ISO 20890-1:2020

INTERNATIONAL ISO
STANDARD 20890-1
First edition
2020-06
Guidelines for in-service inspections
for primary coolant circuit
components of light water reactors —
Part 1:
Mechanized ultrasonic testing
Lignes directrices pour les contrôles périodiques des composants du
circuit primaire des réacteurs à eau légère —
Partie 1: Contrôle mécanique par ultrasons
Reference number
ISO 20890-1:2020(E)
©
ISO 2020

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ISO 20890-1:2020(E)

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© ISO 2020
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Published in Switzerland
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ISO 20890-1:2020(E)

Contents Page
Foreword .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Test systems . 7
4.1 Preliminary remark . 7
4.2 General . 7
4.3 Validation and localisation of reflectors. 8
4.3.1 Pulse-echo technique (PE technique) . 8
4.3.2 Transmitter-Receiver technique (TR-technique) . 8
4.3.3 Tandem technique . 8
4.3.4 Inspection technique with mode conversion . 8
4.3.5 V-transmission technique . 9
4.3.6 Phased-Array technique (PA). 9
4.3.7 Preferred angles of incidence and wave modes for search techniques . 9
5 Requirements .10
5.1 Test personnel .10
5.1.1 Task of NDT personnel . .10
5.1.2 Personnel requirements .10
5.2 Test object .11
5.3 Ultrasonic test equipment .11
5.3.1 Preliminary remark .11
5.3.2 Test robot .11
5.3.3 Ultrasonic test device .12
5.3.4 Data acquisition and analysis .13
5.3.5 UT probe .13
5.3.6 UT probe holders .15
5.3.7 UT probe cable (ultrasonic cable) .16
5.4 Couplant .16
5.5 Reference reflectors .16
5.6 Calibration block and reference or test block .17
5.7 Data storage medium .17
6 Testing .17
6.1 Preparation .17
6.1.1 General.17
6.1.2 Probe data sheets .17
6.1.3 Probe system .17
6.1.4 Test robot .18
6.1.5 Ultrasonic test device .18
6.1.6 Setting the test level .18
6.1.7 Data acquisition system (DAS) .19
6.1.8 Ultrasonic test equipment .19
6.2 Implementation .19
6.3 Visualisation of the digitized and saved measuring data .20
6.4 Analysis of indications .20
6.5 Final measures .20
7 Recording .21
7.1 Recording the setup for the ultrasonic test equipment .21
7.2 Test record and test report .21
7.3 Indication list .21
7.4 Findings record .22
Annex A (informative) Examples of test systems and transceiver probe arrangements .23
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ISO 20890-1:2020(E)

Annex B (informative) Forms .25
Annex C (informative) Findings record .28
Annex D (informative) Amplification compensation .29
Annex E (informative) Standard test procedures and test specifications .32
Bibliography .33
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ISO 20890-1:2020(E)

Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see www .iso .org/
iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 85, Nuclear energy, nuclear technologies,
and radiological protection, Subcommittee SC 6, Reactor technology.
A list of all parts in the ISO 20890 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
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INTERNATIONAL STANDARD ISO 20890-1:2020(E)
Guidelines for in-service inspections for primary coolant
circuit components of light water reactors —
Part 1:
Mechanized ultrasonic testing
1 Scope
This document gives guidelines for pre-service-inspections (PSI) and in-service inspections (ISI) with
mechanized ultrasonic test (UT) devices on components of the reactor coolant circuit of light water
reactors. This document is also applicable on other components of nuclear installations.
Mechanized ultrasonic inspections are carried out in order to enable an evaluation in case of
— fault indications (e.g. on austenitic weld seams or complex geometry),
— indications due to geometry (e.g. in case of root concavity),
— complex geometries (e.g. fitting weld seams), or
— if a reduction in the radiation exposure of the test personnel can be attained in this way.
Ultrasonic test methods are defined for the validation of discontinuities (volume or surface open),
requirements for the ultrasonic test equipment, for the preparation of test and device systems, for the
implementation of the test and for the recording.
This document is applicable for the detection of indications by UT using normal-beam probes and angle-
beam probes both in contact technique. It is to be used for UT examination on ferritic and austenitic
welds and base material as search techniques and for comparison with acceptance criteria by the
national referencing nuclear safety standards. Immersion technique and techniques for sizing are not
in the scope of this document and are independent qualified.
NOTE Data concerning the test section, test extent, inspection period, inspection interval and evaluation of
indications is defined in the applicable national nuclear safety standards.
Unless otherwise specified in national nuclear safety standards the minimum requirements of this document are
applicable. This document does not define:
— extent of examination and scanning plans;
— acceptance criteria;
— UT techniques for dissimilar metal welds and for sizing (have to be qualified separately);
— immersion techniques;
— time-of-flight diffraction technique (TOFD).
It is recommended that UT examinations are nearly related to the component, the type and size of defects to be
considered and are reviewed in specific national inspection qualifications.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
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ISO 20890-1:2020(E)

ISO 5577, Non-destructive testing — Ultrasonic testing — Vocabulary
ISO 8596, Ophthalmic optics — Visual acuity testing — Standard and clinical optotypes and their
presentation
ISO 9712, Non-destructive testing — Qualification and certification of NDT personnel
ISO 16811, Non-destructive testing — Ultrasonic testing — Sensitivity and range setting
ISO 18490, Non-destructive testing — Evaluation of vision acuity of NDT personnel
EN 12668-1, Non-destructive testing — Characterization and verification of ultrasonic examination
equipment — Part 1: Instruments
EN 12668-2, Non-destructive testing — Characterization and verification of ultrasonic examination
equipment — Part 2: Probes
ISO 18563-1, Non-destructive testing — Characterization and verification of ultrasonic phased array
equipment — Part 1: Instruments
ISO 18563-2, Non-destructive testing — Characterization and verification of ultrasonic phased array
equipment — Part 2: Probes
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 5577 and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
analysis scan
test scan with adopted parameters that is required for more precise characterisation of an indication (3.3)
3.2
analysis technique
test technique that is applied for more precise characterisation of indications (3.3) subject to analysis
3.3
indication
representation or signal from a discontinuity in the format allowed by the NDT method used
[SOURCE: ISO/TS 18173:2005, 2.14]
Note 1 to entry: Signal that is initiated by operationally induced damage mechanisms, geometrical as well as,
material or design induced influences
3.4
evaluation
assessment (3.5) of indications (3.3) revealed by NDT against a predefined level
Note 1 to entry: Inspection of the recorded measured data in respect to completeness and analysis capacity,
localisation and registration of indications according to defined criteria, representation of the test results
[SOURCE: EN 1330-2:1998, 2.10]
3.5
assessment
comparison of the analysed measuring results with specified criteria
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3.6
data storage medium
storage medium for storing digital media
3.7
focal length
focal distance
distance from the probe to the focal point
[SOURCE: ISO 5577:2017, 4.2.13]
3.8
focus range
focal zone
zone in sound beam of a probe in which the sound pressure remains above a defined level related to
its maximum
[SOURCE: ISO 5577:2017, 4.2.14]
Note 1 to entry: During measurement with the electrodynamic probe in sound transmission, this value
corresponds to a decrease in the signal level by 3 dB in comparison to the maximum value.
Note 2 to entry: In general limitation by the decline in the signal level by 6 dB.
3.9
focus depth
focal point
point where the sound pressure on the beam axis is at its maximum
[SOURCE: ISO 5577:2017, 4.2.12]
3.10
adjustment
setting the ultrasonic test device based on specified parameters
3.11
calibration
determination of the measuring value range of an ultrasonic test device in relation
to a calibrated test standard
3.12
calibration block
piece of material of specified composition, surface finish, heat treatment and
geometric form, by means of which ultrasonic test equipment (3.43) can be assessed and calibrated
[SOURCE: ISO 5577:2017, 5.4.1]
Note 1 to entry: The calibration blocks according to ISO 2400 and ISO 7963 can be used as calibration blocks
according to this document.
3.13
calibration reflector
reflector of a known geometry and size in or on the calibration block (3.12), test reference block (3.15) on
the test calibration block, for distance or sensitivity adjustment of the ultrasonic test instrument (3.44)
3.14
component
part of a system delimited according to structural or functional aspects, which can still implement
independent sub-functions
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ISO 20890-1:2020(E)

