IEC 62976:2017

Industrial non-destructive testing equipment - Electron linear accelerator

IEC 62976:2017 gives the rules of naming, technical requirements, test methods, inspection, marking, packaging, transportation, storage and accompanying documents for electron linear accelerator equipment for Non-Destructive Testing (NDT). This document applies to NDT electron linear accelerator equipment in the X-ray energy range of 1 MeV to 15 MeV, including the accelerator equipment for radiographic film, computed radiography with imaging plates, real-time imaging, digital detector array and industrial computerized tomography.

Appareils destinés aux essais non destructifs pour le secteur industriel - Accélérateur électronique linéaire

L'IEC 62976:2017 donne les règles qui s'appliquent au nommage, aux exigences techniques, aux méthodes d'essais, à l'inspection, au marquage, à l'emballage, au transport, au stockage et aux documents d'accompagnement des accélérateurs électroniques linéaires destinés aux essais non destructifs (END). Le présent document s'applique aux accélérateurs électroniques linéaires destinés aux essais non destructifs dont le rayonnement X est compris dans la plage d'énergie allant de 1 MeV à 15 MeV, notamment aux accélérateurs utilisés pour les films radiographiques, la radiographie informatisée à plaque d'imagerie, l'imagerie en temps réel, les barrettes de détecteurs numériques et la tomographie informatisée à usage industriel.

General Information

• Status: Published
• Publication Date: 24-Oct-2021
• ICS: 27.120.01 - Nuclear energy in general
• ICS: 33.180.20 - Fibre optic interconnecting devices
• Technical Committee: TC 45 - Nuclear instrumentation
• Drafting Committee: PT 62976 - TC 45/PT 62976
• Current Stage: PPUB - Publication issued
• Start Date: 09-May-2017
• Completion Date: 14-Apr-2017

Relations

• Amended By: IEC 62976:2017/AMD1:2021 - Amendment 1 - Industrial non-destructive testing equipment - Electron linear accelerator
• Effective Date: 05-Sep-2023

Overview

IEC 62976:2017 is an international standard developed by the International Electrotechnical Commission (IEC) that establishes comprehensive rules and technical requirements for electron linear accelerator equipment used in industrial non-destructive testing (NDT). This standard applies specifically to electron linear accelerators operating within the X-ray energy range of 1 MeV to 15 MeV, covering various imaging technologies including radiographic film, computed radiography with imaging plates, real-time imaging, digital detector arrays, and industrial computerized tomography.

The standard outlines essential aspects such as naming conventions, technical specifications, test methods, inspection protocols, marking, packaging, transportation, storage, and documentation related to electron linear accelerator NDT equipment. IEC 62976:2017 ensures consistency, safety, and performance quality for these specialized devices used in critical inspection tasks across industries.

Key Topics

• Equipment Naming and Configuration
  The standard provides clear naming conventions and classifies equipment sets to ensure uniformity in designation and identification of electron linear accelerators used in NDT applications.

• Technical Requirements
  IEC 62976 defines detailed technical criteria including:

  • X-ray beam energy and homogeneity
  • Beam air kerma rate and dose limits
  • Focal spot size and asymmetry
  • Sensitivity and leakage dose controls
  • Safety features like protective grounding, insulation resistance, and dielectric strength

• Control System Specifications
  It specifies design principles and operational procedures for accelerator control systems, including start/stop mechanisms and functional requirements for safe operation.

• Testing and Inspection Methods
  Standardized test methods cover visual inspections, electrical safety tests, performance evaluations of beam characteristics, and reliability tests like continuous operation and recovery.

• Marking and Documentation
  Requirements include clear marking/signage, proper packaging, guidelines for transportation and storage, and detailed accompanying documents such as instructions and supplier certifications.

Applications

IEC 62976:2017 is crucial for industries relying on electron linear accelerators for high-energy X-ray based non-destructive testing, including:

• Aerospace for inspection of aircraft components and composites
• Automotive manufacturing to detect internal defects in castings and welds
• Oil and gas industry for pipeline and pressure vessel integrity testing
• Power generation - examination of turbine blades, generators, and reactors
• Metal fabrication and construction for weld inspections and quality assurance
• Industrial computerized tomography (CT) enables accurate 3D imaging for detailed analysis and defect detection

This standard facilitates product safety, quality assurance, and operational efficiency, empowering industries to maintain high inspection accuracy while complying with international safety norms.

Related Standards

• IEC 61000 series - Electromagnetic compatibility standards related to electrical equipment including accelerators
• ISO 17636 - Non-destructive testing of welds by radiographic testing, complementary for applications involving electron accelerators
• IEC 60529 - Degrees of protection by enclosures, relevant for accelerator equipment packaging and storage
• IEC 61508 / IEC 62061 - Functional safety standards for electrical/electronic safety-related systems, pertinent to accelerator control systems

Adherence to IEC 62976 alongside these standards helps organizations implement robust, internationally recognized NDT electron linear accelerator systems optimized for safety, reliability, and performance.

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Keywords: IEC 62976, electron linear accelerator, industrial non-destructive testing, NDT equipment, X-ray energy range, radiographic film, computed radiography, digital detector array, industrial CT, test methods, safety requirements, accelerator control system, packaging and transportation, inspection protocols.

Standards Content (Sample)

IEC 62976 ®
Edition 1.0 2017-05
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Industrial non-destructive testing equipment – Electron linear accelerator

Appareils destinés aux essais non destructifs pour le secteur industriel –
Accélérateur électronique linéaire
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IEC 62976 ®
Edition 1.0 2017-05
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Industrial non-destructive testing equipment – Electron linear accelerator

Appareils destinés aux essais non destructifs pour le secteur industriel –

Accélérateur électronique linéaire

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 27.120.01 ISBN 978-2-8322-4128-8

– 2 – IEC 62976:2017 © IEC 2017
CONTENTS
FOREWORD . 4
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 Equipment sets, names and work conditions . 8
4.1 Equipment sets . 8
4.2 Name convention . 8
4.3 Operating conditions . 9
4.3.1 Environmental requirement . 9
4.3.2 Power supply . 9
5 Technical requirements . 9
5.1 Appearance . 9
5.2 Control system . 9
5.2.1 Design principle . 9
5.2.2 Operation of start and stop . 9
5.2.3 Functions of control system . 9
5.3 Performance . 10
5.3.1 X-ray beam energy . 10
5.3.2 X-ray homogeneity . 10
5.3.3 X-ray beam air kerma rate . 10
5.3.4 X-ray beam focal spot . 11
5.3.5 X-ray beam asymmetry . 11
5.3.6 X-ray sensitivity . 11
5.3.7 Dose leakage . 12
5.4 Electrical safety . 12
5.4.1 Protective grounding . 12
5.4.2 Insulation resistance . 12
5.4.3 Dielectric strength . 12
5.4.4 Protection against electric shock . 12
5.5 Reliability . 12
5.5.1 Continuous operation . 12
5.5.2 Recovery . 12
5.5.3 Restart . 12
6 Test methods . 12
6.1 General requirements . 12
6.1.1 Testing conditions . 12
6.1.2 Instruments and devices . 13
6.2 Visual inspection . 14
6.3 Control system test . 14
6.4 Performance test . 14
6.4.1 X-ray beam energy . 14
6.4.2 X-ray homogeneity . 15
6.4.3 X-ray beam air kerma rate . 16
6.4.4 X-ray beam focal spot . 16
6.4.5 X-ray beam asymmetry . 18
6.4.6 X-ray sensitivity . 18

