UT Inspection Research Articles

Development and adaptation of Ultrasonic system for Windblades inspection using Unmanned Aerial Vehicles

Europe is facing one of the most challenging decades with the decarbonization of the energy generation. The increase in the use of energy from renewable sources is essential for the climate and energy global goals. In this way, the optimization of maintenance and repair works of the involved production systems is necessary to reduce costs and time of operation, especially in wind farms, where accessibility is reduced and usually dangerous. For this reason, novel technologies and applications are being investigated in the O&M field like the use of unmanned aerial vehicles (UAVs) for structural assessment of wind blade components through non-destructive technologies (NDT). This is the main goal of DURABLE project, where this investigation is framed. This work is focused on the comparative analysis of different ultrasonic technologies and the development of a protocol for the inspections of wind blades for its application by means of aerial vehicles. The inspections tests have been conducted on samples at laboratory level as a previous work for the post implementation of this technology with drones in field. Diverse UT transducers with 4.0 to 5.0 MHz emission frequencies as well as single element and phased array probes have been used to determine the best configuration for the inspection of each material and thickness of wind blades. To characterize the detectability, artificial defects (impacts and flat-bottomed drills) have been introduced in the test samples to analyze the detectability with manual handled UT inspections. Finally, the most suitable ultrasonic probe was selected, adapted and integrated in an end effector for its implementation in a UAV. The applicability of the inspection by using aerial vehicles has been tested in relevant environment (at laboratory) and in real windfarm.

Thickness Reduction Control System on RB, Using Immersion UT Inspection Technology

Thickness Reduction Control System on RB, Using Immersion UT Inspection Technology

Design and research of UT inspection tool in flaw inspection of large-size forging shaft parts

With the development of mechanical equipment towards large-scale and complexity, the size and operational reliability of its key core components is gradually improved. Aiming at the problem of large radial structure size and high mechanical performance of MP1000 miner forging spindle, but low efficiency and reliability of ultrasonic nondestructive testing, which makes it difficult to detect uneven material in forging process, the finite element numerical simulation of ultrasonic flaw detection process of forging spindle is carried out by using software. By analyzing the locations of ultrasonic probes on different buses on the surface of the spindle, the edge areas of the steps and the processing of the ultrasonic probe, the problem is analyzed. The instantaneous distribution of the sound field in the hole position is summarized. The design method of UT testing special tool for large forging spindle is summarized, and the corresponding testing unique tool is designed. This tool can cooperate with UT equipment to effectively detect the uneven defects in the material of shaft parts and effectively improve the detection efficiency of ultrasonic nondestructive testing in the application of heavy forging spindle parts.

Optimization and comparison of ultrasonic techniques for NDT control of composite material elements

This work contains an overview of innovative procedures related to the optimization of non-destructive control ultrasonic techniques for defect investigation on composite plates. The inspection procedure improvement allows developing ideal ultrasonic setup and methods, giving the operator appropriate criteria and guidelines in terms of equipment, material and control procedures.Ultrasonic inspections are conducted on different GFRP laminates with artificial defects; tests are improved using special parts designed for probe positioning and contact conditions on inspected components. The data processing of UT procedures allows comparing detection sensitivity of different probe frequencies and plate material behavior. Contact ultrasonic method presents best results for GFRP plates using 1 MHz Olympus A103S probe, detecting small defects with maximum signal amplitudes. Finally, a statistical study is performed for repeatability demonstration of UT inspections.