3.15
reference block
block of material representative of the material to be tested with similar acoustic properties containing
well-defined reflectors, used to adjust the sensitivity and/or time base of the ultrasonic instrument
(3.44) in order to compare detected discontinuity indications (3.3) with those arising from the known
reflectors
[SOURCE: ISO 5577:2017, 5.4.2]
3.16
time of flight
time it takes an ultrasonic pulse to travel from the transmitter probe through the test object (3.27) to
the receiver probe
[SOURCE: ISO 5577:2017, 3.2.6]
Note 1 to entry: This comprises the lead time in the UT probe and the time of flight in the component; it is the
time that an ultrasonic pulse requires from the oscillator to a reflector and back to the oscillator.
3.17
LLL technique
test technique based on the reflection of the sound package at the back wall and at a planar reflector in
the inspection volume using /utilizing longitudinal waves
Note 1 to entry: See Annex A, no. 7.
3.18
LLT technique
test technique based on reflection of the sound bundle at the back wall and at a planar reflector in the
inspection volume using/utilizing the mode conversion of longitudinal waves and transversal waves
Note 1 to entry: See Annex A, no. 7.
3.19
measurement scan
movement of the UT probes with simultaneous recording of measured data
3.20
raw data
all measured data and setting parameters saved by the ultrasonic test equipment during the
measurement run (recorded and saved data)
Note 1 to entry: Examples of raw data include amplitude, time of flight, and coordinates.
3.21
test section
part of the test area (3.23)
3.22
test supervisor
responsible for application of the test method and for the individual details of the test implementation
including monitoring of the activities for preparation and implementation of the test as well as analysis
of the test results (3.24)
3.23
test area
defined area on the test object (3.27) over which the tests are to be conducted
[SOURCE: ISO 5577:2017, 6.2.2]
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3.24
test result
summarising evaluation of all measured data and comparison with the previous test
3.25
test scan
measuring run with the characteristics specified in the test specifications
3.26
test function
test task assigned to a UT probe or UT probe combination, e.g. coupling check
3.27
test object
object to be tested; object under test or examination; part of a component to be tested
3.28
test robots
scanner
mechanical device with control for guiding the UT probes
3.29
noise level
amplitudes of background noise in an ultrasonic system
Note 1 to entry: 95 % value of the sum frequency of the amplitudes, measured during the reference run or test
run in an indication-free range
[SOURCE: ISO 5577:2017, 6.5.16]
3.30
signal to noise ratio
ratio of the amplitude of a signal arising from a discontinuity in a material to the amplitude of the
average background noise level (3.29)
[SOURCE: EN 1330-2:1998, 2.16]
3.31
reference scan
measuring run for the functional control and functional adaptation of the ultrasonic test equipment
3.32
hysteresis correction
correction to the decrease in the calibration level resulting during the tandem test or during the test
with a comparable test system, if the planar reflectors are not oriented vertically to the surface or
vertically to the sound incidence level
3.33
transmitter-receiver technique (TR-technique)
pitch and catch technique
double probe technique
ultrasonic testing technique involving the use of two probes both of which can be used as transmitter
and receiver
3.34
track offset correction
correction to the decrease in the calibration level of planar reflectors in the middle between two tracks
3.35
tandem zone correction
correction to the decrease in the calibration level of the calibration reflector to the tandem zone edges
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3.36
test block
defined piece of material which allows tests for the accuracy and/or performance of an ultrasonic test
system (3.43)
[SOURCE: ISO 5577:2017, 5.4.3]
