scholarly journals Long-term operation of Russian NPPs taking into account the actual loading of passive components

2020 ◽  
Author(s):  
Alexander Arzhaev ◽  
Kirill Arzhaev ◽  
Sergey Butorin ◽  
Ilya Denisov ◽  
Maxim Konstantinov
Keyword(s):  
Structural Integrity ◽  
Measurement Procedure ◽  
Load Level ◽  
Feed Water ◽  
Term Operation ◽  
Actual Load ◽  
Water Pipelines ◽  
Under Construction ◽  
Acoustoelasticity Method

The paper considers provision of strength and structural integrity for safety relevant passive NPP components - pipelines and equipment - in long-term operation of NPP units. The methods of determining the actual load parameters during equipment installation, adjustment and commissioning are considered. The application of the acoustoelasticity method, which provides measurement of mechanical stresses arising as a result of technological operations, will allow to identify implicit installation preloads and assess their impact on ensuring the design life of pipeline systems, including the equipment installed. Recommendations are given for application of the acoustoelasticity method on NPP units under construction as a fist priority. At the objects of application of the acoustoelasticity method for the construction of the Unit1 of Kursk NPP-2, noted above (ECCS, CS, steam and feed water pipelines), at the present time, in accordance with the certified measurement procedure (CMP), it is possible to reveal implicit installation preloads only at temperatures not higher than 55ºC. Monitoring the actual load level in the "as built" state will be a reliable guarantee of safe operation of Kursk NPP-2 pipelines according to the criteria of strength and structural integrity.

Advanced Structural Integrity Assessment Tools for Safe Long Term Operation: ATLAS+ Project — Status of the Activities of the WP3 on Modelling

2019 ◽  
Author(s):  
Stéphane Marie ◽  
Arnaud Blouin ◽  
Tomas Nicak ◽  
Dominique Moinereau ◽  
Anna Dahl ◽  
...  
Keyword(s):  
Large Scale ◽  
Structural Integrity ◽  
Assessment Tools ◽  
Local Approach ◽  
Coupled Models ◽  
Large Defect ◽  
Ductile Tearing ◽  
Term Operation ◽  
Integrity Assessment

Abstract The main objective and mission of the ATLAS+ project is to develop advanced structural assessment tools to address the remaining technology gaps for the safe and long term operation of nuclear reactor pressure coolant boundary systems. ATLAS+ WP3 focuses mainly on ductile tearing prediction for large defect in components: Several approaches have been developed to accurately model the ductile tearing process and to take into account phenomena such as the triaxiality effect, or the ability to predict large tearing in industrial components. These advanced models include local approach coupled models or advanced energetic approaches. Unfortunately, the application of these tools is today rather limited to R&D expertise. However, because of the continuous progress in the performance of the calculation tools and accumulated knowledge, in particular by members of ATLAS+, these models can now be considered as relevant for application in the context of engineering assessments. WP3 will therefore: • Illustrate the implementation of these models for industrial applications through the interpretation of large scale mock-ups (with cracks in weld joints for some of them), • Make recommendations for the implementation of the advanced models in engineering assessments, • Correct data from the conventional engineering approach by developing a methodology to produce J-Δa curve suitable case by case, based on local approach models, • Improve the tools, guidance and procedures for undertaking leak-before-break (LBB) assessments of piping components, particularly in relation to representing structural representative fracture toughness J-Resistance curves and the influence of weld residual stresses. To achieve these goals, WP3 is divided into 4 sub-WPs and this paper presents the progress of the work performed in each sub-WP after 24 months of activities.

