scholarly journals A Recent Progress in Performance and Property Improvement in Underwater Welding

2021 ◽  
Vol 9 (11) ◽  
pp. 1767-1786
Author(s):  
Ayush Bakrewal
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Weld Zone ◽  
Weld Quality ◽  
Oil Drilling ◽  
Underwater Welding ◽  
Underwater Pipeline ◽  
Recent Developments ◽  
Joint Quality ◽  
Offshore Oil

Abstract: Underwater welding is the process of connecting materials underwater in the presence of water. It is used to maintain and improve the structure in marine and offshore applications. It's utilized for underwater pipeline maintenance, submerged offshore oil drilling, and ship repairs. It can also be found in nuclear power plants and deep-sea mining. Underwater welding is divided into two categories dry welding and wet welding. Dry welding entails enclosing the weld zone in a hyperbaric tank filled with a gas mixture and welding at the prevailing pressure. Wet welding is a type of welding that uses waterproof electrodes and is done directly on the component to be welded. The major benefit of this welding is its simplicity and cost effectiveness, but we can't obtain high weld quality as easily as we can with dry welding. Dry welding, on the other hand, may provide high weld quality, but it is a time-consuming procedure that needs the welder to secure the region with the hyperbaric vessel, and it is also a costly method. Underwater welding has a number of issues, including bubble arc generation, cold cracking, microstructural deformation, and more. We attempted to bring together the most recent developments in the field of underwater welding. We've outlined several techniques that were used to improve welding characteristics as well as important issues that must be addressed. This review article may be used to figure out what measures need to be taken to enhance the underwater weld joint quality. Keywords: Underwater welding, underwater wet welding, underwater dry welding, hyperbaric vessel, underwater welding development

Seismic Fragility of Piping Nozzles in Nuclear Power Plants: A Case for Updating the Current State-of-Practice

2021 ◽  
Author(s):  
Abhinav Gupta ◽  
Ankit Dubey ◽  
Sunggook Cho
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Seismic Analysis ◽  
Nuclear Industry ◽  
Life Extension ◽  
Seismic Loads ◽  
Thermal Loads ◽  
Loss Of Coolant Accident ◽  
Piping Systems ◽  
Recent Developments

Abstract Nuclear industry spends enormous time and resources on designing and managing piping nozzles in a plant. Nozzle locations are considered as a potential location for possible failure that can lead to loss of coolant accident. Industry spends enormous time in condition monitoring and margin management at nozzle locations. Margins against seismic loads play a significant role in the overall margin management. Available margins against thermal loads are highly dependent upon seismic margins. In recent years, significant international collaboration has been undertaken to study the seismic margin in piping systems and nozzles through experimental and analytical studies. It has been observed that piping nozzles are highly overdesigned and the margins against seismic loads are quite high. While this brings a perspective of sufficient safety, such excessively high margins compete with available margins against thermal loads particularly during the life extension and subsequent license renewal studies being conducted by many plants around the world. This paper focuses on identifying and illustrating two key reasons that lead to excessively conservative estimates of nozzle fragilities. First, it compares fragilities based on conventional seismic analysis that ignores piping-equipment-structure interaction on nozzle fragility with the corresponding assessment by considering such interactions. Then, it presents a case that the uncertainties considered in various parameters for calculating nozzle fragility are excessively high. The paper identifies a need to study the various uncertainties in order to achieve a more realistic quantification based on recent developments in our understanding of the seismic behavior of piping systems.

scholarly journals Blowout Accident Impact Analysis Method for the Siting of Offshore Floating Nuclear Power Plant in Offshore Oil Fields

2019 ◽  
Vol 2019 ◽  
pp. 1-7
Author(s):  
Zhigang Lan
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Nuclear Power ◽  
Power Plants ◽  
Impact Analysis ◽  
Oil Spills ◽  
Oil Field ◽  
Oil Fields ◽  
Offshore Oil ◽  
The Impact