Note 1 to entry: Specimen for examining properties of a test method, an ultrasonic test instrument or a test system.
3.37
depth zone
sub-range of the wall thicknesses to be tested
3.38
transfer correction
correction of the gain setting of the ultrasonic test instrument (3.44) when transferring the probe from a
calibration (3.12) or reference block (3.15) to the test object
[SOURCE: ISO 5577:2017, 5.4.5]
3.39
trigger distance
path that the UT probes travels between two test cycles of the same test function following in succession
3.40
scan without couplant
measurement scan (3.19) without coupling between the UT probe and test object (3.27)
3.41
TTT technique
test technique based on reflection of the sound bundle at the back wall and at a planar reflector in the
test volume using / utilizing shear waves
Note 1 to entry: See Annex A, no. 7.
3.42
ultrasonic test equipment
equipment consisting of an ultrasonic instrument (3.44), probes, cables and all devices connected to the
instrument during testing
[SOURCE: ISO 5577:2017, 5.3.1]
Note 1 to entry: Connected devices consist also test robot and analysis unit including software, digitalisation
unit and, if necessary, operating PC including software.
3.43
ultrasonic test instrument
instrument used together with the probe or probes, which transmits, receives, processes and displays
ultrasonic signals for NDT purposes
[SOURCE: ISO 5577:2017, 5.1.1]
3.44
ultrasonic test technique
application-relevant technique for the localisation of discontinuities (internal or surface open)
Note 1 to entry: In relation to the application, requirements result for these ultrasonic test techniques in respect
to the test parameters such as oscillation variable, beam angle, wave type and frequency.
Note 2 to entry: Test techniques are e.g. pulse-echo system (PE), transmitter-receiver system (TR), tandem
system, phased-array system (PA).
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3.45
reference reflector
reflector (natural or artificial) with known form, size and distance from the test surface in the
calibration block (3.12) or reference block (3.15), which is used for calibration or assessment of detection
sensitivity
Note 1 to entry: A reference reflector can also be used as a calibration reflector.
3.46
angle-dependent amplification compensation
correction to the echo level for compensation of the sound pressure change in relation to the beam
angle at phased-array probes
Note 1 to entry: See Figures D.2 and D.3.
[SOURCE: ISO 5577:2017, 6.4.2]
4 Test systems
4.1 Preliminary remark
The suitability of the test technique and the test device system shall be validated corresponding to the
requirements of the applicable national nuclear safety standards.
[6]
NOTE The procedure for the qualification is described in ENIQ report no. 31 .
A general test procedure shall be prepared. Annex E contains the items of the general test procedure.
4.2 General
The test techniques described below are used to locate discontinuities (search techniques). Test
techniques for the analysis of indications can be found in 6.4.
The relevant test sections shall be checked so that the required registration thresholds are complied
with in even the least favourable case. This results in requirements e.g. for the track offset correction,
the transfer correction, the trigger distance and the travel speed, that depend on the relevant selection
of probes (e.g. oscillation variable, test frequency, beam angle) and the depth range to be tested.
Depending on the test assignment, the following probes shall be used in contact technique:
— Single transducer probes;
— TR-probes;
— Phased-array probes;
— Electromagnetic acoustic transducer (EMAT).
NOTE The specific requirements for the use of EMAT probes are not discussed in this document.
In the case of tests on austenitic components and dissimilar metal welds, the test capacity can be
impaired by the weld metal structure (e.g. inherent coarse-grained and/or a directionally-oriented
structure). This can cause variations in attenuation, reflection, refraction at grain boundaries and
velocity changes within the grains. It us
...