Fatigue Monitoring in the Context of Long-Term Operation of the Goesgen Nuclear Power Plant Using AREVA’s FAMOSi

2015 ◽  
Author(s):  
Thomas Wermelinger ◽  
Florian Bruckmüller ◽  
Benedikt Heinz
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Nuclear Power ◽  
Primary Circuit ◽  
Feed Water ◽  
Term Operation ◽  
Operation Modes ◽  
Fatigue Monitoring ◽  
Load Evaluation

In the context of long-term operation or lifetime extension most regulatory bodies demand from utilities and operators of nuclear power plants to monitor and evaluate the fatigue of system, structures and components systematically. As does the Swiss Federal Nuclear Safety Inspectorate ENSI. The nuclear power plant Goesgen started its commercial operation in 1979 and will go into long-term operation in 2019. The increased demand for monitoring and evaluating fatigue due to the pending long-term operation led the Goesgen nuclear power plant to expand the scope of their surveillance and therefore to install AREVA’s fatigue monitoring system FAMOSi in the 2014 outage. The system consists of 39 measurement sections positioned at the primary circuit and the feed-water nozzles of the steam generators. The locations were chosen due to their sensitivity for fatigue. The installed FAMOSi system consists of a total of 173 thermocouples which were mounted in order to get the necessary input data for load evaluation. The advantage of FAMOSi is the possibility to obtain real data of transients near places with highest fatigue usage factors. Examples of steam generator feed-in during heating-up and cooling-down will be given. In addition, spray events before and after the installation of closed loop controlled spray valves will be compared. The measurements and the results of the load evaluation are not only of interest for internal use e.g. in regard to optimization of operation modes (e.g. load-following), but must also be reported to ENSI annually. In addition, by evaluation of stresses and determination of usage factors combined with an optimization of operation modes an early exchange of components can be avoided.

Research Advances in the Interaction among Stratum-Ground Fissure-Tunnel under Subway Dynamic Loading

2012 ◽  
Vol 226-228 ◽  
pp. 1513-1516 ◽  
Author(s):  
Li Qun Yuan ◽  
Hong Jia Liu ◽  
Yu Ming Men
Keyword(s):  
Dynamic Loading ◽  
Dynamic Interaction ◽  
Subway Tunnel ◽  
Ground Fissure ◽  
Ground Fissures ◽  
Term Operation ◽  
Geological Disaster ◽  
Under Construction

Ground fissure is a kind of serious geological disaster. There will be more unprecedented challenges during the construction of the urban subway in ground fissures-developed zone. How to ensure the long-term operation safety of the subway crossing ground fissure belts are the first problems for the subway under construction in the cities with ground fissure developed. One of the important problems is that dynamic interaction and disaster effect control among ground fissure-stratum-subway tunnel under subway dynamic loading, which is also the important problem to be solved in the engineering. This problem involves the following three aspects: (a) the determination of subway dynamic loading; (b) the structure dynamic response of subway tunnel; (c) the interaction among stratum-ground fissure-subway tunnel. According to make a comment on these researches, some issues which are necessary to carry out in this field are suggested.

Advanced Structural Integrity Assessment Tools for Safe Long Term Operation: ATLAS+ Project — Status of the Activities of the WP3 on Modelling in 2020

2020 ◽  
Author(s):  
Arnaud Blouin ◽  
Stéphane Marie ◽  
Tomas Nicak ◽  
Antti Timperi ◽  
Peter Gill
Keyword(s):  
Large Scale ◽  
Structural Integrity ◽  
Assessment Tools ◽  
Local Approach ◽  
Coupled Models ◽  
Large Defect ◽  
Ductile Tearing ◽  
Term Operation ◽  
Integrity Assessment

