rus
Issue #3/2023
C. M. Bechasnov, V. D. Barmasov, A. I. Popov, M. A. Zavialova
System for Endoscopic Control of Heat-eating Assemblies
System for Endoscopic Control of Heat-eating Assemblies
DOI: 10.22184/1993-7296.FRos.2023.17.3.224.230
The system is described for endoscopic control of the inner surface of the guide channels of the heat-eating assemblies of water-watering energy reactors. The main structural elements of the system are presented, including the optical scheme of the image and processing unit. This block provides an angle of viewing of a video system of at least 90°, discretion of the indications of the vertical positioning system of 1 mm and the duration of a single complete inspection of the guide channels 10 minutes.
The system is described for endoscopic control of the inner surface of the guide channels of the heat-eating assemblies of water-watering energy reactors. The main structural elements of the system are presented, including the optical scheme of the image and processing unit. This block provides an angle of viewing of a video system of at least 90°, discretion of the indications of the vertical positioning system of 1 mm and the duration of a single complete inspection of the guide channels 10 minutes.
Теги: endoscopic control fuel assemblies (fa) fuel elements (fe) тепловыделяющие сборки (твс) тепловыделяющие элементы (твэл) эндоскопический контроль
System
for Endoscopic
Control
of Heat-eating Assemblies
C. M. Bechasnov, V. D. Barmasov, A. I. Popov,
M. A. Zavialova
Technological Design Institute of Scientific Instrument Engineering, the Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
The system is described for endoscopic control of the inner surface of the guide channels of the heat-eating assemblies of water-watering energy reactors. The main structural elements of the system are presented, including the optical scheme of the image and processing unit. This block provides an angle of viewing of a video system of at least 90°, discretion of the indications of the vertical positioning system of 1 mm and the duration of a single complete inspection of the guide channels 10 minutes.
Key words: fuel assemblies (FA), fuel elements (FE), endoscopic control
Received on: 24.12.2022
Accepted on: 19.02.2023
Introduction
The endoscopic control procedure (hereinafter referred to as the EC) is highly informative method widely used in many industries. Thus, an internal inspection of various parts and assemblies makes it possible to identify any defects and damage in the inaccessible places. Endoscopy is often the only method that allows to verify the condition of critical parts and assemblies.
In the nuclear power generation complex, EC is used to solve the issues of increasing the service life and reliability of fuel assemblies (FAs) and fuel elements (FEs) [1, 2]. Thus, the main cause of FE depressurization includes the defects resulting from interaction of the shell with foreign matters in the reactor coolant. In addition, there are also shell defects as a result of its interaction with the spacer grid (SG), as well as those related to the irregularities in the FE production process. It has been determined that in 60% of cases, the shell through damage occurs due to interaction with the foreign matter entering the FE bundle from the coolant. In turn, the coolant can contain the remaining material generated during the FE and FA production.
Thus, endoscopic quality control of the FE shells is an important stage in the fuel production process for nuclear reactors. It allows to inspect the inner surface of the FA guide channels and register their inner surface condition. The paper presents the results of development and research of a multichannel endoscopic unit for the internal guide surface inspection of the fuel assemblies in the water-cooled power reactors (WCPR) (hereinafter referred to as the unit).
Unit description
The unit is designed for simultaneous inspection of the internal surface of 19 guide channels (hereinafter referred to as the GCs) and the central WCPR FA pipe by an operator to detect foreign matters and perform video recording of the internal surface condition.
The general view of the unit is shown in Fig. 1. It consists of the following modules:
workplace of the QCD controlling operator;
video data collection and processing unit (hereinafter referred to as the CPU), located on the overhead crane hook with a wired data transmission system to the workplace of the QCD controlling operator;
vertical positioning system for the position of a video data collection and processing unit relative to the end face of the fuel assembly head;
general suspension module with 19 video systems for the internal surface inspection of the guide channels, the central pipe and its bottom. The data and power transmission cables for each video system are located inside the rigid shell. The suspension is attached to the photo and video data processing unit and, in its lowest position, rests on the end face of the fuel assembly head (directly or through the process ring);
process rings for various types of fuel assemblies to limit the immersion depth of video channels.
