maintenance requirements should be minimized, and equipment design must prioritize ease of repair and maintenance Components should be interchangeable without the need for adjustments or pairing Additionally, all equipment must ensure that operating personnel are not exposed to contamination or radiation risks during handling or operations.

Maintenance operations can be performed fully or partially while the plant is in operation Equipment must facilitate remote inspection and adjustment, monitor intrinsic performance drifts, and provide self-testing capabilities Additionally, it should assist in diagnosing issues and indicate anomalies across all components Self-diagnostic features should be accessible via a display.

All electronic equipment shall be provided with a sufficient number of easily accessible identified test points to facilitate adjustments and fault location Any special maintenance tools shall be supplied.

Ease of decontamination

The sampling and detection assembly must be designed to minimize contamination build-up and allow for easy decontamination when needed Additionally, external surfaces should be specially treated to enhance decontamination efforts.

Electromagnetic interference

Precautions shall be taken against the effects of electromagnetic interference either received or emitted by the equipment

Unless otherwise agreed upon between the purchaser and the manufacturer, the following standards shall apply: IEC 61000-4-2, IEC 61000-4-3, IEC 61000-4-4, IEC 61000-4-5,

IEC 61000-4-6, IEC 61000-4-8, IEC 61000-4-12 and IEC 61000-6-4

Levels of severity are given in 5.5.4

Power supplies

Assemblies should be designed to operate from single-phase a.c supply voltage in one of the following categories in accordance with IEC 60038:

Nominal single-phase power in the United States of America and Canada is 117 V and/or

234 V, 60 Hz Nominal single-phase power of 110 V, 50 Hz is also used in the United

In the event of a power failure, manufacturers and purchasers can agree to design equipment that operates from a low-voltage stand-by supply It is essential that the equipment remains functional and does not trigger alarms during the supply switch-over, and a clear indication of this change-over should be included.

By agreement between manufacturer and purchaser, three-phase supplies may be used for air pump motors.

Interfaces

The physical properties of system component interfaces must be clearly defined, including connection types such as pipe couplings and cable connectors, as well as electrical properties and signal interpretations like pinouts Specifications should, whenever feasible, reference widely accepted standards.

When network interfaces are available, it is essential to provide details about the network interface protocols, which typically encompass the logical arrangement of transmitted data bits, the information exchanges between network nodes for data delivery, the quality and nature of data transmission, the organization of data sequences, and the syntax of the transferred data To ensure that the design and performance requirements of network-connected equipment are met, a comprehensive functional validation must be conducted, including tests on data exchanges between subsystems and with the operator.

Equipment integrated into a plant-wide radiation monitoring system must meet the requirements of IEC 61504 and/or IEC 61559-2, unless an alternative agreement is established between the manufacturer and the purchaser.

Sampling assembly

A sampling assembly is essential for the effective sampling, transport, and conditioning of air, gas, steam, or liquid for measurement purposes It must also allow for the isolation and dismantling of both the detector and the sampling control system when required.

The performance of an instrument is significantly influenced by the design of its sampling assembly It is essential for manufacturers to conduct studies that characterize potential sampling losses under both normal and accident conditions, aiming to keep these losses minimal The configuration and length of sampling circuits must align with the instrument's response time, ensuring uniform sampling at the measurement point while preventing the trapping of aerosols and dust, air bubble formation in liquids, and condensation in sampling pipes due to temperature or pressure variations Additionally, considerations should include the construction materials, the condition of the internal surfaces, ease of decontamination, and factors such as electrostatic effects, chemical corrosion, absorption, and condensation, as well as the transit time to the detector, which involves flow, fluid velocity, density, and the chemical forms of the monitored radioelements.

The following characteristics shall be taken into account and shall be agreed upon between manufacturer and purchaser:

• number and optimum position of sampling probes (representativity of the samples, minimum distance between inlet and outlet to avoid recirculation, etc.);

• nature of the material used and in particular effects of chemical corrosion or erosion and static electricity;

• finish condition of internal surfaces;

• curve radii and changes of direction;

• joining of the pipes, connection to external pipes, to the monitor;

• effect of harmful chemicals and steam;

• filtration of the suspended matter

The design of the sampling assembly is influenced by the type of fluid being sampled and the specific measurement conditions It is essential to adhere to ISO standards, such as ISO 2889, which provides guidelines for sampling radioactive particulates.

In addition, the following requirements shall be fulfilled:

• where necessary, the sampling device shall be designed to guarantee the integrity of the nuclear containment;

• an isokinetic probe shall be used if aerosols or iodine are sampled, an omnidirectional probe if sampling takes place in a room;

• where flow or pressure drop have an influence on the measured value (volumetric activity), it shall be constantly measured and controlled;

Devices required for fluid sampling and conditioning, including pumps, filters, pressure or temperature detectors, and solenoid valves, must be compatible with dust conditions in the air and materials suspended in liquids Additionally, these devices should be appropriately sized to operate effectively between two scheduled unit outages.

Pumps should be installed downstream from measurement points and must include pressure and temperature protections to safeguard against abnormal increases in these parameters.

• where necessary, personnel protection devices shall be provided against temperature, pressure, radiation, etc.;

• it shall be possible to isolate each sampling assembly for safety reasons;

• if agreed upon between the purchaser and the manufacturer, devices for collecting samples should be provided for deferred laboratory analysis;

• the acoustic noise level generated by the equipment shall be minimized and consistent with the type of environment for which the equipment is intended.

Quality

High-quality systems and equipment must be developed through a structured process that incorporates conservative design measures Verification and validation are essential to ensure that the correct requirements are established and accurately implemented Additionally, computer-based hardware should be developed following established guidelines.

IEC 60987 Software for category A functions shall be developed according to the guidance of

IEC 60880 Software for category B and C functions shall be developed according to the guidance of IEC 62138

Upon the purchaser's request, all documentation generated throughout the design, manufacturing, installation, testing, and start-up phases will be supplied to verify the system and equipment's proper performance.