6.4.7 Leakage dose rate . 18
6.5 Electrical safety testing . 19
6.5.1 Protective grounding . 19
6.5.2 Insulation resistance . 19
6.5.3 Dielectric strength . 19
6.5.4 Protection against electric shock . 19
6.6 Reliability test . 19
6.6.1 Continuous operation . 19
6.6.2 Recovery . 19
6.6.3 Restart . 19
7 Inspection rules . 20
7.1 Inspection classification . 20
7.2 Inspection items . 20
7.3 Criterion rule . 20
8 Marking, packaging, transportation, storage and accompanying documents . 20
8.1 Marking . 20
8.1.1 Accelerator signs . 20
8.1.2 Component nameplates . 21
8.1.3 Labels . 21
8.1.4 Warning signs . 21
8.2 Packaging . 21
8.3 Transportation . 21
8.4 Storage . 21
8.5 Accompanying documents . 22
8.5.1 Instructions . 22
8.5.2 Product certification . 22
8.5.3 Other documents . 22

Figure 1 – Naming convention . 8
Figure 2 – Sketch map of the test module . 13
Figure 3 – Sketch map of the copper block with a swivelling edge. 14
Figure 4 – Schematic diagram of X ray beam radial uniformity measurement . 15
Figure 5 – Schematic diagram of the testing module in front of the detector . 16
Figure 6 – Schematic diagram of the “Sandwich” test module placement . 17
Figure 7 – Schematic diagram of the copper block test module placement . 17
Figure 8 – Diagram of leakage dose measurement points . 19

Table 1 – Specifications of several commonly used accelerator models . 9
Table 2 – Half value layer of materials corresponding to commonly used X-ray beam
energies. 10
Table 3 – X-ray homogeneity of commonly used X-ray beam energies . 10
Table 4 – X-ray beam air kerma rate of different models . 11
Table 5 – Detection range of equivalent steel thickness corresponding to commonly
used X-ray beam energies . 11
Table 6 – Testing conditions . 13
Table 7 – Inspection items of the accelerator . 20

– 4 – IEC 62976:2017 © IEC 2017
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
INDUSTRIAL NON-DESTRUCTIVE TESTING EQUIPMENT –
ELECTRON LINEAR ACCELERATOR
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
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9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 62976 has been prepared by technical committee 45: Nuclear
instrumentation.
The text of this standard is based on the following documents:
FDIS Report on voting
45/821/FDIS 45/824/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.

The committee has decided that the contents of this publication will remain unchanged until
the stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data
related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
– 6 – IEC 62976:2017 © IEC 2017
INDUSTRIAL NON-DESTRUCTIVE TESTING EQUIPMENT –
ELECTRON LINEAR ACCELERATOR
1 Scope
This document gives the rules of naming, technical requirements, test methods, inspection,
marking, packaging, transportation, storage and accompanying documents for electron linear
accelerator equipment for Non-Destructive Testing (NDT).
This document applies to NDT electron linear accelerator equipment in the X-ray energy
range of 1 MeV to 15 MeV, including the accelerator equipment for radiographic film,
computed radiography with imaging plates, real-time imaging, digital detector array and
industrial computerized tomography.
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.
ISO/IEC Guide 37:2012, Instructions for use of products by consumers
ISO 780:2015, Packaging – Distribution packaging – Graphical symbols for handling and
storage of packages
ISO 19232-1:2013, Non-destructive testing – Image quality of radiographs – Part 1:
Determination of the image quality value using wire-type image quality indicators
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1
target
area on the surface of accelerating tube outlet on which the electron beam impinges and from
which the primary beam of X-rays is emitted
3.2
linear electron accelerator
LINAC
apparatus for producing high energy electrons by accelerating them along a waveguide. The
electrons strike a target to produce X-rays
Note 1 to entry: NDT electron linear accelerator, hereinafter referred to as the accelerator.
[SOURCE: ISO 5576:1997, 2.84]
3.3
X-rays
penetrating electromagnetic radiation, within the approximate wavelength range of 1 nm to
0,0001 nm, produced when high velocity electrons impinge on a metal target
[SOURCE: ISO 5576:1997, 2.129]
3.4
X-ray beam energy
E
maximum X-ray energy in the continuous emission spectrum, equal to the product of the
electron charge and the accelerating voltage
Note 1 to entry: E is expressed in megaelectronvolts (MeV).
3.5
wedge X-ray field
X-radiation field with a dose distribution that changes approximately linearly with distance
from the beam edge along a line perpendicular to and passing through the radiation beam
axis
[SOURCE: IEC 60976, 2007, 3.32]
3.6
half-value layer
thickness of a specified material, which attenuates under narrow beam conditions X- radiation
with a particular spectrum to an extent such that the air kerma rate, exposure rate or
absorbed dose rate is reduced to one half of the value that is measured without the material.
The half-value layer (HVL) is expressed in suitable submultiples of the metre together with the
material
[SOURCE: IEC 60601-1-3, 2008, 3.27]
3.7
X-ray beam focal spot
d
dimension across the focal spot of an accelerating tube, measured perpendicular to the
central beam axis
Note 1 to entry: d is expressed in millimetres (mm).
3.8
X-ray beam homogeneity
ratio, expressed as a percent, of the dose rate in a plane 1 m from the target and normal to
the beam central axis, and acquired at a specified angle from the central axis, to the dose
rate in the plane and on the beam axis
3.9
X-ray beam air kerma rate
K
volume of ionization caused by the x-ray beam in air per unit time at 1 m away from target
Note 1 to entry: K is expressed in centigrays per minute (cGy/min).
3.10
X-ray beam asymmetry
ratio of the difference to the average values of the dose rates measured at equal distances
from the central beam axis and in a vertical plane normal to the x-ray beam

– 8 – IEC 62976:2017 © IEC 2017
Note 1 to entry: This ratio is expressed as a percentage.
3.11
X-ray sensitivity
ratio of the minimum defect size that can be observed in the detector to the thickness of the
penetrated material
Note 1 to entry: This ratio is expressed as a percentage.
3.12
X-ray head
part of an X-ray installation that contains the accelerating tube and its shield
4 Equipment sets, names and work conditions
4.1 Equipment sets
Generally, the equipment consists of the following components:
a) X-ray head,
b) modulator,
c) temperature control unit (TCU),
d) control system,
e) power distribution cabinet,
f) safety interlock system,
g) interconnecting cables (X-ray head to modulator, modulator to console) and hoses (TCU to
X-ray head).
4.2 Name convention
The naming rules of the equipment are shown in Figure 1.
XX XX XXX
- /
Maximum X-ray dose-rate, cGy/min
X-ray energy, MeV
Model
IEC
Figure 1 – Naming convention
The specifications of several commonly used accelerator models are shown in Table 1.