In-service Inspection and Structural Health Monitoring for Safe and Reliable Operation of NPPs

In nuclear power plants, continuous efforts are made to ensure that plants are operated in safe, reliable and economical manner. While utmost care is taken during design, construction and commissioning of the structures, systems& components (SSCs), continued healthiness has to be ensured during operation phase in accordance with the design intent. This is primarily achieved through the establishment of a comprehensive life management programme of surveillance, condition monitoring, periodic In-service inspections (ISI) and maintenance, the purpose of which is to ensure that required safety margins are maintained for all important SSCs throughout plant service life. In any industry, the important mechanisms which lead to SSCs degradation are general corrosion, Flow accelerated corrosion, erosion, thermal effects, fatigue and mechanical wear & fretting. In a Nuclear Power Plant, in addition to these, degradation also occurs due to irradiation and creep. Therefore SSCs need to be designed with due consideration of all such degradation mechanisms. During operation phase, the limiting conditions for operation and requirements of surveillance & condition monitoring for all components important to safety are documented in Technical Specification. A plant specific ISI manual defines and elaborates the ISI internal inspection methods and acceptance criteria. The ISI requirements are decided taking into account best industry practices and operational experience and meet the requirements of existing codes and standards. Both these documents are approved by AERB. In pressurized heavy water reactors, major components covered in ISI programme are coolant channels, feeder pipes, steam generators, heavy water heat exchangers, pressure boundary components, relief valves etc. The inspection methods adopted include use of UT, ECT, DPT and visual inspection. In addition to functional checks for some of the components, ferrography, vibration monitoring and thermography etc are also utilized for rotating equipment. The SSCs where unacceptable indications are revealed by ISI are repaired, replaced or isolated. The base line data generated during Pre-Service inspection is used for comparing and trending of observations. The observations made during ISI are subjected to thorough review and analysis by qualified experts to obtain assurance that unacceptable degradation in component quality is not occurring and it remains fit for service. The containment system of a NPP plays a crucial role in minimizing dose to the public in case of an accident situation. The integrity of Primary and Secondary Containment is assessed by conducting integrated leak rate tests in every Biannual Shut Down. The concrete structure is also subjected to NDT checks on a specified frequency to ensure continued healthiness. Indian nuclear power plants have accumulated an operating experience of more than 380 reactor years of operation. Over the years, the programmes for surveillance, condition monitoring and in-service inspections have been improved significantly and match with best in the industry. As a result, there has been no major age related failure in any of the important SSCs and thus continued safe and reliable operation of NPPs is assured. This paper brings out the ISI & health monitoring methodology adopted at Indian NPPs, to ensure safe and reliable operation.

원전 탄소강 배관의 액적충돌침식 손상에 대한 B-Scan 검사 및 수치해석적 분석

Liquid droplet impingement erosion (LDIE) known to be generated in aircraft and turbine blades is recently appeared in nuclear piping. UT thickness measurements with both A-scan and B-scan UT inspection equipments were performed for a component estimated as susceptible to LDIE in feedwater heater vent system. The thickness data measured with B-Scan equipment were compared with those of A-Scan. Thermal hydraulic analysis based on ANSYS FLUENT code was performed to analyze the behavior of liquid droplets inside piping. The wall thinning rate and residual lifetime based on both existing Sanchez-Caldera equation and measuring data were also calculated to identify the applicability of the existing equation to the LDIE management of nuclear piping. Because Sanchez-Caldera equation do not consider the feature of magnetite formed inside piping, droplet size, colliding frequency, the development of new evaluation method urgently needs to manage the pipe wall thinning caused by LDIE.

Failure analysis of reactor heater tubes SS347H in ISOMAX unit

Cracking phenomenon is one of the most important problems associated with stainless steel alloys applied in industrial processes. In this contribution, investigations have been done about the cracks detected by UT inspections in a reactor heater tubes SS347H of an isomax unit of a refinery during the overhaul.Studies have shown cracking the reactor tube by polythionic acid, arisen from the formation of sulfide scales on the inner surface of the reactor tube in operation. The reactor was exposed to the atmosphere and humidity during overhaul. Then sulfide scales react with oxygen and polythionic acid is produced, leading to cracking in the presence of residual internal stresses at the sensitized material of the reactor tube.

