scholarly journals Predicting and Preventing Flow Accelerated Corrosion in Nuclear Power Plant

2014 ◽  
Vol 2014 ◽  
pp. 1-23 ◽  
Author(s):  
Bryan Poulson
Keyword(s):  
Mass Transfer ◽  
Nuclear Power ◽  
Mass Transfer Rate ◽  
Environmental Parameters ◽  
Theoretical Models ◽  
Carbon Steels ◽  
Accelerated Corrosion ◽  
Material Factor ◽  
Flow Accelerated Corrosion ◽  
Over 40 Years

Flow accelerated corrosion (FAC) of carbon steels in water has been a concern in nuclear power production for over 40 years. Many theoretical models or empirical approaches have been developed to predict the possible occurrence, position, and rate of FAC. There are a number of parameters, which need to be incorporated into any model. Firstly there is a measure defining the hydrodynamic severity of the flow; this is usually the mass transfer rate. The development of roughness due to FAC and its effect on mass transfer need to be considered. Then most critically there is the derived or assumed functional relationship between the chosen hydrodynamic parameter and the rate of FAC. Environmental parameters that are required, at the relevant temperature and pH, are the solubility of magnetite and the diffusion coefficient of the relevant iron species. The chromium content of the steel is the most important material factor.

Flow and Mass Transfer in Bends Under Flow-Accelerated Corrosion Wall Thinning Conditions

2010 ◽  
Vol 133 (1) ◽  
Author(s):  
John M. Pietralik ◽  
Chris S. Schefski
Keyword(s):  
Mass Transfer ◽  
Water Chemistry ◽  
Nuclear Power ◽  
Flow Conditions ◽  
Transfer Coefficients ◽  
Ferrous Ions ◽  
Local Flow ◽  
Accelerated Corrosion ◽  
Flow Accelerated Corrosion

The three groups of parameters that affect flow-accelerated corrosion (FAC) are the flow conditions, water chemistry, and materials. Nuclear power plant (NPP) data and laboratory tests confirm that, under alkaline water chemistry, there is a close relationship between local flow conditions and FAC rates in the piping components. The knowledge of the local flow effects can be useful for developing targeted inspection plans for piping components and predicting the location of the highest FAC rate for a given piping component. A similar evaluation applies also to the FAC in heat transfer equipments such as heat exchangers and steam generators. The objective of this paper is to examine the role of the flow and mass transfer in bends under alkaline FAC conditions. Bends experience increased FAC rates compared with straight pipes, and are the most common components in piping systems. This study presents numerical simulations of the mass transfer of ferrous ions and experimental results of the FAC rate in bends. It also shows correlations for mass transfer coefficients in bends and reviews the most important flow parameters affecting the mass transfer coefficient. The role of bend geometry and, in particular, the short and long radii, surface roughness, wall shear stress, and local turbulence, is discussed. Computational fluid dynamics calculations and plant artifact measurements for short- and long-radius bends are presented. The effect of the close proximity of the two bends on the FAC rate is also examined based on CANDU (CANDU is a registered trademark of the Atomic Energy of Canada Limited) NPP inspection data and compared with literature data.

Flow and mass transfer downstream of an orifice under flow accelerated corrosion conditions

2012 ◽  
Vol 252 ◽  
pp. 52-67 ◽  
Author(s):  
Wael H. Ahmed ◽  
Mufatiu M. Bello ◽  
Meamer El Nakla ◽  
Abdelsalam Al Sarkhi
Keyword(s):  
Mass Transfer ◽  
Accelerated Corrosion ◽  
Flow Accelerated Corrosion

Effects of Flow Accelerated Corrosion on Piping Steady-State Vibration Evaluations

2003 ◽  
Author(s):  
Brian J. Voll
Keyword(s):  
Steady State ◽  
Nuclear Power ◽  
Power Plants ◽  
Pipe Wall ◽  
Vibration Monitoring ◽  
Accelerated Corrosion ◽  
Monitoring Programs ◽  
Wall Thinning ◽  
Piping Systems ◽  
Flow Accelerated Corrosion