Type test report and certificate

At the request of the purchaser, the manufacturer shall present a report on the type tests carried out in accordance with the requirements of this standard (part 1 and specific part)

This test report shall comply with the specifications given in 5.6 of IEC 61069-1 which states that:

The assessment's conduct and results must be documented in a detailed report that presents the objectives, findings, and all pertinent information clearly, accurately, and objectively.

The reports shall include at least the following information:

• the credentials of the institute and/or person(s) responsible for the assessment or evaluation;

When evaluating a system for a specific application, it is essential to include the application's characteristics, such as the type of process, the number and type of input/output requirements, the necessary scan rate, and the system's mission, tasks, and functions.

• a description and identification of the system assessed, including a list showing the hardware with model numbers and the software with released data;

• the objective(s) of the assessment;

• a summary of the salient points arising out of the assessment and the conclusions reached;

This article outlines the procedures, methods, specifications, and tests, ideally summarized in a matrix format and supported by referenced documents It also provides a concise summary of the rationale behind the selection of specific assessment elements presented in the matrix.

The reasons why certain aspects are not assessed should be also recorded;

• any deviation from the assessment plan (additions or exclusions) should be recorded and commented upon;

• measurements, examinations and derived results supported by tables, graphs, drawings or photographs as appropriate;

• a statement of the measurement uncertainties;

• a statement as to whether or not the system complies with the requirements against which the system was assessed

The assessment report shall contain a title page stating the report title, a unique (serial) number, the assessment authority and the date of issue

The format should be standardized and facilitate comparison of assessments of different systems

Any corrections or additions to the report after its release must be documented in a supplementary report that references the original report by its title and number This additional report must adhere to the same standards as the main report.

A certificate shall also be provided with each equipment, giving at least the following general information and the additional information specified in the relevant subsequent part of the standard:

• identification of the entity who draws up the certificate,

• type test program/procedure and report,

General

Tests outlined in this Clause are generally regarded as type tests, but they can also be classified as acceptance tests if agreed upon by both the manufacturer and the purchaser The specified requirements represent minimum standards, which can be adjusted based on the specific equipment or function involved.

These tests do not include additional qualification tests that shall be performed if the equipment is to be qualified in accordance with IEC 60780.

General test procedures

General

General test procedures applicable to all types of monitors are covered in this standard

Test procedures for monitors differ based on their specific characteristics, with specialized requirements outlined in the relevant standards for each monitor type.

The tests described in this standard may be classified according to whether they are performed under standard test conditions or under other conditions.

Tests performed under standard test conditions

Standard test conditions are outlined in Table 2, while Table 3 lists the tests conducted under these conditions, detailing the requirements for each characteristic based on the relevant test method clause.

Tests performed with variation of influence quantities

The object of these tests is to determine the effects of variations of the influence quantities

In order to facilitate the execution of these tests, they can be divided into three categories:

• tests relating to the measurement, alarm and indication assemblies (all types of measurements);

• tests relating to the sampling assembly (off-line measurement);

• other complementary tests relating to postulated performance in volumetric measurement

To evaluate the impact of each influencing factor outlined in Table 4, it is essential to keep all other factors within the standard test conditions specified in Table 2, unless alternative requirements are provided.

To streamline the testing process, it is sufficient to conduct a single test for each individual influence quantity This test will assess the impact of the designated change in influence.

This document is licensed to MECON Limited for internal use in Ranchi and Bangalore, as supplied by the Book Supply Bureau It pertains to activity quantities or dose rate levels that are approximately 50% of the second most sensitive range or decade.

Table 4 presents the tests for measurement, alarm, and indication assemblies, detailing the range of variation for each influencing quantity along with the corresponding limits for the assembly's indications.

The sampling assembly tests are detailed in various sections of this standard related to off-line measurement, outlining the range of variation for each influencing factor and the permissible limits for the parameters being tested.

This section outlines complementary tests for assessing postulated performance in volumetric measurement when real testing is not feasible The calculations and numerical simulations will consider the specified variations in the influencing quantities.

Table 4 outlines the activity or dose rate levels specified earlier, and, if mutually agreed upon by the purchaser and the manufacturer, it encompasses the entire range of measurement.

Calculations and/or numerical simulations

This subclause applies to in-line and on-line instruments, but is also applicable to off-line instruments if agreed upon between purchaser and manufacturer

Upon the purchaser's request, when real testing is impractical—such as when measuring fluid activity under non-reproducible conditions—the manufacturer will supply calculations and/or numerical simulations These will ensure that the performance standards, particularly the detection characteristics tested on point sources, are met under actual usage conditions.

At the request of the purchaser, calculations reproducing the exact geometry of the

The manufacturer must provide an assembly of a volumetric source, collimator, detector, and shielding, incorporating several mono-energetic volumetric sources This is essential for validating detection performance metrics such as limit of detection and sensitivity, and for comparison with actual tests using single isotope point sources or equivalent type-tested configurations.

A detailed analysis shall explain the differences and limitations between real testing and calculations

The purchaser and manufacturer must agree on additional calculations that consider the stream speed or flow rate, along with a multi-energetic volumetric source that closely resembles the actual proposed volumetric source, accompanied by a detailed analysis.

The manufacturer must deliver thorough documentation to verify that the software utilized in calculations and simulations accurately reflects the physical phenomena within the specified range This documentation should include comparisons with other validated calculation methods or qualified codes, sensitivity analysis, results from trials and tests conducted under real conditions, relevant data and correlations from technical publications, and any other pertinent methodologies.

Reference sources

All primary calibration sources used in the reference response test must be traceable to the National Standardizing Laboratory for Radioactivity measurements (NSLR) in the respective country of use.

All sources used for the rest of the type tests or routine or acceptance tests (secondary calibration sources) shall either be prepared from radioactive solutions traceable to the NSLR,

MECON Limited is licensed for internal use at the Ranchi and Bangalore locations, with materials supplied by the Book Supply Bureau The primary calibration will be referenced during the response test to establish a direct link through the transfer factor.