European preparations for the ITER VV sectors manufacture

For the benefit of the bidders for the Call-for-Tender for the 7 sectors of the ITER Vacuum Vessel, launched in early 2010, a large amount of relevant technical information was included to ensure a rapid start to successful manufacture programme, without the need for a full-scale prototype, which would cause an unacceptable delay to the ITER schedule. The methodology of the logical structures of the specification and the additional planned mock-ups are described and the results from nearly a decade of R&D and manufacturing studies carried out inside the EU under the auspices of EFDA and F4E are also summarised. The work covers the evolution of novel manufacturing schemes and technologies, including a modular special local machining centre for making holes in the shell of the vessel with weld preparation included. New results from the combined studies by three parties, and using a round-robin trial system on the UT inspection of single-sided welds, including the successful control of the root side are described. A full-scale, partial prototype has demonstrated the successful construction segments using jigs to control the distortion from conventional welding, from the inner shell to the outer shell, and then the joining of the segments to form a part sector. The paper also summarises the results from the prototype segment, manufactured without jigs and using only EB welds. In order to be able to achieve the required as-welded tight tolerances, two specialised computational techniques have been developed, using SYSWELD and ANSYS codes and calibrated with the mock-ups in order to efficiently predict welding distortions. Based on this successful practical and theoretical work, computer models of the complete poloidal segments or sectors, including jigs, were can now generated and used to investigate many welding sequences in order to optimise the construction and achieve all the tolerances.

Wave Propagation in Coarse Grain Structure in UT Inspection

Removed due to plagiarism The original research was published as: MODELING OF ULTRASONIC PROPAGATION IN A COARSE GRAIN STRUCTURE <https://apps.webofknowledge.com/full_record.do?product=UA&search_mode=GeneralSearch&qid=2&SID=Z1pJDVNJsjgeYkWdsdi&page=2&doc=15> By: Jenson, F.; Fortuna, T.; Doudet, L. Edited by: Thompson, DO; Chimenti, DE Conference: 35th Annual Review of Progress in Quantitative Nondestructive Evaluation Location: Univ Chicago, Chicago, IL Date: JUL 20-25, 2008 REVIEW OF PROGRESS IN QUANTITATIVE NONDESTRUCTIVE EVALUATION, VOLS 28A AND 28B Book Series:AIP Conference Proceedings Volume: 1096 Pages: 1201-1208 Published: 2009

The Study of Corner Echo Inspection with Bulk and Creeping Waves Effect in Ultrasonic Testing

Removed due to plagiarism. The original research was published as: MODELING OF CORNER ECHO IN UT INSPECTION COMBINING BULK AND HEAD WAVES EFFECT <http://apps.webofknowledge.com/full_record.do?product=UA&search_mode=GeneralSearch&qid=2&SID=U2SJlTPsegzt99T6d6T&page=1&doc=8> By: Mahaut, S.; Huet, G.; Darmon, M. Edited by: Thompson, DO; Chimenti, DE Conference: 35th Annual Review of Progress in Quantitative Nondestructive Evaluation Location: Univ Chicago, Chicago, IL Date: JUL 20-25, 2008

ITER nuclear components, preparing for the construction and R&D results

Progress has been made in the preparation of the procurement specifications for key nuclear components of ITER. Detailed design of the vacuum vessel (VV) and in-vessel components is being performed to consider fabrication methods and non-destructive tests (NDT). R&D activities are being carried out on vacuum vessel UT inspection with waves launched at an angle of 20° or 30°, on flow distribution tests of a two-channel model, on fabrication and testing of FW mock-ups and panels, on the blanket flexible support as a complete system including the housing, on the blanket co-axial pipe connection with guard vacuum for leak detection, and on divertor vertical target prototypes. The results give confidence in the validity of the design and identify possibilities of attractive alternate fabrication methods.