Piping steady-state vibration monitoring programs were implemented during preoperational testing and initial plant startup at most nuclear power plants. Evaluations of piping steady-state vibrations are also performed as piping and component failures attributable to excessive vibration are detected or other potential vibration problems are detected during plant operation. Additionally, as a result of increased flow rates in some piping systems due to extended power uprate (EPU) programs at several plants, new piping steady-state vibration monitoring programs are in various stages of implementation. As plants have aged, pipe wall thinning resulting from flow accelerated corrosion (FAC) has become a recognized industry problem and programs have been established to detect, evaluate and monitor pipe wall thinning. Typically, the piping vibration monitoring and FAC programs have existed separately without interaction. Thus, the potential impact of wall thinning due to FAC on piping vibration evaluations may not be recognized. The potential effects of wall thinning due to FAC on piping vibration evaluations are reviewed. Piping susceptible to FAC and piping susceptible to significant steady-state vibrations, based on industry experience, are identified and compared. Possible methods for establishing links between the FAC and vibration monitoring programs and for accounting for the effects of FAC on both historical and future piping vibration evaluations are discussed.

Flow and Mass Transfer in Bends Under Flow-Accelerated Corrosion Wall Thinning Conditions

2009 ◽  
Author(s):  
John M. Pietralik ◽  
Chris S. Schefski
Keyword(s):  
Mass Transfer ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Flow Conditions ◽  
Ferrous Ions ◽  
Local Flow ◽  
Accelerated Corrosion ◽  
Flow Effects ◽  
Flow Accelerated Corrosion

The three groups of parameters that affect flow-accelerated corrosion (FAC) are flow conditions, water chemistry, and materials. Nuclear power plant (NPP) data and laboratory tests confirm that under alkaline water chemistry there is a close relationship between local flow conditions and FAC rates in piping components. The knowledge of local flow effects can be useful for developing targeted inspection plans for piping components, predicting the location of the highest FAC rate for a given piping component, and determining what piping components should be replaced. A similar evaluation applies also to FAC in heat transfer equipment such as heat exchangers and steam generators. The objective of this paper is to examine the role of flow and mass transfer in bends under FAC conditions. Bends experience increased FAC rates compared to straight pipes, and are the most common components in piping systems. When the flow effects are dominant, the FAC rate is proportional to the mass flux of ferrous ions, which, in turn, is proportional to the mass transfer coefficient in the flowing water. The mass transfer coefficient describes the intensity of the transport of corrosion products (ferrous ions) from the oxide-water interface into the bulk water. Therefore, this parameter can be used for predicting the local distribution of the FAC rate. The current paper presents plant and laboratory evidence of the relationship between local mass transfer conditions and the FAC rate in bends. It shows correlations for mass transfer coefficients in bends and reviews the most important flow parameters affecting the mass transfer coefficient. The role of bend geometry and, in particular, the short and long radii, surface roughness, wall shear stress, and local turbulence is discussed. Computational fluid dynamics calculations and plant artefact measurements for short-radius and long radius bends are presented. The effect of the close proximity of two bends on FAC rate is also examined based on CANDU™ NPP inspection data and compared with literature data.

Improvement of FAC Maintenance Program Issued From BRT-CICERO™ via CFD Calculations

2016 ◽  
Author(s):  
Elodie Gipon
Keyword(s):  
Mass Transfer ◽  
Nuclear Power ◽  
Power Plants ◽  
Specific Effect ◽  
Piping System ◽  
Element Analysis ◽  
Accelerated Corrosion ◽  
Wear Rates ◽  
Maintenance Program ◽  
Calculation Algorithms

Flow Accelerated Corrosion (FAC) is very effective for nuclear power plant. This generalized corrosion can lead to the rupture of pipe and in some dramatic cases to casualties. During the last 20 years Electricité de France (EDF) has developed software called BRT-CICERO™ for the surveillance of the carbon steel piping system of its Nuclear Power Plants (NPPs). This software enables the operator to calculate the FAC wear rates by taking into account all the influencing parameters such as pipe isometrics, alloy content, chemical conditioning, design and operating parameters of the steam water circuit (temperature, pressure, etc…). This is a major tool to help operators organize their maintenance and inspections plan. The algorithms implemented in BRT-CICERO™ are based on tests conducted by EDF R&D, empirical results (national and international feedback), literature reviews and on permanent adjustments based on the operating feedback, via statistical studies. However, for some piping components, from the turbine’s hall, flow dynamics are not optimized and calculated FAC kinetics may be too conservative. EDF is committed for optimizing and increasing reliability of its maintenance programs to prevent the risk of pipe rupture due to FAC. As in consequence EDF is leading continuous improvement in parameters and calculation algorithms for BRT-CICERO™. Furthermore studies on the geometric characteristics of the pipes were conducted. In BRT-CICERO™ geometric effect of a pipe component (elbow reduction, tees …) is taken into account by considering a factor called “Geo” in the calculation to tune the thickness loss rate according the component type, its characteristics and specific effect on flow mass transfer. EDF implements finite element analysis software to compute the mass transfer coefficient k and so ascertain the “Geo” coefficient. These computed “Geo” coefficients are compared to those used in BRT-CICERO™. If necessary, current “Geo” coefficients used in BRT-CICERO™ will be adjusted and optimized to improve maintenance programs issued from the software. The presentation deals with the calculation method used for these studies and some results will be shown on tube and elbows.