Abstract The main objective and mission of the ATLAS+ project is to develop advanced structural assessment tools to address the remaining technology gaps for the safe and long term operation of nuclear reactor pressure coolant boundary systems. ATLAS+ WP3 focuses mainly on ductile tearing prediction for large defect in piping and associated components: Several approaches have been developed to accurately model the ductile tearing process and to take into account phenomena such as triaxiality effects, or the ability to predict large tearing in industrial components. These advanced models include local approach coupled models or advanced energetic approaches. Unfortunately, the application of these tools is currently rather limited to R&D expertise. However, because of the continuous progress in the performance of calculation tools and accumulated knowledge, in particular by members of the ATLAS+ consortium, these models can now be considered as relevant for application in the context of engineering assessments. WP3 has been planned to: • Illustrate the implementation of these models for industrial applications through the interpretation of large scale mock-ups (with cracks in weld joints for some of them), • Make recommendations for the implementation of the advanced models in engineering assessments, • Correct data from the conventional engineering approach by developing a methodology to produce J-Δa curve suitable case by case, based on local approach models, • Improve the tools, guidance and procedures for undertaking leak-before-break (LBB) assessments of piping components, particularly in relation to representing structural representative fracture toughness J-Resistance curves and the influence of weld residual stresses. To achieve these goals, WP3 is divided into 4 sub-WPs and this paper presents the progress of the work performed in each sub-WP after 36 months of activities.

Ductile Tearing Prediction of Ferritic Pipe Material by GTN Model for ATLAS+ European Project

2020 ◽  
Author(s):  
Kiminobu Hojo ◽  
Takatoshi Hirota ◽  
Naoki Ogawa ◽  
Satoshi Kumagai
Keyword(s):  
Fracture Behavior ◽  
Structural Integrity ◽  
Assessment Tools ◽  
Pipe Material ◽  
Work Package ◽  
Gtn Model ◽  
Term Operation ◽  
Integrity Assessment ◽  
European Project

Abstract The main objective and mission of the European project ATLAS+ (Advanced Structural Integrity Assessment Tools for Safe Long Term Operation) are to address the remaining technology gaps for the safe and long term operation of nuclear reactor pressure coolant boundary systems. This project includes the development and validation of advanced simulation tools based on fracture mechanics methods using physically based mechanistic models. In the Work Package 3 (WP3), benchmark calculations using different available models are conducted to investigate the accuracy and the capability of the different models for ductile crack growth of different constraint condition, such as laboratory specimens and piping structure, which were tested in the Work Package 1 (WP 1). The authors joined the WP3 activity and investigated the effect of the parameters of the GTN (Gurson-Tvergaard-Needleman) model on the fracture behavior of the specimens. In this paper, the parameters of the GTN model were calibrated to simulate the fracture behavior of CT specimens, notched tensile (NT) specimens and single edge notched tensile (SENT) specimens of ferritic pipe material and the applicability of the GTN model. The adjusted parameters by the CT specimen predicted the fracture behavior of the SENT specimens, but did not those of the NT specimens. The adjusted parameters by the CT specimens were applied to the piping structure mock-up and they predicted the maximum load in high accuracy.

A Structural Integrity Assessment of a Nuclear Boiler Superheater Bifurcation at High Temperature

2018 ◽  
Author(s):  
Brahim Nadri ◽  
Robert X. Wang
Keyword(s):  
Fatigue Crack ◽  
Crack Initiation ◽  
Structural Integrity ◽  
Fatigue Crack Initiation ◽  
Metal Loss ◽  
Term Operation ◽  
Creep Fatigue ◽  
Safety Case ◽  
Creep Fatigue Crack