The optical circuit of the CPU is shown in Fig. 2. A LED light is used to make a ring on the internal surface of the pipes. The reflected beam is clustered using a lens on the camera, the data from which is processed using the special software (SW). The software functions and defect location routine will be described in the next section.
This unit is designed to inspect the internal surface of the guide channels of WCPR fuel assemblies, obtain its digital images and transfer them to the workplace of the controlling operator via an Ethernet cable.
19 video systems and a vertical positioning system are suspended. The maximum length of the submersible part of video channels from the end of the fuel assembly head to the end of the video camera is 4,410 mm. The outer diameter of the video head is 8.2 mm. The reading discreteness of the vertical positioning system reaches 1 mm.
The vertical positioning system relative to the end face of the fuel assembly head is an optoelectronic non-contact measuring device for the suspension immersion depth into the fuel assembly channels, made using the FLS-C10 laser ranging device by DIMETIX.
When inspecting the fuel assemblies, the unit performs the following functions:
functional check of the inspection channels;
functional check of the vertical positioning system;
scanning of video channels and saving the images;
displaying images and the suspension immersion depth on the monitor;
search for suspicious points in the fuel assemblies;
bottom inspection of all fuel assemblies in a separate way.
Unit software
The unit software can be operated in several modes:
administration mode designed to change the unit operation parameters and program settings and view the local protocol;
inspection mode designed to display the images from 19 video systems at the operator’s workplace with the ability to highlight the selected channel and zoom the image;
informative and advising mode designed to process images from 19 video systems in order to identify the ambiguous areas, locate them and provide information to the controlling operator.
An example of video system images in the inspection mode is shown in Fig. 3.
The inspection is completed when the suspension reaches the retaining process ring.
In the administration mode, the operator gives a command to receive and save the inspection results from the CPU. It processes the received data and displays the images of all 19 video channels with the selected immersion depth on the monitor.
The operator is able to view the zoomed-in images and highlight the relevant “openings”.
The “search for suspicious areas” command helps to perform the image processing procedure in order to identify foreign matters. As a result, an inspection report relating to the internal surface of the guide channels is generated.
In the archival file viewing mode, data from the selected archive file is processed.
An example of video system archival image viewing is shown in Fig. 4.
Image processing
to detect foreign matters
Two types of image processing are used: image processing of the internal surface walls of the guide channels and image processing of the guide channel bottom.
The image processing of the internal surface walls of the guide channels is performed using an image gradient, namely a vector indicating the fastest increase direction of a certain value that is changed from one space point to another (scalar field) [3, 4]. In this case, the gradient for each image point (brightness function) is a two-dimensional vector which components are the horizontal and vertical derivatives of the image brightness:
grad I(x, y) = (dI / dx, dI / dy).
At each image point, the gradient vector is oriented in the direction of the greatest increase in brightness, and its length corresponds to the brightness variation value.
To detect foreign matters on the internal surface walls of the guide channels, the gradient vector length at each image point is calculated and compared with a certain maximum allowable value (to be set by the operator during the application setting). Excess of the allowable value is considered to be the detected foreign matter at such a point.
The channel bottom inspection for the availability of foreign matters is performed by comparing the obtained channel bottom image with a reference image from the certain database. For this purpose, a hash function (convolution function) is used that converts an image (input data array with arbitrary length) into an output bit string of a set length (hash) [5, 6].
Conclusion
Thus, the following technical specifications are obtained in the developed multichannel endoscopic unit for the internal guide surface inspection of the fuel assemblies in the water-cooled power reactors:
viewing angle of the video system lens – not less than 90°;
reading discreteness of the vertical positioning system – 1 mm.
the video system provides viewing (clear image) to the entire depth of the FA channel;
the video system removal/installation time is not more than 30 minutes;
the duration of a single full inspection cycle for the guide channels (including any transportation activities and video data archivation) is no more than 10 minutes.
The unit is an autonomous process flow tool as a part of the control and packaging equipment for the WCPR fuel assemblies at the Novosibirsk Chemical Concentrates Plant Public Joint Stock Company.
The development of this unit makes it possible to significantly increase the velocity and credibility of endoscopic inspection of the WCPR FA channels.
Acknowledgements
Financial support for the paper was provided by the Ministry of Science and Higher Education of the Russian Federation.