Effects of Cr Content and Environmental Factors on FAC Rate of Carbon Steels

2009 ◽  
Author(s):  
Yutaka Watanabe ◽  
Kiwamu Sue ◽  
Hiroshi Abe
Keyword(s):  
Environmental Factors ◽  
Removal Rate ◽  
Carbon Steels ◽  
Strong Impact ◽  
Oxide Compound ◽  
Accelerated Corrosion ◽  
Cr Content ◽  
Ph Dependency ◽  
Order Of Magnitude ◽  
Flow Accelerated Corrosion

Combined effects of Cr content and environmental factors, pH and dissolved oxygen concentration, on removal rate of carbon steels due to flow accelerated corrosion have been examined by experiments. The effects of environmental factors on FAC rate have been attempted to interpret based on oxide solubility, which has been precisely evaluated by separate experiments and numerical estimations. pH dependency of the FAC rate has been found to be directly related to solubility of magnetite. Cr content holds a strong impact on the FAC rate regardless of pH values from 6.84 to 10.4. Addition of 1% Cr to a carbon steel reduces the FAC rate by one order of magnitude under the environmental conditions, where magnetite forms. Addition of oxygen up to 1200ppb changes the oxide from magnetite to hematite, resulting in significant improvement in corrosion resistance. Oxide film characteristics, e.g. compositional distributions and types of oxide compound, have been also examined and their correlation to the FAC rate has been discussed.

A Procedure for Determining the Safe Operation Time of Equipment and Pipelines Based on Nondestructive Testing Results

Vestnik MEI ◽  
2020 ◽  
Vol 6 (6) ◽  
pp. 11-17
Author(s):  
Dmitriy A. Kuz'min ◽  
◽  
Aleksandr Yu. Kuz'michevskiy ◽  
Artem E. Gusarov ◽  
◽  
...  
Keyword(s):  
High Pressure ◽  
Wall Thickness ◽  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Operation Time ◽  
Safe Operation ◽  
Accelerated Corrosion ◽  
Equipment And Pipelines ◽  
Flow Accelerated Corrosion

The reliability of nuclear power plants (NPPs) has an influence on power generation safety and stability. The reliability of NPP equipment and pipelines (E&P), and the frequency of in-service inspections are directly linked with damage mechanisms and their development rates. Flow accelerated corrosion (FAC) is one of significant factors causing damages to E&P because these components experience the influence of high pressure, temperature, and high flow velocity of the inner medium. The majority of feed and steam path components made of pearlitic steels are prone to this kind of wear. The tube elements used in the coils of high pressure heaters (HPH) operating in the secondary coolant circuit of nuclear power plants equipped with a VVER-1000 reactor plant were taken as the subject of the study. The time dependences of changes in the wall thickness in HPH tube elements are studied proceeding from an analysis of statistical data of in-service nondestructive tests. A method for determining the initial state of the E&P metal wall thickness before the commencement of operation is proposed. The article presents a procedure for predicting the distribution of examined objects' wall thicknesses at different times of operation with determining the occurrence probability of damages caused by flow accelerated corrosion to calculate the time of safe operation until reaching a critical state. A function that determines the boundary of permissible values of the HPH wall thickness distributions is obtained, and it is shown that the intervals of in-service inspections can be increased from 6 years (the actual frequency of inspections) to 9 years, and the next in-service inspection is recommended to be carried out after 7.5 years of operation. A method for determining the existence of FAC-induced local thinning in the examined object has been developed. The developed approaches and obtained study results can be adapted for any pipelines prone to wall thinning to determine the frequency of in-service inspections (including an express analysis based on the results of a single nondestructive in-service test), the safe operation time, and quantitative assessment of the critical value reaching probability.

Sign in / Sign up

Export Citation Format

Share Document