Table 1 – Specifications of several
commonly used accelerator models
Specification
Model No. X-ray beam energy Maximum X-ray dose rate
MeV cGy/min
XX-2/200 2 200
XX-4/500 4 500
XX-6/1000 6 1 000
XX-9/3000 9 3 000
XX-12/5000 12 5 000
XX-15/12000 15 12 000
4.3 Operating conditions
4.3.1 Environmental requirement
• environment temperature: (5 to 40) °C;
• relative humidity: ≤90 %.
4.3.2 Power supply
• voltage: 380 V ±10 % three-phase four-wire AC system;
• frequency: 50 Hz ±2 % / 60 Hz ±2 %;
• power supply: it is put forward in the product manual according to the accelerator model;
• grounding resistance: special grounding resistance of modulator is less than 4 Ω.
5 Technical requirements
5.1 Appearance
The surface shall be smooth, uniform color, no obvious scratches, bumps or holes.
5.2 Control system
5.2.1 Design principle
The design of the control system shall ensure the safety of the operator, the device and the
delivered dose.
5.2.2 Operation of start and stop
Operation of X-ray source start and stop shall be executed in the control console.
5.2.3 Functions of control system
The basic functions of the control system shall include:
• normal start-up and shut-down,
• display of the status of normal, fault, alarm and auto-stop,
• display of the main operational parameters,
• safety interlock,
• emergency stop.
– 10 – IEC 62976:2017 © IEC 2017
5.3 Performance
5.3.1 X-ray beam energy
Commonly used X-ray beam energies of accelerators are shown in Table 2 and the
corresponding half value layer should not be less than the value in Table 2.
Table 2 – Half value layer of materials corresponding
to commonly used X-ray beam energies
X-ray beam energy Steel Plexiglas
3 3 3 3
(Material density: 7,8 × 10 kg/m ) (Material density:1,7 × 10 kg/m )
MeV mm mm
1 16 ± 0,5 61 ± 2
2 20 ± 0,5 84 ± 2
4 25 ± 0,5 116 ± 2
6 28 ± 0,5 138 ± 2
9 30 ± 0,5 149 ± 2
12 32 ± 0,5 178 ± 2
15 33 ± 0,5 204 ± 2
5.3.2 X-ray homogeneity
X-ray homogeneity shall not be less than the value in Table 3 by using a beam flattening filter.
Table 3 – X-ray homogeneity of commonly used X-ray beam energies
Subtended angle A between beam central axis and axis connecting the
X-ray beam X-ray
centre of focal spot with the point of measurement located on the
energy homogeneity
circumference
MeV (°) %
1 7,5 80
2 7,5 78
4 7,5 75
6 7,5 62
9 7,5 55
12 6,0 50
15 6,0 45
5.3.3 X-ray beam air kerma rate
X-ray beam air kerma rate shall achieve the value shown in Table 4 (can be reduced based
on purpose).
Table 4 – X-ray beam air kerma rate of different models
X-ray beam energy X-ray beam dose rate
MeV cGy/min
1 20
2 200
4 500
6 1 000
9 3 000
12 5 000
15 12 000
5.3.4 X-ray beam focal spot
The diameter of the X-ray spot shall be less than or equal to 2,0 mm when the X-ray beam
energy is less than 9 MeV; the diameter of X-ray spot shall be less than or equal to 3,5 mm
when X-ray beam energy is equal to or higher than 9 MeV.
5.3.5 X-ray beam asymmetry
X-ray beam asymmetry shall be less than 3 % at 7,5° away from X-ray beam center axis when
the X-ray beam energy is less than or equal to 9 MeV; X-ray beam asymmetry shall be less
than 5 % at 6° away from X-ray beam center axis when X-ray beam energy is higher than
9 MeV.
5.3.6 X-ray sensitivity
In the range of the X-ray beam energy and the corresponding equivalent steel thickness
stated in Table 5, X-ray sensitivity shall be less than 1 % as determined by linear
densitometry for imaging detection.
Table 5 – Detection range of equivalent steel thickness
corresponding to commonly used X-ray beam energies
X-ray beam energy Range of equivalent steel thickness
MeV mm
1 36 to 150
2 40 to 200
4 50 to 250
6 50 to 280
9 76 to 380
12 100 to 420
15 100 to 460
NOTE Equivalent steel thickness is the conversion of different plate thickness based on the density of
3 3
7,8 x 10 kg/m steel.
– 12 – IEC 62976:2017 © IEC 2017
5.3.7 Dose leakage
a) X-ray dose leakage
A measure of leakage is given by the ratio of X-ray dose rate 1 m away from the target in
a variety of directions to the X-ray dose rate on the central beam axis. This shall be
expressed as a percentage and shall be less than 0,1 %.
b) Neutron dose leakage (if the accelerator energy is higher than or equal to 10 MeV)
Neutron dose rate shall be no more than 0,01 mSv/h 1 m away from the target beyond the
X-ray field formed by the forward collimator and no more than 0,001 mSv/h in other places.
5.4 Electrical safety
5.4.1 Protective grounding
Separated electric shock protection is essential. The resistance between metal surface and
grounding terminal shall not be more than 0,1 Ω.
5.4.2 Insulation resistance
The insulation resistance between wires (including phase line and zero line) and ground of
each independent electrical part of the equipment should not be less than 1 MΩ when the test
voltage (AC RMS or DC average) reaches to 1 000 V.
5.4.3 Dielectric strength
Electrical equipment with electrical grounding should tolerate the dielectric strength testing of
2 000 V (AC RMS or DC average) with no breakdown and no repeated arcing during the test.
5.4.4 Protection against electric shock
Electrical equipment of the accelerator should have anti shock functionality under the
condition of normal use, the touchable parts should not be hazardous or live. The voltage
between accessible component and ground terminal should be less than AC 30 V or DC 60 V.
The warning symbols for “high voltage” shall be posted near the high voltage device.
5.5 Reliability
5.5.1 Continuous operation
The device shall be able to operate for 8 h with less than 4 interruptions lasting no more than
30 min each.
5.5.2 Recovery
The time of reaching the normal work status shall be less than 15 min when the downtime
without fault is longer than 1 h after shutdown.
5.5.3 Restart
The time of reaching the normal work status shall be less than 150 min when the downtime
without fault is longer than 48 h after shutdown.
6 Test methods
6.1 General requirements
6.1.1 Testing conditions
The test shall be carried out under the conditions of Table 6.