Focused on the utilization of nuclear energy in offshore oil fields, the correspondence between various hazards caused by blowout accidents (including associated, secondary, and derivative hazards) and the initiating events that may lead to accidents of offshore floating nuclear power plant (OFNPP) is established. The risk source, risk characteristics, risk evolution, and risk action mode of blowout accidents in offshore oil fields are summarized and analyzed. The impacts of blowout accident in offshore oil field on OFNPP are comprehensively analyzed, including injection combustion and spilled oil combustion induced by well blowout, drifting and explosion of deflagration vapor clouds formed by well blowouts, seawater pollution caused by blowout oil spills, the toxic gas cloud caused by well blowout, and the impact of mobile fire source formed by a burning oil spill on OFNPP at sea. The preliminary analysis methods and corresponding procedures are established for the impact of blowout accidents on offshore floating nuclear power plants in offshore oil fields, and a calculation example is given in order to further illustrate the methods.

scholarly journals Friction Stir Welding and Preliminary Characterization of Irradiated 304 Stainless Steel

2019 ◽  
Author(s):  
Wei Tang ◽  
Maxim Gussev ◽  
Zhili Feng ◽  
Brian Gibson ◽  
Roger Miller ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Friction Stir Welding ◽  
Base Metal ◽  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Weld Zone ◽  
Fusion Welding ◽  
Friction Stir

Abstract The mitigation of helium induced cracking in the heat affected zone (HAZ), a transition metallurgical zone between the weld zone and base metal, during repair welding is a great challenge in nuclear industry. Successful traditional fusion welding repairs are limited to metals with a maximum of a couple of atomic parts per million (appm) helium, and structural materials helium levels in operating nuclear power plants are generally exceed a couple of appm after years of operations. Therefore, fusion welding is very limited in nuclear power plants structural materials repairing. Friction stir welding (FSW) is a solid-state joining technology that reduces the drivers (temperature and tensile residual stress) for helium-induced cracking. This paper will detail initial procedural development of FSW weld trials on irradiated 304L stainless steel (304L SS) coupons utilizing a unique welding facility located at one of Oak Ridge National Laboratory’s hot cell facilities. The successful early results of FSW of an irradiated 304L SS coupon containing high helium are discussed. Helium induced cracking was not observed by scanning electron microscopy in the friction stir weld zone and the metallurgical zones between the weld zone and base metal, i.e. thermal mechanical affected zone (TMAZ) and HAZ. Characterization of the weld, TMAZ and HAZ regions are detailed in this paper.

Validation of the New Post-RCCM Option From Code_Aster Through Benchmark Comparisons With Other Industrial Codes

2017 ◽  
Author(s):  
Thomas Métais ◽  
Sarah Plessis ◽  
Julien Miralles
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
World Wide ◽  
Computer Code ◽  
Post Processing ◽  
Safe Operation ◽  
Benchmark Analysis ◽  
Time Points ◽  
Post Process ◽  
Recent Developments

Fatigue is identified as a significant degradation mode that affects nuclear power plants world-wide. The various international codes and standards (ASME, RCC-M, JSME, etc...) offer rules to predict its damaging effect on the locations of the various components of an NPP. These rules, which ensure conservatism and safe operation, have grown in complexity over the years because they have integrated R&D results showing aggravating effects (such as PWR environment degradation) that were not explicitly included in the original analyses (such as Environmental Assisted Fatigue [1] [2]) but also because an economically viable design of components has required optimization and refinement of mechanical assessment methods. EDF has been developing since 1989 its own in-house FEA code baptised code_aster that is included in the Salome-Meca mechanical package. Salome-Meca is open-access and can be used freely by international users. It is continuously improved with a release at a rate of one new software version per year and it integrates the most recent results obtained by the EDF R&D, in fields as broad as fracture mechanics, XFEM and fatigue. The fatigue post-processing in code_aster offers a span of criteria (Dang Van, Stress Intensity, etc...) to pick and choose from and even offers the possibility to make up owns one fatigue criteria. It also offers the possibility to post-process fatigue according to the RCC-M rules: this is implemented in code_aster through the so-called POST_RCCM operator. Recent developments have enabled EDF to update the POST_RCCM operator in order to bridge the gap with modern fatigue industrial codes. The update effort has included in particular the development of a new option to evaluate fatigue for nozzles according to the RCC-M Annex ZE-200 as well as the clarification of the methodologies used for combining time points and transients. In addition, POST_RCCM includes the possibility to perform calculations with integration of environmental effects, with significant freedom to design one’s own corrections. The option is even left open to integrate a correction per the methodology proposed in [2]. The overall work scope and progress as of early 2016 was reported in [3] and is now in its validation phase. The validation of a fatigue computer code is not an easy task as the full validation using hand calculations would be a highly tedious effort, given the technicality and the multiple choices to make along the various steps of the fatigue analysis. As a result, an accepted way of validating the results obtained with a given code is to perform a benchmark analysis against another industrial fatigue code. This strategy was adopted for the validation of the new POST_RCCM functionalities and this paper presents the work performed and the results obtained.