All secondary calibration sources should be solid sources

According to IEC 60951, the type of source is specified in a dedicated section, outlining the requirements for measurement and energy equipment To ensure comprehensive coverage, multiple sources may be necessary, each with an activity level suitable for the specific equipment being tested.

The surface emission rate or activity of sources must be determined with an absolute uncertainty of less than 10% (k = 2) and a relative uncertainty compared to other sources in the test set also under 10% (k = 2) When using a pre-calibrated reference instrument instead of a precisely defined source strength, the calibration of this instrument must adhere to a similar standard of uncertainty.

Instruments with sampling must utilize gaseous reference sources that have a known volumetric activity of the relevant radionuclide or radionuclide mixture The specific types of gases to be employed should be mutually agreed upon by the manufacturer and the purchaser.

A calibrated instrument can be utilized to determine the appropriate response to an undefined source activity, serving as an alternative to calibrated gaseous sources It is essential that this instrument is calibrated during the tests unless it has already undergone calibration.

When gaseous sources produce excessive volumes or activities, a viable alternative is to simulate a larger source by strategically placing a smaller source at various distances from the detector The readings obtained from these positions can then be utilized for calculations and numerical simulations of the detector's response It is essential for the manufacturer to validate these calculations.

Instruments with sampling must determine their relative response to solid sources through type tests that involve cross-calibration against gaseous sources This established relative response can subsequently be applied alongside solid source tests when they replace gaseous source tests.

For area monitors, all tests shall be carried out with solid sources, either primary sources or secondary sources cross-calibrated during primary calibration

Reliable physical sources of radionuclides must be used for the assembly under test, ensuring that the source's position relative to the detector is precisely established and consistently reproducible.

For testing with extremely high dose rates, electronic radiation sources may be used

To prevent the use of highly active sources in routine or acceptance tests, the measuring assembly can be evaluated by injecting a suitable electronic signal into its normal detector input.

Statistical fluctuations

In tests involving radiation, if the statistical fluctuations from radiation are significant compared to the allowable variation, it is essential to take enough readings to accurately estimate the mean value This ensures compliance with the test requirements.

The interval between such readings shall be at least three times the response time in order to ensure that the readings are statistically independent.

Performance characteristics

Reference response

The manufacturer must clarify the correlation between the measurement provided by the assembly and the reference dose rate or activity when the equipment is used under standard test conditions as defined by them Additionally, the uncertainty associated with the reference response should be specified.

The test shall be carried out with a set of sources of different representative radionuclide and geometric characteristics, such as defined in 5.2.5

The assembly shall be operated under standard test conditions and set up as defined by the manufacturer with no reference radiation source present The background indication shall be noted

The assembly should be subjected to a suitable reference source that provides a reading near the midpoint of the linear scale or within the second lowest decade of the logarithmic scale or digital display The reference value, R ref, must be calculated as specified in section 3.18.

Sensitivity and relative response for solid sources

For instruments normally tested with gaseous sources, the relative response for solid sources shall be determined by cross-calibration against gaseous sources

The test shall be carried out with a set of sources of different representative radionuclide and geometric characteristics, as defined in 5.2.5

The background measurement must be conducted using the specific geometry designated for the measurement, utilizing reliable sources For instance, the measurement should be taken with the measuring cell empty, and the resulting value should be recorded.

Solid sources with activity levels near the midpoint of the scale should be positioned at specific locations relative to the detector, while maintaining unchanged test conditions for the gaseous source, which will be absent The relative response to the solid source must be recorded In future tests, the instrument's response to the gaseous source will be calculated based on the relative response previously established for the solid sources.

If such a relative response for solid sources is used in routine or acceptance tests, the possible variation in background radiation should be taken into account

Accuracy (relative error)

Under standard test conditions, with the calibration controls adjusted according to the manufacturer’s instructions, the accuracy (linearity error or relative error) shall not exceed

The measurement must be within 20% of the effective range, specifically between 2.5 times the lowest value and 75% of this range, while ensuring that it does not exceed ±30% across the entire effective range It is important to note that the uncertainty associated with the radioactive source is not factored into this measurement.

Tests can be performed in two ways:

• with gaseous or solid radioactive sources;

• with injection of an electronic signal (restricted to ranges of measurement where the use of sources is impossible)

When conducting tests with sources, it is essential to utilize a consistent set of sources that share the same radionuclide and geometric characteristics, as outlined in section 5.2.5 However, for area monitors, it is necessary to employ various types of sources that are available for high dose rates In such instances, the specific sources and their geometries must be clearly defined.

The reference curve is established based on the reference response obtained from tests conducted with gaseous sources, or from the sensitivity measured during the solid source tests as outlined in section 5.3.2.

Type tests should be conducted at approximately 25% of the most sensitive range, 50% of the maximum of intermediate ranges, at the maximum achievable range, and at one point on each range for linearly scaled instruments For digitally or logarithmically scaled instruments, testing should occur on each decade of the effective measurement range Additionally, the ratio between two successive measurements must be at least 10.

At least three of these tests shall be carried out using a radioactive source, including the upper and the lowest values

Electronic test signals must be utilized across all ranges or decades, alongside radioactive sources The manufacturer is required to provide an analysis that demonstrates the system's performance from the highest source test to the maximum range.

Where this test is carried out with gaseous radioactive sources, it shall be performed in accordance with the design of the monitor:

For offline equipment utilizing a measuring cell, it is essential to circulate a reference source through the assembly at the nominal flow rate for an adequate duration to achieve reading equilibrium, or alternatively, to fill the measuring cell with a volume that matches the nominal volume of the reference source.

• For off-line equipment using a concentration device: by concentrating the reference source in the normal operation condition (time of concentration, volume, etc.)

For equipment that operates in-line, on-line, or off-line without a measuring cell, it is essential to position the detector in relation to a sufficiently large volume of a reference source This setup ensures that the conditions mimic the actual operating environment of the monitor effectively.

In order to minimize the effects of possible contamination of the sampling assembly, all tests with gaseous sources shall proceed from low to high values of volumetric activity

Response to other artificial radionuclides

The agreement on the response to radionuclides of interest will be established between the manufacturer and the purchaser Additionally, the assembly's response to radionuclides, excluding the reference, must not vary by more than 20% from the manufacturer's specified value.