Table 6 – Testing conditions
Environmental parameter Reference value Range
Temperature 25 °C 5 °C to 40 °C
Relative humidity 65 % ≤90 %
Atmospheric pressure 101,3 kPa 86 kPa to 106 kPa
Voltage (alternating current) 380 V 380 V ± 10 %
Frequency (alternating current) 50 Hz /60 Hz 50 Hz ± 2 % / 60 Hz ± 2 %

6.1.2 Instruments and devices
6.1.2.1 General
Within the validity verification, the test equipment and instruments should meet the test
requirements.
6.1.2.2 X-ray dose meter
An X-ray dose meter is used to measure the in-beam air kerma rate.
6.1.2.3 Wire-type image quality indicators
Wire-type image quality indicators complying with ISO 19232-1:2013 shall be used to
measure X-ray sensitivity.
6.1.2.4 “Sandwich” test module
The “Sandwich” test module is used to measure the X-ray beam focal spot size. It is closely
superposed by the rectangular (250 mm x 60 mm) copper or lead foil (with white color) and
plastic pieces (with black color) alternately as shown in Figure 2, the foil thickness h1 is not
more than 0,1 mm, plastic film thickness h2 is not more than 0,3 mm, and the superimposing
thickness is not less than 60 mm.
Dimensions in millimetres
IEC
Figure 2 – Sketch map of the test module
6.1.2.5 Copper block with a swivelling edge
The copper block (60 mm x 60 mm x 16 mm) with a swiveling edge ± 15° is a test block using
as alternative method for the focal spot measurement, see Figure 3.

– 14 – IEC 62976:2017 © IEC 2017
Dimensions in millimetres
15°
IEC
Figure 3 – Sketch map of the copper block with a swivelling edge
6.1.2.6 Plate specimen
The plate specimens are 36 mm to 460 mm steel or equivalent thickness of solid propellant to
aid in measuring the X-ray beam energy and X-ray sensitivity. Select the appropriate range of
the plate thickness depending on the energy of the accelerator, as specified in Table 5.
6.2 Visual inspection
Visually check the appearance of the facility with normal illumination to demonstrate that the
requirements of 5.1 are satisfied.
6.3 Control system test
By visual inspection and demonstration to ensure that the control system satisfies the
requirements of 5.2.
6.4 Performance test
6.4.1 X-ray beam energy
Measure the half-value layer of X-ray beam produced by the accelerator in steel or solid
propellant in order to estimate the X-ray beam energy of the accelerator.
When measuring, the dosimeter probe is placed 1 m from the target in the center of the X-ray
beam (the 0° direction), and steel plates with different thicknesses are placed between the
probe and the target. Measure the X-ray attenuation through steel plates with different

thicknesses d and with the same dose rate, D , as measured by a dose meter. In general, in
order to prevent errors caused by low-energy X-rays, the initial plate thickness should be
greater than two times the half-value layer corresponding to the measured energy profile.
Graph the X-ray beam air kerma rates obtained with different thickness steel plates or solid
propellants. Use the least-squares method to calculate µ values according to the formula (1),
further calculate the half value layer d value using the formula d = ln2/µ, and use Table 2

1/2 1/2
to estimate the X-ray beam energy.
  −µd
D= D e
0 (1)
where
d is the plates thickness, in mm;

is the dose rate when d = 0, in cGy/min;
D

is the dose rate, in cGy/min;
D
–1
µ is the linear attenuation coefficient, in mm .
The test results shall comply with the requirement of 5.3.1.
6.4.2 X-ray homogeneity
Measure the X-ray air kerma rate 1 m from the target on the central axis of the X-ray beam,
 
. Measure the X-ray air kerma rates, , in a plane normal to the beam axis and at equal
K K
0 i
and symmetrically opposing distances as shown in Figure 4. Measure at least four rates at
horizontal and vertical transverse points that each make an angle A with the central beam axis
(the values of A are given in Table 3). All measurements are to be made under the same

conditions. Use the minimum of the K acquired to calculate the homogeneity h according to
i h
formula (2).

K
min
h = ×100 %
h
(2)

K
where
h is the X-ray homogeneity;
h

K is the minimum X-ray air kerma rate measured from the set of points A degrees from the
min
beam axis and 1 m from the target, in cGy/min;

is the X-ray air kerma rate value on the central axis 1 m far from the target, in cGy/min.
K
2'
Target
A°
O 1'
A° O
1 m
IEC
Figure 4 – Schematic diagram of X ray beam radial uniformity measurement
The computed homogeneity shall comply with the requirements of 5.3.2.

– 16 – IEC 62976:2017 © IEC 2017
6.4.3 X-ray beam air kerma rate
Place the dosimeter probes in front and 1 m far from the target at the center of X ray beam
axis, set the standard dosimeter mode to “dose” and measure 3 sets of time and dose during
the beam test, calculate the average value of X-ray beam air kerma rate, then multiply the
calibration factor of the certificate and the air density correction factor. The result is the X-ray
beam air kerma rate of the accelerator.
The test result shall comply with the requirements of 5.3.3.
6.4.4 X-ray beam focal spot
6.4.4.1 “Sandwich” test method
The X-ray beam focal spot is measured using a test module made according to 6.1.2.4, as
shown in Figure 5. Place the test module 300 mm, 500 mm, and 800 mm from the target at
the center of X ray beam axis as shown in Figure 6. X-ray beam slits through the
corresponding plastic sheet, and makes the film exposure put at the other end of the test
module; after being film processed, several black lines will appear, the black intensity is larger
at the center and smaller on both sides.
Using the number of black lines whose black intensity is 50 % or greater than the central,
calculate the X-ray beam focal spot according to formula (3).
d = (h + h ) × n (3)
i 1 2 i
where
d is the X-ray beam focal spot, in mm;
i
h is the copper or lead foil thickness, in mm;
h is the plastic piece thickness, in mm;
is the number of black lines whose black intensity is 50 % or greater than the central.
n
i
For each of 3 distances, use the least-squares method for linear fitting, (d = (al + d ) where a
i c
is the linear factor, l is the distance of the testing module to target, and d is the X-ray beam
c
focus spot value when l equal to 0.
The results shall comply with the requirements of 5.3.4.
Detector
Lead foil
Plastic piece
X-ray beam direction
IEC
Figure 5 – Schematic diagram of the testing module in front of the detector

Dimensions in millimetres
Test model
Target
Accelerating tube
X-ray beam direction
IEC
Figure 6 – Schematic diagram of the “Sandwich” test module placement
6.4.4.2 “Copper block” method
An alternative method for the focal spot measurement is a copper block made according to
6.1.2.5. When the copper block is exactly in the middle between target and image detector as
shown in Figure 7, then the detector image shows directly the focal spot size measured.
Otherwise a magnification factor has to be considered. A typical distance between focal spot
and detector is 4 m. The focal spot size is measured as edge unsharpness according to the
Klasens method (unsharpness is the distance of the 16 % and the 84 % points in a profile
across the sharpest edge response in the image multiplied by 1,47).
A horizontal edge position measures the vertical focal spot size and a vertical edge
orientation measures the horizontal focal spot size.
The result shall comply with the requirements in 5.3.4.
Dimensions in metres
Copper block Image detector
Target
Accelerating tube
X-ray beam
direction
IEC
Figure 7 – Schematic diagram of the copper block test module placement

– 18 – IEC 62976:2017 © IEC 2017
6.4.5 X-ray beam asymmetry
Get the difference and the average of the four measurements in 6.4.2 shown in Figure 4 as 1,
1’, 2, and 2’. Calculate the X-ray beam asymmetry h according to formula (4).
  