Innovative high-speed machines with active magnetic bearings for special submerged gas processing

2002 ◽  
Vol 216 (2) ◽  
pp. 183-197
Author(s):  
L M C Mhango ◽  
R Perryman
Keyword(s):  
High Speed ◽  
Nuclear Power ◽  
Power Plants ◽  
Magnetic Bearings ◽  
First Century ◽  
Active Magnetic Bearings ◽  
Electric Drives ◽  
Gas Processing ◽  
Recent Developments ◽  
Gas Circulation

The combination of advances in active magnetic bearings, recent developments in power electronics technology, new design techniques of electrical machines and advances in magnetic materials is contributing to innovative forms of submerged high-speed electric drives which will be suitable for special gas processing applications well into the twenty-first century. Typical applications include submerged industrial high-pressure and high-temperature gas processes, calibration of gas meters, gas circulation in nuclear power plants, etc. This paper looks at the results of case studies of high-speed drives and discusses their benefits and advantages.

ACR-1000® Constructability and Modularization

2008 ◽  
Author(s):  
J. Byrne ◽  
M. Elgohary ◽  
B. Canas ◽  
D. Shemavonian ◽  
R. Ricciuti ◽  
...  
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Oil And Gas ◽  
Worker Safety ◽  
Skilled Trades ◽  
Construction Productivity ◽  
Offshore Oil And Gas ◽  
A Site ◽  
Construction Schedule ◽  
Offshore Oil

Many industries are using skids, modules and prefabrications to enhance construction productivity, reduce schedules and thus reduce costs. The leaders in this regard are offshore oil and gas, chemical and refinery, ship building, etc. Atomic Energy of Canada Ltd. (AECL®) has had considerable success at the Qinshan Nuclear Power project in China with the use of modularization, which proved extremely effective in paralleling of activities and shortening the schedule. Extensive use has been made of skids and modules in Japan and this also has proven effective in shortening schedules in the construction of nuclear power plants. Secondary benefits of modularization and prefabrication include decreased site congestion and logistical issues, increased worker safety, and better quality control of fabrication. Modules and prefabrication allow work to be shifted to areas where skilled trades are more readily available from a site where skilled trades are very limited. One of the objectives for the ACR-1000® (Advanced CANDU Reactor®) project is to produce a design to allow for a very secure construction schedule. The construction method and strategy, consisting of extensive use of prefabrication and modularization, has been defined very early in the ACR-1000 conceptual phase of the layout and design process. This is addressed through a constructability programme that integrates the civil design with site erection and module installation. This paper presents the ACR-1000 construction strategy and methods and show examples of how the integrated civil design approach with modularization and prefabrication are utilized to shorten the construction schedule and reduce the project risk.

Evolution of Fatigue Post-Processing Methods in the EDF Open-Access FEA Code ASTER

2016 ◽  
Author(s):  
Thomas Métais ◽  
Sarah Plessis ◽  
The-Hiep Chau ◽  
Jean-Christophe Le Roux
Keyword(s):  
Stress Intensity ◽  
Open Access ◽  
Fracture Mechanics ◽  
Nuclear Power ◽  
Power Plants ◽  
World Wide ◽  
Post Processing ◽  
Safe Operation ◽  
Post Process ◽  
Recent Developments