The test method described in 5.3.1 using appropriate radionuclides shall be performed.

Response to background radiation

The response to ambient gamma radiation and the decision threshold are interrelated and depend on the specific application of the plant Therefore, the manufacturer and purchaser must agree on the assembly's response to gamma radiation and the decision threshold, considering the anticipated ambient activity.

Similar test methods as agreed upon between the manufacturer and purchaser shall be used for other activities, for example neutrons and/or high energy betas, may affect the reading

This requirement does not apply to area monitors

The manufacturer must specify the decision threshold and the maximum reading value for the detector, which is equipped with ambient gamma radiation protection devices as needed This specification applies when the detector is positioned in a reference orientation defined by the manufacturer and is subjected to a step change in gamma air kerma rate, transitioning from the reference background level to 10 μGy/h due to Cs-137 and Co-60 exposure.

The equipment shall be operated under standard test conditions with no radioactive source present and the background indication shall be determined

Position the Cs-137 source at least 2 meters away from the measurement assembly, which includes the detector and its ambient gamma radiation protection devices Ensure that the gamma air kerma rate at the measurement assembly location, without the assembly present, is 10 μGy/h ± 10% Follow the manufacturer's specifications for the reference orientation of the measurement assembly in relation to the source.

To ensure accurate measurements, record readings at one-minute intervals from the beginning of the exposure, continuing until the readings stabilize After achieving stability, take a minimum of 10 additional readings Finally, calculate the decision threshold using the final readings obtained.

The measurement assembly will be tested in various source-to-detector orientations as mutually agreed upon by the manufacturer and the purchaser It is important to note that if the measurement assembly is equipped with a gamma compensation factor, this setting must remain unchanged throughout the testing process.

The reading of the measurement assembly in each orientation shall not exceed twice the value specified by the manufacturer for the reference orientation

Repeat the same test with a Co-60 source.

Precision (or repeatability)

The coefficient of variation of the indication due to statistical fluctuations shall be less than

10 % for any reading exceeding 10 times the lowest value of the effective range of measurement

Use suitable radioactive sources to give an indication between 10 and 50 times the lowest value of the effective range of measurement

To ensure accurate results, take a minimum of 10 readings at suitable time intervals Calculate the mean value and the coefficient of variation from these independent readings, ensuring that the coefficient of variation remains within the specified limits.

Stability of the indication

The indication from a given source of activity, after the assembly has been in operation for

30 min, shall vary over the following 100 h by not more than:

• 2 % of scale maximum angular deflection for instruments with an analogue display;

• 2 % of the first order of magnitude of the effective range of measurement for instruments with a digital display

Use irradiation equipment (e.g radioactive source or electron beam) to give an indication between 10 to 20 times the lowest value of the range of measurement

After an initial 30-minute reading, additional measurements should be taken at 10 hours and 100 hours without making any adjustments to the assembly or altering the conditions The average of the readings collected during each interval must remain within the specified limits.

Readings shall be corrected for decay of the source if necessary.

Response time

The manufacturer must define the assembly's response time for activities or dose rates ranging from 10 to 50 times the minimum measurement value, providing essential data to assess its accuracy and false alarm rate Additionally, the manufacturer should specify the influencing factors, their value ranges, and the variations they induce in the response time.

The test shall be carried out with sources of the same representative radionuclide and geometric characteristics These sources may be gaseous or solid sources

A recorder, able to record much faster than the response time being measured, shall be connected to the assembly to determine the change in indication as a function of time

Where this test is carried out with gaseous sources, it shall be performed in accordance with the design of the monitor:

To achieve equilibrium in the background reading, circulate a non-radioactive gas through the assembly at the nominal flow rate for a sufficient duration, or fill the measuring cell with a volume of non-radioactive gas equal to the nominal volume.

To achieve equilibrium, a solution with a known volumetric activity of the appropriate radionuclide is continuously injected into the monitor's inlet at the nominal sampling flow rate for the required duration.

• For in-line, on-line or off-line equipment, and especially for area monitors, when the use of a gaseous source is not possible:

To achieve accurate readings, position the detector in an empty volume that simulates the actual operating conditions of the monitor Allow sufficient time for the background reading to reach equilibrium.

• then by rapidly introducing a sufficiently solid source into the empty volume, for the time needed to reach the equilibrium

NOTE In the context of this test, “rapidly” is defined as a much shorter time than the response time being tested

The response time refers to the duration between the injection of a radioactive solution or solid source and the moment when the reading first reaches 90% of its variation In off-line equipment utilizing a concentration device, this response time is expressed as a percentage of the equilibrium value of the first derivative of the output signal over time.

Overload test

The equipment shall maintain full-scale indication or an unambiguous indication when

“exposed” to an appropriate activity or dose rate twice greater than that necessary to give the maximum scale reading and shall perform normally when this overload “exposure” is removed

Unless otherwise specified in the agreement between the manufacturer and the purchaser, an overload indication must be included to alert users when the activity or dose rate exceeds the measuring unit's capacity.

Subject the detector assembly to an appropriate form of activity to give a reading between 10 and 50 times the lowest value of the range; note the reading

Subject the detector assembly to an activity level approximately twice that required for the maximum scale reading Ensure the exposure lasts for a minimum of 10 minutes and confirm that the assembly consistently registers the maximum reading.

To ensure accurate measurements, eliminate the overload source and place the detector assembly under the same conditions as the initial reading After a mutually agreed period, typically under 10 minutes, the subsequent reading should not vary by more than 10% from the previously recorded value.

For some applications this kind of test is impossible In such cases, a demonstration by analysis shall be provided by the manufacturer

Electrical performance tests

Alarm trip range

The ranges of alarm settings shall conform to the requirements of 4.13.3 These requirements exclude the detectors

Using an appropriate electronic signal generator, as specified by the manufacturer, the range of indication of the equipment over which the alarm trip operates shall be determined

These tests shall be performed for the effective range of measurement

For alarms designed to activate with increasing signals, set the alarm to its minimum level and gradually raise the input signal until the alarm triggers Record the equipment's indication at this point.