Evaluation of NDT-signals for use in the fracture mechanics safety analysis

The defect size determination in components is a difficult question which has to be solved for safety analysis reasons. By using non-destructive techniques like UT inspection there remain restrictions related to the difference between UT-signal and real defect size. Extensive investigations of different types of components were made to generate basic data for the correlation UT-signal—real defect size. This paper describes a procedure for the transformation of UT-signals for embedded single defects into a defect size which could be used for the safety analysis by stress intensity procedures. The introduced corrective factor k for the equation AFS = k • EFBH (actual flaw size diameter, equivalent flat bottom hole) is k = 2.0, resp k = 1.7.

Current in-service inspections of austenitic stainless steel and dissimilar metal welds in light water nuclear power plants

A tendency towards growing requirements for the inspection of austenitic piping can be observed in several countries. In Germany the revised KTA rule demands the UT inspection of austenitic and dissimilar metal welds in piping with diameters of 200 mm or more. On the basis of experience gained from austenitic piping with integranular stress corrosion cracking (IGSCC), longitudinal waves and mode conversion techniques are used. Depending on the geometry, material and grain orientation, spurious signals can be observed which require additional evaluation or analysis measurements. A promising new technique is based on horizontally polarized shear (SH) waves generated by electromagnetic acoustic transducers (EMATs). Investigations in the laboratory and field inspections showed that SH waves are well suited for the detection of longitudinal flaws, especially where the weld can be examined from one side only. For the complete solution of a given inspection problem SH waves can be combined with well-known standard techniques in order to provide redundant information for the characterization and sizing of indications. The investigation of possibilities of SH waves showed that the problem of cast austenitic steel inspection might not be solved using this technique. However, measurements using low frequency UT transducers showed promising results.

Survey and comparison of automated UT systems

In the past decade, the limitations of manual UT inspections have become more severe and adverse. Perhaps the best evidence of this has been the problem of intergranular stress corrosion cracking (IGSCC) in boiling water reactors (BWR). The onset of this problem clearly showed that better and more sophisticated UT inspection methods must be developed to assure the industry that an appropriate level of inspection integrity could be maintained. While automated UT inspection systems have been under development for some time, this event certainly spurred this activity and has resulted in a variety of commercial systems. The intent of this project, sponsored by EPRI, is to develop a utility engineer's ‘Buyer guide’ to automated UT systems. Comparison of different automated UT systems along with results of questionnaires on manual UT versus automated UT costs and effectiveness are reviewed.

Italian developments in the ultrasonic examination of pressure vessels

A review of developments being pursued in Italy in ultrasonics for application to pressure vessels is presented. Although nuclear construction in Italy has suffered heavy delays, R & D activities promoted by the Italian Electricity Board in the mid 1970s on advanced UT for non-destructive inspection of thick welded sections made it possible to obtain significant results scored by CISE Laboratories, mainly through the design, construction and qualification of the manual UT spectroscopy and signal processing computerized ARICE system and of the mechanized multifrequency acoustic holography HADIS system. Meanwhile theoretical ultrasonic modelling is actively studied in order to implement software applications and the overall reliability of UT inspections with regard to flaw detection, location and sizing. Selected contributions from manufacturers and service companies with a view to improving UT practice are acknowledged, and still wider technology transfers may be expected in the future, also under ENEA industrial promotion programmes.

615. Method of investigation of the long-term stability of a material under the action of molten metal.: L B Getsov, Zavodsk Lab, 33 (11), 1967, 1425-1428 ( Russian).

Progress has been made in the preparation of the procurement specifications for key nuclear components of ITER. Detailed design of the vacuum vessel (VV) and in-vessel components is being performed to consider fabrication methods and non-destructive tests (NDT). R&D activities are being carried out on vacuum vessel UT inspection with waves launched at an angle of 20° or 30°, on flow distribution tests of a two-channel model, on fabrication and testing of FW mock-ups and panels, on the blanket flexible support as a complete system including the housing, on the blanket co-axial pipe connection with guard vacuum for leak detection, and on divertor vertical target prototypes. The results give confidence in the validity of the design and identify possibilities of attractive alternate fabrication methods.