Steam generating boilers in gas cooled nuclear reactors in the UK operate at high temperatures and some of them have been in service for more than 30 years and are now facing the challenges from long term operation extension demand. The tubular components experience surface metal losses due to exposure to oxidation and corrosive environment and as a result, some tubes suffer from restricted flow which may lead to an increased creep-fatigue crack initiation damage. To maintain or recover boiler heat transfer efficiency, internal chemical cleaning of selected boiler tubes is carried out, which introduces additional metal loss in the tube wall, weakening its load bearing capacity. Some boiler components are subject to high temperature, pressure and mechanical loadings in large number of operating cycles through life, introducing creep in addition to cyclic fatigue damage. In support of an operational safety case and plant long term operation extension requirements, structural integrity assessments have been carried out on a critical boiler component — bifurcation, taking into account tube wall metal loss for extended long term services, including the effects of possible future chemical cleaning operations. This paper presents the finite element analyses and R5 Volume 2/3 assessment work carried out for the structural integrity substantiation of a stainless steel boiler tube bifurcation. The bifurcation is a tubular component subject to significant applied displacement due to long range thermal expansion of the neighbouring components. The initial study following normal industry practice using a decoupled analysis approach showed that the strain ranges obtained would exceed the creep-fatigue crack initiation capacity and plastic ratchetting would occur which would lead to short term, incremental plastic collapse, hence a safety case could not be made. To meet the challenge, the analysis and assessment processes have been examined. A coupled FE analysis approach was used to remove the pessimism associated with the decoupled analysis approach. This approach captures the displacement-controlled nature of the system loads and allows a more realistic assessment. In addition, the plant life has been divided into a number of assessment periods such that the more realistic metal loss appropriate for each period could be used. Furthermore, segregated temperature zones have been considered in the assessment, leading to a significant reduction in the creep-fatigue crack initiation damage and a satisfactory extended long term operation safety case.

scholarly journals REPAIRING THE MAIN SHAFT OF DRYER TOASTER

2018 ◽  
Vol 18 (3) ◽  
pp. 311-317 ◽  
Author(s):  
Y. G. Lyudmirsky ◽  
S. S. Assaulenko
Keyword(s):  
Structural Integrity ◽  
Aggressive Medium ◽  
Medium Effect ◽  
Main Shaft ◽  
Term Operation ◽  
Compressive Stresses ◽  
Anticorrosion Coatings ◽  
Wear And Corrosion ◽  
3D Software

Introduction. The sources of damage and wear of the main shaft of the  drier  toaster  are  analyzed.  The  repair  know-how  and welding operations execution limitations which must be considered when developing the technique providing the restoration of the structure performance  features are studied. The work objective is to develop a technique of repair without dismantling  for  the  main  toaster  shaft.  To  solve  the  task,  a design   repair   structure   was   installed,   and   postwelding operations  that  meet  the  engineering  and  regulatory requirements for this structure were performed.Materials   and   Methods.   In   “Kompas   3D”   software,   the following models were developed: integral shaft (project shaft design); damaged shaft as a result of long-term operation (more than  15  years);  and  damaged  shaft  with  a  welded  repair structure. Numerical simulation of the stress-strain state (SSS) was carried out.Research Results. Software for the computational modeling of the repair structure SSS is developed. The repair shaft structure in which the maximum stresses do not exceed the shaft stresses in the project design is obtained using the model. To eliminate the aggressive medium effect on the corrosion fatigue strength of the shaft, an insulating method is used. A technique for mounting  the  repair  structure  to  the  shaft  allowing  for  the outrun limitation 0.12 mm is developed.Discussion and Conclusions. Torsion shafts damaged deeply by wear and corrosion are considered. To restore their structural integrity, it is worthwhile using the following complex of techniques:— constructive (consists in the installation of optional parts that compensate for insufficient strength, and provides a reduction in stress concentration in the most loaded zones);— processing (reduces residual welding stresses due to the reasonable sequence of deformation that contributes to generating favorable residual compressive stresses);—  isolation  (is  based  on  the  application  of  anticorrosion coatings).The economic expediency of the developed repair technique is obvious. The repairing of the shaft without dismantling costs 180,000 rubles, while a new shaft costs 3.8 million rubles.

Reliability Model of SOFC Anode Material Under Thermo-Mechanical and Fuel Gas Contaminants Effects

2009 ◽  
Author(s):  
Gulfam Iqbal ◽  
Huang Guo ◽  
Bruce S. Kang
Keyword(s):  
Electrochemical Performance ◽  
Anode Material ◽  
Structural Integrity ◽  
Element Analysis ◽  
Degradation Model ◽  
Fuel Gas ◽  
Term Operation ◽  
Serviceable Life ◽  
Sofc Anode