For alarms intended to operate on decreasing signals, operate as above, but slowly decrease the level of input signal.

Alarm trip stability

The operating point of any alarm circuit shall not deviate outside the range 95 % X to 105 % X in the period of 100 h of operation, where X is the nominal alarm set level

These requirements exclude the detector

For any alarm circuit whose nominal trip setting has been determined as X

• For a condition equivalent to 94 % X applied electronically or by software to the assembly, no trip shall occur within 100 h

• When a condition equivalent to 106 % X is applied to the assembly, after 30 min and 100 h of operation, the alarm shall operate in less than 1 min.

Fault alarm

When failure appears in one of these parts of the equipment:

In the event of a failure, an alarm must activate to identify the issue within the sampling assembly For both the electronic circuit and the sampling assembly, a specific fault alarm should trigger within one minute of the failure The manufacturer is responsible for specifying the time needed to receive a detector fault alarm after a failure, considering the detector's background.

The equipment shall provide facilities to simulate failures

Each component, including the detector, electronic circuit, and sampling assembly, must undergo a simulated failure The designated fault alarm should activate promptly, prior to the required time, ensuring that no unrelated alarms are triggered.

Status indication and fault alarm tests

The indication and alarm facilities described in subclauses 4.13.3 and 4.13.4 shall be functionally tested.

Warm-up time — Detection and measuring assembly

When using irradiation equipment, such as a radioactive source or electron beam, the assembly must indicate a value that remains within ±10% of the standard conditions after 30 minutes of steady state operation.

Prior to this test, the equipment shall be disconnected from the power supply for at least 1 h

Use irradiation equipment (e.g radioactive source or electron beam) to give approximately 10 to 50 times the lowest value of the effective range of measurement Switch on the detection and control assemblies

Switch on the equipment Note values of indication of activity or dose rate every 5 min during

1 h Ten hours after switching on, take sufficient readings and use the mean value as the

Draw a graph of activity or dose rate indication versus time, correcting for decay in activity as necessary

The difference between the "final value" and the value read from the curve for 30 min shall lie within the limits specified.

Influence of supply variations

5.4.6.1 Influence of slow supply voltage variations

When several different voltage levels are required by the monitor, each supply voltage is taken as a separate influencing factor

Begin by checking the equipment's functional characteristics at both the upper and lower limits of its rated power supply voltage Next, gradually reduce the voltage from the maximum value to zero.

The variation of the voltage duration shall be at least 1 min

On completion of this test, the performance of the monitor shall comply with the performance stipulated by the manufacturer

5.4.6.2 Influence of sudden supply voltage variation

Unless otherwise specified in the agreement between the buyer and the manufacturer, the duration of voltage loss is defined as one cycle of the power source frequency During this period, the voltage must not exceed 1% of the minimum rated supply voltage limit.

To maintain signal integrity, it is crucial that input signals remain undisturbed while implementing measures to ensure the stability of output signals Following this, the supply voltage will be cut off for a designated duration During this period, output signals will be monitored, starting just before the voltage cut-off, continuing through the outage, and resuming until the voltage is restored.

If the settings or equipment operating mode affects the output signals observed, the configuration producing the greatest variation shall be adopted

For analogue signal outputs, the test is carried out on a stabilized output at the lower, mean and upper levels of the voltage range

For logical (digital) outputs, the test is carried out for both states

Upon completion of this test, the performance of the monitor shall comply with the performance stipulated by the manufacturer

5.4.6.3 Influence of supply frequency variations

Functional characteristics shall be verified at ±10 % of the nominal frequency.

Short circuit withstand tests

The effects of external short circuits on electronic equipment functions shall be verified, particularly for circuits fed by internal power supplies

Short-circuits shall be produced at the external interfaces of the various constituent parts, such as plug-in units inputs and outputs, and power supply units

The functional consequences of these short-circuits shall then be observed, involving, for example:

• the emission of an erroneous output signal, especially by an equipment sharing a power supply with the faulty equipment,

• the appearance of erroneous input data,

• de-energizing of all or part of the equipment

On completion of this test, the performance of the monitor shall comply with the performance stipulated by the manufacturer.

Environmental performance test

Stability of performance after storage

This test shall comply with IEC 60068-2-2 (test Bb), completed by the following:

• the assemblies shall not encounter heat radiating from the walls of the test chamber,

• the assemblies are not energised,

• TA = + 70 °C, t = 96 h, < 1 °C/min heat gradient (unless otherwise specified by the manufacturer on the maximum heat gradient accepted by the equipment)

After completing the test, the assemblies are allowed to stabilize in normal atmospheric conditions for 2 hours to achieve thermal equilibrium The monitor's performance must meet the specifications set by the manufacturer.

This test shall comply with IEC 60068-2-1 (test Ab), completed by the following procedures:

• TB = – 40 °C, t = 96 h, < 1 °C/min heat gradient (unless otherwise specified by the manufacturer on the maximum heat gradient accepted by the equipment)

After completing the test, the assemblies are allowed to stabilize in normal atmospheric conditions for 2 hours to achieve thermal equilibrium The monitor's performance must meet the specifications set by the manufacturer.

This test shall comply with IEC 60068-2-14 (test Nb), completed by the following procedures:

• number of cycles: 5, duration of each test condition: 30 min,

• TB = – 25 °C, TA = +70 °C, < 1 °C/min heat gradient (unless otherwise specified by the manufacturer on the maximum heat gradient accepted by the equipment)

After completing the test, the assemblies are allowed to sit in standard atmospheric conditions for 2 hours to achieve thermal equilibrium The monitor's performance must meet the specifications set by the manufacturer.