ΔD D− D′
i i
h= = ×100 %
(4)
 
 (D+ D′)/ 2
i i
D
max
where
  
DD is the difference of D and D′ ;
i i
  
D is the average of D and D′ ;
i i
 
D and D′ are the dose rates of two symmetry points.

i i
The results shall comply with the requirements of 5.3.5.
6.4.6 X-ray sensitivity
Place the steel plate specimen with the thickness of Table 5 vertically and 1 m from the target
at the center of X ray beam axis. Attach wire-type image quality indicators to the side of the
plate that is closest to the X-ray beam; attach film to the other plate side. Process the film
after exposure, observe the minimum line diameter of image quality indicators in the film, and
calculate the X-ray sensitivity according to formula (5).

d
min
C= ×100 % (5)
T
where
C is the X-ray sensitivity;
d is the minimum line diameter of image quality indicators in the film, in mm;
min
T is the thickness of steel plate, in mm.
The results shall comply with the requirements of 5.3.6.
6.4.7 Leakage dose rate
Block front-end and the surrounding space of accelerator collimator with more than 10 half
value layers of lead or tungsten. Consider a sphere with a radius of 1 m with the target as its
center. Place dosimeter probes at twenty or more locations on the sphere (see Figure 8 for
normative locations; the target is at O) and measure the dose rates normalized to 1 min to

obtain D . The dose rate percentage is calculated for each measurement by formula (6)
i

relative to dose rate D at a distance of 1 m from the center beam of the X-ray to the target
without blocking.

D
i
h = × 100 %
(6)
LDR

D
The test results of each point shall comply with the requirements of 5.3.7.

O
X-ray beam direction
IEC
Figure 8 – Diagram of leakage dose measurement points
6.5 Electrical safety testing
6.5.1 Protective grounding
Ground resistance tester shall be used to measure the resistance of ground-end and the shell,
the test current is 25 A, the result should comply with the requirements of 5.4.1.
6.5.2 Insulation resistance
Using 1 000 V insulation resistance meter, test insulation resistances of phase line, zero line
to ground and metal shell, the result shall comply with the requirements of 5.4.2.
6.5.3 Dielectric strength
Test voltage shall be gradually increased to 2 000 V in 10 s, and maintained for at least 1 min,
the test results shall comply with the requirements of 5.4.3.
6.5.4 Protection against electric shock
Use 2 kΩ resistor in parallel on the AC and DC
...

IEC 62976 ®
Edition 1.1 2021-10
CONSOLIDATED VERSION
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
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Industrial non-destructive testing equipment – Electron linear accelerator

Appareils destinés aux essais non destructifs pour le secteur industriel –
Accélérateur électronique linéaire

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IEC 62976 ®
Edition 1.1 2021-10
CONSOLIDATED VERSION
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Industrial non-destructive testing equipment – Electron linear accelerator

Appareils destinés aux essais non destructifs pour le secteur industriel –

Accélérateur électronique linéaire

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 27.120.01 ISBN 978-2-8322-1043-7

IEC 62976 ®
Edition 1.1 2021-10
CONSOLIDATED VERSION
REDLINE VERSION
VERSION REDLINE
colour
inside
Industrial non-destructive testing equipment – Electron linear accelerator

Appareils destinés aux essais non destructifs pour le secteur industriel –
Accélérateur électronique linéaire

– 2 – IEC 62976:2017+AMD1:2021 CSV
© IEC 2021
CONTENTS
FOREWORD . 5
1 Scope . 7
2 Normative references. 7
3 Terms and definitions . 7
4 Equipment sets, names and work conditions . 9
4.1 Equipment sets . 9
4.2 Name convention . 9
4.3 Operating conditions . 10
4.3.1 Environmental requirement . 10
4.3.2 Power supply . 10
5 Technical requirements . 10
5.1 Appearance . 10
5.2 Control system . 10
5.2.1 Design principle . 10
5.2.2 Operation of start and stop . 10
5.2.3 Functions of control system . 10
5.3 Performance . 11
5.3.1 X-ray beam energy . 11
5.3.2 X-ray homogeneity . 11
5.3.3 X-ray beam air kerma rate . 11
5.3.4 X-ray beam focal spot . 12
5.3.5 X-ray beam asymmetry . 12
5.3.6 X-ray sensitivity . 12
5.3.7 Dose leakage . 13
5.4 Electrical safety . 13
5.4.1 Protective grounding . 13
5.4.2 Insulation resistance . 13
5.4.3 Dielectric strength . 13
5.4.4 Protection against electric shock . 13
5.5 Reliability . 13
5.5.1 Continuous operation . 13
5.5.2 Recovery . 13
5.5.3 Restart . 13
6 Test methods . 13
6.1 General requirements . 13
6.1.1 Testing conditions . 13
6.1.2 Instruments and devices. 14
6.2 Visual inspection . 15
6.3 Control system test . 15
6.4 Performance test . 15
6.4.1 X-ray beam energy . 15
6.4.2 X-ray homogeneity . 16
6.4.3 X-ray beam air kerma rate . 17
6.4.4 X-ray beam focal spot . 17
6.4.5 X-ray beam asymmetry . 19
6.4.6 X-ray sensitivity . 19

© IEC 2021
6.4.7 Leakage dose rate . 19
6.5 Electrical safety testing . 20
6.5.1 Protective grounding . 20
6.5.2 Insulation resistance . 20
6.5.3 Dielectric strength . 20
6.5.4 Protection against electric shock . 20
6.6 Reliability test . 20
6.6.1 Continuous operation . 20
6.6.2 Recovery . 20
6.6.3 Restart . 20
7 Inspection rules . 21
7.1 Inspection classification . 21
7.2 Inspection items . 21
7.3 Criterion rule . 21
8 Marking Signage, packaging, transportation, storage and accompanying
documents . 21
8.1 Marking Signage . 21
8.1.1 Accelerator signs . 21
8.1.2 Component nameplates . 22
8.1.3 Labels . 22
8.1.4 Warning signs . 22
8.2 Packaging . 22
8.3 Transportation . 22
8.4 Storage . 22
8.5 Accompanying documents . 23
8.5.1 Instructions . 23
8.5.2 Product certification Supplier’s declaration of conformity . 23
8.5.3 Other documents . 23

Figure 1 – Naming convention . 9
Figure 2 – Sketch map of the test module . 14
Figure 3 – Sketch map of the copper block with a swivelling edge . 15
Figure 4 – Schematic diagram of X ray beam radial uniformity measurement . 16
Figure 5 – Schematic diagram of the testing module in front of the detector . 17
Figure 6 – Schematic diagram of the “Sandwich” test module placement . 18
Figure 7 – Schematic diagram of the copper block test module placement . 18
Figure 8 – Diagram of leakage dose measurement points . 20

Table 1 – Specifications of several commonly used accelerator models . 10
Table 2 – Half value layer of materials corresponding to commonly used X-ray beam
energies . 11
Table 3 – X-ray homogeneity of commonly used X-ray beam energies . 11
Table 4 – X-ray beam air kerma rate of different models . 12
Table 5 – Detection range of equivalent steel thickness corresponding to commonly
used X-ray beam energies . 12
Table 6 – Testing conditions . 14