About Authors
Bechasnov Sergey Mikhailovich, team leader, Technological Design Institute of Scientific Instrument Engineering, the Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia.
Barmasov Viktor Dmitrievich, Leading Electronic Engineer, Technological Design Institute of Scientific Instrument Engineering, the Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia.
Popov Anatoliy Ivanovich, programming supervisor, Technological Design Institute of Scientific Instrument Engineering, the Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia.
Zavialova Marina Andreevna, Cand. of Scien. (Techn.), senior researcher, Technological Design Institute of Scientific Instrument Engineering, the Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia.
ORCID: 0000-0003-2000-6226
for Endoscopic
Control
of Heat-eating Assemblies
C. M. Bechasnov, V. D. Barmasov, A. I. Popov,
M. A. Zavialova
Technological Design Institute of Scientific Instrument Engineering, the Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
The system is described for endoscopic control of the inner surface of the guide channels of the heat-eating assemblies of water-watering energy reactors. The main structural elements of the system are presented, including the optical scheme of the image and processing unit. This block provides an angle of viewing of a video system of at least 90°, discretion of the indications of the vertical positioning system of 1 mm and the duration of a single complete inspection of the guide channels 10 minutes.
Key words: fuel assemblies (FA), fuel elements (FE), endoscopic control
Received on: 24.12.2022
Accepted on: 19.02.2023
Introduction
The endoscopic control procedure (hereinafter referred to as the EC) is highly informative method widely used in many industries. Thus, an internal inspection of various parts and assemblies makes it possible to identify any defects and damage in the inaccessible places. Endoscopy is often the only method that allows to verify the condition of critical parts and assemblies.
In the nuclear power generation complex, EC is used to solve the issues of increasing the service life and reliability of fuel assemblies (FAs) and fuel elements (FEs) [1, 2]. Thus, the main cause of FE depressurization includes the defects resulting from interaction of the shell with foreign matters in the reactor coolant. In addition, there are also shell defects as a result of its interaction with the spacer grid (SG), as well as those related to the irregularities in the FE production process. It has been determined that in 60% of cases, the shell through damage occurs due to interaction with the foreign matter entering the FE bundle from the coolant. In turn, the coolant can contain the remaining material generated during the FE and FA production.
Thus, endoscopic quality control of the FE shells is an important stage in the fuel production process for nuclear reactors. It allows to inspect the inner surface of the FA guide channels and register their inner surface condition. The paper presents the results of development and research of a multichannel endoscopic unit for the internal guide surface inspection of the fuel assemblies in the water-cooled power reactors (WCPR) (hereinafter referred to as the unit).
Unit description
The unit is designed for simultaneous inspection of the internal surface of 19 guide channels (hereinafter referred to as the GCs) and the central WCPR FA pipe by an operator to detect foreign matters and perform video recording of the internal surface condition.
The general view of the unit is shown in Fig. 1. It consists of the following modules:
workplace of the QCD controlling operator;
video data collection and processing unit (hereinafter referred to as the CPU), located on the overhead crane hook with a wired data transmission system to the workplace of the QCD controlling operator;
vertical positioning system for the position of a video data collection and processing unit relative to the end face of the fuel assembly head;
general suspension module with 19 video systems for the internal surface inspection of the guide channels, the central pipe and its bottom. The data and power transmission cables for each video system are located inside the rigid shell. The suspension is attached to the photo and video data processing unit and, in its lowest position, rests on the end face of the fuel assembly head (directly or through the process ring);
process rings for various types of fuel assemblies to limit the immersion depth of video channels.
The optical circuit of the CPU is shown in Fig. 2. A LED light is used to make a ring on the internal surface of the pipes. The reflected beam is clustered using a lens on the camera, the data from which is processed using the special software (SW). The software functions and defect location routine will be described in the next section.
This unit is designed to inspect the internal surface of the guide channels of WCPR fuel assemblies, obtain its digital images and transfer them to the workplace of the controlling operator via an Ethernet cable.
19 video systems and a vertical positioning system are suspended. The maximum length of the submersible part of video channels from the end of the fuel assembly head to the end of the video camera is 4,410 mm. The outer diameter of the video head is 8.2 mm. The reading discreteness of the vertical positioning system reaches 1 mm.