Mechanical tests

5.5.2.1 Degrees of protection (IP and IK codes)

The tests shall comply with IEC 60529 and IEC 62262 The equipment is not energised

Unless otherwise agreed upon between the purchaser and the manufacturer, the protection indices of the various items of equipment should be:

• IP 65 (measurement and processing device) or IP 44 (sampling devices) and IK 07 (all devices) for assemblies installed locally,

• IP 30 and IK 07 for the assemblies installed in clean and dry rooms (electrical rooms),

• IP 65 and IK 07 for the assemblies installed outside the buildings

This test is used to check the mechanical strength of the assemblies It does not apply to equipment whose stiffness is provided by another system (e.g.: cables, etc.)

The test shall be carried out in three tri-rectangular reference axes It includes three successive phases for each of the three specified axes:

Phase 1: search for critical frequencies (resonance frequencies or frequencies for which defective operation of the monitor has been observed)

The frequency range is thoroughly scanned following the outlined procedures, with the scanning rate potentially reduced to ensure precise identification of critical frequencies This approach ultimately leads to revealing important results.

• an electrical discontinuity between normally closed dry contacts,

• inadvertent closing of the normally open dry contacts,

• defective operation of the monitor,

Phase 2: Endurance by frequency sweeping The frequency varies in accordance with the methods specified below

These test phases are defined in IEC 60068-2-6 (test Fc) They are supplemented by the following procedures:

• The assemblies are energised during phases 1 and 3 of the test and are not energised during phase 2

The vibration table is securely mounted on a rigid structure that ensures accurate test results without distortion It accommodates the assembly using its standard fixing system, while the connected components maintain stability solely through the methods employed during normal operation.

The module experiences sinusoidal rectilinear vibrations applied in three tri-rectangular directions The sweeping process, which covers the specified frequency band in each direction, is continuous and follows a logarithmic speed over time Frequency variation occurs at a rate of about one octave per minute.

• The export frequency range is from 10 Hz to 500 Hz

• The vibrations are defined according to the following characteristics:

• displacement: 0,15 mm peak to peak,

• constant displacement below the transfer frequency,

• constant acceleration of 10 m/s 2 above the transfer frequency

The number of cycles is equal to:

A variation of the critical frequencies between phases 1 and 3 of more than 5 % leads to an inspection

On completion of this test, the performance of the monitor shall comply with the performance stipulated by the manufacturer.

Stability of performance with variation of temperature and humidity

It is essential to test the impact of temperature and humidity variations on equipment or its components, as these factors can significantly affect the measurements and performance in different environments.

Testing the measurement assembly and the detector may require different ranges of variation for influence quantities; therefore, these tests should be conducted in two steps if necessary.

• Test of the influence of the temperature or humidity on the measurement assembly

• Test of the influence of the temperature or humidity on the detector being in contact with the medium to be measured, if applicable

The change in indication shall be less than 10 % over the entire ranges of variation of temperature and humidity

Unless otherwise agreed upon between the manufacturer and the purchaser, the following ranges of variation of temperature and humidity shall apply

The measurement assembly, or a portion of it, may be exposed to appropriate solid sources without its shielding, as specified in section 5.2.5, to ensure that the nominal reading under standard test conditions is accurately determined.

The test shall be performed following the method described in the following IEC standards:

• IEC 60068-2-78 for damp heat, steady state test, supplemented by the following procedures:

• the assemblies are fitted in their reference position,

• they shall not be subjected to heat radiated by the walls of the test chamber,

• duration of the test condition: 96 h

• IEC 60068-2-30 (test Db variant 2) for damp heat cyclic test, supplemented by the following procedures:

• the assemblies are fitted in their reference position,

• they shall not be subjected to heat radiated by the walls of the test chamber,

To begin, power on the instrument, choose the correct range, and position it in an environmental chamber under reference conditions Ensure that the air characteristics within the chamber remain below the manufacturer's specified limits to prevent any potential damage to the equipment.

The detection assembly shall be exposed to suitable test sources in such a way that the nominal reading under standard test conditions is known

The instrument should remain in this state for 30 minutes or until equilibrium is reached If a set-zero control is provided, the operator must adjust it to align the indication with the manufacturer's specified point.

Instruments with a non-linear scale require a control mechanism to adjust the indication to a specific reference point instead of zero This control must be calibrated to ensure the indication aligns accurately with the designated reference point.

During testing, the instrument's indication must be measured After testing, the instruments should be left in normal atmospheric conditions for 2 hours to achieve thermal equilibrium The monitors' performance must meet the specifications set by the manufacturer.

Certain detectors, such as NaI scintillators, are highly sensitive to temperature fluctuations It is essential to implement measures that ensure the manufacturer's specified maximum heat gradient is monitored, while also confirming that the detectors' characteristics remain undeterred.

Electromagnetic compatibility

The test procedures previously defined in IEC 61000-4-12, and now defined in IEC 61000-4-

• service frequency between 50 Hz and 400 Hz and non-synchronized on the network frequency

Injection occurs in common mode through the coupling/uncoupling network If the manufacturer's guidelines indicate that an earth connection is necessary for a circuit conductor, the testing of this circuit must be conducted in differential mode while applying the specified common mode severities.

The severity of the test shall be:

• circuits inside the control room: no test,

• circuits connecting the control room and the other rooms of the electrical building or between the electrical rooms: level 1,

• circuits exiting the electrical building: level 3

5.5.4.2 Electrical transient burst immunity test

This test shall comply with IEC 61000-4-4

• for equipment installed in the control room: level 2,

5.5.4.3 Radiated radio frequency immunity test

Depending on the type of measurements to be made on the monitor, one or the other of the following modes shall apply to the disturbance:

• when the measurement results are instantaneous (less than 1 s), the frequency range is swept slowly (1,5 × 10 –3 decades/s) by maintaining the level of the electrical field constant during sweeping,

When a disturbance is detected in the equipment, a thorough investigation is conducted to identify the specific frequency zone that caused the disruption, as well as the minimum electrical field strength necessary to trigger such disturbances.

When measurement results are obtained slowly, taking over 1 second, a disturbance is applied after the initial sweep The electrical field level is kept constant for specific fixed frequencies: 80, 100, 150, 200, 300, 500, and 1,000 MHz.