– 4 – IEC 62976:2017+AMD1:2021 CSV
© IEC 2021
Table 7 – Inspection items of the accelerator . 21

© IEC 2021
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
INDUSTRIAL NON-DESTRUCTIVE TESTING EQUIPMENT –
ELECTRON LINEAR ACCELERATOR
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
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with the International Organization for Standardization (ISO) in accordance with conditions determined by
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2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
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between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
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services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
This consolidated version of the official IEC Standard and its amendment has been
prepared for user convenience.
IEC 62976 edition 1.1 contains the first edition (2017-05) [documents 45/821/FDIS and
45/824/RVD] and its amendment 1 (2021-10) [documents 45/920/CDV and 45/929/RVC].
In this Redline version, a vertical line in the margin shows where the technical content
is modified by amendment 1. Additions are in green text, deletions are in strikethrough
red text. A separate Final version with all changes accepted is available in this
publication.
– 6 – IEC 62976:2017+AMD1:2021 CSV
© IEC 2021
International Standard IEC 62976 has been prepared by technical committee 45: Nuclear
instrumentation.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
The committee has decided that the contents of the base publication and its amendment will
remain unchanged until the stability date indicated on the IEC web site under webstore.iec.ch
in the data related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct
understanding of its contents. Users should therefore print this document using a
colour printer.
© IEC 2021
INDUSTRIAL NON-DESTRUCTIVE TESTING EQUIPMENT –
ELECTRON LINEAR ACCELERATOR
1 Scope
This document gives the rules of naming, technical requirements, test methods, inspection,
marking signage, packaging, transportation, storage and accompanying documents for
electron linear accelerator equipment for Non-Destructive Testing (NDT).
This document applies to NDT electron linear accelerator equipment in the X-ray energy
range of 1 MeV to 15 MeV, including the accelerator equipment for radiographic film,
computed radiography with imaging plates, real-time imaging, digital detector array and
industrial computerized tomography.
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.
ISO/IEC Guide 37:2012, Instructions for use of products by consumers
ISO 780:2015, Packaging – Distribution packaging – Graphical symbols for handling and
storage of packages
ISO 19232-1:2013, Non-destructive testing – Image quality of radiographs – Part 1:
Determination of the image quality value using wire-type image quality indicators
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1
target
area on the surface of accelerating tube outlet on which the electron beam impinges and from
which the primary beam of X-rays is emitted
3.2
linear electron accelerator
LINAC
apparatus for producing high energy electrons by accelerating them along a waveguide. The
electrons strike a target to produce X-rays
Note 1 to entry: NDT electron linear accelerator, hereinafter referred to as the accelerator.
[SOURCE: ISO 5576:1997, 2.84]
– 8 – IEC 62976:2017+AMD1:2021 CSV
© IEC 2021
3.3
X-rays
penetrating electromagnetic radiation, within the approximate wavelength range of 1 nm to
0,0001 nm, produced when high velocity electrons impinge on a metal target
[SOURCE: ISO 5576:1997, 2.129]
3.4
X-ray beam energy
E
maximum X-ray energy in the continuous emission spectrum, equal to the product of the
electron charge and the accelerating voltage
Note 1 to entry: E is expressed in megaelectronvolts (MeV).
3.5
wedge X-ray field
X-radiation field with a dose distribution that changes approximately linearly with distance
from the beam edge along a line perpendicular to and passing through the radiation beam
axis
[SOURCE: IEC 60976, 2007, 3.32]
3.6
half-value layer
thickness of a specified material, which attenuates under narrow beam conditions X- radiation
with a particular spectrum to an extent such that the air kerma rate, exposure rate or
absorbed dose rate is reduced to one half of the value that is measured without the material.
The half-value layer (HVL) is expressed in suitable submultiples of the metre together with the
material
[SOURCE: IEC 60601-1-3, 2008, 3.27]
3.7
X-ray beam focal spot
d
dimension across the focal spot of an accelerating tube, measured perpendicular to the
central beam axis
Note 1 to entry: d is expressed in millimetres (mm).
3.8
X-ray beam homogeneity
ratio, expressed as a percent, of the dose rate in a plane 1 m from the target and normal to
the beam central axis, and acquired at a specified angle from the central axis, to the dose
rate in the plane and on the beam axis
3.9
X-ray beam air kerma rate
K
volume of ionization caused by the x-ray beam in air per unit time at 1 m away from target
Note 1 to entry: K is expressed in centigrays per minute (cGy/min).
3.10
X-ray beam asymmetry
ratio of the difference to the average values of the dose rates measured at equal distances
from the central beam axis and in a vertical plane normal to the x-ray beam

© IEC 2021
Note 1 to entry: This ratio is expressed as a percentage.
3.11
X-ray sensitivity
ratio of the minimum defect size that can be observed in the detector to the thickness of the
penetrated material
Note 1 to entry: This ratio is expressed as a percentage.
3.12
X-ray head
part of an X-ray installation that contains the accelerating tube and its shield
4 Equipment sets, names and work conditions
4.1 Equipment sets
Generally, the equipment consists of the following components:
a) X-ray head,
b) modulator,
c) temperature control unit (TCU),
d) control system,
e) power distribution cabinet,
f) safety interlock system,
g) interconnecting cables (X-ray head to modulator, modulator to console) and hoses (TCU to
X-ray head).
4.2 Name convention
The naming rules of the equipment are shown in Figure 1.
XX - XX / XXX
Maximum X-ray dose-rate, cGy/min
X-ray energy, MeV
Model
IEC
Figure 1 – Naming convention
The specifications of several commonly used accelerator models are shown in Table 1.