Fatigue is identified as a significant degradation mode that affects nuclear power plants world-wide. The various international codes and standards (ASME, RCC-M, JSME, etc...) offer rules to predict its damaging effect on the locations of the various components of an NPP. These rules, which ensure conservatism and safe operation, have grown in complexity over the years because they have integrated R&D results showing aggravating effects that were not included in the original analyses (such as Environmental Assisted Fatigue [1]) but also because an economically viable design of components has required optimization and refinement of mechanical assessment methods. EDF has been developing since 1989 its own open-source FEA code baptised code ASTER that is included in the Salome Meca mechanical package. Salome Meca is open-access and can be used freely by international users. It is continuously improved with a release at a rate of one new software version per year and it integrates the most recent results obtained by the EDF R&D, in fields as broad as fracture mechanics, XFEM and fatigue. The fatigue post-processing in code ASTER offers a span of criteria (Dang Van, Stress Intensity, etc...) to pick and choose from and even offers the possibility to make up one owns fatigue criteria. It also offers the possibility to post-process fatigue according to the RCC-M rules (POST_RCCM operator). Recent developments have enabled to update the POST_RCCM operator to make it bridge the gap with modern fatigue industrial codes as well as to integrate the EAF calculations per the methodology proposed in [2]. The work is currently ongoing within EDF R&D and will give birth to a stabilized and validated version of the code by end of 2016. This paper presents the updates and the new possibilities of the POST_RCCM operator and gives an update of the work as of early 2016.

Case Studies of Pulsed Eddy Current to Measure Wall Loss in Feedwater Heater Shells

2003 ◽  
Author(s):  
Marvin J. Cohn ◽  
Jordan W. Norton
Keyword(s):  
Eddy Current ◽  
Nuclear Power ◽  
Power Plants ◽  
Cost Effective ◽  
Accelerated Corrosion ◽  
Pulsed Eddy Current ◽  
Catastrophic Failures ◽  
Recent Developments ◽  
Wall Loss ◽  
Flow Accelerated Corrosion

There have been several feedwater heater shell failures in nuclear power plants caused by flow-accelerated corrosion (FAC). This failure mechanism may be one of the most important types of damage to mitigate because FAC damage has occasionally resulted in catastrophic failures and human fatalities. Predicting, detecting, and eliminating significant FAC damage can significantly reduce future forced outages and increase personnel safety. This paper describes the implementation of recent developments to perform cost-effective examinations. These advances include the use of specialized pulsed eddy current (PEC) hardware and software to scan for wall thinning without removing insulation. APTECH has performed more than 50 nuclear power plant projects on hundreds of feedwater shells, as well as numerous pipe examination projects, using the PEC equipment as a cost-effective screening tool for the detection of areas with significant wall loss. Results of shell wall loss measurements using ultrasonic examination (UT), the PEC average wall thickness (AWT) estimate, and the PEC evaluated Defect Algorithm are compared in this study.

scholarly journals Analysis of cable force on steady-state motion of remotely operated vehicle for reaction pool underwater welding

2019 ◽  
Vol 16 (3) ◽  
pp. 172988141985729
Author(s):  
Zhan-Dong Li ◽  
Jian-Guo Tao ◽  
Hao Sun ◽  
Jing-Kui Li ◽  
Yang Luo ◽  
...  
Keyword(s):  
Steady State ◽  
Numerical Method ◽  
Nuclear Power ◽  
Power Plants ◽  
Critical Factor ◽  
Vehicle Design ◽  
Remotely Operated Vehicle ◽  
Underwater Welding ◽  
Steady State Motion ◽  
Cable Force

Remotely operated vehicle is a reliable and efficient tool in routing inspection of reactor pools of nuclear power plants. While, there is still no study on steady-state motion of remotely operated vehicle which is crucial for reaction pool underwater welding reported. In practice, the cable force has been considered as a critical factor affecting the vehicle’s operation. To evaluate and predict the disturbing effect caused by the cable mounted on the tailing of a vehicle, a numerical simulation can be employed. In this work, we set up a theoretical model of a cable partially in reaction pool water and air to validate the remotely operated vehicle design and reduce the prototype developing time. We programmed the model governed by an ordinary differential equation set, which was considered as an initial value problem following a dimensionless treatment to be solved. The influence by factors (i.e. velocity, water depth, entry water angle, water density and cable length on tension, normal shear force, and binormal moment) was quantified by a numerical method. The test of a cable force was carried out to verify an authenticity of the three-dimensional mechanical model and a numerical method. The results demonstrated that the presented method could be used to evaluate the effect of real environment factors on a remotely operated vehicle steady-state motion and held a potential to improve the remotely operated vehicle design and control strategy.

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