This document is licensed to MECON Limited for internal use in Ranchi and Bangalore, as supplied by the Book Supply Bureau It discusses the addition of multiple and sub-multiple clock frequencies of the tested subsystem.

The severity of the test for all the equipment shall be level 3, unless otherwise agreed upon between the purchaser and the manufacturer

Discharges must be performed on all sensitive components of the equipment that operators may touch, including various discontinuities such as LEDs, displays, pushbuttons, switches, and terminals, as well as the surfaces of cabinets or boxes, including both front and rear doors subjected to testing.

The contact test takes place on conducting surfaces, on insulating surfaces for the test in the air, and the plate test close to each side

The severity of the test for all the equipment shall be:

• air discharge (and at the plate): class 3

This test adheres to the standards set by 61000-4-6 It is important to note that since nuclear power stations are not located near radio transmitters, the effects of disturbances in specific frequency bands, whether attenuated or absent, are not considered.

The severity of the test for all the equipment shall be level 3

5.5.4.6 50 Hz magnetic field immunity test

This test shall be performed in compliance with IEC 61000-4-8 or the absence of components sensitive to magnetic fields shall be demonstrated

The severity of the test for all the equipment shall be level 3

5.5.4.7 Surge immunity test (high energy)

Only the a.c supply and the connections that could leave the electrical building shall be tested

• a.c supply: level 3 in common mode (between phase and earth) and level 2 in differential mode (between phases),

• input or output that could be connected to an electrical building outgoing cable: level 2 in common mode

5.5.4.8 Non-aggression test: radio disturbances

Table 2 – Reference conditions and standard test conditions

Influence quantity Reference conditions Standard test conditions

Reference radiation sources See specific parts of IEC 60951 See specific parts of IEC 60951

Warm-up time: (whole equipment)

Atmospheric pressure a 101,3 kPa 86 kPa to 106 kPa

Power supply voltage Nominal supply voltage U N U N ± 1 %

AC power supply frequency b Nominal frequency Nominal frequency ± 0,5 %

AC power supply waveform Sinusoidal Sinusoidal with total harmonic distortion less than 5 %

Gamma radiation background Air kerma rate in accordance with manufacturer’s specification Air kerma rate in accordance with manufacturer’s specification

Electromagnetic field of external origin

Negligible Less than the lowest value that causes interference

Magnetic induction of external origin

Negligible Less than twice the value of the induction due to the earth's magnetic field

The sampling flow-rate should be adjusted to the nominal flow-rate specified by the manufacturer, allowing for a tolerance of ± 5% Assembly controls must be set for normal operation, and if the detection technique is highly sensitive to atmospheric pressure variations, conditions should be maintained within ± 5% of the reference pressure Additionally, a DC power supply may be utilized, with no specific frequency required in this case.

Table 3 – Tests performed under standard test conditions

Characteristics under test Requirements Reference

Reference response In accordance with the manufacturer’s specification 5.3.1

Sensitivity and relative response for solid sources

Accuracy (relative error) < 20 % (between 2,5 times the lowest value and 75 % of the range of measurement)

Response to other artificial radionuclides Variation < 20 % from the manufacturer’s specification 5.3.4

Precision (or repeatability) Coefficient of variation < 10 % for any reading exceeding 10 times the lowest value of the effective range of measurement

Stability of the indication < 2 % of scale maximum angular deflection (analogue display) or of first order of magnitude of range of measurement (digital display)

Response time In accordance with the manufacturer’s specification 5.3.8

An overload test ensures that a device maintains full-scale or clear indication when subjected to a dose rate or activity that is double the level causing full-scale deflection Additionally, the device should function normally once the overload condition is eliminated.

The alarm trip range can be adjusted between 10% and 90% of the scale reading for linear scales, from 50% of the lowest decade to 90% of the highest decade for logarithmic scales, and from 10% of the second least significant decade to 90% of the highest decade for digital displays.

Alarm trip stability No deviation outside the range 95 % to 105 % of the nominal alarm set level during 100 h

Fault alarms As specified in design criteria 5.4.3 and 5.4.4

Warm-up time Variation of indication < 10 % from value under standard test conditions

As specified in design criteria 5.4.7

IP 65 (measurement and processing devices) or IP 44 (sampling devices) and IK 07 (all devices) for the devices installed locally

IP 30 and IK 07 for the devices installed in clean and dry rooms (electrical rooms)

IP 65 and IK 07 for the devices installed outside the buildings

Mechanical vibrations As specified in design criteria 5.5.2.2

Table 4 – Tests performed with variation of influence quantities

Influence quantity Range of values of influence quantity

Limits of variation of indication

In accordance with the manufacturer's specifications

Upper and lower limits of supply voltage and down to zero

In accordance with the manufacturer's specifications

Sudden supply voltage variation < 1 % of the lower limit of supply voltage during 20 ms

As specified in design criteria 5.4.6.2

AC power supply frequency ± 10 % of nominal frequency As specified in design criteria 5.4.6.3

Dry heat storage T = + 70 °C, t = 96 h As specified in design criteria 5.5.1.1

Cold storage T = – 40 °C, t = 96 h As specified in design criteria 5.5.1.2

As specified in design criteria 5.5.1.3

Stability of performance with variation of temperature and humidity

Damp heat T = + 40 °C, t = 96 h Cyclic damp heat: 6 cycles

Change in indication < ± 10 % over the entire ranges of variation of temperature and humidity

As specified in relevant test As specified in relevant test 5.5.4

NOTE 1 For assemblies having a non-linear scale, a linear instrument may be substituted for the indicating meter of the assembly to verify the performance specified in this table

NOTE 2 DC power may be used, and in such a case the AC power supply frequency test does not apply

IEC 60050-393:2003, International Electrotechnical Vocabulary – Part 393: Nuclear instrumentation – Physical phenomena and basic concepts

IEC 60050-394:2007, International Electrotechnical Vocabulary – Part 394: Nuclear instrumentation – Instruments, systems, equipment and detectors

IEC 60532, Radiation protection instrumentation – Installed dose rate meters, warning assemblies and monitors – X and gamma radiation of energy between 50 keV and 7 MeV

IEC 60761-1:2002, Equipment for continuous monitoring of radioactivity in gaseous effluents

– Part 2: Specific requirements for radioactive aerosol monitors including transuranic aerosols

– Part 3: Specific requirements for radioactive noble gas monitors

– Part 4: Specific requirements for radioactive iodine monitors

IEC 60768:2009, Process stream radiation monitoring equipment in light water nuclear reactors for normal operating and incident conditions

IEC 60861:2006, Equipment for monitoring of radionuclides in liquid effluents and surface waters

IEC 60951-2:2009 outlines the standards for radiation monitoring equipment essential for safety in nuclear power plants This standard specifically addresses the equipment designed for continuous off-line monitoring of radioactivity in gaseous effluents and ventilation air during both accident and post-accident conditions.