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© IEC 2021
Table 1 – Specifications of several
commonly used accelerator models
Specification
Model No. X-ray beam energy Maximum X-ray dose rate
MeV cGy/min
XX-2/200 2 200
XX-4/500 4 500
XX-6/1000 6 1 000
XX-9/3000 9 3 000
XX-12/5000 12 5 000
XX-15/12000 15 12 000
4.3 Operating conditions
4.3.1 Environmental requirement
• environment temperature: (5 to 40) °C;
• relative humidity: ≤90 %.
4.3.2 Power supply
• voltage: 380 V ±10 % three-phase four-wire AC system;
• frequency: 50 Hz ±2 % / 60 Hz ±2 %;
• power supply: it is put forward in the product manual according to the accelerator model;
• grounding resistance: special grounding resistance of modulator is less than 4 Ω.
5 Technical requirements
5.1 Appearance
The surface shall be smooth, uniform color, no obvious scratches, bumps or holes.
5.2 Control system
5.2.1 Design principle
The design of the control system shall ensure the safety of the operator, the device and the
delivered dose.
5.2.2 Operation of start and stop
Operation of X-ray source start and stop shall be executed in the control console.
5.2.3 Functions of control system
The basic functions of the control system shall include:
• normal start-up and shut-down,
• display of the status of normal, fault, alarm and auto-stop,
• display of the main operational parameters,
• safety interlock,
• emergency stop.
© IEC 2021
5.3 Performance
5.3.1 X-ray beam energy
Commonly used X-ray beam energies of accelerators are shown in Table 2 and the
corresponding half value layer should not be less than the value in Table 2.
Table 2 – Half value layer of materials corresponding
to commonly used X-ray beam energies
X-ray beam energy Steel Plexiglas
3 3 3 3
(Material density: 7,8 × 10 kg/m ) (Material density:1,7 × 10 kg/m )
MeV mm mm
1 16 ± 0,5 61 ± 2
2 20 ± 0,5 84 ± 2
4 25 ± 0,5 116 ± 2
6 28 ± 0,5 138 ± 2
9 30 ± 0,5 149 ± 2
12 32 ± 0,5 178 ± 2
15 33 ± 0,5 204 ± 2
5.3.2 X-ray homogeneity
X-ray homogeneity shall not be less than the value in Table 3 by using a beam flattening filter.
Table 3 – X-ray homogeneity of commonly used X-ray beam energies
Subtended angle A between beam central axis and axis connecting the
X-ray beam X-ray
centre of focal spot with the point of measurement located on the
energy homogeneity
circumference
MeV (°) %
1 7,5 80
2 7,5 78
4 7,5 75
6 7,5 62
9 7,5 55
12 6,0 50
15 6,0 45
5.3.3 X-ray beam air kerma rate
X-ray beam air kerma rate shall achieve the value shown in Table 4 (can be reduced based
on purpose).
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© IEC 2021
Table 4 – X-ray beam air kerma rate of different models
X-ray beam energy X-ray beam dose rate
MeV cGy/min
1 20
2 200
4 500
6 1 000
9 3 000
12 5 000
15 12 000
5.3.4 X-ray beam focal spot
The diameter of the X-ray spot shall be less than or equal to 2,0 mm when the X-ray beam
energy is less than 9 MeV; the diameter of X-ray spot shall be less than or equal to 3,5 mm
when X-ray beam energy is equal to or higher than 9 MeV.
5.3.5 X-ray beam asymmetry
X-ray beam asymmetry shall be less than 3 % at 7,5° away from X-ray beam center axis when
the X-ray beam energy is less than or equal to 9 MeV; X-ray beam asymmetry shall be less
than 5 % at 6° away from X-ray beam center axis when X-ray beam energy is higher than
9 MeV.
5.3.6 X-ray sensitivity
In the range of the X-ray beam energy and the corresponding equivalent steel thickness
stated in Table 5, X-ray sensitivity shall be less than 1 % as determined by linear
densitometry for imaging detection.
Table 5 – Detection range of equivalent steel thickness
corresponding to commonly used X-ray beam energies
X-ray beam energy Range of equivalent steel thickness
MeV mm
1 36 to 150
2 40 to 200
4 50 to 250
6 50 to 280
9 76 to 380
12 100 to 420
15 100 to 460
NOTE Equivalent steel thickness is the conversion of different plate thickness based on the density of
3 3
7,8 x 10 kg/m steel.
© IEC 2021
5.3.7 Dose leakage
a) X-ray dose leakage
A measure of leakage is given by the ratio of X-ray dose rate 1 m away from the target in
a variety of directions to the X-ray dose rate on the central beam axis. This shall be
expressed as a percentage and shall be less than 0,1 %.
b) Neutron dose leakage (if the accelerator energy is higher than or equal to 10 MeV)
Neutron dose rate shall be no more than 0,01 mSv/h 1 m away from the target beyond the
X-ray field formed by the forward collimator and no more than 0,001 mSv/h in other places.
5.4 Electrical safety
5.4.1 Protective grounding
Separated electric shock protection is essential. The resistance between metal surface and
grounding terminal shall not be more than 0,1 Ω.
5.4.2 Insulation resistance
The insulation resistance between wires (including phase line and zero line) and ground of
each independent electrical part of the equipment should not be less than 1 MΩ when the test
voltage (AC RMS or DC average) reaches to 1 000 V.
5.4.3 Dielectric strength
Electrical equipment with electrical grounding should tolerate the dielectric strength testing of
2 000 V (AC RMS or DC average) with no breakdown and no repeated arcing during the test.
5.4.4 Protection against electric shock
Electrical equipment of the accelerator should have anti shock functionality under the
condition of normal use, the touchable parts should not be hazardous or live. The voltage
between accessible component and ground terminal should be less than AC 30 V or DC 60 V.
The warning symbols for “high voltage” shall be posted near the high voltage device.
5.5 Reliability
5.5.1 Continuous operation
The device shall be able to operate for 8 h with less than 4 interruptions lasting no more than
30 min each.
5.5.2 Recovery
The time of reaching the normal work status shall be less than 15 min when the downtime
without fault is longer than 1 h after shutdown.
5.5.3 Restart
The time of reaching the normal work status shall be less than 150 min when the downtime
without fault is longer than 48 h after shutdown.
6 Test methods
6.1 General requirements
6.1.1 Testing conditions
The test shall be carried out under the conditions of Table 6.

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Table 6 – Testing conditions
Environmental parameter Reference value Range
Temperature 25 °C 5 °C to 40 °C
Relative humidity 65 % ≤90 %
Atmospheric pressure 101,3 kPa 86 kPa to 106 kPa
Voltage (alternating current) 380 V 380 V ± 10 %
Frequency (alternating current) 50 Hz /60 Hz 50 Hz ± 2 % / 60 Hz ± 2 %

6.1.2 Instruments and devices
6.1.2.1 General
Within the validity verification, the test equipment and instruments should meet the test
requirements.
6.1.2.2 X-ray dose meter
An X-ray dose meter is used to measure the in-beam air kerma rate.
6.1.2.3 Wire-type image quality indicators
Wire-type image quality indicators complying with ISO 19232-1:2013 shall be used to
measure X-ray sensitivity.
6.1.2.4 “Sandwich” test module
The “Sandwich” test module is used to measure the X-ray beam focal spot size. It is closely
superposed by the rectangular (250 mm x 60 mm) copper or lead foil (with white color) and
plastic pieces (with black color) alternately as shown in Figure 2, the foil thickness h1 is not
more than 0,1 mm, plastic film thickness h2 is not more than 0,3 mm, and the superimposing
thickness is not less than 60 mm.
Dimensions in millimetres
IEC
Figure 2 – Sketch map of the test module
6.1.2.5 Copper block with a swivelling edge
The copper block (60 mm x 60 mm x 16 mm) with a swiveling edge ± 15° is a test block using
as alternative method for the focal spot measurement, see Figure 3.