Solid Oxide Fuel Cells (SOFCs) work under severe environment which deteriorate anode material properties and reduce its serviceable life. Besides electrochemical performance, structural integrity of SOFC anode is essential for successful long-term operation. SOFC anode material is subjected to stresses at high temperature, thermal and redox cycles and fuel gas contaminants effects on its structure during long-term operation. These mechanisms can degrade anode microstructure and decrease electrochemical performance and structural properties. In this research an anode material degradation model is developed and implemented in finite element analysis. The model incorporates thermo-mechanical and fuel gas contaminants degradation effects and predicts long-term structural integrity of SOFC anode. An analytical solution is also developed for button cell deformation under uniform pressure to establish correlation between the degradation model and experimental measurements. Preliminary results of the model application on the planar co-flow SOFC are also presented.

Advanced Structural Integrity Assessment Tools for Safe Long Term Operation (ATLAS+)

2018 ◽  
Author(s):  
Sebastian Lindqvist ◽  
Kim Wallin ◽  
Dominique Moinereau ◽  
Mike Smith ◽  
Stéphane Marie ◽  
...  
Keyword(s):  
Nuclear Reactor ◽  
Structural Integrity ◽  
Assessment Tools ◽  
Experimental Proof ◽  
Term Operation ◽  
Integrity Assessment ◽  
Safety Margins ◽  
Piping Systems ◽  
Reactor Pressure

The main objective and mission of the ATLAS+ project is to develop advanced structural assessment tools to address the remaining technology gaps for the safe and long term operation of nuclear reactor pressure coolant boundary systems. This is achieved by development and validation of: • innovative quantitative methodologies to transfer laboratory material properties to assess the structural integrity of large components, • enhanced treatment of weld residual stresses when subjected to long term operation, • advanced simulation tools based on fracture mechanics methods using physically based mechanistic models, • improved engineering methods to assess components under long term operation taking into account specific operational demands, • integrated probabilistic assessment methods to reveal uncertainties and justify safety margins. Additionally, the objective is to disseminate the findings of the work through special training sessions and links to the NUGENIA association. The project scope of work focuses on piping systems of the reactor coolant pressure boundary components (RCPB) excluding the reactor pressure vessel (RPV). The project is aimed on an experimental proof of concept and validates the developed methodology both at the laboratory scale and the full scale level. The ATLAS+ project contains 4 main technical work packages and one training and dissemination package. These are summarised here.

Fatigue Life Evaluation for the Repair Methods of High Pressure Gas Pipeline

2019 ◽  
Author(s):  
Woo Sik Kim
Keyword(s):  
Finite Element ◽  
High Pressure ◽  
Residual Stresses ◽  
Stress Analysis ◽  
Structural Integrity ◽  
Gas Pipeline ◽  
Optimum Process ◽  
Term Operation ◽  
Steel Sleeve

Abstract High pressure gas pipeline must maintain structural integrity during the design life. To do this, periodic pipeline inspections are carried out, and fitness-for-service assessments are performed on defects found by inspection. Defects that do not meet the evaluation criteria should be repaired and replaced to ensure the integrity of the pipeline structure at the same level as before the defect. High pressure gas pipeline repair method is applied to repair of composite reinforced sleeve and repair of steel sleeve. Although there have been many studies on the short-term structural integrity evaluation of rupture pressure in these repair methods, there is insufficient research to verify whether the long-term operation of the repair pipeline maintains the long-term structural integrity of the repaired pipe. In this study, an optimum process to improve structural integrity was established by investigating effect of the process variables on fatigue lifetime of steel-sleeve repair welds in buried gas pipeline. Residual stresses in the repair welds were derived through sequentially-coupled temperature-stress analysis using ABAQUS, which is a commercial finite element analysis program. In addition, variations of operating stresses were derived by finite element linear elastic stress analysis. Fatigue lifetimes of the steel-sleeve repair welds were evaluated by substituting the derived weld residual stresses and operating stress variations into the structural stress/fracture mechanics approach as input. Appling this method confirms long-term integrity over 200 years in terms of fatigue the abstract here in italics.

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