IEC 60951-3:2009, Nuclear power plants – Instrumentation important to safety – Radiation monitoring equipment for accident and post-accident conditions – Part 3: Equipment for continuous high range area gamma monitoring

IEC 60951-4:2009 outlines the standards for radiation monitoring equipment essential for safety in nuclear power plants This part specifically focuses on the continuous in-line or on-line monitoring of radioactivity in process streams during both accident and post-accident conditions.

IEC 61000-4-11:2004, Electromagnetic compatibility (EMC) – Part 4-11: Testing and measurement techniques – Voltage dips, short interruptions and voltage variations immunity tests

IEC 62302:2007, Radiation protection instrumentation – Equipment for sampling and monitoring radioactive noble gases

4.1 Exigences de base liées aux fonctions 59

4.4 Activité minimale détectable (ou limite de détection) 62

4.10 Protection contre le bruit de fond ou mécanismes de compensation 63

4.11 Exigences liées aux conditions accidentelles 64

4.14 Essai du système, dispositifs de maintenance et facilité de décontamination 67

4.20 Rapport des essais de type et certificats 70

5.2.2 Essais réalisés dans des conditions d’essai standard 71

5.2.3 Essais réalisés avec des variations des grandeurs d’influence 71

5.2.4 Calculs et/ou simulations numériques 72

5.3.2 Réponse relative et sensibilité pour les sources solides 75

5.3.4 Réponse aux autres radionucléides artificiels 76

5.3.5 Réponse aux rayonnements en bruit de fond 76

5.4.2 Stabilité de l’alarme d’arrêt d’urgence 80

5.4.4 Essai des alarmes de défaut et d’information d’état 81

5.4.5 Temps de mise en fonctionnement — Ensemble de détection et de mesure 81 5.4.6 Influence des variations relatives à l’alimentation 81

5.4.7 Essais de résistance au court-circuit 82

5.5 Essai de performance aux conditions d’environnement 82

5.5.1 Stabilité des performances après stockage 82

5.5.3 Stabilité des performances en présence de variations de température et d’humidité 84 5.5.4 Compatibilité électromagnétique 86

Tableau 1 – Vue d’ensemble des normes couvrant le domaine de la surveillance des rayonnements 50

Tableau 2 – Conditions de référence et conditions d’essai standards 89

Tableau 3 – Essais réalisés en conditions d’essai standards 90

Tableau 4 – Essais réalisés avec variations des grandeurs d’influence 91

CENTRALES NUCLÉAIRES DE PUISSANCE – INSTRUMENTATION IMPORTANTE POUR LA SÛRETÉ –

SURVEILLANCE DES RAYONNEMENTS POUR LES CONDITIONS

1) La Commission Electrotechnique Internationale (CEI) est une organisation mondiale de normalisation composée de l'ensemble des comités électrotechniques nationaux (Comités nationaux de la CEI) La CEI a pour objet de favoriser la coopération internationale pour toutes les questions de normalisation dans les domaines de l'électricité et de l'électronique A cet effet, la CEI – entre autres activités – publie des Normes internationales, des Spécifications techniques, des Rapports techniques, des Spécifications accessibles au public (PAS) et des Guides (ci-après dénommés "Publication(s) de la CEI") Leur élaboration est confiée à des comités d'études, aux travaux desquels tout Comité national intéressé par le sujet traité peut participer Les organisations internationales, gouvernementales et non gouvernementales, en liaison avec la CEI, participent également aux travaux La CEI collabore étroitement avec l'Organisation Internationale de Normalisation (ISO), selon des conditions fixées par accord entre les deux organisations

2) Les décisions ou accords officiels de la CEI concernant les questions techniques représentent, dans la mesure du possible, un accord international sur les sujets étudiés, étant donné que les Comités nationaux de la CEI intéressés sont représentés dans chaque comité d’études

3) Les Publications de la CEI se présentent sous la forme de recommandations internationales et sont agréées comme telles par les Comités nationaux de la CEI Tous les efforts raisonnables sont entrepris afin que la CEI s'assure de l'exactitude du contenu technique de ses publications; la CEI ne peut pas être tenue responsable de l'éventuelle mauvaise utilisation ou interprétation qui en est faite par un quelconque utilisateur final

4) Dans le but d'encourager l'uniformité internationale, les Comités nationaux de la CEI s'engagent, dans toute la mesure possible, à appliquer de faỗon transparente les Publications de la CEI dans leurs publications nationales et régionales Toutes divergences entre toutes Publications de la CEI et toutes publications nationales ou régionales correspondantes doivent être indiquées en termes clairs dans ces dernières

5) La CEI n’a prévu aucune procédure de marquage valant indication d’approbation et n'engage pas sa responsabilité pour les équipements déclarés conformes à une de ses Publications

6) Tous les utilisateurs doivent s'assurer qu'ils sont en possession de la dernière édition de cette publication

Tiêu đề	Instrument Monitoring for Nuclear Power Plants – Part 1: General Requirements
Trường học	Unknown
Chuyên ngành	Electrical and Electronic Technologies
Thể loại	Standard
Năm xuất bản	2009

Định dạng
Số trang	96
Dung lượng	1,36 MB