© IEC 2021
Dimensions in millimetres
15°
IEC
Figure 3 – Sketch map of the copper block with a swivelling edge
6.1.2.6 Plate specimen
The plate specimens are 36 mm to 460 mm steel or equivalent thickness of solid propellant to
aid in measuring the X-ray beam energy and X-ray sensitivity. Select the appropriate range of
the plate thickness depending on the energy of the accelerator, as specified in Table 5.
6.2 Visual inspection
Visually check the appearance of the facility with normal illumination to demonstrate that the
requirements of 5.1 are satisfied.
6.3 Control system test
By visual inspection and demonstration to ensure that the control system satisfies the
requirements of 5.2.
6.4 Performance test
6.4.1 X-ray beam energy
Measure the half-value layer of X-ray beam produced by the accelerator in steel or solid
propellant in order to estimate the X-ray beam energy of the accelerator.
When measuring, the dosimeter probe is placed 1 m from the target in the center of the X-ray
beam (the 0° direction), and steel plates with different thicknesses are placed between the
probe and the target. Measure the X-ray attenuation through steel plates with different

thicknesses d and with the same dose rate, , as measured by a dose meter. In general, in
D
order to prevent errors caused by low-energy X-rays, the initial plate thickness should be
greater than two times the half-value layer corresponding to the measured energy profile.
Graph the X-ray beam air kerma rates obtained with different thickness steel plates or solid
propellants. Use the least-squares method to calculate µ values according to the formula (1),
further calculate the half value layer d value using the formula d = ln2/µ, and use Table 2

1/2 1/2
to estimate the X-ray beam energy.
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  −µd
D= D e
0 (1)
where
d is the plates thickness, in mm;

D is the dose rate when d = 0, in cGy/min;

D is the dose rate, in cGy/min;
–1
µ is the linear attenuation coefficient, in mm .
The test results shall comply with the requirement of 5.3.1.
6.4.2 X-ray homogeneity
Measure the X-ray air kerma rate 1 m from the target on the central axis of the X-ray beam,
 
K . Measure the X-ray air kerma rates, K , in a plane normal to the beam axis and at equal
0 i
and symmetrically opposing distances as shown in Figure 4. Measure at least four rates at
horizontal and vertical transverse points that each make an angle A with the central beam axis
(the values of A are given in Table 3). All measurements are to be made under the same

conditions. Use the minimum of the K acquired to calculate the homogeneity η according to
i h
formula (2).

K
min
η = ×100 %
h
(2)

K
where
η is the X-ray homogeneity;
h

K is the minimum X-ray air kerma rate measured from the set of points A degrees from the
min
beam axis and 1 m from the target, in cGy/min;

K is the X-ray air kerma rate value on the central axis 1 m far from the target, in cGy/min.
2'
Target
A°
O 1'
A° O
1 m
IEC
Figure 4 – Schematic diagram of X ray beam radial uniformity measurement
The computed homogeneity shall comply with the requirements of 5.3.2.

© IEC 2021
6.4.3 X-ray beam air kerma rate
Place the dosimeter probes in front and 1 m far from the target at the center of X ray beam
axis, set the standard dosimeter mode to “dose” and measure 3 sets of time and dose during
the beam test, calculate the average value of X-ray beam air kerma rate, then multiply the
calibration factor of the certificate dosimeter probe and the air density correction factor. The
result is the X-ray beam air kerma rate of the accelerator.
The test result shall comply with the requirements of 5.3.3.
6.4.4 X-ray beam focal spot
6.4.4.1 “Sandwich” test method
The X-ray beam focal spot is measured using a test module made according to 6.1.2.4, as
shown in Figure 5. Place the test module 300 mm, 500 mm, and 800 mm from the target at
the center of X ray beam axis as shown in Figure 6. X-ray beam slits through the
corresponding plastic sheet, and makes the film exposure put at the other end of the test
module; after being film processed, several black lines will appear, the black intensity is larger
at the center and smaller on both sides.
Using the number of black lines whose black intensity is 50 % or greater than the central,
calculate the X-ray beam focal spot according to formula (3).
d = (h + h ) × n (3)
i 1 2 i
where
d is the X-ray beam focal spot, in mm;
i
h is the copper or lead foil thickness, in mm;
h is the plastic piece thickness, in mm;
n is the number of black lines whose black intensity is 50 % or greater than the central.
i
For each of 3 distances, use the least-squares method for linear fitting, (d = (al + d ) where a
i c
is the linear factor, l is the distance of the testing module to target, and d is the X-ray beam
c
focus spot value when l equal to 0.
The results shall comply with the requirements of 5.3.4.
Detector
Lead foil
Plastic piece
X-ray beam direction
IEC
Figure 5 – Schematic diagram of the testing module in front of the detector

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© IEC 2021
Dimensions in millimetres
Test model
Target
Accelerating tube
X-ray beam direction
IEC
Figure 6 – Schematic diagram of the “Sandwich” test module placement
6.4.4.2 “Copper block” method
An alternative method for the focal spot measurement is a copper block made according to
6.1.2.5. When the copper block is exactly in the middle between target and image detector as
shown in Figure 7, then the detector image shows directly the focal spot size measured.
Otherwise a magnification factor has to be considered. A typical distance between focal spot
and detector is 4 m. The focal spot size is measured as edge unsharpness according to the
Klasens method (unsharpness is the distance of the 16 % and the 84 % points in a profile
across the sharpest edge response in the image multiplied by 1,47).
A horizontal edge position measures the vertical focal spot size and a vertical edge
orientation measures the horizontal focal spot size.
The result shall comply with the requirements in 5.3.4.
Dimensions in metres
Copper block Image detector
Target
Accelerating tube
X-ray beam
direction
IEC
Figure 7 – Schematic diagram of the copper block test module placement

© IEC 2021
6.4.5 X-ray beam asymmetry
Get the difference and the average of the four measurements in 6.4.2 shown in Figure 4 as 1,
1’, 2, and 2’. Calculate the X-ray beam asymmetry η according to formula (4).
  
ΔD D− D′
i i
η= = ×100 %
(4)
 
 (D+ D′)/ 2
i i
D
max
where
  
∆D is the difference of D and D′ ;
i i
  
D is the average of D and D′ ;
i i
 
D and D′ are the dose rates of two symmetry points.

i i
The results shall comply with the requirements of 5.3.5.
6.4.6 X-ray sensitivity
Place the steel plate specimen with the thickness of Table 5 vertically and 1 m from the target
at the center of X ray beam axis. Attach wire-type image quality indicators to the side of the
plate that is closest to the X-ray beam; attach film to the other plate side. Process the film
after exposure, observe the minimum line diameter of image quality indicators in the film, and
calculate the X-ray sensitivity according to formula (5).

d
min
C= ×100 % (5)
T
where
C is the X-ray sensitivity;
d is the minimum line diameter of image quality indicators in the film, in mm;
min
T is the thickness of steel plate, in mm.
The results shall comply with the requirements of 5.3.6.
6.4.7 Leakage dose rate
Block front-end and the surrounding space of accelerator collimator with more than 10 half
value layers of lead or tungsten. Consider a sphere with a radius of 1 m with the target as its
center. Place dosimeter probes at twenty or more locations on the sphere (see Figure 8 for
normative locations; the target is at O) and measure the dose rates normalized to 1 min to

obtain D . The dose rate percentage is calculated for each measurement by formula (6)
i

relative to dose rate D at a distance of 1 m from the center beam of the X-ray to the target
without blocking.

D
i
η = × 100 %
(6)
LDR

D
The test results of each point shall comply with the requirements of 5.3.7.

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© IEC 2021
O
X-ray beam direction
IEC
Figure 8 – Diagram of leakage dose measurement points
6.5 Ele
...