The vertical positioning system relative to the end face of the fuel assembly head is an optoelectronic non-contact measuring device for the suspension immersion depth into the fuel assembly channels, made using the FLS-C10 laser ranging device by DIMETIX.
When inspecting the fuel assemblies, the unit performs the following functions:
functional check of the inspection channels;
functional check of the vertical positioning system;
scanning of video channels and saving the images;
displaying images and the suspension immersion depth on the monitor;
search for suspicious points in the fuel assemblies;
bottom inspection of all fuel assemblies in a separate way.
Unit software
The unit software can be operated in several modes:
administration mode designed to change the unit operation parameters and program settings and view the local protocol;
inspection mode designed to display the images from 19 video systems at the operator’s workplace with the ability to highlight the selected channel and zoom the image;
informative and advising mode designed to process images from 19 video systems in order to identify the ambiguous areas, locate them and provide information to the controlling operator.
An example of video system images in the inspection mode is shown in Fig. 3.
The inspection is completed when the suspension reaches the retaining process ring.
In the administration mode, the operator gives a command to receive and save the inspection results from the CPU. It processes the received data and displays the images of all 19 video channels with the selected immersion depth on the monitor.
The operator is able to view the zoomed-in images and highlight the relevant “openings”.
The “search for suspicious areas” command helps to perform the image processing procedure in order to identify foreign matters. As a result, an inspection report relating to the internal surface of the guide channels is generated.
In the archival file viewing mode, data from the selected archive file is processed.
An example of video system archival image viewing is shown in Fig. 4.
Image processing
to detect foreign matters
Two types of image processing are used: image processing of the internal surface walls of the guide channels and image processing of the guide channel bottom.
The image processing of the internal surface walls of the guide channels is performed using an image gradient, namely a vector indicating the fastest increase direction of a certain value that is changed from one space point to another (scalar field) [3, 4]. In this case, the gradient for each image point (brightness function) is a two-dimensional vector which components are the horizontal and vertical derivatives of the image brightness:
grad I(x, y) = (dI / dx, dI / dy).
At each image point, the gradient vector is oriented in the direction of the greatest increase in brightness, and its length corresponds to the brightness variation value.
To detect foreign matters on the internal surface walls of the guide channels, the gradient vector length at each image point is calculated and compared with a certain maximum allowable value (to be set by the operator during the application setting). Excess of the allowable value is considered to be the detected foreign matter at such a point.
The channel bottom inspection for the availability of foreign matters is performed by comparing the obtained channel bottom image with a reference image from the certain database. For this purpose, a hash function (convolution function) is used that converts an image (input data array with arbitrary length) into an output bit string of a set length (hash) [5, 6].
Conclusion
Thus, the following technical specifications are obtained in the developed multichannel endoscopic unit for the internal guide surface inspection of the fuel assemblies in the water-cooled power reactors:
viewing angle of the video system lens – not less than 90°;
reading discreteness of the vertical positioning system – 1 mm.
the video system provides viewing (clear image) to the entire depth of the FA channel;
the video system removal/installation time is not more than 30 minutes;
the duration of a single full inspection cycle for the guide channels (including any transportation activities and video data archivation) is no more than 10 minutes.
The unit is an autonomous process flow tool as a part of the control and packaging equipment for the WCPR fuel assemblies at the Novosibirsk Chemical Concentrates Plant Public Joint Stock Company.
The development of this unit makes it possible to significantly increase the velocity and credibility of endoscopic inspection of the WCPR FA channels.
Acknowledgements
Financial support for the paper was provided by the Ministry of Science and Higher Education of the Russian Federation.
About Authors
Bechasnov Sergey Mikhailovich, team leader, Technological Design Institute of Scientific Instrument Engineering, the Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia.
Barmasov Viktor Dmitrievich, Leading Electronic Engineer, Technological Design Institute of Scientific Instrument Engineering, the Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia.
Popov Anatoliy Ivanovich, programming supervisor, Technological Design Institute of Scientific Instrument Engineering, the Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia.
Zavialova Marina Andreevna, Cand. of Scien. (Techn.), senior researcher, Technological Design Institute of Scientific Instrument Engineering, the Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia.
ORCID: 0000-0003-2000-6226
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